While driving to our campsite in South Haven MI, I hit a section of very rough pavement with my left front tire. I was slowing down for a red light at a intersection, light turned green so I was going maybe 20 mph then hit the rough pavement and it set off a violent shake in the front end. My wheels and steering wheel started shaking which caused me to crap my pants well actually I just hit the brakes and pulled over to the side of the road.

The shaking quit when I hit my brakes and pulled over. I got out and checked my front end everything was still there. Nothing felt loose so I climbed back in and continued to campsite. Drove great like normal, I didn't feel any slop in the steering, the coach handles great drives like a giant Cadillac.

So I was really caught off guard when this happened. What do you guys think?

Thanks!

Although chassis is very different, could be a problem my Breakaway developed -- loose attachment of steering gear to frame.

Whoa Nellie! Something got bouncing together... other than excessive play (which you checked for) it might be be an issue with shock absorbers. If they get worked hard multiple times they may foam inside and quit doing their shock thing.

Maybe some of the other P30 guys have found this?

I guess this rules out off-road racing in my Barth... darn.

Tom, Your pic makes me think you're of the Ford/John Deere/Oshkosh clan, in which case I'm clueless.
But if it's a P-30/32, I might first suspect a missing/worn-out steering damper.....basically a shock absorber mounted horizontally between steering gear and chassis. It's purpose is to dampen some of the
symptoms you experienced. We're curious as to your final solution - please post.

I have experienced this with both my '75 and '85 Barths (both p30 chassis) and it was bad tires one time and bent wheel the other.

I'm with Steve on this......."Something got bouncing together."

I would thoroughly check the front end or any looseness. Lie down and observe while DW moves the wheel back and forth on concrete. (concrete provides more resistance than gravel)

There is a procedure for checking ball joints. I believe the GM manual is linked here somewhere. If not, holler, I can scan and send pages from my '84 shop manual.

Do you know what your front end alignment situation is? Lots of motor homes are set for potato chip truck specs. GM calls out special MH specs, which are mostly more caster. Be aware that the tilt of the frame rails affects caster. GM covers that. A Pee chassis really likes proper caster and level frame rails. Caster increases the natural trailing force to resist little impulses to go right or left. Sort of a geometric steering damper.

Your front wheels will respond to caster forces more willingly if the tires are at spec or slightly higher pressure. Have you weighed your front end and set tire pressures accordingly?

I like the Bilstein shocks and dampers. We regularly travel washboard to and from our place, and this has never happened. We also have an IPD heavier sway bar.

Having said all that, certain speeds on certain washboard will made some vehicles lose contact with the road. Our 4Runner will float a little sideways at a couple of spots on our road at certain speeds. I know one person who went off the road without excessive speed on washboard.

The very first trip I took with my Commercial Conversion to Pocono I developed this same thing. As soon as I slowed down and stopped, it went away never to return. That was 2004...

It felt like my entire front end was falling out of the coach. I have felt this in other Ford Products I've own with the twin I beam suspension.

The front end of my coach is a Straight I-Beam setup. It's a severe steering oscillation condition. I know I remember seeing this on tv from the mid 80s - something like an investigate report or 60 minutes.

Here is a link to what we're talking about. At about the minute mark of the video, it should queue up there.

http://youtu.be/8EuQ6f8rgT4?t=1m1s

You'll see that after he hits a bump the front end shakes violently, then it'll go to an interior shot. Watch it a bit from both angles.

Whoa Nellie is right, the video is spot on that is what my Barth did for a couple seconds and that was enough for me.

My coach is the Chevy P30. I haven't had a wheel alignment done so I don't know how the setup is. I really never suspected any issues because of the way the coach drives and handles. I run 80 psi in the front tires, the data tag says 60 psi I just figured 80 rolls better, most motorhome drivers tell me they run higher psi, they had 100 psi in them when I bought the Barth . I have front air bags which I inflate to 70 psi. Does anyone know what the airbag pressure should be? I was told to put enough air in to get a nice ride and not to go over 90 psi I've never seen an inflation chart tried to find one on the enternet.

I'm camping unntil Sunday and man we have gotten the rain all day long, a couple of badly needed inches. So when I get back home I will be throughly checking all the sugestions, I'm really thinking the steering damper is the issue makes a lot of sense. I could feel the wheel going back and forth while I was going over the rough pavement then it just started to go crazy. I didn't feel any damping of the steering wheel.

But anyway I'll check it all out, I have a trip coming up the end of the month into Labor day.

Ha ha what the heck it gives me an opportunity to work on the Barth.

You Guys are the greatest, Thanks

About 25 years ago, my Cadillac started doing something similiar. It would start out smooth and then between 25mph and 32 mph it would shimmy so bad you'd think the front end was going to fall off. Above 32mph, it was smooth as silk. I remember taking off the front tires and rolling them down the sidewalk. One tire rolled perfectly and the other wobbled. I realized one had a slipped belt. Air had leaked through the innerliner and was between the belts creating a raised place or hump between the steel belts....new tires, no more problem.

I'd take off the tires and roll them on a flat surface and see if they roll straight. You'll spot a bad tire pretty fast.

This problem is not new. When Dodge was the main supplier of MH chassis it happened often. I beams have more of a problem than IFS although if you have a very heavy stabilizer bar it almost acts like an I beam.

Have it happen twice. 30 years or so ago on a Dodge chassis and again in the mid-90s with our bus. In both cases slow down, stop and then continue. So don't panic.

quote:

Originally posted by Tom & Loraine:
they had 100 psi in them when I bought the Barth

Check the wheels for max pressure. Usually on the inside under the dirt.

quote:

Does anyone know what the airbag pressure should be?

Nope. Every coach is different. Fully loaded, you should have 1 3/4 to 2 1/2 inches bump stop clearance. Sometimes this can not be achieved by simply adding air. If this is the case, jack the coach so the front wheel is unloaded and inflate the bag to its max pressure. Than release the jack and deflate the bag until the bump stop clearance is in that range.

quote:

I'm really thinking the steering damper is the issue.

A shimmy damper can keep worn steering parts from being so noticeable, so a new steering damper might keep the looseness from being so apparent, but the looseness will still be there, waiting to upset you again. So, at least check it out or have it checked. Things like Safe T Steer of Steer Safe will also provide some centering force which will mask loose steering. All Pees did not have steering stabilizers OEM. My '85 27 footer did not, and did not even have attach points.

FWIW, there used to be a kit out to use double dampers, as well. One on top of the other.

quote:

Many things can cause this.

... add bad shock and/or poorly balanced wheel.

http://www.offroadtoybox.com/R...AlignmentProcess.pdf

While surfing the web I came across this pdf file that has a ton of info on the frontend of the P series motorhome chassie. It contains in detail the information that you guys are telling me.

Sorry about not getting a direct link to the pdf file, I tried copy and paste and moving the link directly with no luck.

Thanks Tom. That PDF on alignment seems very informative and I plan to share it with the guy who is going to be aligning our Regal.

Kirk

I'd check for Gremlins!