Suspension Tune or Brake Problem?

[latch5]

Sympton - vibration in steering wheel during medium braking. Light or very hard braking no problem -

What I have done recently -
1. Changed brake pads after track day (scuffed off rotor residue build up before bedding in street pads - Brake system is Brakeman (similar design to Wildwood) w/13" rotors.
2. R&R front coil over struts to have Tein replace the upper mounting bushing.

I was thinking that problem could be -
A. I did a crappy job of cleaning rotors
B. Warped rotor (hard to believe because never warped stock rotor and the ones I have now are supposed to be "race proven").
C. Front end needs alignment _ If I do this , should I install a bumpsteer kit and/or X5 ball joints.

Any other possible causes?

Car is dual purpose - about 10 days of open track/year - using Nitto NT01

 

[Philostang]

When I had my brake ills (similar to what you describe, but included a visible wobbling of the steering wheel and a very visceral sense of the rear doing a shark dance) it turned out to be a bad alignment (toe was out of whack).

If you can string your car, you can check it pretty easily on your own. If you don't know how to do it, maybe someone in your area can show you how (THANKS DAVE!).

I should add that in my case it was more noticeable the heavier the braking got.

Best,
-j

 

[pcdrj]

How did you scuff off the track pad material ? Rotors don't really warp but they can build up unevenly as the pad material transfers to the rotor. You may have to remove more material from the rotor. This should be done on a lathe or resurfacing machine. If you do it by hand you can lose the parrallelness which will definitely cause vibrations.

I keep an extra set of rotors/pads for street use. This way you don't have to worry about mixing and bedding pads on the same rotor.

 

[latch5]

Used a 7" air sander to remove pad material

 

[Steedman07]

get the rotors re-surfaced...

 

[pcdrj]

get the rotors re-surfaced...

ditto

 

[latch5]

Checked the toe last night. Toe "out" by abt an inch

 

[ArizonaGT]

Checked the toe last night. Toe "out" by abt an inch

Jesus. That's quite a bit!

 

[latch5]

Yeah - Hope I measured wrong - car goes to the alignment shop tmrw

 

[STEVE_POE]

Jesus. That's quite a bit!

lol, you don't say ....

 

[latch5]

OK .. OK I can't use a tape measure (blaming it on a cold poorly lit garage.

Got it aligned (toe was out) - symptoms gone.

Tks all for their help

 

[Philostang]

I WIN!!