Holy clunk Batman!

[driftin jo]

"Also a very good idea if you are changing the pads as the surface finish after skimming is ideal for the pads to bed in."



Actually this is not the case , new discs are better bed in using used pads as bedding in new discs and pads at the same time adds to the problems of the bedding in process .

[driftin jo]

For those people running DS 2500 pads if you read the article you will see that if you drive easy on the street for a wile you will have removed some of the transfer layer on the discs and before giving it a thrashing on a track day or private road :mischeif: you should re run the bed in process so as not to end up with uneven pick up.

[A80Avant]

personally i have tried everything to get the pads to work properly. I gather its either going to be the servo pump problem, or discs, or both. Ill report back tomorrow

[driftin jo]

personally i have tried everything to get the pads to work properly. I gather its either going to be the servo pump problem, or discs, or both. Ill report back tomorrow

It sounds like your problem may be cementite build up on the disc caused by hot spotting due to not bedding pads in properly, or having driven slowly for a wile after bedding properly thus getting uneven friction transfer layer on the disc. Once it is formed a lot of cementite you may as well throw your discs away .
High performance race pads can also be a nightmare on the street unless you never drive slow .
Motorways are all so a pain in the **** as you end up with cold discs all the time then go from cold to hot with no warm up .

[Boghopper]

Actually this is not the case , new discs are better bed in using used pads as bedding in new discs and pads at the same time adds to the problems of the bedding in process .

I have read the article and it all makes sense. The problem with road car brakes is that they are not used under their optimum conditions. Therefore we see different wear / problems to that seen on race cars.

Leaving your car parked up, discs rust and then driving again causes uneven disc wear, for example.

Putting new pads on old, polished discs does not allow the pad or disc to bed in properly. New discs always have a 'surface finish' to allow the pad to 'bite'. Also the used disc is invariably thinner at the outer edge than the inside edge. This means the piston cannot press the pad evenly against the disc surface, causing a crap pedal and uneven pad wear.

Skimming the discs, if they are not too thin, is a very cost effective way to return your discs to as new condition.

Porsche recommend that every NEW disc is then skimmed to make sure it is perfect on that particular hub.

Just my 2p

Pete

[Boghopper]

I charge £50 per pair / axle.

Cheap when you look at the cost of new discs.

Ideally done on the car as that also accounts for any hub runout. Can do them off the car also.

Pete

[driftin jo]

I charge £50 per pair / axle.

Cheap when you look at the cost of new discs.

Ideally done on the car as that also accounts for any hub runout. Can do them off the car also.

Pete

new s8 323 mm discs from brembo that I and many others use are about £120 for the pair , so I wont bother with re-cutting them . I program CNC machines for a living and have access to a huge amount of machines that can do a much better job than you on car lathe and cost me nothing but my time and I still don't bother.

[driftin jo]

I have read the article and it all makes sense. The problem with road car brakes is that they are not used under their optimum conditions. Therefore we see different wear / problems to that seen on race cars.

Leaving your car parked up, discs rust and then driving again causes uneven disc wear, for example.

Putting new pads on old, polished discs does not allow the pad or disc to bed in properly. New discs always have a 'surface finish' to allow the pad to 'bite'. Also the used disc is invariably thinner at the outer edge than the inside edge. This means the piston cannot press the pad evenly against the disc surface, causing a crap pedal and uneven pad wear.

Skimming the discs, if they are not too thin, is a very cost effective way to return your discs to as new condition.

Porsche recommend that every NEW disc is then skimmed to make sure it is perfect on that particular hub.

Just my 2p

Pete

So what you are saying is that when porsche build a car they skim the discs once they have put them on the car ? I can assure you they don't .

your machine is of no use for proper floating disc set-up anyway .

[A80Avant]

It sounds like your problem may be cementite build up on the disc caused by hot spotting due to not bedding pads in properly, or having driven slowly for a wile after bedding properly thus getting uneven friction transfer layer on the disc. Once it is formed a lot of cementite you may as well throw your discs away .
High performance race pads can also be a nightmare on the street unless you never drive slow .
Motorways are all so a pain in the **** as you end up with cold discs all the time then go from cold to hot with no warm up .

my discs and pads were new when i came from greece and i did have to do some hard decel while tuning the new setup. Otherwise i use textar pads and porsche discs which only show minimal wear.
I was expecting no such problems after cryogenic treatment that i did to the discs but apparently it either doesnt work, or they never did it.

i will have them checked tomorrow anyway. I must say a large amount of my vibration did decrease when i changed the brake fluid,which is why it makes me feel that it could still be the brake system failure which i have.

[newsh]

I tried Textar pads om my Monoblock setup on the Coupe, they were terrible, threw them away.

[A80Avant]

pad choice is a personal preference. I have been using textars from day 1 after having horrible squeels with the pagids.Never had a problem, and since porsche and audi is using them thats good enough for me. Uneven pad wear can also be the reason of my problem, so we'll have a look at that as well.

[Rusty]

Having tried them, Textar work on the road but are useless on track, they're just not up to the job.

[A80Avant]

i dont track much so...

got back from the garage.
My front discs were very slightly uneven, so we decided not to do anything yet until i change the brake servo. So there you go.

[Rusty]

Right, back to my original thread...

Just been for a decent drive and I'm annoyed with both my clunkins suspension and juddering brakes. Will have to get this sorted soon as it's annoying the hell out of me.

Managed to take off the drop link that I hoped (as it's cheap) might be the issue and it's fine, drove the car down the road, same clunk is there. I think it's a top mount but they're non-standard and I'd hoped that it would last longer than this. Only other thing I can think of is that a bolt is loose on the wishbone or subframe but that doesn't make too much sense, I checked everything on the car before ADI so if it's come loose then that's the curse of track driving again

Will have to get it up in the air and do some digging around and disassemble / inspect / clean the brakes. If that doesn't fix the judder then new discs sound like the order of the day. The ones on there are <2k old too - not so cheap Zimmerman crap

[Rusty]

OK.

Taken the promount out... in 2 parts... That'll explain the clunk then. <1k miles and it's broken. Oh dear. At least Mance offers a lifetime warranty.

Swapped both off for the original greens, they're not new but they should work OK.

Next I took a good look at the brakes. I've removed the discs, cleaned the hubs and disc mounting face with a wire brush attachment on a drill, they were worth at least £400 by the time I'd finished I then applied a thin film of copper grease to all mating faces and reassembled.

Checked that all the pistons are moving freely on the monoblocks, they're Ok but I think I'll be having the calipers refurbished at some point - any ideas who?

Finally, cleaned up both faces of the disc with brake cleaner, put a little copper grease on the monoblock retaining pins and put it all back together.

Also cleaned up the wheel mounting face with the wire brush (I've had 3 sets of wheels with the same symptoms so this is just as a matter of course).

Test drive in 10 mins and some pics of the ex-promount