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Topic: Tires contact wheel wells above tire when parked or no pressure in airbag. (Read 1518 times) previous topic - next topic

Tires contact wheel wells above tire when parked or no pressure in airbag.

On my 1996 U320, there are rubber washers located on the "H" members that form the suspension. The rubber washers, which are about 1/2 thick look like they were intended to be stops but the tire also acts as a stop when parked because it contacts the wheel well. Increasing the thickness of those stops would reduce the tire rub when parked while not raising the travel height of the coach. This would be an easy fix, but I wonder why Foretravel did not install thicker stops at the factory! I do not see a negative to this change, except that when parked the first step when entering the coach would be an inch or two higher. Thicker rubber stoppers could also allow driving a coach in the event of air bag failure.

Barry Beam indicated that starting with 2003 year models the tires will not rub the wheel wells.

I found a few memos (circa 2007) regarding some folks who added 1.5 inch solid steel spacers between the axles and the H frames, effectively raising the coach 1.5 inches. I would not do this because low center of gravity is a big benefit of Foretravels.

Building a wheel well which sticks above the floor would accomplish no tire rubbing and I have seen this on SOB's (inside closets). Foretravel could have done this but did not. I definitely see negatives to this.

Another way to reduce tire contact when parked would be smaller diameter tires, ie 275 70 instead of 275 80 or whatever size tire is available that would carry the load. Perhaps there are not any.
 
Has anyone installed thicker suspension stops?

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #1 –
I have had a problem with the situation you describe.  If one stops someplace for a few minutes and levels up due to having lunch or something and happens to be parked on a downslope you can have a problem.
The front end will raise to a high point and the rear end will drop down onto the tires.
When you leave, and FAIL to WAIT until the rear air bags raise (which seems to take forever) to the ride position, you will carve grooves in the wheel well covering above the wheel.  I had that happen more than once apparently and repaired the problem with mastic when I changed my air bags.  You are correct, in that, WHO WOULD HAVE THOUGHT THAT COULD HAPPEN.
Regards,

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #2 –
The only down side to adding thicker stops is that you will reduce your leveling capacity by that much.  I actually would like more travel in my suspension just for leveling - especially for FORWARD and AFT.  I know some of the new IFS suspensions (not necessarily FT) have only 6 to 6.5 inches of travel compared to our 7.5" of travel.  That extra inch can make a big difference.
I imagine just about every FT out there prior to 2003 has skid marks above the tires from what Jon Twork mentioned.

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #3 –
What is the problem if tires touch top of wheel well when parked?

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #4 –
It takes some of the "rockin'"  out of the coach, so no one will know if it is ok to be "knockin'" ;D

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #5 –
What I have discovered about having the rig resting on the tops of the tires is that the rig rocks more, since the shocks are now not doing anything to help you.  We try to keep it off the tires when leveled, and sometimes that means doing manual leveling. (the HWH tries first to level by letting air out of the high side, and that may put you down on the tires.)

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #6 –
My FT had those skid marks in the wheel well when I bought it and I haven't done anything about it.  I don't consider it a problem.  To me it seems a little more solid when the air bags are deflated.  It will rock a little just from the tires flexing.  I usually walk around the vehicle after starting the engine and checking that the travel light is on.  The travel light only indicates that the leveling system is in the travel mode, the coach may not be at the proper height for travel.  Depending on initial air pressure it may take a few minutes for that to happen.  One actually has to look at the top of the wheels to see that it is ready for travel.  While walking around you might also hear an unusual noise, spot a leak, etc.

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #7 –
I always thought that the skid marks were caused by the suspension travel when driving and hitting pot holes or large swells in the road, etc.

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #8 –
Hi Peter,
  I think you are correct. Many Foretravels seem to have these rough road markings. There was a discussion where an owner installed rubber bump stops of some kind to prevent this. I do not know if you are hurting the coach with these occasional, light, tire rubbings

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #9 –
Correction - I said in Reply#1:
"On my 1996 U320, there are rubber washers located on the "H" members that form the suspension. The rubber washers, which are about 1/2 thick look like they were intended to be stops"

The washers are not rubber, they are steel and they do not touch, so, I believe there must be a stop inside the airbag.

Thanks for all these comments, I just learned some more things about Foretravel.

I believe that 1/4 inch spacers under airbags would stop tire rub while raising the coach only 1/4 inch and maintaining full suspension movement. Anyone seen this done?

I also believe that most of these tire rubbing marks are created by driving away before air pressure builds sufficiently to stop tire/wheel well rub (see John Tworks' reply).

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #10 –
Hi P. Wyatt,
  There is, or was, a member of this group that has drawings for spacer plates that raise the coach about an inch. You may be able to find his postings with the search available here.

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #11 –
Quote
  There is, or was, a member of this group that has drawings for spacer plates that raise the coach about an inch. You may be able to find his postings with the search available here.

I think this is it.
http://www.foreforums.com/index.php?topic=4344.msg17312#msg17312

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #12 –
Thanks to Barry for showing how other Foretravel owners raised their coaches 1.5 inches by installing 1.5 inch thick steel spacers between the axle and the frame. I would not want to raise mine that much, perhaps 1/2 inch. Installing 1/4 plates would not require replacing the bolts and might keep tires from rubbing.

I believe putting 1/4 in spacers under/over (16 spacers) airbags would stop tire rubbing and would be easier for us back yard mechanics. Does anyone have pictures of removed airbags or know what they look like?

I investigated Michelin tires available and found 305 70R 22.5 tires are 1 inch smaller diameter than 275 80R tires. This would provide tire - well clearance and provide higher weight rated tires. It would however, lower the coach 1/2 inch, and raise engine RPM from 1200 to 1230 at the same speed.

How low is too low for our coaches, ie has anyone punched a hole in a tranny by hitting a raised casting or a rock?

The other sizes of tires that would work are: 270 80, 285 75, 310 70 but I could not find any.

Wyatt 

 

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #13 –
Hi Wyatt,
  Will the larger tire, and it's larger width, work when the coach is turning?

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #14 –
My immediate question is whether or not the rear tires will rub each other.  There was some previous discussion along those lines. 
 

Re: Tires contact wheel wells above tire when parked or no pressure in airbag.

Reply #15 –
Rear duals tire kissing causes problems and must a avoided.

Michelin tables shows minimum wheel spacing for 305 70R 22.5 on duals to be 13.5 inches with 9 inch rims but about 13.3 inches with 8.25 rims which we have. My dual spacing is 13.5 inches, however, there is a balancing tube mounted between the duals on my rig which adds some space (not sure how much).

Therefore 305 70R 22.5 are OK as duals on my U320. 

Wyatt