Lifting rear of coach

[grantracy]

For better or worse I have an hydraulic bike lift on the back of our coach. Between the weight of the lift and the bikes ( plus the cantilever effect) we were occasionally dragging when negotiating some curves thogh the NC mountains. I attempted to raise the rear of the coach using chassis air adjustment but coach would settle back to previous position. Vantare advised that while in drive mode suspension height is preset. Any suggestions.

[dalej]

You may not like my advice ;)





Get rid of the lift, just don't like to see a body strssed like that! Besides your bike will love to travel in a trailer

[grantracy]

I hear you,however because of schedule issues occasionally the boss drives the coach and I meet up with her later,she doesnt want to deal with trailer.

[dalej]

I would just try and modify the lift and not the bus then. But in a pinch you can turn off the auto level and raise the back to get through the draging, but wouldn't run that way to long, since your bags only travel so far.

[GDeen]

Not trying to hijack the thread, but does a bike lift seriously stress the structure of the shell on a Prevost. Obviously I understand hanging 1/2 a ton at the fartherest point outward on the chassis is significant but I guess I had assumed if the fiberglass units could handle it certainly a Prevost could??

We have and electra glide and I seriously considered this as a good way to transport on a future coach while pulling the toad.

[dalej]

Although I have never had one, I have wanted one. But just looking at the way the bike hangs on for dear life, I keep mine in a trailer.

I do think that it works....but just don't like that much weight bouncing back there on the rear, A lot of the roads we travel on just are not that smooth, so it seems to just add to much stress on the bracket.

I think that if they can come up with one that has an assist wheel that spins 360 degrees, then it will be worth putting on. Somthing like cement trucks have for there tag, they can lift it when they want to. The air bag on it could handle 1000 pounds and travel enough to go thru dips and humps.

[garylstevens]

Dale here is one example I found for carrying that single heavy bike on the back, with out adding all of the extra weight to the back of the bus. Check out their website. http://www.motorcycle-carriers.net/motorcycle_carriers.html

You would not be able to pull a toad too, but this might solve some of the problem of all that extra weight on the back of the bus.

[dalej]

EXACTLY.. that's what I'm talking about. Never seen that before, but would like to see it in person.

Thanks Gary

[ken&ellen]

Dale, I am with you....put it in the trailer. The lift, as discussed in earlier posts, can stress the chassis of a Prevost. Remember that rear of the back wheels is already a very heavy engine! The trailer protects the bike and allows for some storage. Ellen & I have a single axle motorcycle trailer, but are currently looking to move to a tandem axle unit to improve stability in the event of a blowout. The unit in the picture, while interesting, is relying on a very small tire rotating at very high RPM!!!! Ellen drives the Liberty with the trailer...no problem. We both practised with the trailer at the school yard prior to departure. Ken & Ellen

[merle&louise]

Not trying to hijack the thread, but does a bike lift seriously stress the structure of the shell on a Prevost. Obviously I understand hanging 1/2 a ton at the fartherest point outward on the chassis is significant but I guess I had assumed if the fiberglass units could handle it certainly a Prevost could??

We have and electra glide and I seriously considered this as a good way to transport on a future coach while pulling the toad.

Gordon,

I remember a few months back a discussion on motorcycle lifts. I think that it was under Vehicles Other - Motorcycle lifts. Anyway, JPJ said that a lift should not be put on any Prevost except an XL. XLV and XL II's will not handle the load; rivets will pop etc. Maybe Jeff can elaborate further.

[grantracy]

Dale, I am with you....put it in the trailer. The lift, as discussed in earlier posts, can stress the chassis of a Prevost. Remember that rear of the back wheels is already a very heavy engine! The trailer protects the bike and allows for some storage. Ellen & I have a single axle motorcycle trailer, but are currently looking to move to a tandem axle unit to improve stability in the event of a blowout. The unit in the picture, while interesting, is relying on a very small tire rotating at very high RPM!!!! Ellen drives the Liberty with the trailer...no problem. We both practised with the trailer at the school yard prior to departure. Ken & Ellen


I probably misspoke when I said "she didnt want to deal with it" I meant she didnt want to deal with the possibility of having to back a trailer down in a tight situation. I am all for a trailer and admit the lift looks like it is out there,however I ran it by Vantare before installing and they didnt seem to think it was a problem. Jury is still definitely out on this one.For what its worth it is an XL

[GDeen]

Thanks for the info Tuga - will see what I can find on that discussion.

As to the trailer, I don't mind pulling one a bit. I do want a toad though and a trailer to pull the toad and bike would them be something I would have to deal with all the time when parking or "camping", and not sure I want the trouble of finding a place to dump it. Maybe that is less hassle than I am making it out to be.

[Ray Davis]

lift should not be put on any Prevost except an XL. XLV and XL II's will not handle the load

I'm no expert in this, but I believe that when Tuga indicated XLV, that includes your coach. I believe that XL = 40 ft, but XLV = 45 foot. I think your signature indicates a 45 foot, which makes it an XLV?

Ray

ps: just did a search and found this reference post from Jon
http://forum.prevostownersgroup.com/showthread.php?t=365

[Just Plain Jeff]

Elaborating....

A bike lift, if properly installed can go on a 40' XL. You don't want to put one on an H3-45 or an XLV due to the structure of the frame members and the engine mounts.

The 'right' way to install same is to pull the center bumper off the rear (duh) of the coach and have a plate welded to the two carrying frame members. From there, you build out the support brackets from the frame so that the weight is distributed properly from side to side (streetside to curbside).

We did this on our Angola by the guy who did the original OverBilt lifts (out of business) at his shop in New York. It was a big job, but he said that most of the problems he'd had were those with improper installation. His lift, BTW, was much lighter than a hydraulic lift as it had a 12v starter-type motor and cable system for lifting.

I don't have bit a moment right now, but if you use the search feature either here or over on Prevost-stuff, you will see there have been a couple of conversations about this over the years.

Lastly, Liberty has seen XLV coaches with rivets popping out of the rear from bike lifts that either weren't done right or on the wrong coach.

Hope this helps.

[Jon Wehrenberg]

Gordon,

When Prevost created the 45' motorhome shell they cantilevered an additional 27" behind the tag and drive axles.

That doesn't seem like much because it is easy to think of the Prevost coach as being overbuilt because it is intended for millions of miles.

But if you look at the structure under the coach you will note the engine cradle and the frame supporting it hangs from the rear of the structure that carries the drive and tag axles. Some of the load can be seen as being shared with the truss frame and the upper structure of the shell.

Prevost has determined that the limits of that structure are 1000 pound vertical load at the ball hitch. The ball hitch typically is within 6 inches of the bumper. You are creating a long lever arm with the lift for the motorcycle and the weight of the lift plus the motor cycle probably exceeds the Prevost limit by a factor of for or five times if not more.

The first sign you are exceeding the limit is the air bags are not recovering to give you the road clearance. Further signs are going to be stress cracks first visible in the rear cap, and you are likely going to experience some structural failure.

To prove the actual impact of what you are doing, weigh the coach and each axle on a truck scales loaded with all the stuff you normally carry, full fuel and full fresh water with empty holding tanks.

Repeat the weighing process with the motorcycle lift and the bike on the coach. You will likely not a substantial reduction in front axle weight affecting both steering and braking (adversely), and a dramatic increase in tag and drive axle weights, probably exceeding their limits.

[dalej]

And just add the added weight when you hit a bad bridge, the ones that leave the coach bouncing. Think of the stress on the brackets that attach the bike lift.

[Joe Cannarozzi]

I'll take that a step further. We pull a toad 4 wheels down and I would not hesitate to pull a trlr but you can bet I'd make sure I could load it with either no more tongue weight than it has empty or even slightly less, depending on what that tongue weight is empty. One disclamer- If I had unlimited recources I wouldn't worry about it at all.:D

This leads me to a question I've been wondering about. What is the tongue weight on these stacker trlrs? Can they be loaded neutrally? If the tongue is exessive can they be loaded to reduce the tongue weight slightly?

I've been told by 2 different folks, one mechanic and 1 charter owner, both of many years and did not know or work with each other, to watch the frame rails above the drives for stress cracks. This is advice givin from experiances with XLs, 40ftrs that never pulled anything! Ahhhhhhhhh the beauty of the tow-bar.

For those still interested try

www.rvliftsofamerica.com

[wrongagain]

maybe skid wheels is the answer.
several rv places have these, even camping world.

http://www.pakindustries.com/skid_wheels.html

[grantracy]

thanks for the insights..may be time to rethink lift.Don"t much like the look of it anyway.

[lewpopp]

Joe C.,

What the frig is a toung? Is it a chinese TONGUE?

Yes, I am getting better each day, sorry.

[GDeen]

Jon,

Thanks for taking the time to explain the limitations of the chassis and frame. 1000 load limit at the ball location explains it all really. Adding a lever of a few more feet beyond the ball with 1000 lbs is a bad idea.

[Joe Cannarozzi]

Lew

Glad to see I could be of some help.

Concidering I have always been a terrible speller and I still have not figured out how to get the spell checker to work, I think I've been doing pretty good.

I am sure I have had the dictionary in my lap more times since I've joined this group than the entire rest of my life.

I am also sure that it is deffinatly helping me become a better speller. Look, now I have learned the correct spelling for tongue, and I'm sure I will not forget.

God bless you get well soon and feel free to keep those corrections comming.

[garyde]

Regarding what a Vantare rep said, I would be very careful in taking advice from Sales people. In this RV Industry there is a huge degree of opinion based upon supposition not backed by research or 1st hand experience or knowledge. One of the great things about this forum is the fact no one has a vested interested in an outcome.

[grantracy]

agreed,however it was a service rep I consulted with. As is pretty evident we are new at coach ownership and consulted with sources we thought were knowledgable/credible.Lift is coming off when coach returns to Florida,now the task of choosing a trailer.

[Just Plain Jeff]

We wound up with a subsequent coach using a pickup truck as a toad and putting the bike in the bed of the pickup. Not always a pretty picture, but it took the vertical load off the back of the bus and worked out better; as taking off the lift, which is theoretically possible, is a real PITA when you don't want to use it.

[grantracy]

Loading the bikes in the pick up is a real impediment,done it plenty of times and always a little thrilling. Probably gonna go with a trailer we can throw a car in (although I did see a car towing operation that had a bike rack perpindicular across front,but I am not so sure you don't have tongue weight issues) in terms of trailering; is the radius in turns greatly increased?are they reasonable to back up and manuever? Never backed a trailer with a vehicle with such a long wheel base.

[Jon Wehrenberg]

Almost everybody that wants to bring their car and a bike uses a trailer that holds both. There are many options and considerations there as well. I don't think it is so widespread that it is a serious consideration, but with a 45 foot coach almost any trailer makes your overall length greater than the 65 feet almost every state allows.

I have spoken to several owners that have been ticketed for exceeding the 65 foot length and the opinion appears to be that the benefits of the trailer are greater than the cost of the tickets.

But there are other options. There are devices that load a bike onto a pickup to avoid the excitement factor of driving up and down a plank. Some folks have gotten an H3 and stored the bike in the first bay (it is tall enough on an H to do that) and then just towed the car.

The Prevost limit is 1000 pounds hitch (tongue) weight and 10,000 pounds for the towed weight. Prevost has engineered a reinforcement modification that I believe allows a 2000 pound tongue weight and a 20,000 pound towed weight. If Kevin is reading the forum maybe he can comment on this.

[MangoMike]

So Jon is saying that there is a benefit in owning a plastic H3.

mm

[merle&louise]

What parts of an H3 are plastic? I know that the front and rear caps are fiberglass (plastic), but are the exterior walls fiberglass or carbon fiber also?

Sorry for the thread creep.

[Jon Wehrenberg]

OK Mike, you got me.....there are distinct advantages to the H. Actually the H3 has a lot of advantages and few disadvantages. But except for the fact that it is glued plastic construction (yes Tuga, the whole outer skin is plastic bonded to a stainless steel frame) it is a Prevost through and through. Just remember, it is the same construction as the Trukster's pride and joy.

For those bike riders the H is very commonly used to carry the bike in a bay (or a golf cart or some other transportation device like a scooter).

[Toy Box]

To Grantracy... when you get back home, stop by if I can show you what I have learned during the past 20 years of RV's , bikes and trailers.

[grantracy]

Thanks for the offer,will do. My cell is 305-799-4193.Will be in town most of next week. Thanks, Granvil Tracy. grantracy@aol.com

[Petervs]

This thread has been going on for quite a while now, and I think perhaps one item has been overlooked. Granvil said he dragged the back of the coach on a few dips in the road. The first thing to check is to see if the ride height is set correctly. There are small lever arms at each axle that provide a signal to the air system to add or lose air from the air bags. When the Level low is in the drive mode, these sensors constantly signal the suspension to remain level. But if they happen to me mis adjusted, well, then you can drag the back end, and perhaps you are driving off level all the time. They are easy to adjust too.

The service manual has a simple test method which involves measuring the height of the coach body with a ruler while the engine is running. Start with this before deciding all the rest.

As for the weight and load from the bike and rack on the back, even with it on there all the axle and wheel loads can easily still be within limits. Just weigh the coach axle by axle. Trust, but verify, remember?

[hhoppe]

Peter: I think they all were trying to say he is putting his coach in peril with the possibility of breaking the frame and pulling the back cap off. Our busses are not built with full frames front to rear. The have a short frame in front designed to support the front running gear only. They have a short frame in the rear designed to support the rear suspension, engine, transmission, and other associated mechanical parts. They have a defined weight amount allowed for a trailer. Hanging large cantlevered loads onto the hitch is detremental to the whole coach. Between the two subframes is a unibody skeletin small tube frame designed to support the center body sections only.
Adding height to the rear suspension via air bag levers does not eliminate the above described problem.

[Petervs]

I am not suggesting he should add height to the air bag system so he can carry the motorcycle, only that he check to see if it is set correctly. If it is misadjusted then the bus will drag even without the bike and rack on there.

As for the frame members being strong enough or not, well the frame truss between the front and rear is plenty strong even if it is not one continuous hunk of steel channel. I do not like the way the typical bike rack is mounted only to the very rear end on the bottom, that is a bad design. And they want you to weld it all together which prevents unbolting things in order to remove the engine for overhaul without cutting it all apart again.

Again, I am not in favor of those "Overbuilt" style bike carriers, I was only suggesting he check to see that the air bag system was operating according to spec.

[Jon Wehrenberg]

I think the issue of bike carriers on the rear of our coaches is one in which not only is the design apt to lead to structural issues because so much weight is cantilevered off the hitch, but it may also impact handling and safety.

The weight of a full size heavy motorcycle located around 24 to 30 inches beyond the rear bumper is a fairly long lever arm from the drive/tag axles. If the weight of the bike was directly over the drive/tag axles the bus would handle it nicely, but with it extended that far to the rear it becomes a multiple of that weight and the air bags, their air supply lines, the valve orfices, and the shocks in the rear are not sized to handle that additional weight. As a result several things happen even if the ride height is adjusted perfectly.

First, the jounce from going over a bump is exagerated. That increases the magnitude of suspension travel. If the bus is cornering while this happens it worsens the situation. The rear air bags on a normally loaded coach actually do not require a lot of air pressure relative to the front air bags to inflate, but since there are six of them they require a lot of air flow. Add weight such as the bike and that air just can't get to the air bags quick enough and the result is the tail of the bus drags.

Driving on moderately curvy roads will allow the air bags to deflate faster than they can be refilled. I think as long as time delay ride height valves are used the situation will be less severe for curves of short duration, but more severe for curves of long duration. If the instant response valves are used, such as in replacements or newer coaches the air will be going out much faster than it comes in so the airbags over time on a curvy road are going to deflate. The air compressor is going to be working hard.

Where safety is affected is in braking distance. I am sure that the fronts will be less effective and when the ABS kicks in there may not be any drama in braking, but the fronts will tend to slide faster than when fully loaded. Whether the rear axles will have sufficiently greater braking to offset that I don't know.

[Petervs]

Jon,
Usually we are on the same page engineering wise on most things. On this one I think you are overly concerned and your concerns are unfounded.

These coaches are reallly big and strong, and the engineering is not barely adequate and marginal. These are not flying machines where every last ounce must be removed to increase useful load, etc. The thing is built like a tank!

If you hang an 800 pound motorcycle and a 400 pound lift off the back, that is not much different than if 6 200 pound people on a transit bus walked to the very rear of the coach all at once to use the bathroom. OK, they cant walk 2 feet beyond the back wall but it is pretty close. Nobody would think doing that would overstress anything. And it would not affect braking either.

Do the math on the weights involved. That same 1200 pounds is the same weight as 150 gallons of water. Does your coach really brake or drive on curves different if the water tank is full or empty? The 1200 pounds is only3% of the 48,000 pound gross weight of the coach. It is trivial.


What is not trivial is the way these motorcycle lifts are welded to the lower rear frames. That part can cause flexing of the rear lower part, and since the skins are pop riveted to the frames, that can cause wrinkles and popped rivets.

When I hang my 1600 pound Smart car on the back, plus the 350 pounds worth of lift ; it reduces the weight on the front axle by just under 1000 pounds. The front axle gross is 14,000 I think, and mine goes from 13,000 to 12,000. I am sure that is less than what an empty transit bus would have on its front axle. The rear weights go up a little, but they both remain well below their rated limits. The real difference in my design is that I am not carrying all the load from the area of the trailer hitch, mine attaches also to the upper portion of the truss which distributes the loads much better.

[Jon Wehrenberg]

Your design Peter is unique in that the "cradle" shares the load with the upper structure.

Our hitches rely exclusively on the engine cradle which does not place any of the load above that point. There are two POG owners that have cracking along the lower portion of the fiberglass cap and around the fasteners that attach the forward perimeter, indicating there was some force pulling downward, and someone has posted I believe about stress cracks in the axle frame structure.

But apart from that the steering gets squirrelly when the coach is not at ride height. I know because I once had something in the level low system stop working and the tail was lower than the front and the coach darted side to side until I stopped and manually got the coach to the correct ride height.

I do not disagree about a bunch of heavy people standing in the rear of the coach, but they are above the floor, which is carried in part by the side trusses.

[lewpopp]

Try stepping out on a diving board and jumping up and down 3-4 feet from the end and see how much stress you put on the board. Practically nothing. Go to the end of the board and jump up and down and the stress is multiplied by many, many hundreds of times. This makes a lot of sense to me to not load the rear of the exterior of the coach which is the end of the diving board.

[Jim_Scoggins]

I digress a bit from the original topic:

I spent years trying to work out easy convenient ways to carry a motorcycle along on trips. A pickup seemed a good solution after I broke the code to easily load or unload the bike: All towns have a store of some kind with a ramped loading dock. In a press used a strap under the bike frame and had a garage lift it on and off with a car lift. Of course, with smaller trucks we were left in a lurch about carrying four people to go some where.

Did the enclosed trailer trick, then we had no car for bad weather, etc.

What I finally came down to was the realization that fooling with a bike was an injustice to motorcycling and coaching. So now when I go coaching I just pull a nice four passenger Toad. When my motorcycle blood gets going I just saddle it up and head out on the bike-usually spring and fall when the weather is the best!

[Jeff Bayley]

Jeez I'm way late on this perpetual suject and deffinitley not a pro and forget who said what becuase it was so lengthy but here goes.

Regarding the $1,000 of weight, my opinion (from Dum and Dumber........i'm both) is the same as the member that answer Johns concern about the bus handeling differently and all that stuff. No way that extra weight is going to be noticed by a tag, drive axle or anything else.

Next, whever the "rating" for the specs are are probabley concervitive. Case in point, the thing is supposed to have a 10,000 lb limit right ? I pulled that stacker from CA to FL and weight it on the way and it was 17k pounds. Further to the breaking isssue Jon mentioned, I drove the trailer around (empty at 12k pounds) getting the electrick brake controler installed and yes I could feel a difference but had not problem stopping. So the extra $1,000 pounds on a already 45k pound coach.........immaterial (again, I'm dumb and dumber).

Since I'm rigging up a truck tool box to go on the hitch (a fraction of the weight discussed so far) I'm interested in (I thin it was Kevins) eleboration on modifying the hitch to avoid the left to right sway. putting the box in the single hitch won't work. I either need to remove the bumper and make cut out's in it for some stabalizing rods that might insert or possibly go ahead nad proivision it at that time with two addition Reese hitches if I decide to try carrying something heaver later (like the motor bike carrier you all have been bantering on) Peeking under the coach, I'm not certain where those femal Reese connectors would go and they wouldn't need to be rated at 10,000 pounds, they would just be "hamburger helper" for stabilizing mostly. I thought about riggging up turnbuckles to tighten up. The triple Resse hitch would be a bit unsightly I guess but then again I plan on having the box and aux gen there all the time.

One thing nobody touched on too much was getting the motorcycle lift (and in my case the full size truck tool box, up off the ground enough to prevent dragging. I'm supposing on having something fabricated to get the bottom of my box at leat a foot higher than my bumber unless they make those adjustment adapters for raising or lowering the height with enough travel. Anyone know what max size is on those ?

[Just Plain Jeff]

I forgot (big surprise) to add another part of the Overbilt-style lift into the discussion.

Not only are you hanging 1K lbs out over the rear of the coach, but also extending the hitch by about 18 inches beyond the rear bumper of a coach.

So the hitch is not only adding additional weight to the rear of the coach (which in some conversions may 'lift' up the front, bringing it back to factory specs, BTW due to being front heavy), you are creating a pivot point for the tow vehicle yet another foot and a half or so beyond its original design.

That weren't in the plans at the factory when the shells were assembled.

[lewpopp]

Jeff B.,

I guess it goes without saying that even "spell check" was so confused that is just threw up its' hands and sent it thru.

You guys are saying I'm feeling better the way I'm starting to scratch backs with roughness, but what you don't know is I haven't been myself for over 3 years and when I come out of this I will become uncontrolable.

[gmcbuffalo]

I saw a guy at Havasu Lake who had a trailer attached to his MH with two trailer hitches and the trailer had two pivoting wheels on the back. The
trailer then was than a fixed extension of the MH and the wheels carried the back half of the load and turned with the MH. He carried all his ATV's and PVC's on it.
GregM

[Joe Cannarozzi]

Lew thanks to you I have mastered the spell checker.

TA DA

Thank you for your push. Who knows how long it would have taken without you.

I was trying to figure out what you might poke me about now.:eek:

[merle&louise]

Peter,

In light of all the discussion about raising the front of the coach when a motorcycle and lift are added to the rear; would you be willing to measure the vertical clearance of your front bumper from the ground with the Smart car mounted on the back of your bus. And then measure the same distance with it not mounted. This would tell us how much the extra weight in the back will affect the way the bus handles, n'est pas?:rolleyes:

[Jon Wehrenberg]

Tuga,

With any lift attached to the rear, unless there is excessive weight that goes beyond the ability of the air bags to support, the heights front and rear are unaffected by changes of load, such as the addition of the Smart car.

The valves which determine the height of the bus when it is in the road position add or release air pressure to regulate the height based on the position of and arm which pivots up and down. The only limitation to whether the coach can maintain a specific height is the pressure of the air system, and usually the front air bags will require a greater pressure to bring the front end up to the proper height, than the rears. Adding a heavy weight to the rear actually reduces that requirement.

What will be affected with changes of weight is the rate of speed for the bus to return to the road height. In the case of Peter's coach he is adding weight to the rear, and reducing weight on the front so if the coach starts out with all bags deflated, it will take a little longer for the rear air bags to bring the coach up, and a little less time for the front air bags to raise the coach up.

When travelling down the road it is the rate at which the air bags recover that determines if the rear of the bus will drag.

[truk4u]

Should be the same if the leveling valves are working correctly!

[Petervs]

Hi Jon and Tom and Tuga,
Jon and Tom are right, the height is the same with or without the Smart on the back. When you first load it, before you start the bus engine, the back sags down about one half inch. Not much.

The weight on the front axle goes down 1000 pounds, from 14,000 to 13,000 give or take. Same effect as if 5 men walked from the front row of a transit bus to the bathroom in the back! It is a trivial change in weights and moments.

I believe there is no problem adding weight back there, but there is a big problem if you only weld on huge steel brackets at the bottom and cantilever all the weight off the rear bottom end. My design attaches top and bottom and so it just extends the truss. If I remove the rack, the only thin visible is 2 3/4 inch holes above the tail lights. They were covered with a little piece of tape at POG II, nobody noticed.

Hope that clarifies.

[gmcbuffalo]

Peter can you send pictures of your Smart on the back and the rach attachments.
GregM

[Ray Davis]

There were some photos posted in this thread:

http://forum.prevostownersgroup.com/showthread.php?t=1252&highlight=smartcar&page=5

ray