Suspension Question

[Jeff]

Hi All,

I have had a vibration in my steering for about a year now.
I have replaced shocks and most recently the front tires in
an attempt to alleviate it. It is still there. My front-end tech
mentioned something about "rack feedback". What is this?
How does one test for this?

Thanks for any input.


Jeff :shake:

[ctrcbob]

Can't answer about "Rack Feedback" (don't think there is such a thing) however back in February when I first test drove my used 03MM (my gosh, has it been that long now) it had a "Front End Shimmy" bad enough that the steering wheel would shake. Dealer Service Department checked it out, and said it was the front tires causing the problem, and he installed brand new fronts on it. Shimmy gone! Dealer took care of all my concerns.

[FordNut]

Several of us have had the shimmy problem and corrected it by "road force" balancing followed by on-the-car finish balancing. May be difficult to find somebody to do it, I got mine done at Butler Tires in Atlanta.

[Jeff]

Several of us have had the shimmy problem and corrected it by "road force" balancing followed by on-the-car finish balancing. May be difficult to find somebody to do it, I got mine done at Butler Tires in Atlanta.

Ok! Great! Now, what is "Road Force" and "On-The-Car" Balancing?

[Bradley G]

my understanding is Ford changed the steering of our cars to rack and pinion.The steering rack is bolted directly to our chassis,allowing additional feed back to the driver through the steering wheel ,floor pan and in my case go pedal.

I had this symptom for several months early on.
Actually it is comming back from the front tires are not wearing even.
The inside of the tire is "Featheredged".
If you run your hand over the thread you can feel the surface is not smooth but choppy.
Several attempts to road force balance the origional tires, did not help.countless other fixes were executed by my selling dealer.
The fronts were replaced by Goodrich per my service Mgr's request under warranty.
The car(steering wheel) still shook:mad:
It was not till the new tires were Road force balanced that the shimmy was corrected.I drove it several months this way.
I was given countless excuses why Marauders had these symptoms,and to this day I am being told "all Marauder do that" as far as the abnormal tire wear is concerned.:censor: I guess it's time to move on to a better dealer.:shake:
Bradley G

[Bluerauder]

Ok! Great! Now, what is "Road Force" and "On-The-Car" Balancing?
Jeff, you need to find a place that has the special Hunter GSP9700 system. Check the Link Here (http://www.trafficjams.com/hunter/Bal_Info.htm) for some additional information. Basically, it is a dynamic wheel/tire balancer that attempts to duplicate driving conditions and effects (i.e. Road Forces). :D

FWIW .. there have been some reports here that some dealers are doing front end alignments using Grand Marquis vice Marauder specifications. Could be an alignment issue if your service reps are using the wrong spec. :dunno:


My front-end tech mentioned something about "rack feedback".
This sounds like a variant of "all Marauders" are like that" :bs: comment !! Sounds to me like thay don't have a clue at that shop. :rolleyes:

[SergntMac]

There is a repair directive from Ford regarding the racks on 1998 Mark VIII, that address a loose rack. But, before you jump on this as the problem, get your tires balanced, and "road force balancing" as mentioned ny FordNut, it the way to go.

Dayum...EDIT. I had more stuff here, and a linky too, but Bluerauder's 411 is better. Thanks, Blue!

[Jeff]

Thanks all! I just knew you guys would have a handle on this thing!
I'll find that Hunter GSP9700 and get my new tires balanced. Man, I'm ready for this thing to stop shakin'! :beer:

[RF Overlord]

The Blackbird had no shaking or shimmy at ALL with the original tires...of course, due to the incorrect factory alignment, they wore out prematurely. Immediately after having new tires installed, we noticed a slight shimmy at highway speeds only. Having the alignment corrected did nothing. We just today had the local Ford dealer do a Road Force balance on the fronts, and they found the left one had a "hard spot" (is that like a flat spot?) that was out of spec...called it "36 pound" and said anything over 15 was unacceptable (the right tire was 9)...went back to the tire place and got a replacement under warranty which checked out at a 4. I'm not sure what these numbers mean, but we never would have known one of our brand new tires was actually BAD, not just out-of-balance, without it being "Road Forced"...

[carfixer]

The Hunter GSP9700 measures road force. It has a load roller that applies force to the tire while it is spinning slowly. It measures the hardest and softest part of the tire. The difference is called "road force variation" and is measured in pounds.
The machine has you measure runout of the wheel.
Now the machine knows the high and low spots of the tire and wheel. It has you mark the high spot on the tire and low spot on the wheel. Break down the tire and put the marks together. That is force matching the tire and wheel.

[Jeff]

I have new tires all of the way around, all of them road forced.
Problem still existed. Gray-Daniels Ford did some research and
came back with a Steering Pre-Load adjustment. I think that they have finally fixed my problem! :D