steering wheel wobble.. Help

grego37 · #1 (**permalink**) 01-24-2005, 12:38 PM

I have a 1968 shelby clone with all global west components and a rack and pinion from Total Control Products. I run 17" PSE Trans -Am wheels with BFG G-Force KD tires.

At highway speeds Im getting steering wheel wobble (pretty bad)
I've allready ruined a set of tires because of this problem.

The car has been aligned to global west specs twice.
and I've had the wheels balanced 3 different times.

I feel safer in my lifted Toyota Tundra at 110mph than I do in my Mustang at 60mph. This thing should handle like its on rails.

Does anyone know what else I can check

jams · #2 (**permalink**) 01-24-2005, 12:49 PM

You might want to add the size of your tires to the post. I know when I switched to a smaller size front tire my small wobble went away.

Also, have you tried to have them balanced at a different shop? Maybe their equipment is off.

Did a balance weight fall off?

Manual racks tend to make you feel evey bump and wobble. this is not saying you don't have a real problem!

grego37 · #3 (**permalink**) 01-24-2005, 01:11 PM

My front tires are 245/45/17 , Y rated, maximum performance level on tirerack.com, if you've seen these tires they're pretty serious for a street tire, nice big blocks.

I had them "match balanced" this last time at Americas tire.
They position a certain partof the wheel with a certain part if the tire for best possible balance. I even told them not to worry about putting the weights just on the inside (for appearance).
To put weights in the best possible spot for best balance . Ended up with a little on the outside and some on the inside.
I've been there so often they're beginning to know me by name.
And at 20.00 a pop it's starting to get expensive.

Over the weekend I put my brothers wheels/tires on to try to rule out my wheels/tires.
I did definately wobble less , but his tires are much thinner and less aggressive. I really dont think it's my Wheel/tire combo.

Next I'll try:
1) My wheel/tire combo on my brothers car
2) Adjusting the slight play out of my rack and pinion (1/2" at steering wheel)
3) Balancing my wheel/tire combo while on the car.

Any other suggestions are greatly appreciated
thanks.

lovehamr · #4 (**permalink**) 01-24-2005, 02:12 PM

What shocks and springs are you using? You said that you ruined a pair of tires, how so? Were they cupped, bald on one side, chunked etc.? What were the specs that it was aligned to? Did they give you a print out of them? One more question. Are you sure you don't have any slop in any of the suspension points of movement; i.e. tie rods, ball joints, rack mounts, etc.?

jams · #5 (**permalink**) 01-24-2005, 02:14 PM

Sounds like you are doing everything in your power.

This is just a long shot but do you have any play in your ball joints or other suspension components. Maybe a small tire wobble would turn into a big one if other parts are worn or lose.

I am far from an expert but I am sure one will chime in soon.

grego37 · #6 (**permalink**) 01-24-2005, 03:17 PM

Im running adjustable Koni's up front (mid adjusted)
Im running Global west front coils 620lbs (540,620,680) perf. sm.block weight

I had a set of Goodyear F1 go bad ,not too sure on the exact details I think they ended up with a flat spot?, but luckily I purchased road hazzard warranty and they were replaced.

The specs global west reccomended were
Caster: +2deg (pass side)
+1.5 deg (driver side)
Camber: -1/4 deg
Toe in: 1/16

I dont remember exactally but they got close to these #'s

as far a parts loose, everything from what I can tell is tight and tourqued with cotter pins etc...

To test ball joints, I jacked car up , grabbed the wheel and tried to move it from 6 o'clock to 12 o'clock . Im a big guy, and I couldnt get any movement. The lower ball joints were new with my new lower arms last year.
any and all parts are basically new; tie rods, tie rods ends,
I'll get back under there tonight and tripple check everything.

Boy, this website is awesome.
Thanks for the input, keep the ideas comming.

Bob In Ct · #7 (**permalink**) 01-24-2005, 05:35 PM

It's the tires. They are not dimensionally and/or dynamically round. This problem has been discussed at length on this forum. Does the steering column have a rag joint?

Many Cobra owners have the same problem. Big tires, light car, no rag joint, imperfect tires = lots of steering wheel shake around 60MPH. It's not balance. Try having the tires trued.

Bob

rdorman · #8 (**permalink**) 01-24-2005, 07:58 PM

Dynamic balance. You might be able to balance out, you might not. Typical speed for the problem to show.
Rick

Double Venom · #9 (**permalink**) 01-24-2005, 08:08 PM

Take Bob In CT's post to heart.
Have the tires 'trued' or shaved.

Assuming your steering joints, shaft and column are up to par... 'true' up the tires.

DV

Mr.Fixit · #10 (**permalink**) 01-25-2005, 12:28 AM

Quote:

Originally posted by Bob In Ct

It's the tires. They are not dimensionally and/or dynamically round. This problem has been discussed at length on this forum. Does the steering column have a rag joint?

Many Cobra owners have the same problem. Big tires, light car, no rag joint, imperfect tires = lots of steering wheel shake around 60MPH. It's not balance. Try having the tires trued.

Bob

yep, seen it numerous times

grego37 · #11 (**permalink**) 01-25-2005, 09:03 AM

Ok, Since the problem occured with my old set of tires,
and the problem still exists with my current tires,
and the problem is still slightly present when using my brothers wheel/tire combo, Im focusing elsewhere for the problem right now, but will keep the advice on trueing up the tires and come back to that if I cant find problem elsewhere. I feel this wobble is causing the tires to go out of round.

I dont have a rag joint, just a female/female splined swivel knuckle thing that connects my steering column to the rack and pinion.

I have a feeling it might not have enough positive caster (shopping cart wheel syndrome). when I asked global west for alignment specs the caster they wanted me to run was +1.5 on Drvr. side and +2 on pass. side. I looked at my instructions for the Total Control Products Rack and pinion and they reccomend +2.5 to +3 on each side.
Im not sure if adding +1 deg. of caster would cure everything, but its worth looking into. Im going to call them both today again. Maybe running these 2 companies parts together calls for different specs?

Last night while under the car I did find that one of the end links of my sway bar wasnt connected or came undone, Im not sure if this was my problem , but im hooking it back up.

I'll chime back in when I find more info.

Gatorac · #12 (**permalink**) 01-25-2005, 03:58 PM

Go here and find one of these Hunter GSP9700 machines in your area. They balance the tire with a load on it. This detects things a regular balance machine can't. A tire can be round and balanced but still have a harder spot on it. This causes the vibe.

It's not as easy as you think to find a tire that isn't messed up.

grego37 · #13 (**permalink**) 01-25-2005, 04:05 PM

that's the machine they used on my tires at America's tire they call it "road matching"
Im sort of ruling out the tires/wheels right now, but I may come back to that.
thanks

REDSC400 · #14 (**permalink**) 01-25-2005, 04:26 PM

I was reading an old article on sports car suspension tuning. The real term "British" for the symptom is JUDDER.

The article implied that judder is typically caused in order of probablility (assuming the tire and wheel are balanced):

1) out of round tires or separated belts/plies
2) out of round wheel or bent wheel
3) steering rack slop or mis-alignment
4) loose lug nut(s) or pins
5) worn tie rods or bushings
6) hung brake caliper or drastically warped rotor
7) bad bearings or spindle
8) non-isolated steering column (no rag joint or bushing)

It appears that most of us have 8.
However, 8 does not cause Judder it just allows the vibration to be felt at the wheel.

grego37 · #15 (**permalink**) 01-25-2005, 04:39 PM

REDSC400
Thanks, that list is a great place to start.

I spoke to Tech at Total Control Products today, he told me how to adjust any excessive play out of the rack and pinion. (steering rack slop)

He said with front end off the ground (no load) see how much play at steering wheel is present. Up to 1/4" is ok and if there's any more it should be adjusted down to 1/4".

Im hoping this is the problem and an end to my worries. (fingers crossed)
I should be able to test tonight. rain pending.
thanks.

REDSC400 · #16 (**permalink**) 01-25-2005, 08:38 PM

Grego:
Eliminating the rack and pinion as a source of play would be a good thing.

If that does not do the trick, then pick Bob in CT's brain. Bob has been working (obsessing) on this monkey for at least a year now and he has tried just about everything. He also has some real data as to which things pay off and which do not.

It may appear that some individual tires are just "crap" oddballs, being out of round and beyond reasonable balancing and shaving cures.

I personally, took my tires and rims to a local shop with the new Hunter machine and breaking the tires and rotating them on the rim to minimize the effects along with a series of balancing did the trick for me.

However, none the less, if I drive the Cobra at about 75 MPH, if I hold the wheel loosely I can feel JUDDER. If I hold the wheel with a tight grip, then no JUDDER.

Odd but true.

How do you hold the wheel??

grego37 · #17 (**permalink**) 01-26-2005, 08:41 AM

I was able to adjust some of the play out of the rack and it seemed to help a little (or might of been my wishful thinking, placebo effect), but the wheel shimmy is still present.

I need to see if I can rule out the Tires and or wheels for good, After work I'll take them and get everything checked again at another shop:

1)Wheel bent or out of round
2)tire out of round
3)balance

If the tires are out of round and need to be trued (shaved back round) where would I start looking for someone who does that?

grego37 · #18 (**permalink**) 01-27-2005, 01:05 PM

Update:
I took the wheels/ tires into a reputable tire shop that had the Hunter DSP9700, It found no problem ., It actually was perfect the way they were set up form the last Hunter DSP9700 balance job I had a few weeks back at a different shop.
I asked if anything was out of round or bent, they said the machine would of found that.

Must focus on other possibilities now.

?????

Edley Rondinone · #19 (**permalink**) 01-27-2005, 09:38 PM

I am just guessing, but is the frame straight?
Is the frame "square"?
Is the wheelbase the same on both sides of the car?
Are the shocks worn to a point that there is "judder" emanating from them?
Are the shocks adjusted the same?
Are the coil springs adjusted the same?
Is the steering column mounted securely to the frame and everywhere else?
Are the universal joints in the steering column in good shape?
Is the steering wheel mounted securely to the column?

grego37 · #20 (**permalink**) 01-28-2005, 08:20 AM

Update 1-28-05
I have a buddy who owns a brake shop. Last night I asked about rotor warpage and caliper hang up. He told me to remove wheel and to spin rotor with my fingers and see if I could feel any excessive drag or high spots. Sure enough, on each revolution there was an area on the rotor which had more drag while going through the caliper. Hopefully this is the problem I've been searching for. I have to take the car to him and see about turning the rotors or getting new rotors.
more to come soon.