[66candy]

A few days ago I posted a question about my brand new SSBC brake setup and the strange fact that the car stars vibrating when braking.
Yesterday I did some more tests and found out that when I'm driving 70 mph the car brakes nice till I reach about 55 mph, then the car starts to vibrate to about 40 mph where it disappears.
I checked everything again yesterday and can't find nothing wrong, suspension or brake wise. What the he!! can this be?

 

[66stangFb]

Sounds like the rotors have some run out. I'd guess that either they are warped, or they are not properly installed. Check the bearings and races and make sure you have them properly installed and that you didn't leave too much play in the disc.

Good luck,

 

[66candy]

I did check the rotors for runout on my fathers lathe. Both rotors are fine.

 

[Billgear]

check you rotor for pad transfer, that can make them vibate also.

 

[Buboola]

It seems like you have eliminated everything I was thinking of after I saw your original post on this problem, which was bushings, control arms, rotors, bearings, ect. The part that gets me is its' only in a specific speed range, 55-40, not higher or lower. Do you think its' possible that it could be transmission, u-joint or rear end related? When you use the brakes, not are you only slowing the rotation of the rear wheels, but the rear wheel bearings, axles, differential, u-joints and transmision, which would all be under a sort of "back pressure" from the engine still trying to push forward. Since you've tried just about everthing else, check for play in the axles & u-joints, and I'd give a shot at popping it in to neutral while trying to slow down in that speed range, see if it doesn't do it then. Keep me posted, this one is taxing my brain too! Good Luck!

 

[camachinist]

Hi Erwin,
I'll assume the vehicle didn't exhibit vibration prior to the suspension/brake change.

Is this a 4 wheel conversion?

What method did you use to bleed the brake system? What type fluid are you using?

Have you verified the proper torque or all brake-related fasteners?

Describe method employed to verify lateral and longitunal (concentric) runout of brake discs. Be specific.

What type material is disc made of? Any drilling and/or grooving of disk?