brakes

[ian harvey]

My brakes are in need of some attention. The problem has been brewing for a while - at my last track day vibrations soon developed but reduced with use. Since then the vibration can recur if repeated high speed braking takes place. Once cooled, no problem.

The pads are approaching half worn so I've got some replacements to help keep heat under control. I'm wondering about the discs, though. They do not seem to be overly worn, cracks around the drilling are 3-4mm. However, I remember mention of other concerns than just obvious wear on discs such as hard to spot damage to the surface, possibly caused by heat, resulting in grabbing which feels like warped discs?

Does this ring a bell and if so can the discs be treated in any way or is it time to change. It would not be hard to simply try the new pads and see how it goes. If i need new discs I will probably try changing them myself. If so, is there anything in particular to be aware of? What are the torque settings for tightening the disc, what grease to use?

As usual, any information gratefully received.

Ian

 

[oldtimer]

Simple enough to check if there is any runout on your front disks Ian . If not then it may be the actual alloy hubs , only shows up when they are hot . Replacement is expensive , unless you go to cast iron C2 hubs. These things are 20 years old , and like the mag wheels , dont last forever.

 

[h_____]

You can check the run out, although as you say, it can be build up of pad material. You can get the disks skimmed, whcih is far cheaper than new disks. I wouldnt fit new pads if you arent sure the disks are right, as you run the risk of trashing the pads (not cheap on an RS).

As Oldtimer says hubs could be the caused, although I'd be tempted to skim the disks first. I had vibration on my brakes when I first got the car. I swapped all 4 disks and pads, which cured it. Not to say yours is the same.

Oh and is pretty easy job. Things to watch are access to the rear caliper bolts, make sure you have the right tools, allen T bar set if I recal, and remember the hand brake is in the drum of the disk at the rear (back it off first). Otherwise the same as any other car. I always reassemble with a bit of Copper grease or the Wurth equivalent and of course use a nut sealant (loctite 242 or 243) on the caliper bolts.

 

[Melv]

Sounds like warped discs

You can get them skimmed but I've found this has lasted one trackday

Replacement is the only solution. Keep it OE with OE/Pagid pads. Drill out the brake dust after every trackday and this helps them last -also learn how to brake properly!! Short, hard and sharp......not looooong.....

 

[Hacki]

+1

 

[ian harvey]

Thanks all

I do look after my discs, always drill them out before each track day, never garage the car when wet, or atleast take it back out to dry everything off on the rare occasion it gets wet.

If the discs are warped, why do they only judder when extremely hot and why was I eventually able to progress through the problem on track with the vibration disappearing altogether, not returning for about 1000 miles?

Is the build-up/contamination theory not plausible? I expect to swap the discs soon anyway but not before I need to if something else is going on.

How common are warped hubs btw and what is the cost of replacement, please?

Thanks again

 

[h_____]

yes could be build up / contamination, and worth trying that you can clean them with emery cloth, done that successfully on other cars, its a pain though. Certainly worth trying first.

 

[ChrisW]

Sorry to say that new discs are probably the only solution.

I went through all this, skimming seems to work at first but not for long, it's as-if the bell of the disk develops a problem which then "pulls" the discs out of true with heat cycles ...

I believe Paul Clares also has some experience of this ...

 

[ian harvey]

Chris

I'm sure you're right about the ultimate need for new discs which I have budgeted for. However, are some pads causing this type of problem more quickly than others? I have never experienced it before ( I am on Pagid blues for the first time). I have seen reference to people discarding new discs after just 3 tracdays with similar concerns.

Previosly I have used Porterfields to good effect; superb performance, fade resistant and easy on discs, maybe 6 - 8 tracdays and plenty of road miles per set. Admittedly they are a tad noisy but who cares? I could not find any last time I swapped but would buy some more in future.

Ian

 

[Konstantin]

H_______ + 1

Done it as well..... My money is on contamination from pads , clean and renew but with different pads ....
At least it a cheap check.....

 

[Hacki]

ORIGINAL: ian harvey

I am on Pagid blues for the first time

Best experience with Pagid yellow (RS 19, newer version is RS 29)here. They need a little bit of temperature, then they bite great, last long and are relatively disc friendly. (and a bit noisy)

Hacki

 

[RSGulp]

If anyone wants a good set of Pagid 29 Yellow front and rear pads I have a set available.

 

[ChrisW]

Sorry for the late reply Ian.

I had it with Performance Friction set-up on the GT3.

I even skimmed the discs and fitted new Standard pads --- it cost me a track day a lot of messing around.

Since when I have kept it all standard. Discs last well, brakes work well, but pads need replacing very frequently.

What I will do when a set of front pads no longer last a track day, I'm not sure []