Need some help to diagnose a problem with my 964 Brakes.
Model 1993, RSA, 77k miles.
Symptom: Brake pulsing, shuddering. seems to be originating from front brake
Remediation Activites: Replaces all brake rotors and pads, Change brake fluid 3x, bedded brakes to SOP.
Other details: the shuddering is most apparent when 1st lightly applying brakes, continues to shudders with about 1/2 force application. When full application i.e. coming to a full stop, shudder stops.

Any help with resolving would be great.

Thanks in advance.
Rob

 

Have you checked your wheel bearings and steering linkage for looseness or play?

 

Thanks, will puit these on the list to do.

 

Am I right in thinking that the shuddering started only AFTER changing the rotors and pads? If so, I would check what I had just done i.e. are the wheel nuts and caliper bolts correctly torqued up?

 

It started prior to new rotors and pads. I replaced these component thinking this is the root cause. Nonetheless, I'll retorque the fasteners.

 

Calliper and pads are all where they are supposed to be and secure?

Rob, you have a C4 or C4?

 

C2 RSA

 

In that case, I'd go along with Rob's idea that it's something chassis/steering related rather than the brakes. Worn bushes on the suspension arms might be something too look at.

 

Since you were experiencing this prior to the pad and rotor change, check wheel bearings as suggested in a previous reply.

 

Other thing to check may be caliper plate lift. Much documented here, the plates that constrain the edges of the brake pad get raised by corrosion of the underlying caliper causing the pads to bind - possibly with the symptoms you are experiencing.
Tell-tale supporting symptoms would be uneven brake pad wear and pulling to one side when braking. Its a straightforward but tedious fix involving removal of the plates, filing the seat smooth again and sealing the refurbished/replaced plates back on to the caliper.

Z

 

What brand pads & rotors did you use?

 

Zimmerman rotors
Mintex pads

 

I'm having the same problem on a 864 Turbo , wheel shudders inder light braking goes away when brakes are applied hard. I thought I had a warped disc but they are fairly new.

 

I have this problem too. Steering wheel shudder under braking until certain amount and not happen when hard braking. This happen after I replace the brand new pagid front brake disc and its pads set. Still thinking how to identify the problem.

 

All,
Fascinating! 3 964s with the same phenomena.
There must be a diagnosis and cure out there!
RDean