Thread: Need diagnostic help on SEVERE steering wheel shake

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Would appreciate some ideas as to what is causing the following and how to resolve it:

Have an intermittent problem with severe (& I mean SEVERE) steering wheel side to side shake! Starts for no apparent reason, stops only after I make a full stop and start up again. Can be traveling a steady 55 mph and the steering wheel slowly starts to feel "bumpy" then begin to have a rapidly increasing side to side shake. Gets so severe that you cannot hold the wheel. The entire time the car will be driving straight. Slight improvement if I slow down, but doesn't stop until I apply the brakes. Car does seem to pull to the right slightly when I apply the brakes, but not enough to seem to be a major issue in itself. Problem started after rebuild which included a replacement of all the suspension bushings, addition of a brake booster, new rims, wheels, etc. So I cannot look at just one area of issue, though it seemed worst with smaller wheels.

Here's what I'm running:
'34 Ford Model 40 sedan 350/350 B&M Street stick,
Mustang front end 9" ford rear, (all bushings new- checked by 2 different mechanics and no issues seen)
Edelbrock carb (original)
chassis mounted dual master cylinder with dual 7" boosters, (new)
new rear slave cylinders (drum)
no scoring on front disc brakes,
185/60/15 front tires balanced on Rocket rims 15x6
225/15 rear tires balanced on 15x7 rockets
balanced all wheels and aligned yesterday

I was originally running 155/60/15's on the front when the problem started, replaced with the 185's yesterday (new) to eliminate tires as an issue after an alignment and visual inspection of the front suspension failed to resolve the problem.

I don't see anything abnormal under there.

Could the problem be somehow related to the front discs? This was one area we didn't redo... but the problem came up after everything else was done... maybe related to the addition of power brakes from manual. As an aside, before the power brakes, it felt like I was pushing on a brick to stop the car.

Please advise...

Sounds like a classic case of death wobble, but generally that occurs in straight axle front ends, like early Fords had. But I guess it can happen in any type of front end, just never thought about that.

I have heard that MMII frontend kits are not all created equal. Some omit the steady rods (or whatever the proper term is) from what the factory had originally installed. I have seen articles about how it is important to keep these in place, but really didn't pay much attention as I have never used one of these in a car.

I think we need more info so one of the guys on here who know these can help you more. Whose front end kit is it? Did you install it or have it done, or maybe you bought the car this way. Has it always done this, or did it just start. You provided a lot of info, which is good, but I think you need to give more specific info about the front suspension/steering, as that is probably what is causing it.

Don

Originally Posted by Itoldyouso

Sounds like a classic case of death wobble, ... Whose front end kit is it? Did you install it or have it done, or maybe you bought the car this way. Has it always done this, or did it just start. You provided a lot of info, which is good, but I think you need to give more specific info about the front suspension/steering, as that is probably what is causing it.

Don

Car came with the front end as is, as near as I can tell it's an early 1980's Mustang II front end. manual rack/pinion. All I did with it was add adjustable coil overs and replaced all the bushings. My buddy, a shade-tree mechanic, races a Mustang with the same front end set up, just larger discs, so he was familiar with it. After which, the last thing done was to replace the manual brakes with power. It did not do this until after my buddy & I replaced the manual brake system with power booster/dual master...
Classic case of "don't fix it if it's not broken"?

Before the coilovers and power brakes, did the car ever have any issues? How many miles do you think you drove it prior to the new work? Do you know whose kit was used to put the MMII stuff on the car? Are those rods I mentioned in place or omitted?

Don

Originally Posted by Itoldyouso

Before the coilovers and power brakes, did the car ever have any issues? How many miles do you think you drove it prior to the new work? Do you know whose kit was used to put the MMII stuff on the car? Are those rods I mentioned in place or omitted?

Don

Only issues were related to some wandering and hard as a brick braking... drove the car a couple hundred miles before laying her up to work on. No "Death Wobble" at all. Sorry, Don't know whose kit was used as the installation was done almost 20 years ago and PO has no idea. Don't see an steady rods installed.

I reread your original post and you said you had it aligned. What specs did they use? Reason I ask is that I think I remember seeing somewhere that if your MMII suspension has power steering they like a little more caster than a stock Pinto/'MMII would call for, something like 3 degrees, I think. Could it be that when you changed the coilovers you also lowered the front end, which would reduce your caster? Insufficient caster can cause some goofy handling issues, like you describe.

Don

Something is loose in the steering/suspension, whoever inspected it missed something. Did they unload the ball joints when they checked? You may not be able to detect a bad ball joint under load. The death wobble Pops refers to on beam axles is usually loose king pins which allow the harmonics of the rotating wheel/tire to do the wobble. Very likely that at least one of the components that holds the wheel straight is loose or broken. Strut rods like Pops mentioned would show up on braking too, so another symptom to check.

Originally Posted by Itoldyouso

I reread your original post and you said you had it aligned. What specs did they use? Reason I ask is that I think I remember seeing somewhere that if your MMII suspension has power steering they like a little more caster than a stock Pinto/'MMII would call for, something like 3 degrees, I think. Could it be that when you changed the coilovers you also lowered the front end, which would reduce your caster? Insufficient caster can cause some goofy handling issues, like you describe.

Don

Looking at the paperwork, they used the specs from a 1974 Mustang. I did lower the front end, when running 155.60.15's, but since have raised it back to original height & I put on 185's yesterday.. problem still evidenced this morning.
Any possibility that the problem is related to the caliper's? though I see no scoring on the disc surfaces... just a thought.

Originally Posted by Bob Parmenter

Something is loose in the steering/suspension, whoever inspected it missed something. Did they unload the ball joints when they checked? The death wobble Pops refers to on beam axles is usually loose king pins which allow the harmonics of the rotating wheel/tire to do the wobble. Very likely that one of the components that holds the wheel straight is loose or broken. Strut rods like Pops mentioned would show up on braking too, so another simptom to check.

I don't know if they did unload the ball joints, so I'll put her up on the lift later today and look. Will check the strut rods as well.

Strut rods..........thanks Bob, couldn't remember the correct term.

Don

MM II front end with the stock type lower arms only need the strut rods, because of the narrow mounting, the ones with the wide spread don't use them.
Sounds like they said, something must be loose, and you missed it. Are you sure your new rims are seated all the way to the rotor flat, and not hanging up on the center of the bearing hub somewhere?

Pat

Originally Posted by HemiTCoupe

MM II front end with the stock type lower arms only need the strut rods, because of the narrow mounting, the ones with the wide spread don't use them.
Sounds like they said, something must be loose, and you missed it. Are you sure your new rims are seated all the way to the rotor flat, and not hanging up on the center of the bearing hub somewhere?

Pat

I don't doubt that I must have missed something, but , for the life of me I cannot see anything! I just had her on the lift and rechecked everything I could reach/see. Didn't take the rims' off, but they look, from the back/side to be fully seated. I do see about a 1/4" of spline showing where the steering rod mates to the rack...
Bart

First, check the balance of the rear tires, they can sometimes set up a shake that transfers to the front end.
Are all four tires the same make? Some brands are just incompatible.
The new front bushings on the inner A-frame ends, are they Ford or aftermarket? Some are too soft, allowing movement. Then again, some are too hard, causing flex somewhere else.
Finally, get a buddy to drive beside you and watch what's happening when it shakes.

Did you check the brake rotors for cracks or warpage? Could be as simple as a wrong sized, loose or worn wheel bearing.... Another possiblity that comes to mind is the center hole on the wheel, is it large enough to fit over the hub correctly and not hold it away from the mounting surface of the brake rotor?

"20 years ago"

I have over the years repeatedly had occurrances where brake rotors have cracked at the parting line in the inner fins---causing a very violent wobble feeling as when they do start separating the rate increases and the wobble gets worse

You can check the disc thickness with a mike of dial caliper and if this is the case it will be easily measured---new discs are the only fix