Ifs

[doodlebug45]

I'm almost done feeling sorry for myself and ready to get back at this bus searching thing. Thanks to everybody who commented during the last fiasco I sure know a lot more about what to look for. One of the coaches on my list right now has IFS but I know nothing about this on Prevost units and can't seem to find it discussed anywhere. I know I love it on my cars and especially my GMC Sierra but does it work out well on the bus? I would sure appreciate any comments, opinions or other input you guys may have on this subject.
Hugh (D'Bug)

[Jon Wehrenberg]

The IFS equipped coaches have a tighter turn radius than a coach of the same vintage with the solid axle so it is a benefit in that regard.

There may be an advantage during normal driving, but I have about 300,000 miles of straight axle driving, and about 300 of IFS driving, and I probably cannot tell one from another during normal driving. Others more in tune with the feel of the coach may be in a better position to address it from a driving point of view.

[BrianE]

I probably cannot tell one from another during normal driving. Others more in tune with the feel of the coach may be in a better position to address it from a driving point of view.

Meaning: You probably need to drive faster than 62.5 mph to gain any handling advantage. :)

[Jerry Winchester]

Brian,

That's way harsh..........:D

But at 62.5 mph he could probably just roll along on the hubs and not tell the difference.

[Jon Wehrenberg]

I was hoping you wizards that have experience driving both would provide some words of wisdom, but apparently you are going to let poor old Hugh dangle in the wind never knowing if IFS is hype or a good thing.

Hugh, ignore these turds and somebody with real knowledge will answer your question. With regard to the 62.5 mph, I have been known to go wild and crazy. Once I got it up to 63 mph. Ask fast Roger...he knows.

BTW, the discussion about IFS is kind of academic. If you happen to focus on a specific coach and that is the one you like due to appearance, features, decor, price, converter, etc. you either get IFS or you do not. The change to IFS happened somewhere around serial number T5883? or thereabouts, a late 96 shell probably titled as a 97 coach.

[truk4u]

Hugh,

I've had both, no difference other than turning radius.

[MangoMike]

Hugh,

I have both and agree and with Trukman.

My serial is T5885, so it's after this.

Mike

[doodlebug45]

Thanks guys. From your comments Jon I take it that all coaches built after that date have IFS. I like the idea of the tighter turning radius. Apparently there must not be any issues regarding alignment, maintenance, etc or someone would have chimed in. I usually notice IFS has a positive influence on rougher roads. Things like potholes seem to be absorbed better than with a solid axle. I appreciate the input.
Hugh

[Jon Wehrenberg]

Whoa.....don't leap to conclusions about not having any maintenance issues.

The IFS has parts. Lots of parts. It may be built tough, but because it has moving parts it can be expected to have more maintenance issues than a solid axle that has the simplicity of an anvil.

Unless the seat of your pants has the sensitivity of a race car driver or aerobatic pilot it is probable you will not be able to feel any difference between the two axles, but there may be times when a tighter turn radius may prevent you from blocking a highway. But despite that I would not walk away from a straight axle coach if I liked it.

[JIM CHALOUPKA]

If anyone had a couple pictures to post of the IFS without the wheel mounted it would be nice to see.

It seems that there would be more to changing the front air bags than with a solid axle.

[Jim_Scoggins]

I had a Bluebird with IFS and an older one without. Current coach does not. The IFS coach I had was a pain in the ass--alignment. Since my current coach is a 40 the IFS is a non issue regarding the turning radius. IFS would neither a deal breaker or maker for me.

For the way I use a coach solid axle is fine with me. Less moving parts, the better.

I don't think I can tell the difference in terms of the ride.

[Petervs]

This thread has mentioned the issue of turning radius several times. On of my pet peeves is not being able to back up while towing a car, so I have found it is important to know the amount of space required to make a U turn. Turning radius as published is not so useful, because do they measure the tire tracks or the corner of the coach for the measurement? And since most places where you turn do not have dimensions painted on the ground, at best all you have is an eyeball guess.

How many times have you pulled into some small road, driveway, park entrance, etc. and wondered if you were going to be able to make it out of there without having to stop and unhook the car? Annoying!

One day we pulled into a dead end street with a nice round cul-de-sac at the end....I was wondering if it was big enough to make it around, and lo it was. So I used that opportunity to get out and pace off the diameter of that circle, so I would know in the future what was needed. That one happened to be 100 feet in diameter, and it was adequately sized.

Last month we were at Prevost in Mira Loma when faced with the same problem. Whew, for a shop that deals in big rigs, the lot is exceptionally poorly designed unless you can back up. Anyway, I walked around back to see if it would be possible to make the turn around and was able to pace off 97 feet between obstacles. Figured it was worth a try, since the only option was to disconnect anyway, and once again I made it around.

Mine is a 94 XLV at 45 feet, and my tow car remains inside my wheel tracks at all times. Your situation might be different. But I think it is a good thing for each bus driver to know. Anyone could find a big open lot somewhere, set up a cone or two ( or wife acting as a cone) , and so test their own rig and pacing distance for themselves. I think it would be 10 minutes well spent.

[Jon Wehrenberg]

And so Peter, when you are trying to make a turn on a busy highway (no, I will NOT go into details) are you suggesting we just stop, tie up traffic, pace off the distance, and then make a decision?

With time our sense of whether we will make a turn gets pretty good, but I can tell you that there are times it doesn't matter what the radius is, or how good we can judge. We are going to unhook.

Further, and I hope everybody realizes this, no matter what the turn radius of the coach is, there will be times when we will have to use the full capability, and there will be times we won't make it.

[Petervs]

Jon, of course on a busy highway you do not do this. On a busy highway, by definition, you are not on a dead end road.

My example applies when turning down some odd little street or lane. And if you have to get out to unhook anyway, you might as well have the info so you can pace off the space, then you might not unhook for nothing.

[Jon Wehrenberg]

As witnesses will attest, no matter the anticipated outcome I make the turn, hope for the best, and then unhook (or not).

[Ray Davis]

I still think Peter makes a good point, and that's about learning how your bus will react in different driving situations. I've never really attempted to try a U turn in a an area that I wasn't sure I would make. I did, one time going into a KOA camp slot have to unhook, because I couldn't make the turn. At least knowing your turning radius will be helpful. Of course the helpful KOA lady remarked, "oh, I should have sent you in the other direction with a big rig!"

I think a similar learning point is backing into a camping spot the first time! I remember all to well doing the "intuitive" thing the first time I backed the bus, and not getting close to the inside edge before starting my swing. And of course I was way too wide to make the turn.

It becomes obvious after you have done that one or two times that you always start with the bus on the inside lane, close to the turning edge, giving yourself enough room to swing.


I had 15+ years driving a 27 coach (GMC with front wheel drive). Believe me, that doesn't hardly prepare you for how a bus turns.


Ray

[rfoster]

Does anyone know or have enough experience to state definitively that lifting the tag axle would reduce the turning radius. As in Peter's example if his 45" takes a 100 diameter circle to make the turn- would raising the Tag Axle improve or reduce the diameter of the 100' diameter circle to say 75",80', or 90'.

One of these days I will experiment on my own.

What say ye?

I personally don't like to unhook. I always have a number of witnesses. Once upon a time, I don't think a one of them could speak English. I spoke to them in a Redneck dialect.

[merle&louise]

I like Peter have measured the turning radius of my coach; it takes me about 90' to turn around. If I pace off 30 giant steps that equals about 90 feet. The turning radius of the coach is a good thing to know, I would suggest everyone to take the time to try this little experiment.

Does anyone know what the published turning radius is on a 45' Prevost XLII? I think that I remember reading that it was 41.5'; which would mean that you could turn one around in 83'. That is a pretty sharp turn around:D

[JIM CHALOUPKA]

I like Peter have measured the turning radius of my coach; it takes me about 90' to turn around. If I pace off 30 giant steps that equals about 90 feet. The turning radius of the coach is a good thing to know, I would suggest everyone to take the time to try this little experiment.

Does anyone know what the published turning radius is on a 45' Prevost XLII? I think that I remember reading that it was 41.5'; which would mean that you could turn one around in 83'. That is a pretty sharp turn around:D

Tuga, the last 1/3 of the article in the link contains some of the information you were asking about.

http://www.fmca.com/fmc2004/decmag/prevost.asp

[merle&louise]

Thanks Jim, that was a great article.:)

[Petervs]

Hey, rfoster, I was not born yesterday....any time I am in a tight situation I always raise the tag.....but I am also curious how much difference that makes. Will have to drive a circle on a dirt lot one day and see.

And yes, that was a nice article.

[doodlebug45]

Whoa.....don't leap to conclusions about not having any maintenance issues.

The IFS has parts. Lots of parts. It may be built tough, but because it has moving parts it can be expected to have more maintenance issues than a solid axle that has the simplicity of an anvil.

Unless the seat of your pants has the sensitivity of a race car driver or aerobatic pilot it is probable you will not be able to feel any difference between the two axles, but there may be times when a tighter turn radius may prevent you from blocking a highway. But despite that I would not walk away from a straight axle coach if I liked it.

Thanks Jon. That's more what I was looking for. So the bottom line seems to be that IFS has a tighter turning radius but no detectable difference in ride or handling. Also, there are more maintenance and possibly alignment issues. As for coach selection, it seems like your comment about it being a non-issue is about right.
Hugh

[Just Plain Jeff]

I had a Bluebird with IFS and an older one without. Current coach does not. The IFS coach I had was a pain in the ass--alignment. Since my current coach is a 40 the IFS is a non issue regarding the turning radius. IFS would neither a deal breaker or maker for me.

For the way I use a coach solid axle is fine with me. Less moving parts, the better.

I don't think I can tell the difference in terms of the ride.


Jim's got it right here. Having driven solid axle coaches, independent suspension coaches and IFS coaches, you can't tell the difference. There is a slight turning radius difference in independent suspension coaches. The better idea here is to plan ahead if possible to avoid situations where that difference matters. Not too long ago in TN I witnessed a POG member heading for a Sewage Treatment Plant to turn around instead of having to venture into the unknown and have to actually learn how to back up his camper with a Toad attached. The old guy said that he had some experience with Sewage Treatment Plants, but no one wanted to know much more than that. It was more fun going off-road in the camper than sit around in a Sewage Treatment Plant anyway.

[Jon Wehrenberg]

Yeah, but the old guy just motored around the sewage plant to return to the road all without unhooking, while the other two were actually the ones heading down a gravel road where they could practice their unhooking techniques.

Go back to severing your fingers.

[Just Plain Jeff]

Aha! We have an admission! 'Tis a much better thing to have wood in a camper than to hang around Sewage Treatment Plants. A guy has to wonder about the elderly who hang around such places. IFS or not.

[Jim Skiff]

--------------------------

[Jon Wehrenberg]

Two good looking old guys. Especially the senior in black. Bragging about his SS and Medicare benefits.

[Just Plain Jeff]

Ah, one forgets ever so quickly. Indeed this was yet another moment of attempting to explain the workings of a camper to an elderly gentlman in his dotage.

[truk4u]

Sure is a nice CC in the background!;)

[Jon Wehrenberg]

Anybody talking to you? Go back to sleep.

[Just Plain Jeff]

No sleeping. I was busy providing certain POG members' email addresses to a friend in Nigeria who is looking to park big money in the U.S. Maybe we could use that to get Jim C a camper?

[Jon Wehrenberg]

I wasn't talking to you. I was talking to the CC guy. But isn't it time for your nap?

[Just Plain Jeff]

No, actually what I do during the day is what you call w-o-r-k. But in the foto, if a guy would look carefully, one might find some flat spots on the tires on the Toad. How about an updated explanation of that...again?

[tdelorme]

No, actually what I do during the day is what you call w-o-r-k. But in the foto, if a guy would look carefully, one might find some flat spots on the tires on the Toad. How about an updated explanation of that...again?

WOW, way harsh. JPJ, are you out of firewood? Does this happen every winter? I'm thinking a sun lamp might help. Somebody do something. I'm calling 911.

[Loc]

I have driven 110,000 miles with a straight axle and 7,000 with an IFS. The ride quality is pretty much the same except when you encounter really rough roads and then the IFS is a little better. The biggest difference is the turning radius. The new 45 foot with IFS feels like it turns tighter than the old 40 foot with the straight axle. I wouldn't let a straight axle be a deal killer. Both ride really good.

[doodlebug45]

Thanks Loc. Glad somebody on this site is serious. Looks like the "girls" got off on a mud slinging tangent and forgot the original question. Oh well! What's life if you can't stick it to your friends every once in a while.
Hugh

[Jon Wehrenberg]

Doodlebug, your question was answered, and then we encountered a little ruckus from the peanut gallery. He had to be dealt with.

As to the way harsh flat spot remark, all I can say to that guy, is if he is going to post a picture of a bus wheel, you would think he would have made an effort to polish some of the corrosion off of it. But I guess the Mother's Polish will have to thaw out for that to happen.

[rfoster]

Hey, isn't that photo of JPJ back when he still had all his fingers?

[Just Plain Jeff]

Awright, the dread thread creep happened.

On chassis year 2000+ H3-45 coaches, there were significant problems with the IFS system. Due to all the moving parts, Prevost did a 'quiet' recall and redid as many coaches as came in. The job involved a lot of re-welding and fitting of new parts. These coaches chewed up a whole bunch of front tires.

If you had such a coach, you wouldn't have to look hard to find if there was a problem as the damage to them was very obvious in a short period of time. We bought some of those returned tires from Doug Stolfo when he was at Camp Prevost and put them on our Angola on the drives and they turned out to work very well in that application.

As Jim Scoggins noted, there are lots of moving parts in an IFS system. Simple is good.