Vibration when driving above 70mph and braking.

[blacklist74]

I'm having vibration problems when going above 70mph and during braking above 40mph at the front of the vehicle. Could it be that the rotors are warp? I changed them with stillen crossed drilled that I bought from Joe about 4 months ago. Another possibility is that the rack & pinion had a little play by the rack boots. Should it have any play?I've changed the springs, struts, and upper control arm.The outer tire rods looks good, no movement. Any input would be very helpful.

[maxnix]

Just put my new rack on SPL polyurethane bushings. You might inspect yours. Should be no play in rack.

[Q45tech]

Note in FSM the proceedure for measuring the hub runout, and rotor installed runout. Put a good rotor on a rusty warped hub will soon force the good rotor to conform and exhibit an amplified warp.

[blacklist74]

Thanks for the information. Guess I'll need a new rack and I'll check out hub and see if it's warped.Thanks again guys!!!

[maxnix]

I doubt if you will necessarily will need a new rack, but check the bushings first as they are easy to replace.

The hub runout is critical, so I would measure that second.

[blacklist74]

What bushing?Could it be the inner tire rod that's causing the boot to move when shaking the wheel while off the ground?

[maxnix]

What bushing?

Just put my new rack on SPL Energy polyurethane bushings.

Check the FSM.

[Unnatural1]

Note in FSM the proceedure for measuring the hub runout, and rotor installed runout. Put a good rotor on a rusty warped hub will soon force the good rotor to conform and exhibit an amplified warp.

Forget, the rack and bushings, etc.... This appears to be a text book symptom of excessive rotor runout. I realize the rotors are nearly new but the fact remains, if you feel vibration under braking ONLY (especially at higher speeds) then you've probably got excessive runout.

If the wheel lug nuts are not torqued uniformly this can result. Try loosening and then re-torquing all lugs on the front wheels. If this makes no difference then you need to use a dial indicator to check the rotor surface for excess runout.

Are you sure it's the front wheels? Do you feel it in the steering wheel? or just the brake pedal?

[blacklist74]

OK, I need new rotors!!!Do I also have to change out the front wheel hubs?

[Unnatural1]

No. But it wouldn't hurt clean them up with a piece of sandpaper or 3M abrasive disk, etc.

Since I've never owned a set of Stillen cross drilled rotors I'm unaware of the min. machining specs. But, if it's possible to machine these rotors you may try that first. If they end up causing a vibration later you are no worse off than you are right now.

If not, you may be better off with a set of slotted (not drilled) rotors.

[blacklist74]

Thanks everyone for the great advice...

[maxnix]

Measure the hub runout after you clean them. Should be easily inside OEM minimum specifications.

I run Stillen and regular Brembo OEM repalcement rotors with great success and for long duration between trueing (3x - 4x longer than OEM rotors).