Front end gyrations and more...

[expo]

Hi folks,

I've got a class A 30' on a Ford F-53 15,700# chassis.

About once a year I hit a bump (usually with one tire, not both) that starts the front end gyrating where the steering wheel goes left and right uncontrollably for a few seconds. I've always been able to slow down quickly and it goes away.

The other day this happened again in a construction zone and really started whipping violently. I finally got below 20 mph and it stopped. Now when I stop quickly the tires squeal and didn't before this episode. It steers and tracks well with no pull either way.

Has anyone had this happen to them?

[RoadRohrers]

Don't know for sure. Tires could be flat spotted, though doesn't seem likely. I would recommend you get the motorhome to a good tire repair facility. I don't know where you are located, but near Ingram Texas, A&A Tire has been very good at advising me on tire and suspension issues. If you are in the Murphy NC/Blue Ridge GA, I, had the need to get a tire repaired. Nicholson (Nichols) Tire just north of Mineral Bluff, GA did a terrific job.

Probably not has much help as you need, but all I have.

[TXiceman]

This is a known issue with that chassis. There is a Henderson track-bar that is easily added and it stops the side to side shake you are getting at time. Several others offer them. I believe it is sometimes referred to as a Panhard rod.

It basically is attached to the axle on one side and across the chassis it is atached to the frame. It allows the up and down movement, but stops the lateral movement.

ken

[LVJ58]

I would say you have a serious problem with your front suspension and/or steering linkage that needs to be corrected ASAP. I would take it to a heavy duty front end specialist and have it thoroughly inspected before doing any further traveling.

Just checked with my friend at a HD front end shop and he said if when lubing the king pins if you don't get the weight off the wheels and they don't get properly lubed they can wear and result in the problem you describe and also bad tie rods.

I would recommend checking all those areas out for excessive wear.


Best of luck and let us know your findings

[expo]

I've talked to 1 truck repair shop, 2 RV repair shops and 2 suspension parts suppliers and most agree with Txiceman's statement that this is an inherent problem with certain motor home suspensions. Most suggest the solution is the installation of a steering damper (dampener?) between the front axle and steering arm. A shock absorber dampens the up down motion of the body on the suspension otherwise you'd go down the road like a pogo stick. I was told a steering damper is similar to a shock absorber and acts similarly but the valving in it is different and helps center the steering.

Little did I know there are many motor homes that come with a steering stabilizer from the factory. I just wasn't lucky enough to have one.

After searching for something I can install myself and with a fair price I came up with this Bilstein product offered with free shipping that I'm going to order:

http://www.truckspring.com/bilstein-...3-6735-h1.html

Since my unit didn't come with one originally I'll have to purchase the brackets required for installation. All said, it's going to cost me around $200.00.

I see from the ordering form this product is only offered for the F-53 and Roadmaster chassis' so I'm guessing the others (Workhorse etc.) don't have the problem.

Since this gyration thing only happened to me about once a year it's going to be hard to report back that this device cured anything. I know for sure I'll be aiming at a few bumps rather than avoiding them for a while.

Thanks everyone for the replies.....expo

[TXiceman]

HERE is the info on the Davis or Henderson Track Bar. The steering dampener is not the answer to the suspension oscillations. With the solid front axle, the springs are the only thing to locate the axle under the frame. Some road conditions will cause an oscillation to occur with the front axle. The track Barr locates the axle to stop the oscillations.

A steering dampener will not correct the problem you are experiencing.

Ken

[expo]

Ken, I appreciate your input and zeal regarding my problem.

As I stated in my above post, I did some research before deciding on the Bilstein steering dampener. That came to about 5 hours worth on the phone.

One of the suspension parts distributors I researched was, who you recommended, SuperSteer, the distributors and installers of the Henderson and Davis TruTrac bar. Explaining my symptoms to their tech dept. they advised the TruTrac bar will NOT cure my problem. They explained TruTrac bars are designed for sway and handling problems, symptoms I don't have. They did recommend their Saf-T-Plus steering damper and were confident this would cure my gyrating steering problem. The kit was described to me as a self centering dampener that bolts between the tie rod bar and the axle. The picture in their web site looks like a shock absorber. http://www.safe-t-plus.com/SafeTPlus.aspx Pricing came to $660 with the shock, bracket and shipping. Comparing this to the Bilstein I mentioned in my above post, the Bilstein looks the same and is advertised as performing the same function for $206 AND has a lifetime guarantee.

Bilstein has an excellent reputation so 1/3 the price, the guarantee and does the same job convinced me which direction to go. I'm not going to order this until the beginning of August and will consider more suggestions from IRVers.

Thanks, expo

[TXiceman]

As a mechanical engineer, I have to disagree with the installers. I hope it fixes your problem and I am wrong. Keep us posted. I would ask for a full money back guarantee in writing.

The Safe-t-plus has a spring return to center as well as a damping. The Bilstein is dampening only with no spring return to center...they are not the same.


Ken

["007"]

expo, the front tires are balanced and you have not lost a weight on one of them.
Didn't see this mentioned,your first post is why I ask.

[LVJ58]

In the 9 years and 65k miles we have on our 2000 coach with the F53 chassis, I have Never experienced a condition as expo described and our coach doesn't have a steering damper.

I still suspect there is a serious problem existing with his front suspension and/or steering linkage.

I sure hope he gets the problem resolved without too much difficulty

[expo]

OP here.

I went to a truck chassis shop today and explained the problem I had and explained our discussion on line along with the optins of a trac bar or steering damper.

The mgr. explained that certain vehicles have a propensity to have (what he called) "alternating inertia episodes". He explained it as...one of the front tires hits a bump, slightly altering the vehicle's track. The steering components resist and correct this movement, usually back to center but sometimes oscillating the other way even further. This action usually corrects itself but sometimes it causes the axle to start moving and the springs try to correct the oscillation. The axle and frame begin moving in opposite directions farther each time and get everything shaking. Mine starts off subtle and gets worse.

He said both the steering damper and the trac bar would help in different ways. The steering damper installed between the tie rod and axle would prevent their opposite oscillation in the first stroke preventing it's progress to the chassis/axle movement. The trac bar installed between the axle and chassis would not allow the steering action to progress to the axle/chassis oscillation.

He recalled owning an early 70s VW Beetle OE equipped with a steering damper smaller than a screen door closer cylinder. The damper would wear out every 20,000 miles or so indicated by the front end of the bug shaking after hitting a bump. He said the damping action between the worn one and the new one wasn't that much but the smallest amount of resistance would prevent the steering from oscillation.

He said worn steering parts could initiate this condition but since mine has been doing it since new the cause could be contributed to extra flex in the lighter springs on my chassis. A heavier spring may help but I don't want a stiffer ride.

I'm glad he had some time to spend with me and his explanation made sense. I hope someone else gets some benefit from it. What do you think TXiceman?

007, yes, the original wheel weights are still on there.

LVJ58--what's the max weight on your chassis?

[TXiceman]

The tracbar will help what has been termed the "Death Shake". It is an oscillation which is generally caused by one wheel hitting a bump and it causes the axle to shift to one side. There is nothing on the coach to prevent or dampen the side shift and springs being springs have a natural frequency at which they will resonate. If you get the side to side oscillations started, about the only way to stop them is to slow down until it stops or you loose control.

The only thing locating the front solid axle are the springs and the shocks. There is nothing to prevent the side to side swing unless a tracbar is installed to positively locate the axle. The steering dampener may provide some resistenance to the side movement but that is not it's purpose.

It is your call on how to proceed.

Ken

[LVJ58]

expo, our 37' 8" coach with tags is built on the 228" wb chassis, however, the tags extend the wb to 242". Base chassis GVWR is 20,500lbs with the tags it's rated at 22,000 GVWR.

Loaded for travel with full fuel tank, 1/2 tank fresh water full propane and two bodies, it weighs out at approximately 21,000lbs. We tow a 3,600lb vehicle.

Jim

[expo]

Quote:

Originally Posted by TXiceman The tracbar will help what has been termed the "Death Shake". It is an oscillation which is generally caused by one wheel hitting a bump and it causes the axle to shift to one side. There is nothing on the coach to prevent or dampen the side shift and springs being springs have a natural frequency at which they will resonate. If you get the side to side oscillations started, about the only way to stop them is to slow down until it stops or you loose control. The only thing locating the front solid axle are the springs and the shocks. There is nothing to prevent the side to side swing unless a tracbar is installed to positively locate the axle. The steering dampener may provide some resistenance to the side movement but that is not it's purpose. It is your call on how to proceed. Ken

That makes alot of sense and it should make it easier to drive with side gusts.
Reading more on the Henderson's site they also recommend the rear trac bar for better control. I guess there's no end to stability control (or marketing strategies)

Thanks for everyone with your inputs. I'm still going to ask around at some local rv repair shops and get some pricing with shipping and installation.

I need a stiff drink.