Suspension Creak

[BrianE]

When driving on a bumpy or undulating road that excercises the shocks, the front suspension creaks as it flexes up and down. This is an IFS bus and I recently replaced the upper and lower A arm bushings and shocks which did not solve the problem. Am now suspicious of the torsion bar mounting bushings. Has anyone experienced this problem? Solutions?

[lonesome george]

Mine makes a noise like that after the bus has been sitting for awhile and I believe it is the sway bar mount bushings, it seems to get better after driving 500 miles or so. I'm going to take the mounting brackets off and make an attempt to lube the bushing bores with some type of snake oil and see what happens. The bushings on this bus look to be in good conditon but with two on each side it has a ton of surface area to make the rubber groan when the shaft turns in the bushing and I think that is what's making the racket.

[BrianE]

Thanks George. I removed one of them when rebushing the A arms and it was in such good shape I didn't replace them. Please pass on the formula for the snake oil if it works.

[GDeen]

Interesting post Brian - I had the same problem and after replacing all the sway bar bushings the problem was solved. Now I have a different noise. Only noticeable at very low speeds like going over a speed bump in a parking lot, whereas the prior creaking was most evident going down the road on dips that caused the coach to lurch up and down. A couple of weeks ago while at Prevost getting a Transmission service, I had the tech walk around under the coach with me checking things out. He noted the upper A arm bushings were going and said that would make noise......now here comes the question, he also said the bushings were not replaceable - had to replace the whole A arm assembly. Obviously if you were able to swap the bushings this is not correct?

Edit: Called Prevost and questioned the upper A arm bushing comment made by the Tech - he said it is absolutely replaceable, but they normally suggest replacing the entire piece as their labor for pulling it apart to replace the bushing makes it almost as expensive as a new arm.

[Kevin Erion]

Gordon, You must have a very special A-arm set up that is the only one! I did mine on my XLII and I would bet that you have the same A-arm. They must have an overstock of new parts that need to find a new home!

[GDeen]

Certainly what it sounds like Kevin. I told the tech that didn't make any sense to me, and meant to take it up with Ryan the service coordinator, but got off on another tangent and forgot to.
See edit to post above .....

[travelite]

Folks,

What is the life expectancy of the suspension A-arm bushings? (How many miles)?

Thanks,
Prevost Wannabe

[flyu2there]

Brian,

Get in there and squirt around some snake oil, and certainly not WD-40...try Aerokroil....it really does work!

[BrianE]

John, Thanks will try the Aerokroil.

David, My coach had approximately 100K when I replaced the bushings. Don't know if that's typical for an IFS chassis.

Gordon, Replacing the A arm bushings was a snap. It does however take an arbor press to do the job and two sets of hands is helpful also. I believe George came up with a tool that he built for Joe C. that allows changing them without using a press. I also had a bad ball joint in one of the upper A arms. Changing them requires a special fixture which is expensive. When I contacted a Prevost field rep to determine what is involved in replacing them, he advised replacing the whole A arm which the service centers do and which I also did. After reconsidering the project however it occurred to me that the service centers probably send them back to Montreal for a rebuild. And yes, ball joint rebuild kits are available. The cost difference is significant if you're doing the job yourself. Considering Prevost labor cost, replacing the entire assembly probably makes more sense to them.
Kit-Ball stud PN 611108, $65.84ea. Upper V-Link (A arm) with Lub points PN 611347 (old 611203) $381.75ea

[lonesome george]

David, I replaced the upper A-arm bushings at 42K (10 years) I think it is related to time and the amount of time the bus sits at the bottom of the suspension travel, at full bump. The lower A-arm bushings last longer than the uppers and I think it is bacause the upper arms are shorter than the lowers and at full bump tavel the angle of rotation is much higher on the upper arm, more twist in the bushing. The lower A-arm bushing has a larger diameter than the upper bushings and that reduces the rotational stress on that one. The rubber in the bushings I replaced was fractured and not dried out and I believe the fracturing is a function of father time and sustained rotation of the A-arm, IMHO.

How are you doing on the engine compartment detailing, super bling project? I want pictures!

[GDeen]

Brian - thanks for the excellent explanation for the newbie still trying to learn his way around these things.

[Jon Wehrenberg]

I have a straight axle so bushings are not a typical service item, but I question why it appears they have a short life.

I drive and have driven cars and my buses for years and a lot of miles and have never replaced any rubber or urethane bushings in the suspension, sway bars, or any other undercarriage components. I understand rubber or similar materials age, get brittle and crack, but something seems to suggest to me at the young age and low miles reported for these replacements if something else is not at play here.

Are the parts clearly lined up when reassembled? Is there any indication of forces or stresses in a direction that would compromise the life of the bushings? Are any of the buses exceeding the axle weight limitations? Given the presumed service life of these coaches, if bushings are a routine maintenance item I would think the Prevost maintenance schedule would spell out when they would be replaced. Otherwise it seems something may not be right.

[BrianE]

Couldn't agree with you more Jon. The sad fact is that the front end suspension bushings seem to have a very short life indeed. The IFS buses get noisy and "clunky" when these bushings get worn. There are small urethane bushings associated with the front and rear sway bars that seem to be especially prone to short life. They are easy to replace and in my case component alignment was very good. Haven't a clue why this happens.

[dale farley]

I replaced all those orange bushings in my front and rear sway bars when I first got the bus (70K miles). A couple of them were completely worn out. The good thing, is that it was an easy and quick fix, and all the parts cost about $50 total. I think Jim Keller said that a Prevost tech told him that these orange bushing need to be replaced about every 60K miles.

[GDeen]

Many of my sway bar bushings were completely gone when I had Prevost put the bus on the lifts in January. The remaining ones were badly worn. Good news is that replacing them tightened up the ride considerably, and eliminated the groaning I was hearing on dips. Will keep an eye on them.

[Jon Wehrenberg]

I have a sway bar and there are no indications of wear or the need to replace. About 230,000 miles and 14 years old. Since a sway bar just resists lean and is common to IFS and straight axle coaches, is there something in the rolling motion of IFS suspensions that put unusual forces on the sway bar bushings?

I cannot imagine entertainer coaches getting bushings replaced at the miles suggested here.

[JIM KELLER]

Dog bone bushings is what the Prevost Tech called them when installed at 60,000 miles in my Bus. At 100,000 miles we are starting to get the same type noise again.

[truk4u]

Brian,

Orange bushings, noisy front end...... I don't have any of them there hickeys on the Green Machine!:p

[BrianE]

Male bus owners as viewed by some female bus owners. Older is less complicated, less independent, has fewer moving parts and is usually more reliable. They do creak occasionally however, which can be temporarily corrected with proper lubricants. :rolleyes:

[Jon Wehrenberg]

It would be too easy to just throw stones at the IFS, but while more complex, I don't think an IFS front end should require maintenance at the short intervals reported here. If Jim Keller is averaging 50,000 miles for bushing replacement it suggest commercial and entertainer operators are pulling their coaches out of service every 6 months or so to replace bushings. If that is the case Prevost won't be serving that marketplace very long.

Remember these are the folks that may run their oil changes to 20,000 or 30,000 mile intervals so it seems absurd to consider bushing replacement at intervals just a little longer than oil filter change intervals. Something smells very fishy.

Remember IFS owners, our cars have had front ends that use the same technology for many years. Those front ends use A frames with rubber bushings, sway bars, and they can go decades and hundreds of thousands of miles with zero maintenance on the bushings. I think something is wrong if a commercial vehicle designed to have a service life 5 or 10 times that of the average car can have such a design defect.

[Russell Coachworks]

FYI - In my experience I have found that on our fleet of Prevost coaches, we are replacing A-arm bushings ONLY, around 400,000 - 450,000 miles based upon the unit and it is always been noise related, not performance related. So, when it does its "creaking", we find that it is noticeable, not so much when driving but when people are coming in and out of the coach or in regards to driving, when you are in a turn at 50 - 60 mph on the interstate (slight lean to the left or right). In our experience at Russell Coach we have found when replacing the A-arm Bushings, a front end alignment is required. Parts, alignment and labor, we are spending somewhere in the neighborhood of $900 - $1,300. We put approximately 75,000 - 85,000 miles a year on each unit. Any questions, feel free to call Rob Russell directly at Russell Coach 865-525-3888

[ajducote]

Are you doing this work in house? If so, your cost seems to be VERY GOOD. If you are doing it in house, would you tackle this job on POG coaches? If you are sending it out to get done, could you share that information?

The reason I asked, I did some research on redoing the front end of my 1998 XLV and the cost seemed to be a lot higher then what you have said. Please tel me it can be done for $900 to $1300 !!!!

What about the ball joints? It seems that the rubber boot on the ones I have looked at are almost always torn. How do you deal with that, and ball joints in general?
With the miles you are running on your coaches, you are a great source for "REAL WORLD" data points on things like this. Thanks for sharing your knowledge with us.

Thanks

[Coloradobus]

Marathon once told us that especially in the "H"3-45 the upper A-Arm bushings are in a pinched position by design. Our 2002 XLII one slide Marathon creaked and moaned espiecially when in cold weather wioth only 18K miles on it. We were also told, even new coach shells they say creak and moan. Hey Truk, lets hear it for the solid front axles. Hip hip who, ray!

[Jon Wehrenberg]

The King and I talked to Rob Russell today, specifically about the issue of "A" arm bushings. As you can see from his post the bushings do have a significantly longer life than has been reported here.

The costs he provided are the cost of new bushings, the labor to remove the old ones and reinstall new ones and the front end alignment that is necessary after reassembling the front suspension. Since Rob is "hands on" and reliability on his coaches is a mandate he can answer specific questions such as raised by Andre. I presume, but would want Rob to confirm that if there are additional associated repairs they are included in that range he has provided above. I know he wants to do maintenance and repairs on coaches other than his own so it might not be a bad idea to give him a call. He is not as much fun to talk to as his wife Wendy however. She really runs the place.

I think we in POG are lucky because we have such good sponsors such as Coach Worx and Russell Coach that are qualified to answer our questions and address issues and I would urge that POG members with specific issues contact these folks who bring a lot of experience to this forum. When they answer our questions as Rob Russell and Ben Cummings did the answers are not theoretical, but are based on actual experience.

[Denny]

I think that mileage and age must make a difference on the bushings that are being discussed. Let's face it, we will never put 75, 000 miles a year on our busses as Russell Coach does or any other transportation company. We will never see 400,000 miles on our busses when used as we do. There are too many incidents about bushing/A arm replacements on POG for it to be a fluke or a Prevost ripoff. When I had my bus at Prevost NJ, they tried to replace the lower ball joints since they were out of stock of the complete A arm. They could not remove them to replace. The covers had deteriated and water was getting in rusting everything. They could have been soaked in penetrating oil and pressed out eventually but it was less costly to replace the whole arm assembly than go thru this process. I had some bushing that came out in pieces when the arms were removed. The dog bones did not have any bushing in them in two places.

I was there to watch the techs work and saw what was bad and what needed to be replaced. All of this took place on a 10 year old bus with less than 100,000 miles on it. Many parts on our busses can wear out from use or from lack of use and on our coaches I feel it is from lack of use. This is a problem on IFS front ends rather than the straight axle suspension. Since there are a lot more bushing on the IFS than on the straight axle, we notice the problem more. Also, the IFS busess that are having this problem are hitting the 10 to 12 years old bracket. Does Russell Coach have any units that are this age with under 150,000 miles on them? I am not doubting or questioning what Rob said nor am I trying to reflect any negativism on him. His use of a bus is totally different than ours. We are Not comparing apples to apples when comparing ours to an over the road bus.

[GDeen]

Intuitively I agree completely Denny that age has to be part of the equation. 400k miles on one of Rob's buses is likely the same amount of time as one of ours takes to get to 60k-100k miles. All the bushings are wearable parts and I think deteriorate with time as well as use. No different for tires, hoses, belts etc. I too saw the upper A arm bushings that were going bad on mine and can hear the noise from them now. When I called and asked for clarification on replacement, Ryan at Prevost told me no hurry to replace if I can live with the noise (which isn't near as prevalent as the sway bar noise).

Likewise my lower A arm bushings are going to need replacement. The seal boot on both sides is torn, which means the friction surfaces will now corrode and fail. The seal boot is rubber, which as we know ages no matter whether it is used or not - in fact, less use can accelerate deterioration. The sway bar bushings as I said before were mostly completely gone. Again, no doubt they had failed and needed replacement.

What I don't know is when and if any of these components have been replaced before. That is the missing bit of information necessary to put a service time on the parts in my particular case. My bus now has 141k miles and is 10+ years old.

Also would like to offer my thanks to Rob and the other professionals who lend their experience to the group. Very much appreciated.


I think that mileage and age must make a difference on the bushings that are being discussed. Let's face it, we will never put 75, 000 miles a year on our busses as Russell Coach does or any other transportation company. We will never see 400,000 miles on our busses when used as we do. There are too many incidents about bushing/A arm replacements on POG for it to be a fluke or a Prevost ripoff. When I had my bus at Prevost NJ, they tried to replace the lower ball joints since they were out of stock of the complete A arm. They could not remove them to replace. The covers had deteriated and water was getting in rusting everything. They could have been soaked in penetrating oil and pressed out eventually but it was less costly to replace the whole arm assembly than go thru this process. I had some bushing that came out in pieces when the arms were removed. The dog bones did not have any bushing in them in two places.

I was there to watch the techs work and saw what was bad and what needed to be replaced. All of this took place on a 10 year old bus with less than 100,000 miles on it. Many parts on our busses can wear out from use or from lack of use and on our coaches I feel it is from lack of use. This is a problem on IFS front ends rather than the straight axle suspension. Since there are a lot more bushing on the IFS than on the straight axle, we notice the problem more. Also, the IFS busess that are having this problem are hitting the 10 to 12 years old bracket. Does Russell Coach have any units that are this age with under 150,000 miles on them? I am not doubting or questioning what Rob said nor am I trying to reflect any negativism on him. His use of a bus is totally different than ours. We are Not comparing apples to apples when comparing ours to an over the road bus.

[Jon Wehrenberg]

Denny is correct about age. However if the posts on this thread are any indication some of the issues with the bushings are happening at reasonably young ages. I think the jury may be out on the possible reasons for this. When we talked ot Rob that was one of the concerns. Was a motorhome inherently different from an entertainer coach, with the focus on leveling. That was not the case because the Russell entertainer coaches all have leveling systems and they are levelled every night. We were concerned that the full range of motion, either all the way up or all the way down was a factor and apparently it is not.

Because of the various moving parts and how they must function, how they must be maintained, and how they can be damaged by lack of maintenance it does appear that lubrication, protection from the elements (such as a torn boot) and even a little ArmourAll sprayed on from time to time may contribute to longer life. I'm not making up the ArmourAll thing. That was Rob's suggestion. It's not in the Prevost shop manual.

I don't think any of us knows if the calendar, or steady use as opposed to occasional use, or a combination of both defines the life like we have been able to do with reasonable accuracy on things such as air bags. Whatever the factors are I think as a group the information should be posted so it can at some point be factored in to a preventive maintenance schedule.

[jack14r]

There are other things to consider such as front axle weight,the coaches that Russel has may not weigh nearly as much on the front as a double slide late model coach.Entertainer coaches have a 17,200 Lb front axle and we have a 18,000 LB front axle,are the parts(bushings,etc.) different,I would imagine they are but I don't have knowledge in this area.

[truk4u]

C-bus - Ya buddy, old is good!:rolleyes:

[Steve Bennett]

We have seen problems with both the sway bar link bushings, and the a-arm bushings. As John indicated I think a lot of the problem is the leveling of the coach as it causes the coach suspension to remain in a significantly different position the ride height. We have replaced quite a few a-arm bushings that were very cracked and damaged on the outer edge. When it is removed the bushing was still in reasonably good shape in the area that supports the suspension. I think that they should be replaced when you hear creaking or have an alignment issue. The sway bar bushings are a different story. If you look at the bushings with the coach dropped in the front (sitting on the stops in the bags) the links are pulled causing a significant load on the bushing. Over time this will cause even the harder urethane bushings to fail quickly. Having said that, as indicated they are easy to replace, and very inexpensive. We have seen coaches that have been run many miles with the bushings missing (sway bar links) and it does not appear to do any damage to the components.

[GDeen]

Because of the various moving parts and how they must function, how they must be maintained, and how they can be damaged by lack of maintenance it does appear that lubrication, protection from the elements (such as a torn boot) and even a little ArmourAll sprayed on from time to time may contribute to longer life. I'm not making up the ArmourAll thing. That was Rob's suggestion. It's not in the Prevost shop manual.



Exactly what I have been wondering about - would some lubrication help keep the parts from binding and extend the life. Good to know.

[rfoster]

I just want to add my thanks and appreciation for the contributions our sponsors are making to the forum now. We wanted this kind of input way back when we started POG, and now thanks to Steve Bennett, Ben C. , Rob Russell and others we are able to benefit more and more from our POG membership. Pooling the info from years and miles of experience is invaluable.

Especially when most of us have to do something else to get fuel money.

Thanks a bunch guys!

[Russell Coachworks]

Hello to all. I have read all comments since my last post and will try to address all thoughts. In regards to axle weights in entertainer coaches, to the best of my memory, when the entertainer slide came out, the axle weight for an entertainer coach was changed to 18,000 pounds for the slide out and for the non-slide units. With talking with the parts department at Prevost, the parts are the same, unless they have been superceeded by an improved part, i.e. by changing the part number.

In response to the post about the cost and whether or not it is done in house, parts are ordered through Russell Coach and we partner with a local alignment shop who performs the work. The quote I gave is what it costs me. So, depending on parts having a rate increase, the shop having a rate increase, etc. this number may fluctuate somewhat.

Regarding the posts about age, use of coach, etc. it is known to all that rubber ages and wears out. It is like anything, the more you exercise it / use it, the more it lasts.

My recommendation....hit the road, see all States and rack those miles up!!

Good evening to all!

Oh, thanks to Jon for recognizing that Wendy runs it all....ha ha!!

Rob Russell
Russell Coach

[BrianE]

This has been an interesting thread. Thanks to all who participated, especially sponsors Rob and Steve. In January when I tore into the front end of our 11 year old bus I was dismayed to find that every single grease retainer boot on the steering rod ends as well as all four ball joint dust covers were in tatters. The result was of course an inability for components to retain their grease. The upper A arm bushings were cracked and the dog bone bushings were distorted and loose. I also found the upper left A arm ball joint badly galled due to a bad zerk fitting which evidently had been clogged for a very long time.

Considering the input from most of us, it appears the non commercial use of our buses might be a liability. Maybe we could minimize service issues by observing the work being done during service checks. An over zealous lube tech can easily blow a hole in a grease retainer boot by over-greasing as well as completely missing some important lube points (steering gear zerks for example).

By the way the sway bar bushings that started this thread are in beautiful condition, no checking or cracking......There still a'creakin' though.

[BoaterAl]

Any advice on replacing current shocks with Koni on the front ? 2005 XLII What adjustment setting is preferred ?

[jack14r]

AL,I have a friend that replaced the shocks on a XL with the Koni's and i think he used the stiffest setting,he could not believe the difference.If you do it let me know how it works out.

[Kevin Erion]

I think if you go to the Koni web site, they have a very good chart that shows the adjustments and what they do.

[BoaterAl]

I spoke to Marathon about the front Koni's. On all there customer request for the Koni they set up the shock to the firmest/stiffest setting. As the coach front weighs in at about 16,000 lbs. this seems to be working good on this setting. I'am going to follow there advice and then give it the bumpy road test. As we live in Missouri I won't have to travel far to find one with bumps. I did download the info from Koni on the adjustments.
Al
05 Marathon XLII
2010 GMC arcadia AWD

[Jon Wehrenberg]

The purpose of our shock absorbers is to dampen rebound. I am sure many remember cars with bad shocks bouncing up and down for quite a while after going over a bump. The same thing applies to our buses and if the shocks are worn or not adequate we end up with a front end that feels like it is floating out of control and we also have a potentially worse situation. That is a bus that travels through the full suspension range after a bump because there is inadequate dampening to control the compression or extension of our air bags.

If the shocks are set too firm the comfort level of the ride will suffer, and if the shocks are not firm enough the bus could be banging against the limits of suspension travel.

Somewhere in the middle of the two is the right setting for the shocks and I have no clue how to evaluate and decide where to set the shocks.

One thing everyone needs to be aware of and that is the shock adjustment is going to be determined to a great extent on how much weight is on a given axle. The more weight, the greater the compression and rebound of the suspension, and thus the greater need for dampening. I often am concerned when I hear of coaches that are at or over the axle weight limits. Our air bags are designed for and actually marked with a warning not to exceed 100 PSI. Coaches that are heavy on a given axle may require full air system pressure to come up to ride height. If the coach is sitting on over inflated air bags due to the weight they must carry, when the bus hits a dip in the road that causes the air bags to compress, those air bags will see a significant spike in the internal air pressure as the bags compress. This is why it is especially critical to use good shocks and to have them set properly (if adjustable).

At one time there were coaches being converted with excess weight on the front axle. In addition to developing a fix in the form of a larger air bag to help carry the front end with less internal pressure, Prevost also developed a retrofit to add a second set of shocks to the front end to dampen the jounce the coaches were experiencing. If you own a coach that is heavy (at or in excess of the Prevost axle limits) you may want ot consider discussions with Prevost regarding the addition of a second set of shocks. This goes beyond ride comfort, because as the coaches reach the suspension travel limits steering control is compromised and safety becomes a bigger concern than comfort.

If you want to see how suspension travel impacts handling, find a deserted road. Use the level low to raise the front of the coach to its limit, and then drive down that road at slowly increasing speeds. At some point you will find the bus is no longer easily steered or controlled and this happens at a relatively low speed.

[BoaterAl]

New shocking development's in Missouri..... (I just couldn't resist to us the phrase)
New Koni's (front) on the coach at adjustment "max firm". On the road test the coach did preform with much better ride, as little continued bounce and very little side to side. I was impressed with the noticeable difference right out of the box. As the old shocks were still serviceable the firm setting does change the shock and ride in the compression stroke. As your suggestions were all max firm that appears to be the right adjustment with all factors considered. Overall much improvement. Project is very easy once you have the coach up in the air.
AL
2005 XL II Marathon

[Jon Wehrenberg]

Not to pick on boater Al or Marathon I am not surprised the setting needs to be at max firm. A coach that has less weight on the front may find that setting unacceptable. What is your front axle weight Al, not what Marathon says, but what the scales say?

[BoaterAl]

Jon,
I went with the setting that I heard from other owners. Asking the question of Marathon on weight, around 16 K. When I get some extra time I'll take your suggestion to the scales. Just for grins has anyone weighed the front end of an '05-'07 Marathon XLII double slide with or with out the family dog ?
AL
05 Marathon 2s

[Jon Wehrenberg]

When in Spearfish we saw one that topped the charts at somewhere around 19,000.

[BoaterAl]

There you go, was that porker an XL II or HS-45 ? At that weight there speaks for the setting for full firm or you will be prematurely wearing out your front end parts. I did notice that the up and down seemed a little excessive on the trip to Omaha. I had 2 sets of Koni's on my Affinity with the setting oppox 1 turn off max firm. That seemed to work best. Concern was the heavy weight of the XL II and with input from members was confirmed max firm was probably be the setting. After about 500 miles I'll know for sure about this current setting.
TIRES....I also had that minor pulling problem on the Affinity. Seemed to be aggravated by excess road crown. I decided to cross the tires before driving on to the alignment rack. There were 20 K miles on new Michelins , no visible wear, no cupping. On Country Coach the problem tire is the right front. That solved the issue immediately.
AL
05 Marathon XLII 2S

[Jon Wehrenberg]

The Marathon weighed in Spearfish was an XLII.

[Ray Davis]

I'm curious. My coach really hates the cross-cut cement roads that we have here in CA. I feel every separation, and at times it can be really annoying to almost bone jarring.

I get a little (but not a lot) of what I would consider to be bouncing type of motion that I would associate with bad shocks. I've asked, and have been told that 45'ers tend to oscillate a bit more than the 40s (my 40ft didn't bounce at all).

So, I'm curious if new shocks might help with this cross-cut type of roads?

Ray

[jack14r]

Al,What is the Koni part number?

[Jon Wehrenberg]

The correct tire pressure combined with a shock set for the particular coach or driver's needs will do what can be done, but I don't think our suspensions can make all roads feel like a magic carpet.

If our coach requires a lot of air pressure for its air bags, by its nature the ride is going to be compromised and if the shocks are bad the coach is going to have very little dampening.

I am not sure what you mean by cross-cut, but there is a stretch of I-59 from the northern AL state line towards Birmingham that has expansion joints or some variations in the slab heights at the joints and my coach just gets hammered going down that road. I do not experience anything like that anywhere else. But I won't look to make any changes in my bus because of that road. It is just the way that road feels and I suspect all vehicles are affected.

[sswindle14260]

You are correct about the stretch of I-59 in AL. One of the worst sections I have traveled too. I ride the left lane and you do not get beat up quite so bad.

[Jon Wehrenberg]

I do ride the left lane and let everyone pass on the right. I-10 west through Louisiana used to be like that many years ago, but last time we were on it it wasn't bad.

[dale farley]

The last time we had the POG at Kerrville, I-10 was terrible. After bouncing all the way there and back; I changed my shocks on our 40' Marathon as soon as I got back home, and I didn't really see any diference. It was just a bad road.

[BoaterAl]

Koni part number for XLII is 90-2574. Does anyone have any suggestions for cold tire pressure? I have heard 105-95-85 from several sources.
AL
05 Marathon XLII

[Jon Wehrenberg]

Pressures are based solely on weght.

http://www.michelintruck.com/michelintruck/tires-retreads/load-inflation-tables.jsp

[jack14r]

AL,Thanks for the part #,I had a non slide 2001 Marathon and it weighed about 17,000 on the steering axle,Jon is right,go weigh your coach and then you know from the chart what air pressure to run.I bet that 16,000 is not even close.

[BoaterAl]

OK ...currently what pressure are you carrying in an XLII ...2 slide ? I just want to have a starting point as a referance from you more experienced Prevost owners. What do you think of 105-95-85 Lbs. (cold). Where is this chart your speaking of Jack ? I'am the new kid on the block.
AL
05 Marathon 2 S
010 GMC Arcada AWD

[BoaterAl]

Jon,,quick question ....how did I become a senior member when I just joined the group ?
AL
05 Marathon 2 S

[Jon Wehrenberg]

Well you look old so that makes you a senior. Just like the rest of us. Just kidding.

The number of posts it takes to become a senior is a setting the webmaster controls. Apparently he got some complaints in the past about how many posts it takes to reach senior status, so he set the number so low everybody gets there with their first post.

[jack14r]

Al,Jon's post # 53 has the Michelin chart website,just click on it.I have 115,100,100.I like a little extra and I am not concerned about the ride.

[GDeen]

Drove my bus across some CAT scales last summer so the State of TX could decide what to charge me for registration. 2000 Marathon XLV full of fuel, full of fresh water, 20% full on black and gray tanks.

Front axle: 14,420
Drive axle: 19,260
Tag axle: 11,960

Total: 45,960

GVWR: 48,900

[BoaterAl]

Today was weigh in at the CAT scale. Our 2005 Marathon XL II 2/slide...fuel under !/2 tank, water at 50%. Front axle 17740.... Rear 34140 for a grand total 51880 lbs. I was thinking it would be in the low 16000 range and was surprised. Jack 14r you were correct in your post that 16000 wouldn't even be close. Maybe it was the extra weight of that clear shield bolted on the front cap ...Jon.
Cost of weight at Flying J $ 9.00.
AL
2005 Marathon XLII 2/slide

[jack14r]

That is great,at least you are under on the front axle.Most weigh with waste tanks empty and fuel and fresh water full,also most Flying J scales can weigh 3 axles,that way you know how to adjust air in the drive and tag.

[truk4u]

Jack,

Adjust air in the tag and drive? No understand Kimosabe..

[jack14r]

I should have said drive tires,tag tires.

[truk4u]

I know, I was just pulling your chain!:)

[Prevost.Rick]

a couple of tidbits ,i never see age of tires,brought up when we talk weights ,pressures,u can have proper air ,old tires and still be setting on the side of the road,it is extremely important to get the date codes off of your tires(most of the time on the inside of the tires)because of the intro of slides and the addition of all the acc.the coaches got heavier ,the the axle uprating that was done by putting 125lbs of air in the 315s,and raising chassis air pressure,for the brakes,to get to a 17200 lbs axle,and many coaches were over this so if you have a old set of tires with over 90 % air(130lbs max) on a hot road ,the tire rating will not be the same as when the tire was new,they did,nt upgrade any steering componants,so that puts stress on the components,and shortens there life this thread is talking about this now so the shock that is factory may need upgraded with this in mind ,there are 06 xl2 out there with 03 365 tires on them,i,ve had cust. lose a tire with proper air pressure(the tread came off without losing air pressure) it does,nt matter steer or tag ,one both ,it seems this year tire if you can have too much air he had ck,d tires before leaving (he,d already lost one on pryor trip)115 to 120 lbs he drove from naples thru jacksonville at 67 mph and it was 87 degree at the time ,he lost the tread i had him ck air pressure it ,135lbs so ck your year of tire,weight of coach ,and put speed rating,and watch tag pressure,with your tag down it put about 1500lbs to your front axle(when weighing front axle dump tag to find out)so the more air in your tag tire the more front axle can weigh,so if you are heavy on your front axle,you can make it worst

[jack14r]

Rick,I am going to try this when I get home next week,I have 100 Lbs in the tag,if I reduce it to 85 do you think that it will show on the scales?What you are saying does make sense.

[Jon Wehrenberg]

Just to stir the pot I'll bet it makes no difference. If you could change the air pressure in the tag axle air bags it would make a very big difference. I am not advocating that or suggesting anyone modify their coach to do that because when that is done it affects other things.

Post the change Jack, but try to hit the exact same points on the scales, or better yet, pull on them with 100 PSI in the tag, and without moving drop the pressure to 85 and see if it shows up. The reason I bet against it is because while the rolling radius may change by a fraction of an inch, the tag axle air bags will adjust for that fractional change because the ride height valves are sensed ahead of the drive axle and not at the tag.

[BoaterAl]

What about ride height, and I'm thinking with the front axle as it take most of the abuse. If this is in specs which should be about 11 3/4 front and 11 5/8-11 3/4 rear, how will that effect the ride and air pressure ? With my weights as determined on the scale a few days ago (17770 frt and 34700 rear) what should my tires pressure be ? Presently at 105-95-85
That is my next project to check ride height and I already know the front bag is a fraction under 11 inch and of course this does effect the overall ride of the bus.
After playing around with ride height,shocks, air pressure on the Country Coach Affinity what really worked was dropping the overall ride height of the coach 1 inch. I realized this when investigating the shock extension travel. When set to max bag CC factory specs there was a possibility of breaking a tower bolt. The long and short of this story was a better ride and nearly elimination of rear end wine. IMHO I think the specs were wrong on the coach from the get go. I never had any more ride issues with that coach. Even the buyer remarked how different my Affinity road, steered compared to another he was considering to buy. Many CC owners wear out the right frt tire at an alarming low mile point. I know why.
Got a little of tract and probably more useless info
AL
2005 Marathon XLII 2/s

[jack14r]

Jon,I know from race cars that air pressure front to rear will not change the weight,at the place I weigh you must exit the scales to be re-weighed.I will change the weight and then weigh it again,I know that the air bags would change it but I hope the tire pressure will also,I will report the results next week,I am in France now.

[Jon Wehrenberg]

Al, the alignment on our coaches is done at the ride height and if we adjust afterwards it "MAY" impact the alignment. I do know that as the coach is raised towards its high position in the front the steering and handling are considerably compromised. I do not know at what increase in height the changes begin to be felt. I am sure fractions of an inch will have no measurable impact.

If you are looking for a "softer" ride you are getting into an engineering issue. For example, the valving in our shocks and the diameter of the air bags control how harsh a bump feels. Lowering the bus ride height in essence reduces air bag pressure so the bumps will be less harsh, but in doing so the risk of the bus bottoming increases. Conversely, raising the ride height increases the air bag pressure making bumps feel more harsh and risking a rebound to the full extension of the suspension and as you surmise damaging the shock eyes or the attach bolts.

The way our air bags are engineered, by setting the bus at the correct height we have presumably equal up and down travel and the steering geometry is optimised for that position. When we adjust heights (actually by lowering or increasing air bag pressure) we depart from that ideal. I would make sure the bus is set within specs and use adjustable shocks that you can play with to dial in the ride that suits your needs.

As to tire pressures they are totally dependent upon the tire size and the weights they carry. This chart should help you find the right settings:

http://www.michelintruck.com/michelintruck/tires-retreads/load-inflation-tables.jsp

[travelite]

If you are looking for a "softer" ride you are getting into an engineering issue. For example, the valving in our shocks and the diameter of the air bags control how harsh a bump feels. Lowering the bus ride height in essence reduces air bag pressure so the bumps will be less harsh, but in doing so the risk of the bus bottoming increases. Conversely, raising the ride height increases the air bag pressure making bumps feel more harsh and risking a rebound to the full extension of the suspension and as you surmise damaging the shock eyes or the attach bolts.

Jon,

I'm far from an expert but I think your quote above needs a bit of clarification. The air pressure in an air bag (air-spring) is essentially the load on the bag divided by the cross sectional area of the air-spring piston. This psi doesn't change as you add or remove air from the bag (assuming a cylindrical piston profile) because neither the load nor the cross section change. When you add or remove air from an air-spring you're simply raising or lowering the bus. The pressure stays the same, but there will be some ride stiffness change in exactly the opposite way as was quoted above. Long air-springs (lots of air above the piston) makes the spring rate softer; short air-springs (less air) makes the spring rate firmer. The ride stiffness (spring rate) is directly proportional to the cross sectional area of the air-spring piston and inversely proportional to the air-spring length (the column of air above the piston); i.e., increase the spring diameter and you've stiffened the ride, increase the spring length and you've softened the ride. Of course, a real air-spring is far more complex than my simple explanation, but the fundamental principles remain the same. Please correct me if I'm wrong.

[Jon Wehrenberg]

David,

It has been my observation that as my air pressure in the auxiliary system builds (and feeds the air bags) the bus begins to rise.

I can bring my air bags on my present coach up to ride height in the front with about 105 PSI. To increase the height to full extension I have to increase the pressure. Having said that you may be correct in that the internal pressure remains the same, but the volume of air increases until the bag reaches its limits in height and then the pressure internally increases.

I may have my foot firmly implanted in my mouth and the only way to verify this is to put a gauge on the air bags and see what happens to the pressure as the air bag rises or drops.

Has anybody done this?

[travelite]

John,

That's right. Say your coach is at ride height equilibrium with 100 psi in the air-springs. You crank open the auxiliary tanks and shove 125 psi into the air-springs. The air-spring then rises, increasing it's internal volume, until the pressure in the spring is restored to 100 psi. If you continue to shove 125 psi into the spring, it will continue to rise.

The thing is, when you increase the height of the spring, the spring rate has gone down and the ride has become softer. When you decrease the height of the spring, the ride becomes firmer. This is easier to grasp when you realize that regardless of the height of the vehicle, the air pressure in the air-spring is the same. It's at the 100 psi equilibrium required to carry the load. What's changed is the quantity of air in the bag. More air, softer ride; less air, firmer. A simplified spring rate formula looks something like this:

Spring Rate (K) = (internal Pressure) * (piston cross section area) / (height of air column above piston)

[BoaterAl]

Jon,Truk,jack,Rick.and travelite....Your comments are well taken and I appreciate everyones impute in this ride handling issue. Lots to be learned on getting the best ride as we already have the best built. Simply put minor adjustments make a big difference. I have an appointment at the shop tomorrow with a Prevost tech which will check the ride height. Bag height as per specs doing this on a level surface. The tech does the adj from a pit and rechecks at least 4 times deflate and recharge. I believe the front is low by about an inch and I've only said the coach does not sit level appearing low in the front. Normal inspection of front end parts, shocks,(new Koni's installed air) air bags and any signs front end damage will also be looked at. The way you have put "equal up and down travel and the steering geometry is optimized" well put and I would take that one step further as ideal ride ability.
Next stop the air pressure site.
Thanks
AL
2005 Marathon XL II

[travelite]

Al,

If you're really an inch low up front, which is a lot considering that compression travel is only around 3 to 4 inches, then you're in for a treat. Your ride will almost certainly be better, softer, more compliant. Please keep us informed. Good luck!

[BoaterAl]

This is the continuing adventure on ride height of an XLII......lets get it right. The air bag measured in at an height of 10 1/2 in the front and was adjusted to 11 3/4 by the tech. The rear was checked and that was OK at 11 3/4, both sides. Road test and recheck and all is OK, the coach sits level now. On the way back to storage there is a remarkable improve meant on the ride.
Did a very close inspection of the front end and found no problems, air pressure was checked and adjusted per the scale weighing last week. Also gave me a good tip on the unfortunate chance of a flat tire in the front on where "not" to put the jack... hollow suspension tubes. Bet the tech tell what the XL II weighed in his opinion on the front axle and was within 100 lbs. The bus is "more better".
AL
2005 Marathon XLII

[BoaterAl]

Is anyone riding on Road King shocks on front of an XLII ? I was reading the bru-ha-ha on there claims of bigger better best.
AL
2005 Marathon XLII ....with clear shield,... Koni shocks..., ride height adjusted,... air pressure adjusted to weight,

[BoaterAl]

Is anyone riding on Road King shocks ? I posted this message and then it disappeared. This is one thing I don't understand .....the midday wash of the messages.
AL
2005 Marathon XLII

[jack14r]

I weighed the coach today with 110 LBS in the tag and then re-weighed with 80 LBS. in the tag and as Jon said nothing would change,he is right.

[BoaterAl]

Good news on that item. Did the bus weigh in close to mine ? My front was at 17770.
AL
2005 Marathon XLII

[jack14r]

Close,18,040 Lbs. but I knew that.I had Liberty add 2,8D batteries for a total of 6,and I have added a freezer,etc.all of this is in the front two bay areas.

[Jeff Bayley]

I'm getting the bus serviced as I write this over a pit in MN. Found a place here that owns a Tour Bus company (all Prevosts, mostly my vintage) and the mechanics are all Prevost trained / certified. That means they learned how to bill for an hours work while standing around the water cooler for half that time. 101 first thing they must teach at Prevost training.

I don't have a bundle to spend right now and am only wanting to address the anything critical. I'm posting this here because one of the issues is with a leak in the air system making the bus lean but it's not bad and an initial search didn't find the leak so I'll probably let that ride until it get's worse and subsequently easier to find. But I was looking for Jon's post on full replacement of the air components in the suspension system. Can't find it. Maybe Jon or someone else remembers that thread for me to re-read it. They are putting a new cartridge in the air dryer for the main air system on the coach. I just found out that was supposed to be serviced (duh). I've had the coach 50,000 miles and 5 years and never changed it and who knows when it was changed before I got it. Is a cartridge change usually adequate or do you need the whole "Kit" as Prevost calls it. Mechanic here seem to think the cartridge change is adequate.

I had the undercarriage lubed at Oreen's shop a few months ago but I might as well have them relube it again since the guy was on a crawler and now I'm on a lift and first guy could have missed some fittings. Checked the brakes at Oreen's also. Since I'm 7 years into bus ownership and continually finding out "I didn't know about that maintainence item", can anyone suggest other obvious PM stuff they should check while under the belly of the beast ?

[Jon Wehrenberg]

Unless a bus company has buses with level-low systems (which I doubt) fixing the leans can produce a bill somewhat akin to the California debt.

In simplest of terms the components likely to be the cause of the leans (not in any particular order) would be the air bags, the five port Norgren valve for that location (front, LH rear, RH rear) or in the case of the rears the three port valve between the drive and tag axle air bags.

Obviously fittings can leak either at the air line or where they thread into the components, but if they haven't leaked previously they are not high on the list of things I would suspect.

I think replacing the air dryer only was the correct thing to do, and I hope he also drained the air tanks, starting with the front working rearward to both drain moisture, but to also verify the protection valves are working.

BTW, moisture in the air system will mess up the Norgrens if they collect moisture and corrode. Failure to service the bus and air system regularly is much more expensive than servicing it per the Prevost maintenance schedule that can be accessed through the Prevost web site.

[Jeff Bayley]

Jon- First, thank you for your reply.

Yes, they drained the tanks and said there was not a lot of water in them. After changing the cartridge, they purged the system several times by bleeding the air off by way of multiple pressing of the brake and letting it recharge. They said this was somehow a process after changing the cartridge to insure it was (primed ?,) or so to speak. I feel like I'm in competent hands, at least more so than a Prevost service center frankly but of course doing the job yourself is the best way but I'm outside my knowledge base here so have to divert to them. My understanding (from them) is that changing the cartridge will do little to clean up any moisture in the system and do repair. That if that moisture got past the filter it's there to stay. Is that right ?

[Jon Wehrenberg]

If it got past the cartridge is is going to be in the tanks and in the system, but unlikely to be in the form of water in the system. Any reaching the tanks should have been removed by bleeding the tanks down to zero in turn. If any pressure remained in the tanks it would allow water to remain.

I think what they did with respect to the braking system is push air that has passed through the new dryer cartridge into the brake system and likely purged any moisture laden air. That's a guess.

But unless they did this also, they failed to exercise the entire suspension system which uses auxiliary air. By raising and dropping the coach a few times the aux system air was also purged. If you want to get it all blow the horn, sit on the driver's seat, exercise the door lock, etc.

Your air system is always exhausting air so normal operation of a system with a new cartridge and tanks which have been drained will have dry air throughout. Even as you drive the airbags are inflating and deflating in response to the bus normal movements.

[Jeff Bayley]

Thank you again for the reply. There seemed to a lean (the last few days only). Maybe it was just an intermittent problem. It's gone for now. Might see it again. I'll work the air system some more as suggested. My air loss overnight seems to be a bit less.