GaryN

Hi Rob,

Have you managed to fix this problem of brake shudder?? The reason I ask is that I have exactly the same problem.
Car went in for a major service (JZMach) did all disc's and pads (OEM) after about 6k miles under braking there was a heavy vibration on the steering wheel, especially at speeds of around 60Mph. Which was never there before. Took car back to JZMach they replaced disc but not pads as I assumed it was warped discs. This cured the problem for about 300 miles but now the problem is back to exactly the same thing!!
I do subscribe to "911 and Porsche World" so I have read Phil Rabie's caliper report. Is this the Cure???? or not??

Any help will be appreciated.

Thanks
Gary '91 C2

robmug

...how about Big Red Underpants?

Phil Raby

Look out for skid marks

Phil Raby

Gary, if the pads have been ground to make them fit, then it can cause juddering. I can't believe JZ would have done this, though...

Also, Autofarm maintains that it's a good idea to skim new discs to ensure that they are true to the axle. Maybe yours aren't. Be worth getting JZ to check them.

Phil

robmug

Gary

Not fixed yet - probably going to go down to Autofarm in the next couple of weeks. They can skim the discs on the car and also check my calipers. I have 2 things to sort really, the current problem and also preventing it from happening again.

johnfm

NEvber had judder, but brake squeal is driving me mad!! Replaced discs & pads & the squeal is unbearable - worst on hot days. I think a caliper overhaul may be needed, as something clearly isn't 'right'.

tonytaylor

Rob,

Your problem is likely to be either to be warped discs or corrosion in the caliper and without stripping down the brakes and testing the discs to see if they are true it probably unknowable as to which it is. If your calipers are OK then track time is the only way you`ll warp the discs. If your calipers have never been rebuilt or not rebuilt for some time then the chances of them needing attention is very high. The corrosion causes the pads to meet the discs unevenly and this is felt as judder.
As to upgrades IMHO for road use big reds are a retrograde step. The C2 master cylinder will not support the increased slave cylinders which gives poor pedal feel and affects the ABS ( in my experience). Stopping distances are not improved. I can think of cheaper ways of preventing fade ( I would also suspect a fault if fade occurred on the road). The conversion is expensive and replacement pads and discs are expensive.
If your car is mainly for road use I would think that replacing the discs and rebuilding the calipers would give the best results.( and is cheapest)

robmug

Thanks Tony. Upgrading the brakes was never really on the cards...I'll just be happy with no juddering, so I'll be sorting this out next.

joey bagadonuts

David K brought this Stoptech White Paper to my attention in a thread regarding track pads. It was written by Carroll Smith who spent time as Carroll Shelby's team manager at Le Mans. He explains the issue and remedy.

Not a flame ... just food for thought.

GaryN

Thanks Phil and Rob.

Rob after your visit please let me know what cured the problem.

Cheers
Gary '91 C2

Christer

Rob

I was looking for the article that Donuts just posted a link to. I am a firm believer in the theory contained therein.

When you had your brakes done, did you 'brake' them in properly? Did the specialist? Of course, skimming the disc in this situation if the theory in the article is correct will fix the problem, but the only way to keep it from happening again IMHO is to break the discs/pads in properly - you can follow the suggestion in the article.

I have never had this problem but then have not had to change discs yet. Front and rear pads at different times, yes - and no problem. Perhaps it also happens more commonly when the discs are new as well as the pads?

robmug

Joey - I'd read this before and found it absolutely fascinating; I hoped my original post would have suggested that I'd understood this point - so no flame at all!

Upshot is though that I have juddering brakes and I need to find a solution, 'cos changing the discs and pads only helped for a few hunderd miles...

Christer

Rob, the breaking-in procedure cannot be emphasized enough. As I said above, the skimming of the discs may sort the problem out if done properly (see grinding in the article), but unless they are broken in properly it will lilely happen again.

Were they broken in properly before? If you suspect not then I would get the discs and pads done again and do the break-in procedure myself. As the article says, the uneven deposits are invisble to the eye, therefore claning them up can be difficult and the problem will reoccur.

I presume you have checked that the discs and pads are OEM?

Phil Raby

Rob, I'd also be worried about those ground pads - they'll be wobbling around inside the calipers as you brake.

Phil

robmug

Christer - Funny you should say that...I took the car back the first time because they had put non OEM discs on.

In the few weeks it took to get them changed to OEM, the juddering had recurred - this means that 2 new sets of discs have started to judder.

Like I said, I don't think I'm at fault, but I could be...it has never happened before on any of my cars...