steering wheel wobble.. Help

[REDSC400]

When you hit the brakes on the Cobra do you feel a "pulsing" which is fast (at higher speed) and then slows down (as your speed slows)? This is typically the sign of a warped rotor(s). The pulsing is felt at the steering wheel and the brake pedal whilst braking if from the front wheels and sometimes from the brake pedal and stick shift if from the rear brake rotor(s).

Almost all disk brakes will eminate a slight "schooop schoop" from the wheels when they are spun (the noise coming from one or more pads slightly touching the rotor). However if you feel some stronger resistance and then a release while spinning them then you may have a warped rotor.

Last evening, when thumbing thru the latest Hemmings Muscle Machines magazine, I noticed a firm with a half page ad advertising an aftermarket universal joint, for a steering column. This joint appears to have an integrated judder dampener in it. Kind of like a rag joint but not visible. Interesting. And probably a solution to many a problem.

[grego37]

RED,
the strange part is, I dont notice any pulsing or vibration while braking, it just at speeds of 65+. This is why I didnt start looking at the brakes/rotors to begin with. There is deffinately a tight area while spinning with my fingers. I would say 3/4 or a revolution of the rotor is good and 1/4 is tighter.

Thats funny you mention the stick shift vibration. When Im on the FWY during test drives, While in 5th gear The tranny will kick it self out of 5th and into nuetral. I have to keep my hand on the shifter to keep it in gear.

The rotors are factory mustang disc 68? I did have a brake job 300 miles ago but again that was 7 years ago (long term project)
Im wondering if by sitting that long, allot of the time outdoors if corrotion set it?

In the rear I have Drum brakes , which I recently converted to the wider factory ford equipt. I think they orig. came off a big block early station wagon. Wider brake pads and rotors (2 1/2" ?)

That damper integrated ujoint sounds great, can you give me any more info on this (I dont get Hemmings).
Greg

[Double Venom]

Greg,

Following your diagnostic test with a lot of interest. Here is the one that RedSC was probably talking about. "Flaming River" makes every type a Cobra could want, and they work well. I don't think this is the problem, but it sure wouldn't hurt.



DV

[grego37]

Thanks Double Venom,
Hopefully it's the rotors, but regardless this looks like a great idea for absorbing some of the road going to your hands.
by the way it's a mustang I have.
Greg.

[grego37]

I installed my wheels and tires on my brothers 64 falcon. No vibration at any speed. I can now fully rule out my tire/wheel combo.

My factory rotors are too thin to cut again, Im in the process of changing out the front disc brakes. I think im going with Baer 'Track series' with 13" rotors.

I'll chime in with results as they come.

[Bob In Ct]

I'm glad you're not testing the systems I run. Just because there is not wobble on the Falcon does not rule out the tires. The Falcon may have a damper of some kind in the steering.

Bob

[grego37]

Bob,
Im not sure what "systems I run" means.
but Im am open for suggestions.

I dont think there's any other tests I can do on my tires??. I've had them balanced on two different Hunter DSP9700 machines with great results. I was told if there was any run out or out of round tire the machine would of detected it and they wouldn't of balanced.

If there's any other meathod of testing, I'm all ears.
Do you know of another meathod I can try?

I do know that the wheels and/or tires are the culprit in 90% of shudder/ wheel wobble / shimmy cases. I just dont know how else I can check these to see if they're 'true' round.
Thanks.

[Bob In Ct]

Greg:
All I'm saying is that the fact that the Falcon does not have steering wheel wobble does not rule out the tires. The only way I was able to reduce the problem on my SPF was to have the tires trued. PM me your phone number and I'll give you a call.

Bob

[grego37]

Hi Bob,
PM sent this morning.

[grego37]

Update 02/03/05,
Last night I removed my rotors to have them turned. Upon removal I noticed a difference between the two calipers.
The caliper on the pass. side, the piston was basically flush with the cast iron body ( in the relaxed position)
But on the caliper on the driver side, the piston was protruding out of the cast iron body 1/4" . (in the relaxed position)
Does this mean it is stuck in the depressed position 'Hung'. (brake drag?)

I did this late last night and had no one to press the pedal while I watched the piston move. (I'll test tonight)
Does anyone know which one is correct, where the piston should be in the relaxed position, and how much travel it should have while pedal is depressed.

Regardless, I will be upgrading the brakes to either Baer brakes, or Global West set up soon, But im still interested in finding the culprit of this problem.

Making progress.

[speedlab93]

Is it just me or doesn't anbody else find it odd that the trans kicks its self out of fith ? What type of trans? have you checked the u-joints in the drive shaft? I had a ranger that had a vibration at one speed, checked every thing, couldn't find any thing wrong until the u-joint broke, problem solved! check the drive shaft for u-joint play , or bent drive shaft missing balance wieghts, an out of balance drive shaft , bad u-joints, will shake the hole car!Just another thought!

[grego37]

The trans. is a Doug Nash/Richmond 5 Speed. It kicks itself out of gear only when its in 5th gear at 65mph+ due to front end vibration/shimmy. Driveshaft is new and balanced, u-joints are tight and new (Spicer).

However, I recently took my tires/wheels again to a new guy. Had him disassemble them and check for run out on the wheels. Sure enough , I had around .100 up and down runout on each wheel. definately not 'true'.I called the guy who made the wheels and he's sending me two free replacements.
Its amazing how 3 different tire places told me there's nothing wrong with my wheels and tires.

And believe me, when I get the replacements, Im going to bolt them up to my hub and do my own runout test.

hopefully this is my problem.
I'll post feedback after testdrive.
Greg

[speedlab93]

Speaking of wheel fit ment I was working for The Racers Group 2 years ago for a race or two, and they purchased three new sets of wheels for the cars, the hub was to tight and during the race at sears point, Tire change and the rear left wheel wouldn't fit all of the way on the hub, due to the heat ( from the brakes) the hub had expanded and the new wheel would not fit properly!
If the car would have started the race with the new wheels never would have been able to get them off. As it was took tree laps to fix the problem. But hell the wheels only cost 20k for the three sets!
But glad to see that you found the problem!

[grego37]

Update 3/18/05

Had the calipers rebuilt, installed new rotors with all new bearings and races.Checked for run out on rotors hub surface and braking surface, checked out good. Got 2 new front wheels, checked out ok for run out both lateral and centrifical. Took them to balance shop had them balanced with Hunter road force machine balanced out good, I even had them put the weights where they worked the best (on the out side, yuk!)

Test drove, steering wheel shimmy still present at 60mph+

Again I've put these wheels/ tires on my brothers car, no shimmy at any speed.

All steering components are new:
tie rod ends
ball joints
Global West upper arms
Global west lower arms
Total Control Rack and pinion
Aligned to Global West specs.
Cant find any play in steering assy.

Im running out of things to change or check, and there are only a few hairs on my head left to pull out.

Any suggestions. Thanks

[HighPlainsDrifter]

Hi,
I see you have spent many$$ trying to fix this. The shorter the car the more vibration will be on the front when it's actually the rear end causing the trouble,I have seen this on 2 other cars. Seeing as you fixed everything else,may I suggest you check the rear bearings (axle and pinion] If you have a detroit locker it may be broken.
Good Luck,
Perry.

[grego37]

HIGH PLAINS DRIFTER


Hey it wouldnt hurt to check.
I did notice some unexplained grease on the inside of the rear drivers wheel. All I did was pull the drum to inspect, there was no grease or oil inside the brake assy.

Im assuming I pull the axels out, how do I know if the bearing is bad?

[HighPlainsDrifter]

Hi,
After you undo the 4 bolts holding the retainer,Use an axle puller,slider hammer to pull the axle. The grease means the housing seal or axle bearing is gone and seeps out between the housing and reatainer. The axle bearing wll be noisy or eneven when turned if bad instead of smooth,you can only feel this when the axle is pulled out.Normally the seals leaking are an indication of a bad bearing. If one side is bad,I'd replace both bearings and replace the housing seals anyway,cheap insurance.When the axles are out rotate the driveshaft and see if the pinion bearing feels smooth.
Perry.

[grego37]

Thanks Perry.
I 'll have them out tonight.

I'll have an update monday.

[lovehamr]

Greg, I've followed your trials and tribulations with interest, as several of the mods you have made I'm considering for my own Boss 302. My control arms are lowered about the same as yours are (via a negative wedge kit), my springs are 600# and I've run 17" and 16" wheels at varying times with no adverse effects. The one area where your car and mine seem to be very different is the rack and pinion set up. Did you ever put an isolator in the steering shaft? Did you ever increase your castor settings? As a side note; what headers are you running and did you have any clearance problems with the rack?

Thanks, Steve

[Bruce Edwards]

I have read all of these post and have a question. Did you check to be sure your rack is firmly bolted to the frame? I know sounds dumb but if the rack is not held tight to the chassis it will cause this same kind of problem. Just because the bolts are tight does not mean the rack is tight. If the bolts are to long you may be running out of thread before you get the correct crush on the rack bushings.
One other thing to check, with out seeing your set up I am shooting a bit in the dark if you are running more than two u-joints do you have any "play" in the shaft? This will give a feel like a loose rack at the wheel and making the rack tighter will mask the real problem. Have someone turn the wheel and watch the steering shaft to be sure it stays true and does not bind. If the shaft is moving around with the steering wheel it will beat you to death in the car when the tires try to find the groove at speed.
Had an old car and every time you would get to one speed the whole front end would start to shake so bad you would think it was going to fall off. A quick shake of the wheel right to left and it would stop. Turned out to be a bad joint in the steering and a bad front spindle. The inner wheel bearing had worn a groove in the bottom of the spindle and at speed when the tire started to grow a bit it would start to bounce on the inside edge and that would start the shake. By changing the load on the front end I could stop the shake till I dropped below that speed at which the tire changed shape.
Boy that was long winded. Sorry about that.