Cars Jumping Guide Rails

I've been having a problem for the past few months with SUVs jumping the guiderail. Most SUVs are jumping the right-hand rail, although I've had one incident where the SUV jumped the left-hand rail (that was a real pain!). Both rails are round-rails with the left-hand rail covered in a hard plastic material to protect against scratched rims. The chain is setup as a front pull system with pop-up rollers. It doesn't matter what the size of the SUV is, I've had Lincoln Navigators, Ford Expeditions, Ford Explorers, Nissan Armadas, GM Suburbans and Ford Windstars (a minivan!) do it.

It used to happen almost 2-3 times a week. The changes I made were to lay down a 3' wide strip of diamond plate (that the passenger side wheels could ride along) the entire length of the tunnel, slow the chain speed down and lower pressure on the wraps & side brushes (I thought they might be "pushing" the car over the guide rails). Right now, I'm down to 2 cars a month jumping rails, but this still seems waaaaay to high to me.

Incidentally, I've noticed that Ford vehicles have a high tendency for the steering wheels to turn 90 degrees to the right causing the tire to squeal quite abit all the way down the entire length of the tunnel. I know Ford has had issues with their power steering pumps for a number of years now, but has anyone else noticed this?

Any suggestions or ideas I can look into to fix this?

- J.

J
Have you considered raising your passenger side floor plate up a little. Increasing the height will help to keep the car more to the left. I have a front wheel pull surface conveyor and had similar problems several years ago. My passenger side is one inch higher than the drivers side. I haven't had a jumper since - it's been at least 8 years. Also, my inside rail has 3/4" round stainless bar welded against the top of the rail - full length of the conveyor. The tire rides this bar. The tire can't grip on to the bar.

Joe

I agree with Joe. Many car washes have poor cement work and are not at proper levels. Some older washes have also worn down the cement over decades of use. The passenger side cement height will affect if the vehicle toes in or out. The welding of the 3/4"-1" bar/pipe is a common fix on surface conveyors because tires can climb the c-channel. The hard plastic on the outside rail is UHMW.

Well, I just went out with a level and checked every 10' down the tunnel. The passenger side of the tunnel is very slightly higher than the driver side the entire length of the tunnel. I also never noticed it before but there is some round bar welded to the top of the inside rail. It measured 5/8" diameter though, not the 3/4"-1" that was recommended. Think I should remove the 5/8" round bar and go with some 1" instead?

I do plan on putting some more diamond plate on the passenger side to raise the level even higher so, we'll see what happens with that.

Thanks for all the advice so far!
- J.

Do you know who built your conveyor? Is it O/U or surface? Can you post some pictures?

Put down tracking bars.

Jin,
I would leave the 5/8 tracking bar as is, but the bar should be smooth or shiney. My passenger side floor plate is smooth stainless steel. My thinking years back was that if the left side were going to keep the car in the track then there had to as little friction as possible (so the tire would no possibility of gripping the surface) on the passenger side. So the driver side could keep the car "dragged to the left". Again, this was just my own thoughts. Some washes have put wood under the passenger side plate to raise it up. Use plywood. This is a cheap see and what happens fix. I know it will toe more to the left, but how much wood you need is the question. Once you find the right height then decide on a more permanent fix. Tracking bars are also a good possibility.

Joe

We just put in a new Sonny's 150' conveyor last summer. We are front wheel pullOur 48 year old concrete is worn as well as having stell plates at certain points down the tunnel.

Initially we had all kinds of problems with SUVs and even minivans jumping to the inside. It was so bad that we began pushing these vehicles by the back wheel and cars by the front wheel which worked out fine until the attendant forgot and a minivan jumped both wheels off the conveyor. We were told to put tracking guides in (1970's solution). However we did not have this problem on our old conveyor becasue we had installed the UHMW angle on the inside guide rail. Sonny's said it wouldn't work and the installer said just it was the painted steel causing the jumping.

Well, to make a long story short, we purchased 150' of UHMW plastic from Sonny's, ground off the welds on the 1/2" round bar on top of the inside guide rail for the entire 150', purchased flush mounted carriage bolts and placed it in the inside guide rail. We have not had a problem since and all vehicles are now loaded via the front wheel.

I have also heard that Sonny's now sells their front wheel pull conveyors with the plastic on both the inside and outside guide rails.