Thread: Need diagnostic help on SEVERE steering wheel shake

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UPDATE! See "POSSIBLE ANSWER" on page 6 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!


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...