here's the deal: every 12 seconds while driving the car's steering wheel will shake (excessively at 70mph+) and then slowly calm down and be smooth as butter for exactly 12 seconds again. this is very rhythmic and is always this way. it's not always 12 seconds, but the on/off times always match. somedays it's 20, and some 8 seconds. acceleration, speed, turning, and road surface have no affect on this problem. very weird to say the least.

i just put new rotors and brakes on not long ago and they shake when i brake already. i think the steering wheel shake is screwing up my brakes. i also had leaking cv axle boots(but the axles are new). i fixed them and they haven't leaked since. i've tried switching the front tires to the back to see if it's a wheel balance problem, but it's not it. the car was recently aligned also.

what the hell else could it be? i'm stumped as hell!

 

That is strange. If you could replicate this shaking at will then we could decipher the cause, but this seemingly calculated shaking is most difficult to diagnose.

I'll take a gander and say it's related to your rotors. If they shake now when you brake, then obviously that is the first thing you should correct. Get em turned, get new pads, then see how that affects this problem.

 

but why would warped rotors cause periodic shaking even when i'm not pressing the brakes?

btw, could a sticking caliper cause this? i had a caliper stick and uneven pad wear last set of rotors/pads. so i recently replaced them and also cleaned and lubed the calipers.

 

btw, the brake shake only occurs sometimes. it seems to go with the shake from the steering wheel. that's why i said it seems like the steering wheel shake is causing the brake problem. sorry i didn't specify there.

i just thought of something else, i have my front sway bar connected at the frame but NOT connected to the LCA's by the end links. i'm thinking that maybe since the LCA's don't have that extra support from the sway bar that they are vibrating while going down the road.

my end link broke when i was replacing alll bushings this winter. if anybody has one, please msg.