Last weekend I hit a curb doing about 35-40 MPH with the driver's side front wheel. The curb was tall enough (6-8") that it bent the wheel and also required replacement of the wheel hub assembly. I have replaced all four wheels with an aftermarket setup of 18X8.5 in the front and 18X9.5 in the rear; the wheels came balanced and mounted with Kumho SPT's. I had a local tire-wheel shop perform an all-wheel alignment, check for any other damage and provide me with a computer generate spec sheet on my final alignment specs. Everything aligned within spec except for the left front caster. The caster could only be adjusted to 5.1 degrees (0.4 degrees out of the acceptable range of 7.5-5.5 degrees). They and I could not visually see damage to the any of the suspension components.

I took the car out for a ride through the city, down 81 and out to 380. Everything felt great, no shimmy, no vibration, no drift and steering is spot on. Once I got out to 380 I had an opportunity to push the speed up to 85 MPH when I started to feel a vibration in the steering wheel, as the speed increased the vibration only got worse.

Has anyone experience similar circumstance or have any suggestions on what might be causing the caster issue, which, I am assuming is causing the vibrations?

 

Replace the control arms .......probally bent slightly...happened to me about a month back...slapped a curb doing 15 front passenger wheel....replaced the wheel and what not then had to go in and replace the arm...

 

could also be a bent upright, subframe, or chassis

but FWIW, I only run 4.3 deg caster on mine (intentionally)

 

Thanks for the advice. Given in and took the 8 to Mazda today They say bent lower, possibly upper as well, control arms. I'm going to order the lower and put it on, have an alignment and see how it feels this time around.

 

I'm looking at doing the lower control arm replacement myself. I've got a question on the removal for someone who has done it before. How do you handle the shock absorber when you disconnect it from the lower control arm? Is it under a lot of pressure?

 

I think for your question on is it under pressure I will quote from the shop manual:

Warning
• Before removing the piston rod nut, secure the shock absorber and spring in the SSTs. Otherwise, the shock absorber and spring could fly off under tremendous pressure and cause serious injury or death, or damage to vehicle parts.

Might want to get someone to do it that knows about strut type suspension and has the tools, there have been people killed by the spring flying out.

 

The shock and spring will come out as one unit.....you don't need to separate them to replace the control arms...you don't have to worry about " exploding parts"

 

the shock is pretty tight on the control arm, but it won't pop out and kill you. the spring is still compressed in it. just loosen the bolt attaching the shock to the lower control arm and take it out. Then just pull the shock toward you to move it off the control arm.

 

you have to have both front wheels off the ground and drop the lower shock bolt on both sides or undo the swaybar link on one side, this lets the control arm(s) drop fully, then take the stut top bolts out, then take the upper control arm loose, at which point you should be able pivot the strut assembly out, then you can proceed to remove/replace the lower arm

and I came across my last alignment, it was only 3.8 deg caster ... LOL

 

Thanks for the feedback everyone.

The shop manual has me removing, first the front suspension tower bar, and then the following items to remove the lower control arm:

1: Caliper and mounting support
2: Disc plate
3: Tie-rod end
4: Front lower arm bolt joint
5: Front upper arm ball joint
6: Stabilizer control link nut
7: Shock absorber and front upper arm
8: Front lower arm

I'm not looking to compromise the repair, but is it necessary to remove all of the above mentioned parts before removing the lower control arm?

 

no, you do not have to remove all those. it'd probably make taking out the shock easier... but you'll be spending way to much time putting it all back on afterwards.

strut bar + tower, upper control arm bolts (17mm), lower control arm (17mm). That's basically it.