964 RS Brake judder!?

[escobar]

I have just returned from the PCGB Isle of Man trip over the weekend. The trip was somewhat spoiled, or at least frustrating, because I suffered from a lot of judder through the steering wheel under braking.

This was annoying as it meant I had to brake earlier and enter bends/corners slower to try and reduce the judder as it obviously didnt fill me with confidence.

Anyway a Friend has just read the article in April's Porsche Post regarding 964RS brakes and it states a lot of judder under Braking is due to deposits on Pads.

I posted ealier regarding this matter as I was concerned that a new (done 2000 - 3000 khm) set of Official Porsche Discs may have warped.

Has anybody had the same problem and found that a new set of Pads corrects the problem?

Maybe some Pagid (fast road/track) would cure and improve braking!?

['95 993]

usually this problem is caused by the pad depositing material on the disk which builds up high spots which then cause the judder.

Most people talk about brake disks warping, which is generally crap, however, getting rid of the deposits is not easy:

Try in order of ease of cure:

1) Rubbing the disks off with fine wet and dry - worked for my friends 4s

2) Putting in some very aggressive "hard" track pads and with some hard braking maybe this will solve the problem

3) Skimming the disks

4) New disks

Good luck

John

[cyberface]

As far as I know Porsche discs hardly ever warp. They are damn thick ventilated discs. There's a famous much-linked rant on the net that says that virtually all 'warped discs' cases are simply due to pad material fused to the disc, making the disc surface not flat.

Unfortunately I have no garage and park outside all year round, so I know a lot about corroded discs and stuck pads The Porsche pads seem incredibly good at welding to the discs, even if you dry the discs before stopping by light braking, and ensuring the discs are cool before putting the handbrake on. Obviously you need to avoid holding the brakes on or using the handbrake if the brakes are very hot (e.g. trackday use, coming into the pits after a few hard laps).

I'd be very interested in knowing if there's an aftermarket pad that either minimises this sticking-pad behaviour, or is abrasive enough to clean the discs afterwards if the pad does stick. I can state with some certainty that the OEM pads aren't aggressive enough to 'cut' the discs back if you do suffer from fused pad material.

My discs have virtually no wear but are now completely shot due to corrosion and a couple of vicious sticking-pad events (i.e. needing nearly 3000 rpm and clutch in 1st and reverse to free the brakes, went against my sense of mechanical sympathy...). Given that it appears that I'll need to renew discs every year regardless of wear, I'd be happy with nasty abrasive pads that eat discs, as long as they self-clean.

Beware - once there's pad material fused to the disc, braking performance is compromised big style.

[phelix]

cyberface said:

The Porsche pads seem incredibly good at welding to the discs, even if you dry the discs before stopping by light braking, and ensuring the discs are cool before putting the handbrake on. Obviously you need to avoid holding the brakes on or using the handbrake if the brakes are very hot (e.g. trackday use, coming into the pits after a few hard laps).

Going off topic but perhaps worth mentioning... the handbrake has its own drum (built into the bell of the disc) and shoes and doesn't use any part of the hydraulic caliper. So using the handbrake when it's wet/damp shouldn't cause pads to stick to discs but might cause shoes to stick to drums.

[robmug]

Plenty of places now have the skimming machines which skim the discs on the car. My previous 964 must have had problem hubs, because each new set of dics would judder after about 1000 miles. Had them skimmed on the car and they were fine thereafter. Cost £65 ish I think

[Gulliver911]

'95 993 said:

usually this problem is caused by the pad depositing material on the disk which builds up high spots which then cause the judder. Most people talk about brake disks warping, which is generally crap, however, getting rid of the deposits is not easy: Try in order of ease of cure: 1) Rubbing the disks off with fine wet and dry - worked for my friends 4s 2) Putting in some very aggressive "hard" track pads and with some hard braking maybe this will solve the problem 3) Skimming the disks 4) New disks Good luck John

Can you details procedure 1 ? (Disk rubbing ?)

Cheers,

JL

[slippydiff]

I changed the front discs and pads on my Mk 1 GT3 this weekend, I've never seen such badly corroded discs.
I'm hoping they're the originals (34,000 miles but never tracked) If they aren't and I have similar problems after 12-18 months I'll be looking for some better quality (more chromium in them ?) ones in the future. Any ideas who could supply better quality ones ?

[fergus]

Autofarm skim the discs on the car, that way they are guaranteed to be true. My RS had slightly warped hubs. don't rule that out. Also check your front wheel bearings.

[escobar]

I am going to get the hubs and discs checked this week. Then more than likely fit some Pagid Blue's or similar, they are more aggresive on the disc but it may help avoid the pad fussing as has been mentioned above!!

I dont have any noise from the front that sounds like a wheel bearing at all.