Yet another "Big Brakes" thread. !!!

[S3 Paul]

Right, I was going to ask this within one of the many threads BUT they all seem to get stroppy fast !
The top and bottom of it ?...
Im asking regardless of what set up i have now ( brembo GT jnr kit up front with EBC yellow pads and standard rears other than grooved discs)
What is the "best" set up people who drive their cars hard?
Yes i know there are many threads about what people have done but ive never realy seen much feed back?
My set up has never realy given me confidence when pushing on,
On the current discs ( grooved) ive tried DS2500, Stock mintex and the current EBC pads. The mintex actualy felt the best but lasted about a month. The fluid was changed to ATE racing blue but again not much improvement .
So i guess its time to change things big time???
Ive concidered the GT3 front calipers with R32 discs, But no real reveiws as to the "feel" after a few big stops and pedal feel ?
I was told by a tuner when i mentioned the set up that anything bigger than what i have caliper wise would result in " dodgy" pedal feel?
Ive got a pair of LCR brembos sat in my unit ... These are different calipers but are they basicaly the same as mine ? would feel the same and work the same?
As for the rears im currently looking at the B6 S4 disc swap but to be fair thats 60/40 looks/ brake upgrade as the standard ones look lost behind my wheels.The "unsprung weight" issue has made me put this on hold though. In the same way the standard R32 set up has been disregarded too.

I want a good pedal feel with the ability to stop from three figures more than once without the pedal staying hard but very little speed being lost like it does now.
If im going to need to change alot of things... i can only afford this once realy.

Please be helpfull .
I expect the " do your research " answers but isnt asking the questions part of that??

 

[Prawn]

I'll be helpful Paul I'm usually stroppy, but it's only because muppets don't explain things properly, or do their own research before posting you have, thank god for that!

The honest answer is, it's all in the pads.

I'll discount 312's totally for the sake of this argument, as it's clear that you're heavy on brakes, and have long since moved on from them.

On my Porsche setup, with 330mm discs, and 996 front calipers, I originally ran Pagid RS29 pads. On a full weight road car, these were absolutely face destroying, time and time again, from any speed you care to reach, they just worked, always, and never ever failled on my. Sub 9 minute laps of the Ring back to back no trouble, and never a hint of fade.

I then changed to some ATE 'fast road' pads, and the brakes suddenly became VERY average, really no better than a set of 312's truth be told. OK for my daily drive, but rubbish when you started to push on.

The car has now been sold to Frenchman, who has overhauled the front brakes with new grooved discs, and some DS3000 pads. once again, the face distorting monster braking power is back, and he's got a car that stops quicker than the porsche from which the brakes came.

On my track car, I'm running standard LCR brembos with 323mm grooved discs, and I've used DS3000's, Mintex 1177's, and most recently CarboTech XP8's, and all 3 pads have been absolutely fantastic. Stopping regularly from 130+ mph with complete confidence every time, on track they last a good 20 minute session before you start to notice they're feeling 'warm' but even then they keep working. Some simple ducting could reduce temps loads, and I'm sure they'd stay absolutely 1005 indefinitely then.

I've used DS2500's on various setup's in the past, and whilst they're an OK road pad, if you're hard on brakes, and drive fairly hard, they're not really up to it. They tend to not deal with extreme heat too well and start to break down. I wouldn't use them again myself.

So, I guess what I'm saying is, try a 'proper' pad before you go spending loads of money on stuff you probably don't need

 

[Prawn]

A little bit about piston sizes to help you in your quest.....

In a single piston sliding caliper, you need to work out the area of the single piston, then double it, because on a sliding caliper, the opposite fixed pad in the caliper applies an equal and opposite force to counter the force from the single piston, this is why the disc isn't 'pushed' over to one side by the single pot.

If you DO decide to look at other calipers, just to the maths on the piston sizes and you can get an idea of how it'll effect the pedal feel.

So, the S3 has a 54mm piston as standard, which has an area of 2290mm², which doubled, gives 4580mm². This is what you need to match to retain an OEM pedal feel.

On a fixed 4 pot caliper, you consider each piston just once, as they work in opposite pairs.

The porsche 996 front calipers, and LCR Brembos, both have 36 and 40mm pistons. each 36mm piston has an area of 1018mm², and each 40mm piston has an area of 1256mm².

2 of each gives you a total of 4549mm², surprisingly similar to the 4580 of the standard setup. it's only 0.7% different infact, so a very good match indeed. This is why the pedal feel still remains good. You also get much less flex with the 4 pot calipers compared to a nasty sliding iron caliper.

 

[S3 Paul]

Thankyou very much Prawn !
I heard something about carbotech pads but couldnt find any info on them and if they made them for my calipers.
Would you sack the fluid off? is it Motul people seem to be using now?
My car is a road car and a daily to boot ! So its full on fat *** , Maybe part of the problem is the weight but i need a car that can be all things to me ( if that makes sence)
All i found with the Ds2500 was they killed my discs alot faster but didnt help the stopping very well.
I think me being hard on brakes comes from me having a big crash a few years back where i think it was down to me taking too much speed into a sweeping corner and deciding mid corner i needed to shed some speed ( worst possible out come followed) so now i seem to brake hard before a corner and then feed in the power as i leave it...

 

[S3 Paul]

I have a mk2 golf which if i had to decide which car to do a BIG stop in i would pick every time over the S3,
I is stripped out to an extent but uses G60 280mm front brakes with budget pads , That how bad i feel it is ! if you lived local to me i would be asking you to drive the car and tell me im not imagining it !

 

[Prawn]

on a heavy car like the S3, with a keen driver, DS2500's just arn't enough!

My 3000's were remarkably kind on discs too!

 

[S3 Paul]

Ive just read that Carbotech Xp8 pads are mega noisey ? and are not recomended for a road car?
I was told the same about the Ds3000 but dont know anybody who runs them to ask.
Dust wise i dont mind having to wash the wheels each week but if the disc is going to be very metalic and bite in hard to the wheels im not sure i could put up with that.

 

[Prawn]

i won't lie, they're all noisey and squeal at low speeds, but it's a race pad, that's just how they are.

The DS3000's were probably about the quietest noise wise. All were dusty, although the dust from the DS3000's and XP8's seems friendly enough, the dust from the Mintex 1177's was a proper wheel killer. they seemed to have a VERY high metallic content.

 

[Ryan_W]

Prawny, give Performance Frictions 01 (PF01s) a go next time. Best pad I've ever used. Makes DS3000s feel like cheese!

I'm still on the look out for some cheap Cayenne Turbo brakes (18z caliper). Can get both 358 & 368mm discs for under £250 a pair!

 

[future]

With 4 pots i would say the best braking performance i have felt is the pagid rs249's and in my feelings nothing comes close. However you need to be well equipped with lube when heading to buy them.
I have the 6pot cayennes on mine and absolutely love them, the pedal feel is fantastic and even with mediocre pads they pull your face off very successfully.
Im going to be at aitp if you would like a test/feel to help your decision?

tom

 

[Sam_]

Prawny, give Performance Frictions 01 (PF01s) a go next time. Best pad I've ever used. Makes DS3000s feel like cheese!

I'm still on the look out for some cheap Cayenne Turbo brakes (18z caliper). Can get both 358 & 368mm discs for under £250 a pair!

Are they straight fit or require some re-drilling etc? That's going to be a heavy disc if it's 1 piece!

 

[aragorn]

Dont ignore the rears.

They do about a third of your overall braking, and if neglected when you install your massive dinnerplate fronts the bias shift will lengthen stopping distances, and reduce overall maximum braking effort.

 

[superkarl]

Dont ignore the rears.

They do about a third of your overall braking, and if neglected when you install your massive dinnerplate fronts the bias shift will lengthen stopping distances, and reduce overall maximum braking effort.

good shout.
so you think its a good idea to go proportionally bigger on the rear aswell? to maintain that balance, with identical pads all round?

 

[aragorn]

yep

Cars are setup slightly front biased anyway, as it keeps them more stable under braking.

But imagine a perfectly balanced car under heavy braking...

Lets say for arguements sake, the maximum torque the front wheels can apply to the road is 400nm, and the rears 200nm (weight transfer means your rears end up about 50% less than the fronts)

So in total your applying 1200nm to the tarmac at the absolute limit of the tyres grip.

With the standard crappy brakes your heaving on the pedal like a madman, and the system line pressure is 2000psi to generate those torques.

So now you go get your awesome front brakes, huge disks, DS3000 pads, etc etc.

Your still limited to applying 400nm to the road surface from the front wheels, because that limit is set by the tyres grip on the road surface. However your massive front brakes only need 1500psi to generate that torque, IE your pressing the pedal less hard, because they're bigger, stronger and work better.

That means your rear calipers, which arent upgraded, are now only receiving 1500psi as well, rather than the 2000 they were getting before, so they now apply proportionally less torque to the road, say 150nm.

Total braking force applied to the road surface? 1100nm.

So your brake upgrade has in effect reduced the maximum torque available, because two of the wheels are no longer operating at their limits.

The more you upgrade the fronts, the bigger the gap becomes, and the worse the problem gets.

Some reading here if your interested:

Technical White Papers

 

[superkarl]

something people do tend to ignore indeed!

i keep telling my mate his track cars rear brakes are doing sod all, you can feel the front wilwoods doing EVERYTHING, and the rear disks look hardly used.
if there is more torque at the front the car will dive more too, reducing the torque limit on the rear, making it worse again i suppose?

 

[aragorn]

It cant dive any more than the limit of grip from the front tyres though.

Fitting slicks however will push the weight transfer further forward due to their enhanced grip, meaning you need less effective rear brakes, so for a track or race car things arent quite as clear cut.

With a road car however, you want to maintain the OEM bias, or if your feeling brave, tweaking it slightly rearward from the OEM position will improve stopping distances, but with the risk that the car could become unstable under heavy braking.

 

[Prawn]

Interesting thoughts Kev. I'd never thought about it in terms of Line pressure.

With 323's and 256 rears you're maintaining the OEM balance of an LCR, and I'm fairly sure they didn't have any different hardware to the S3 to compensate for it. I guess the uprated front pads do throw that a tad though.

I've been looking into upgrading my rears for a while now, but don't want to pay the silly money of an ECS rear kit.

 

[badger5]

Prawny, give Performance Frictions 01 (PF01s) a go next time. Best pad I've ever used. Makes DS3000s feel like cheese!

I'm still on the look out for some cheap Cayenne Turbo brakes (18z caliper). Can get both 358 & 368mm discs for under £250 a pair!

Pf pads make things run a lot hotter
more bite over ds3000's but these ran too hot for me and ate disks

 

[<tuffty/>]

Dont ignore the rears.

They do about a third of your overall braking, and if neglected when you install your massive dinnerplate fronts the bias shift will lengthen stopping distances, and reduce overall maximum braking effort.

Not convinced they contribute that much tbh Kev but I have thought about changing the rears for something a little larger as it kinda makes sense to balance them out on a heavy car liek the S3..

I know Bill had bias issues on his race car and runs very little bias to the rears but then his car weighs a lot less than my porky S3 lol...

Perhaps I should develop a kit with Bill

<tuffty/>

 

[aragorn]

Yeh, as i say race/track cars on slicks and semislicks tend to get away with it or even require more front bias than stock, as the increased grip from the tyres (plus the weight saving) means more weight is transferred forward and the rear ends up with less downforce and so cant apply as much braking force as the factory bias would apportion rearward.

Full race cars often run an adjustable bias valve, to allow the driver/team to fine tune the bias and get all the brakes working optimally.

the LCR setup with its 323mm fronts is probably very slightly more front bias than a stock S3, but given the cars different weight distribution, it probably balances out. Obviously you want to run the same or similar pads all round so the performance curves dont shift around as the pads heat up and the rears fade.

The bigger you go, the worse the problem becomes, especially if you start installing things like 996 Turbo or Cayenne calipers, which have much bigger piston area than stock, and result in a massive forward shift in bias.

The issue then is if you fit rediculously oversized front brakes, and want to fix the bias, then you need to install rediculously oversized rear brakes. The net result is kilos of additional weight, all in the wrong place, and little to no net improvement to braking over a properly specified system of the correct size.

 

[S3 Paul]

Interesting thoughts Kev. I'd never thought about it in terms of Line pressure.

With 323's and 256 rears you're maintaining the OEM balance of an LCR, and I'm fairly sure they didn't have any different hardware to the S3 to compensate for it. I guess the uprated front pads do throw that a tad though.

I've been looking into upgrading my rears for a while now, but don't want to pay the silly money of an ECS rear kit.

I was thinking the same. Obviously if i went for a non stock set up such as GT3 callipers with R32 discs... its a bit unknown but at the moment its kind of a heavier LCR?

With regards the rears... Would simply fitting better pads do the trick?
The B6 set up ( 300mm vented rear discs and stock caliper) ... would the extra unsprung weight be more of a bad thing than the gain in stopping power?

 

[BuuBBa]

If the front brake setup is designed for TT (8N) can I use it on my S3?

 

[aragorn]

I was thinking the same. Obviously if i went for a non stock set up such as GT3 callipers with R32 discs... its a bit unknown but at the moment its kind of a heavier LCR?

With regards the rears... Would simply fitting better pads do the trick?
The B6 set up ( 300mm vented rear discs and stock caliper) ... would the extra unsprung weight be more of a bad thing than the gain in stopping power?

I'd run the same compound front and rear.

You really need to do the sums, and its always going to be a bit of a guess.

Ideally you only want to fit a larger disk if your having thermal issues. Using a larger disk to combat bias increases weight, which isnt ideal, but sometimes its the only way, as your stuck with using stock components.

What you need to do before touching the rears, is work out how much you've increased the effective radius of the front brakes by. this is the measurement from the hub centre, to the middle of the brake pad. It will be roughly 5% at a guess (312 to 330, though you've not actually said how big your front disks are). This means if you wanted to pull the bias back to stock, you'd want a similar % upgrade on the rear. Going to 300mm rears would be a ~15% increase at the rear, which isnt really what you want, unless you go bigger on the front as well.

GT3 calipers arent ideal, due to the larger pistons. If you did use those, the 300mm rears might then be a decent match. But running GT3 fronts on their own will really mess things up IMO.


Out of interest, what did the Golf R32 do with its rear brakes when they fitted the 334mm twin piston front caliper?

 

[Jason.s]

Nothing, still has 256 discs

 

[aragorn]

So one would imagine they either used smaller than stock pistons in the caliper or valved the Master Cylinder in such a way that it provides more pressure to the rears to compensate (another luxury of being the person designing the car, rather than someone trying to modify it later!)?

Can you confirm the piston sizes?

 

[Jason.s]

Nope no information like that.

 

[aragorn]

ELSAWin has all the sizes for the Audi models, I've never installed the VW bit so havent looked there. I'm away from my computer so i cant check though.

I believe its in Workshop manual, Running gear, brakes, technical information.

 

[Ryan_W]

Are they straight fit or require some re-drilling etc? That's going to be a heavy disc if it's 1 piece!

Brembo Front Vented Brake Disc fits Porsche CAYENNE (955) S (P/N# 09.9870.11): Amazon.co.uk: Car & Motorbike

Can't see how it would be 'that' much heavier than a two piece?

 

[Gops]

Interesting stuff here Aragorn! Thanks

 

[Barks]

Perhaps I should develop a kit with Bill

<tuffty/>[/QUOTE]

Hello Paul, I have got some EBC D1422 300x22mm A4 rear discs sat in the garage and a 'fag packet' bracket drawing if you fancy having a play. It was what I was planning after Bill had the rear discs blue after some 'Road Tests'

 

[Sam_]

Brembo Front Vented Brake Disc fits Porsche CAYENNE (955) S (P/N# 09.9870.11): Amazon.co.uk: Car & Motorbike

Can't see how it would be 'that' much heavier than a two piece?

They aren't 5x100 and the offset is probably totally different?

If you've held an OEM R32 disc (which is kinda two piece) and then the ECS proper floating two piece, you'd realise the difference. Has other benefits as well as weight loss. It's a pretty key place to keep weight low too. 334mm would be fine. Easier to get the adapters for too. 350mm might also work but like I said in the other thread, only compbrake done them in the right offset and don't any more. Might be worth a call though.

 

[Ryan_W]

If only the ECS Stg 5 kit wasn't such a pant pulling down price hey...

The ML55 discs are 355mm IIRC, I know they fit after the centre bore is machined to 63mm and the PCD is amended...

Oh well, the hunt continues for the perfect BB setup!

 

[Big Al]

My big brake kit shortly to be fitted on my S3 8L is -

Front
Porsche Brembo 18Z 6 pot calipers (pistons 30/34/38) -Ebay
New fluid & dust seals, bleed screws & brake lines - Porschecalipers.co.uk
New brake pad pin kit - Design 911
Brembo HP2000 fast road pads - Design 911
Caliper adapters & bolts - Lee Morris (pm me for his mobile no) - also on Ebay (jack-the-lad-uk) & R32OC (CNC-MACHINIST)
VW MK4 R32 / Audi TT 8N V6 334x32mm 2 piece floating OEM discs - VW/Audi
10mm spacers (with OZ Superleggera 18"s)

Rear
OEM caliper repainted
Brembo HP2000 fast road pads - Design 911
Audi single piece OEM discs

Motul RBF600 brake fluid (5 bottles)

This kit I put together myself, just waiting for some extra cash before visiting Badger 5 for fitment.

By the way I've seen several ECS stage 5 front kits and the brackets/discs quality are rubbish!

Hope that helps!

Alistair

 

[JoeD]

Interested to see what the best option for rear brake upgrades is. I've got a pair of 18z cayenne calipers myself, but I'm delaying fitting them until i can find the right rear upgrades. Was thinking R32 but would like to see more options.

 

[jojo]

Interested to see what the best option for rear brake upgrades is. I've got a pair of 18z cayenne calipers myself, but I'm delaying fitting them until i can find the right rear upgrades. Was thinking R32 but would like to see more options.

Just wanted to let you know Golf4 R32/8L S3/Mk1 LCR all run the same rear brakes.

 

[StaceyS3]

My big brake kit shortly to be fitted on my S3 8L is -

Front
Porsche Brembo 18Z 6 pot calipers (pistons 30/34/38) -Ebay
New fluid & dust seals, bleed screws & brake lines - Porschecalipers.co.uk
New brake pad pin kit - Design 911
Brembo HP2000 fast road pads - Design 911
Caliper adapters & bolts - Lee Morris (pm me for his mobile no) - also on Ebay (jack-the-lad-uk) & R32OC (CNC-MACHINIST)
VW MK4 R32 334x32mm 2 piece floating OEM discs - VW
10mm spacers (with OZ Superleggera 18"s)

Rear
OEM caliper repainted
Brembo HP2000 fast road pads - Design 911
Audi single piece OEM discs

Motul RBF600 brake fluid (5 bottles)

This kit I put together myself, just waiting for some extra cash before visiting Badger 5 for fitment. :thumbsup:
View attachment 5839

Will look like this kit on a Golf R32 -
View attachment 5838

By the way I've seen several ECS stage 5 front kits and the brackets/discs quality are rubbish!

Hope that helps!

Alistair

You may need some bigger spacers to clear them Calipers as their huge and I'm running the 18z Caliper with 19"Oz superleggera's admittedly their et45 but I needed a 25mm spacer to clear them, I did try with 20's and all was ok up in the air but once driven the spokes just about hit the Caliper taking the paint off

 

[aragorn]

Facelift B5 S4's use a caliper thats very similar to the S3 one, but has a bigger 43mm piston rather than the 38mm one the S3 has, might be an option to correct the rear bias after fitting massive front calipers, but i suspect your master cylinder will start to struggle with the huge increase in fluid displacement with larger front and rear calipers.

 

[JoeD]

Just wanted to let you know Golf4 R32/8L S3/Mk1 LCR all run the same rear brakes.

Fair enough, I was eyeing up some R8 rear's anyway

 

[Sam_]

My big brake kit shortly to be fitted on my S3 8L is -

Front
Porsche Brembo 18Z 6 pot calipers (pistons 30/34/38) -Ebay
New fluid & dust seals, bleed screws & brake lines - Porschecalipers.co.uk
New brake pad pin kit - Design 911
Brembo HP2000 fast road pads - Design 911
Caliper adapters & bolts - Lee Morris (pm me for his mobile no) - also on Ebay (jack-the-lad-uk) & R32OC (CNC-MACHINIST)
VW MK4 R32 / Audi TT 8N V6 334x32mm 2 piece floating OEM discs - VW/Audi
10mm spacers (with OZ Superleggera 18"s)

Rear
OEM caliper repainted
Brembo HP2000 fast road pads - Design 911
Audi single piece OEM discs

Motul RBF600 brake fluid (5 bottles)

This kit I put together myself, just waiting for some extra cash before visiting Badger 5 for fitment.

By the way I've seen several ECS stage 5 front kits and the brackets/discs quality are rubbish!

Hope that helps!

Alistair

Not sure if you'll have the same issue as me but I have to grind some of the hub back to fit the adapter in it's 334mm mode (it can be flipped to run a 350mm disc). Lee said sometimes it has to be done, sometimes not. I bought some proper floating two piece R32 discs from ECS, the OEM ones are mad heavy! Nice design though.

 

[jezzy]

Why don't you upgrade your haldex controller to a competition one
this mimics the Torsten system . This engages the rear axle when braking.