robmug

Phil, I know you're worried - posting 3 times really gets the point across!

Phil Raby

Rob, no I only posted once - look. What did you drink at lunchtime.

Seriously, this site seems to screw up at about this time everyday, must be teething troubles...

Now, did I mention my concerns about those ground pads...

Phil

PC2

John,

I have the exact same problem!!! Please post your results after the caliper overhaul.

Thanks!!!

GaryN

I have noticed The "Common" element here with this brake judder problem is that the cars having problems all seem to be Tip's. Surely that can't have anything to do with this... can it???

Regards
Gary '91 C2 Tip

johnfm

Gary

I think Peter C is referring to brake squeal problem, not judder!! I don't have judder either, but as mention, the brake squeal is killing me!! I can't believe that squeal can be accepted as 'normal' in a car that originally cost £60K.

joey bagadonuts

For street use, I've had very good luck with the Ferodo Premier pads. Earlier, I noticed they lacked bite when cold. But after a few hundred miles, they seem to be working as well as OEM pads BUT with less dust and no noise. I also used them for autocross and they provided excellent stopping power and feel. In fact, I unplugged my ABS and had no problem locking up my brakes.

In the US, this is the Ferodo street option offered by Peformance Products. At $84/axle, they're not exactly cheap BUT their 20% off summer sale starts tomorrow, 7/23, so that should take away some of the sting.

Of course, this is no guarantee that the squeals will go away--your experience may vary.

PC2

Yup, it's the squealing! Squealing is bad enough (embarrassing) can't imagine getting the judders too!

Joey B, thanks for the 20% off summer sale tip. I hope it applies to H&R suspensions!

Regards,

GMS

The brake judder can also be caused by warped hubs. Installing new discs will "cure' the problem for a short time and then the new discs will be warped by the hub face. Porsche published a lengthy technical service bulletin about this which refers to the front brakes, although the rears hubs could warp too.

Firstly remove the calipers and run a dial indicator on the disc, if the readings are out of spec, remove the disc and turn it one or two studs so that one screw will still secure the disc and check it again. If it's still out, remove the disc and check the run out of the hub. If the hub is warped you will need a new hub and hub bearing.

I have never seen juddering caused by the pads being ground to fit corroded caliper pad guides. You should obviously check for the free movement of the caliper pistons, although seized or partially seized pistons will eventually warp the disc it's not the main cause of brake judder. Always change the brake fluid every two years anyway.

robmug

GMS - thanks for this response; I'm hoping to get my brakes (and hubs) looked at next week locally and I'll post an update then.

Phil Raby

I have!

Phil

Jeff Curtis

...I just skimmed over this thread, after reading the first post and want to clear up a few things, as I am "King of Brake Judder"!!

The "warped rotor" feeling is mainly caused by four items:

1) residue left on the brake rotor, caused by the extreme use of track pads, such as the Pagid Orange compound that Joey B. mentioned...Pagids are famous for this issue, but I still LOVE them!

2) loose ball joints or front suspension point wear, coupled with a toe OUT scenario under braking...causing a wobble under hard braking.

3) worn, cupped or CHEAP tires that are actually out of round, and/or maligned tread blocks whether due to wear or manufacturing process...goes the same for a bent or out of true wheel.

4) of course, warped or out of true rotors.

All of these will cause the "judder" described by many...the cure??

Ensure your 964 has a decent alignment and good front "A"-Arm bushings, ball joint, etc. - same goes for the rear. Check the front rotors for residue, as wobble under braking is mostly caused by the front brakes/suspension/tires. Then consider how long it's been since you've replaced your front rotors.

Brake wobble or "judder" is not caused by backing plates, brake pads being uneven or "ground to fit" or caliper issues, it is primarily caused by the braking surface that rotates, that being the rotor...and anything directly related to it, such as your wheels.

I put up with this on both my tow vehicle and my 964...as I am a spirited driver and tend to use my brakes HARD whether it's on the street, the highway or the track.

Every tow vehicle I have ever owned had warped front rotors, I had them turned on my last Silverado and the issue came back after a few hauls to the track.

My latest tow vehicle has HD suspension and BIG brakes, rotors too. I keep my trailer brakes "up to snuff" but they just aren't enough to slow what amounts to 10,000lbs of truck, trailer, gear and 964...so they will eventually get a lot of heat in them and warp.

Something people can do is either get larger rotors, have them cryogenically treated, turned on the spindle, etc.

If you guys are truly warping your rotors on the street...you do need to consider other alternatives...like BIG Reds!

The front rotors on my 964 are slightly warped, I can feel it the first few laps at any track, but they smooth out once they're heated up, it seems. I do have BIG Reds and use 965 front rotors...I abused the HELL out of them at Gingerman Raceway last weekend and couldn't believe that the car kept stopping as it did on lap #1...I owe a debt of grattitude to the pad manufacturer as well.

As far as squeeking, that's a whole nuther issue! Thats primarily caused by either residue on the rotor, using "hard" pads like track compounds and not having some type of vibration dampening between the caliper pistons and the brake pad.

Hopefully this was helpful, after all it's my "Braking Manifesto"...it's MY story, and I'm sticking to it!