When I had my alignment done recently I was told my inner tie rod bushings were badly worn, and that he couldn't do a good alignment without replacing them. I did so, and after that (and of course after the alignment) the occasional shake/shimmy that had been irking me for a some time previously disappeared.

My point ? This could be a worn tie rod or link issue.

 

+1

 

Could be a wheel bearing but would be generating some noise.

 

An easy way to check for worn tie rod bushes is to lift the front of the car a few inches off the ground. Then grab each tire at 3 and 9 o'clock and rock in a horizonal twisting motion. Any lash or play will indicate wear that should not be there. Next is to have someone feel around different areas to help pinpoint the source of the lash if it is not obvious.

 

I'm betting on a bent wheel.

 

Exactly. It could also be a wheel bearing, as stated above, but when a wheel bearing is going bad, you can hear it (most of the time).

It would seem odd that an alignment would cause a vibration, but I've seen it happen before.

Please post back with the before/after specs of the alignment.

- Anthony

 

I went through a similar investigation last year on my 03 Cab. New rear tires, had the wheels looked at and one straightened, all 4 tires balanced - twice.

Issue was a bad front wheel bearing. Had that replaced (and new rotors put on the front brakes) and all was well again.

Not a great answer $$-wise, but worth a look.

Good Luck!

 

How many miles were on your car? Was it sitting a lot?

Also, did you have any noise - usually you'll hear a humming when the wheel bearing is going bad.

 

Like other mentioned, could be a bad tire(s). Try swapping another set of wheels from someone and see if the shaking still occurs.

worn front shocks is possible also.

 

a little grain of salt advice from the newbie....had a similar sounding problem with my kids Mazda Protege. Had a sticky caliper on the left front wheel. Pulled a little to the left from start up. No vibration in first few miles until the rotor heated up a bit and started to shimmy. After stopping, the rotor cooled, and the caliper released its grip a bit. rebuilt the caliper. Rotor was fine.

 

OK, I know this is pretty basic, but has the tire been checked for the "feathering" or "scalloping" condition? You can actually feel some bulges when you run your hand around the circumference of the tire. Tires with this condition cannot be balanced, or not well balanced. The only solution is to replace the tire.

...Rickker

 

I am back from the shop...Unfortunately the shaking is still there, coming right above 55MPH, at 65MPH it is there clearly, stay same up until 80mph. Did not push it faster than that

Mechanic diagnostic and check:
- Alignment was done, apparently there was a pretty bad to toe problem (3/4) on one front tire. Consequently that tire is worn on the side, but the mechanics tell me it will wear back evenly, with time.

Alignment values:
Front: L R
caster 7.1 7.3
camber -.5 -.5
toe .1 .1

Back: L R
camber 2 2.1
toe .1 .1


- Tires were balanced again today and apparently they were a little off. Note that I had those tire balanced the day before on a Hunter road force machine... So I wonder why they loose the balancing overnight...anyways

- Mechanic said he checked for bearing play, flat rim or spot on the tire but could not find anything.

I am a bit confused as the shaking is still there. I am afraid I will have to start the debugging by replacing parts

I heard in the past that it is possible to balance tires while they are ON the car. Do this really exists ? at least I could confirm my problem in a logical way.

I think I will switch the tires first. I have michelin pilot sport sp2 right now, pricey to change just for the test, do you think I can try some cheap sumitomo in the front for the sake of this testing ?

 

At this point I would be willing to bet that it's a tire. I've had this happen on more than one vehicle in the 3000 or so years that I've been driving. Can you find someone else nearby with a 996 or 993 that you could swap tires with for a test? You could just swap out the fronts, go for a drive, and then swap them back.

 

I'd put money on a bad tire. Once it's scalloped, it will never be the same.

 

Try a set of the Sumi IIs on front. They are an excellent tire for your test, if the shaking goes away, order a pair of rears. Also, like anything else, re the Hunter balancing, Snap-On tools do not guarantee quality work. Good Luck