Brake disc thickness

[kimosabby]

Lady and gents,

once again I come humbled to the font of all knowledge. Pads pretty much gone on the rear so need replacing. There is a "bit" of a lip on the disc so they are starting to go but not convinced they need doing yet. Could do with changing just pads this time around. Whats the minimum disc width for the rears? I got a 2001 S. Also does this vary amongst different makes of discs or are they pretty much consistent minimum thicknesses for all brands. Also, any recommendations on brake disc measuring devices?

Also looking at EBC pad replacement. Whats the best for fastish road and occasional track day use. Any one have experience of the yellow stuff ones or other recommendations.

Also, (this is like war and piece), I notice the drillings have started to clog up with brake pad matter. Any advice on clearing them out. This was noticeable after a track day

As ever, many thanks in advance

K

 

[spyderman]

The cross-drills always clog - and will do so again just as you clear them. Quickest way is with an airline, slowest with a drill bit!

Note that using track-biased pads on road discs may result in squealing (as with mine), and that you may have problems using new/different pads on old discs because of the transfer layer still on the discs from the previous set of pads. Unless you're able to bed them in properly, you could end up thinking you've got warped discs.

Chris #88

 

[kimosabby]

Once again Spydy to the rescue. Thanks for that on the drill action.

Surely you can mate new pads to existing discs? Are you saying that track biased discs are less likely to mate?

 

[spyderman]

Exactly that. There will have been some transfer of old pad material to the discs. This may prevent material transferring from the new pads when you try to bed them in. This may result in brake judder that you won't ever shift without skimming the discs. If your discs are on the way out, change them at the same time.

Incidentally I went for Performance Friction PF06 pads, which are full-on race pads. Brilliant on track but they squeal like the proverbial squealy things at low speed.

 

[Motorhead]

In answer to your original question Kimo, I think that the recommended minimum disc thickness is 28mm front/24mm rear which corresponds to 2mm of wear before replacement is necessary. Also you need to check for cracks forming around the cross-drilled holes - small cracks are OK but if any cracks connect the holes, the discs are scrap.

You'll need either a micrometer or vernier gauge to check the thickness.

Take note of what Chris is saying - sqealing brakes are really annoying.

Jeff

 

[Richard_Hamilton]

Those are the brake disk thicknesses when new Jeff. This is what the manual says:

 

[Motorhead]

Thanks for correcting me Richard - I'll have to squirrel that info away for future reference.

Jeff

 

[kimosabby]

Thank you gents - a mine of information

 

[Motorhead]

Just a thought Kimo but if you don't have access to a micrometer or vernier gauge you could measure the depth of the lip (inner and outer) at the edge of the disc. Rather crude I know, but if the combined value is approaching 2mm then it's time to buy some new discs.

Jeff

 

[kimosabby]

Probably approaching 1 mm on outer. Will check tomorrow in daylight.

Was looking at this to measure
http://www.amazon.co.uk/Draper-4661...5QUO/ref=sr_1_1?ie=UTF8&qid=1355602364&sr=8-1

 

[Motorhead]

Very nice, but I think that there may be insufficient cutaway a the top of the jaws to fit over the lip.

And if you're measuring 1mm at the outer lip, the inner's going to be about the same - so there's your 2mm.!

Jeff

 

[Bob987s]

For the last forty years I have witnessed drilled discs crack from hole to hole even on the warmest of performance cars.

You now have the oportunity to replace those drilled discs with a good alternative, in Performance Friction discs which are only 4mm countersunk rather than fully drilled , coupled with either their Z-rated road / track pad or their 01 track pad you won't have any sqealing or discs cracking and about an 80% reduction in brake dust on your rims.

They may cost more (Fully floating) but both discs and pads will last longer, and your rims will remain cleaner for longer.

Well worth the investment, but the added bonus will be the considerable improvement in stopping power over the standard oem setup.

 

[kimosabby]

Sterling counsel Mr Bob987s.

Any particular brand/link you have got for me. Am looking at occasional track day. What we looking at prices starting at

K

 

[Bob987s]

Kimo sorry for the delay.

I've had Performance Friction on my last three cars, and before that AP's nothing wrong with AP's, it's just that we have the advantage of good calipers on the the Boxster to start with so no point in wasting money chaning them.

Performance Friction are an American company ( don't be put off) they have a UK factory in Banbury.

It really comes down to the choice of you doing all the work yourself or if you like a garage to do the work for you.

You can buy direct from PF or use Design 911, I find design 911 generally very good, but on the day I called for Boxster specific information regards FP, it must have been bring an idiot to work Friday as the bloke I spoke too did not have a clue ( very unusual for Design 911)

I spoke direct with PF sales 01295 221020 uksales@performancefriction.com.

I wanted to keep my Porsche calipers, but wanted fully floating front discs and Z-rated pads, whilst they were happy to sell these to me direct, they pointed out that I'd probably get a discount via a stockist and they directed me to Deutsch Tech in Milton Keynes 01908 579229 email; services@deutschtech.co.uk, they offered me a great deal on supply and fit so I went with them.

Both my front and reat Porsche discs were in good nick, I just wanted a perfromance upgrade, so I had fully floating PF discs on the front with Z-rated pads front and rear whilst leaving the rear Porsche discs untouched.

Whilst the car was there I had the brake fluid changed out for AP racing fluid and a full set of braded hoses, I need to find the sales invoice to tell you how much it cost, but you'd be better off asking them for a quote via email or call them for a chat.

I can tell you now that these will cost you more money than buying standard discs from say EuroParts, but they are far superior and will outlast anything else I have tried over the years.