The moderately informational brake thread....

jojo

Looking for Boost!
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This info was taken from UK-MKIVs forum with permission.

(please note... information here is not definitive, its a little out of date but still informative non the less)

A full guide on brakes for the Golf4 Platform all within one thread.

Heres all the brake sizes on the VAG range, and what they are fitted to as standard.

VW Golf R32 | Audi TT 3.2 Quattro

- The Front brakes are 334mm x 32mm Vented 2-piece Discs, Twin piston(32mm/42mm) calipers
- The Rear brakes are 256mm x 22mm Vented Discs, 38mm Lucas singles

Seat Leon Cupra R

The Front brakes are 323mm x 28mm Vented (grooved/drilled option) discs with 4 piston(34/38mm) Brembo calipers
The rear brakes are 256mm x 22mm Vented , with 38m Lucas single piston calipers

Audi S3 Quattro | Audi TT-Quattro (225hp) | VW Golf anniversary | Golf GTI AUQ | Skodá Octavia VRS | VW Golf V5 170 | VW Golf V6 4 Motion
- The Front brakes are 312mm x 25mm Vented Discs, 54mm ATE single piston calipers
- The Rear brakes are 256mm x 22mm Vented Discs, 38mm Lucas single Piston calipers

Audi TT (180hp)
- The Front brakes are 312mm x 25mm Vented Discs, 54mm ATE single piston calipers
- The Rear brakes are 232mm x 9mm Solid Discs,

Audi A3 1.8/1.8T | Audi A3 1.8T Quattro | Audi A3 TDI 130 & Quattro | Golf GTI 1.8T | Golf 130/150 TDI | Golf V5 150 | Seat Leon 130/150 TDI and 20VT
- The Front brakes are 288mm x 25mm Vented Discs, 54mm ATE single piston calipers
- The Rear brakes are 232mm x 9mm Solid Discs

Audi A3 1.6 | Audi A3 TDI 90 | Golf 2.0 8v | 1.8 | TDI 115 | TDI 110 | TDI 100 | TDI 90
- The Front brakes are 280mm x 22mm Vented Discs, Single piston calipers, caliper carrier integrated into hub (FS III's)
- The Rear brakes are 232mm x 9mm Solid discs

Golf 1.4 16V | Golf 1.6 16v | Golf 1.6 8v | SDI
- The Front brakes are 256mm x 22mm Vented Discs, single piston calipers, carriers integrated into hub (FS III's)
- The Rear brakes are 232mm x 9mm Solid Discs


BRAKE DISC INFO

Heat capacity
Heat capacity is the amount of energy that can be absorbed by the disc before the temperature gets high enough to cause brake fade. The mass of the disc is proportional to the heat capacity. Therefore, a lighter disc will not allow as much energy to be absorbed as a heavy disc.

Solid vs Vented
Vented discs are hollow with internal vanes. This increases the surface area of the disc and allows air to cool the disc mass more effectively. A 5Kg vented disc will cool much quicker than a 5Kg solid disc. In many cases, a vented disc can weigh less than a solid disc and still provide more effective braking because of the cooling effects alone.

Curved vs straight vanes
The vanes inside vented discs provide structural integrity to the disc itself as well as cooling. There are several different styles of vanes:
Straight vanes are the most common because they are easy to manufacture.
Curved vanes are common in higher performance cars as they promote better cooling better than straight vanes.

Where does the air go?
For solid discs, all the air travels over the surface of the disc - the same surface as the brake pads.
For vented discs, a considerable amount of air flows through the interior. Because it's spinning so fast, it creates a vacuum and air is sucked into the center of the disc and forced out through the edges. The air follows the pattern of the internal vanes.

Drilled discs
A common misconception is that the purpose of drilled discs is to promote cooling. This couldn't be further from the truth, The real purpose is to reduce weight.
Drilling can allow brake dust and gases to escape, but with modern brake pads, this usually isn't a problem. Choosing a drilled disc for that purpose doesn't make a whole lot of sense.
Many high performance cars like Porsche and Mercedes AMG come with drilled discs from the factory. For these cars, the drilling is mainly about the looks, just like bright red calipers. When people do serious high-performance driving on a trackdays, they usually swap to regular plain discs.
Drilled discs generally wear out brake pads faster and produce much more brake dust as a result.
Drilled discs have a shorter service-life than plain discs and tend to develop stress fissures/cracks over their lifetime

Grooved Discs
Grooved discs keep the pad surface clean and allow certain gasses to escape which improves performance. not too many grooves though, you only need 6 or so, anymore and it it just for looks(e.g tarox cheese graters)
For street driving they may make a marginal improvement in initial brake "bite"
Grooved Discs are great for shedding water and mud off the rotor surface as in Rally racing or wet-weather racing.
Grooved Discs do accelerate pad wear and produce more dust just like drilled discs do. They also add noise and vibration into the system. For many these issues are annoying enough to not choose grooved discs, unless you do alot of rallying!

Two-piece discs
Two piece discs have several advantages including lower weight while maintaining most of the heat capacity and better cooling by having a more open center section
Two piece discs increase costs and generally a poor choice for street cars. For racing, they are great!

Plain discs
Plain discs are the best choice for 99.9% of applications

Name brand vs non-name discs
Why pay double the money for a Brembo discs vs. GSF cheapo's? You guessed it there is pretty much no benefit. Its all the same stuff, Spend you money on brake pads

Specialist Discs (carbon, carbon-ceramic, carbon-kevlar, etc.)
Some really expensive cars come with an option for fancy brake materials. These brakes are excellent for trackdays since they are relatively lightweight but can withstand extreme temperatures without brake fade. This provides a competitive advantage for racing.
For the street, it doesn't help much at all, and they squeal alot and wear fast.

Warped discs
If your discs are warped its because you have heated them up too much during hard breaking. probably nackered but you might be able to get them skimmed.

BRAIDED BRAKE LINES

Braided Brake hoses
Braided brake lines don't expand or bulge out, therefore reduce pedal travel, and increase the force applied to the brakes. I have never tried braided lines before, I think they don't really do alot on modern cars (especially the golf) because the servo makes the pedal feel soft anyway. It is a FACT that they apply more power to the caliper, but the caliper can easily apply twice the amount of pressure to the discs than the tyres are capable of handling anyway, i mean unless you have a track car with wide slick tyres, these are not really necessary.

BRAKE FLUID

If you want to improve your braking power on a budget, try using a Performance brand of Brake fluid and bleed your brakes. it makes alot of difference!
Chances are your fluid now is old and has absorbed some water and air and is not as good as it should be so the pedal will feel spongy. Sort this by bleeding your brakes and use a decent brand of fluid, ATE Super Blue Racing sounds good, and it's blue! how cool is that! anyway, it does make it easier to see when the new fluid has come through, and it has a low viscosity, it resistant to absorbing water, and has a boiling point of 200°C, which means less brake fade. another one is Castrol SPF Racing, it's expensive though!

BRAKE PADS

There's lots of different types of these on the market, EBC, Mintex, Tarox, Pagid, Black Diamond, Brembo to name a few.
They are just made better, and depending on what you go for, they will provide better braking power / low dust etc..
They come in different levels of agressiveness, for example the EBC range is as follows:

EBC Blackstuff - Standard use
EBC Greenstuff - Street
EBC Redstuff - Fast Street
EBC Yellowstuff - Track
EBC Bluestuff - Race

if you go for the "race"option be prepared to get more dust, squealing/vibrations and accellerated pad wear and a harsh feel to the brakes - unsuitable for normal driving so thats why theres a range.
buying performance brake pads will make a difference to your braking power, for not alot extra cash over the standard pads.

BRAKE BIAS

Ever wondered why the front brakes are always bigger? By design most original factory brake systems do not split the brake force 50/50 between the front and rear axles. This is because under braking the front tires offer increased traction as weight is transferred forward. This additional traction can be utilized by increasing the brake force applied to the front axle vs. the rear. The outcome is a bias split that is more in the order of 70 front/30 rear resulting in shorter and more controlled stops.


BIGGER IS NOT ALWAYS BETTER........
Putting bigger brakes on may not always be a good idea.
For chipped/re-mapped cars the obvious upgrade is 312mm fronts because it's so easy, and only requires carriers and discs for most models(not SDI, TDI 90, 100, 110, 115, 2.0 8v, 1.6 8v, 1.6 16v, 1.4 16v,).and because you have increased the power of the engine, the power to wheel will not be de-creased as it would if you just put bigger brakes on.
# But, putting the 312mm conversion on a 1.4 for example, along with bigger wheels than standard and you will be adding alot of weight to your wheels, and the engine will be put under more strain, therefore reducing your accelleration. and Big brakes, contrary to popular beleif, don't actually do as much as people think in terms of stopping power increase, it's mainly that the disc heats up less, cools faster and therefore can stop the car more effectively, corner after corner without getting brake fade. IMO, the best brake mod for the smaller engined cars would be Performance pads and Performance Brake fluid, I wouldn't bother with drilled and grooved discs they just make your wallet lighter.

PICTURES
LCR Brembos
brembos.jpg


.:R32 Fronts
r32.jpg


312mm and 256mm Setup from an Octavia VRS
brakes.jpg


288mm Fronts
288FRONTS.jpg


280mm FS-III Fronts
fsIIIs.jpg


256mm FS-III Fronts
256mm.jpg


256mm vented rears
DSC01063.jpg


232mm Rears
232s.jpg



PART NUMBERS

256mm Rear splash Guards 1J0615609 & 1J0615610
256mm Caliper Carrier right 1JO 615 425 E
256mm Caliper Carrier left 1JO 615 426 E
256mm Caliper right 8NO 615 424 C
256mm Caliper left 8NO 615 423 C
256mm Discs 8LO 615 601
256mm OEM Pads 4BO 698 451
Rear Wheel hub with bearing 1JO 501 477 A

Front left 312mm Shield 1J0615312B
Front right 312mm Shield N90305302

UPGRADES

Front

The easiest upgrade of all is the 288mm to 312mm front setup. All this requires is 312mm Carriers and Discs(splash guards if you want, but they are not essential)

Upgrading 280mm FSIII's (AKA un-moddable without major work) take a bit more work as you have to change the hubs. these can be acquired from a breaker for relatively cheap, if the bearings have a little bit of play in, thats OK they will tighten up once the driveshaft is in place. if in doubt consult a garage. You can get new bearings fitted for relatively cheap so it might be worth it in the long run to get them changed whilst they are off the car. then once you have the hubs, you will need 312mm Calipers, Carriers, Pads and Discs, and splash guards.

Upgrading 256mm FS-III's to 280mm can be done by changing the hubs and discs alone, the calipers and pads are the same.

Rear

The standard 232mm Solids can be upgraded for the 256mm Vented setup, the bigger carrier/caliper just bolts straight on. If the calipers/carriers have come off a Quattro/4 Motion then you will need some 6mm spacers.
You will need to modify your standard splash guards as they curl in over the top of the std disc, and would catch on the new, larger disc. or alternatively you can fit 256mm splash guards, but the bearing has to come off, this can be tricky to do without spliting the bearings, a hydraulic puller and hammer chisel to free the race from the stub axle is what i used.

splashguardmod.jpg


Upgrading the rear brakes does not do much in terms of braking power, reducing your stopping distance. The rear brakes only account for about 30%. Most people upgrade just for looks.


PORSCHE CALIPERS

Porsche calipers are monoblock which means they are machined out of 1 solid peice of metal and are lighter and more rigid. LCR brembos are not monoblock, and heavier and not as rigid.
996 rears:

996 rears can be fitted on OEM 312mm discs with custom carriers which are available from DaveB1970. also available from him are some 325mm X 25mm discs which use the same carriers with another spacer to accomodate the larger disc. contact him for more info and prices. these calipers are readily available, and go on ebay for about £250 a pair which makes this a very reasonably priced upgrade. they have 28mm/30mm pistons thickest disc you can fit in them is 25mm.

The calipers you need are part numbers 996.352.421 and 996.352.422 but beware that this is the same part number as Boxster rears and DO NOT FIT! luckily you can tell the difference by just looking at the calipers, see the pics below:

996 REARS will be either red, silver or gloss black
996rears2.jpg


BOXSTER REARS are a dull anodized black finish
boxsterrears.jpg


There is an M6 hole drilled next to where the brake line connects on the 996 rears, shown in the photo below:
holes.jpg


Boxster fronts

Part numbers for these calipers are 986.352.421 and 986.352.422, they are very similar in appearance to the 996 rears above, but have some subtle differences. the geometry is the same though, so the same carriers are used as above with the 996 rears. they also have larger pistons which are 36mm and 40mm

996 fronts / 996 turbo rears

The part numbers for these are 996.351.425 & 996.351.426 (996 fronts) or 996.352.425 & 996.352.426 (996 turbo rears)
piston sizes for the 996 turbo rears are 28mm and 30mm, and these use a slightly larger pad then the rest of the Porsche rear calipers.
piston sizes for the 996 fronts are .................
these require a 28mm disc, there is a 330mm disc available from DaveB1970 which is much taller than the 312mm or 325mm disc and means there's less chance of needing a spacer to clear the calipers

for the bigger calipers 429&430 and 431+432 then you need a 34mm discs.

WHEEL CLEARANCE

Before you get excited and rush out to buy a BBK, you gotta think about your wheel clearance.

***NOTE*** rims are different sizes,different thickness walls, and therefore some may not fit.
these are the minimum wheel sizes, some may be very close, and may need the wheel re-balance with the weights put on the outside(not the rim face, but just not in the way of the caliper)
also some rim designs may require some spacer to fit around the caliper.

***alot of BBS split rims or deep dish rims will struggle to clear brembos or other monoblock calipers, normally a 10mm spacer is all thats needed to clear them***

334mm R32 brakes require 17"wheels
312mm TT brakes require 16"wheels
288mm Brakes require 15" wheels
280mm Brakes require 15" wheels

256mm Rears need a 16"to clear the caliper(15"spare doesn't fit)

Most porsche brakes need a 10mm spacer on the front


PAINTING CALIPERS

Most people paint there calipers to make them look better, the general consensus on the forum seems to be with big brakes go Anni Red or .:R32 Blue, but if you have standard calipers then a more subtle tone(black, silver, gunmetal grey) might be in order, because nothing looks more "max power" than small bright red/orange/yellow calipers.
before you paint them you will have to remove all the brake dust and the majority of the rust. then mask up the area you don't want paint on and paint. Hammerite smooth and B&Q Japlaq seem very popular. these are cheaper than a special caliper painting kit, which is just in a smaller pot and probably comes with a tin of brake cleaner worth a fiver, and costs more than twice the price.

give them a few coats and for best results don't drive in-between!


BLEEDING BRAKES
gunson.jpg


It's important to do this properly, having even a little bit of air in there and its negating the big brakes you've just put on! I reccomend using the Gunson Eezi-Bleed system, it costs about 10-15 IIRC.
you just fill up the bottle, fit the correct resevoir cap from the box, then connect up the bottle to the spare tyre (20psi works best). the system is now pressurised and as soon as you crack a nipple fluid will come out, just wait untill the new stuff comes through then close it off. simple!
bleeding the brakes the old school way (as suggested by haynes manuals :think:) can damage the seal in the master cylinder and cause the brake pedal to feel soft all the time and travel quite far. this is because under normal circumstances the piston only moves 5-10mm at most, but when the piston goes the full length of the cylinder it goes over the rough and pitted surface, this can damage the seal and sometimes flip it rendering the MC useless.


DIRECT LINK TO THREAD ON UK-MKIVS FORUM
 
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Epic. Legend.

Steve, Brembos weren't standard or an option. They are an aftermarket addition.
 
Cool, paniced for a minute thinking I'd bought a lemon, lol.

Good write up though that :respekt:
 
I thought LCR brake disks were different sizes to standard S3 brake disks . . . ?
 
I thought LCR brake disks were different sizes to standard S3 brake disks . . . ?


They are mate, Jo you will need to amend the following as its factually incorrect..
Change...
Audi S3 | Seat Leon Cupra R

The Front brakes are 323mm x 28mm Vented (grooved/drilled option) discs with 4 piston(34/38mm) Brembo calipers
The rear brakes are 256mm x 22mm Vented , with 38m Lucas single piston calipers
..to...
Seat Leon Cupra R

The Front brakes are 323mm x 28mm Vented (grooved/drilled option) discs with 4 piston(34/38mm) Brembo calipers
The rear brakes are 256mm x 22mm Vented , with 38m Lucas single piston calipers

...and
Audi A3 1.8T Quattro | Audi TT-Quattro (225hp) | VW Golf anniversary | Golf GTI AUQ | Skodá Octavia VRS | VW Golf V5 170 | VW Golf V6 4 Motion
- The Front brakes are 312mm x 25mm Vented Discs, 54mm ATE single piston calipers
- The Rear brakes are 256mm x 22mm Vented Discs, 38mm Lucas single Piston calipers
..to
Audi S3 | Audi TT-Quattro (225hp) | VW Golf anniversary | Golf GTI AUQ | Skodá Octavia VRS | VW Golf V5 170 | VW Golf V6 4 Motion
- The Front brakes are 312mm x 25mm Vented Discs, 54mm ATE single piston calipers
- The Rear brakes are 256mm x 22mm Vented Discs, 38mm Lucas single Piston calipers

...and
Audi A3 | Golf 2.0 8v | 1.8 | TDI 115 | TDI 110 | TDI 100 | TDI 90
- The Front brakes are 280mm x 22mm Vented Discs, Single piston calipers, caliper carrier integrated into hub (FS III's)
- The Rear brakes are 232mm x 9mm Solid discs
...to...
Audi A3 | Audi A3 1.8T Quattro | Golf 2.0 8v | 1.8 | TDI 115 | TDI 110 | TDI 100 | TDI 90
- The Front brakes are 280mm x 22mm Vented Discs, Single piston calipers, caliper carrier integrated into hub (FS III's)
- The Rear brakes are 232mm x 9mm Solid discs

While I can't speak with authority on the other VAG stuff (Golf's etc), with the S3, A3 quattro and Leon Cupra R I do at least do have a bit of experience of :)

<tuffty/>
 
I'm interested in the R32 set-up. Isn't there more from?
 
Thanks to both, Joe obviously got bored of the four threads a day ;) (mine included!)
 
Thanks to both, Joe obviously got bored of the four threads a day ;) (mine included!)

Haha, I came accross the UK-MKIVs link in another thread, and thought it was good info, PM'd the OP of the thread for permission, then copy and pasted the text over, but I spent another 15 minutes on it for it to look right on ASN!(making a few mistakes in the process).

But yes, this answers a lot of braking questions for 8L A3/S3 owners who want to uprate or upgrade!
 
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I'm interested in the R32 set-up. Isn't there more from?
you'd be better off with the brembo setup to be honest better stopping power and also replacement parts are cheaper have you seen the cost of discs for r32 setup?? brembo stuff is as chaep as oe stuff really so no hidden costs come replacement also it will cost much the same to do a 2nd hand r32 setup with new discs and pads as it is to do a complete new brembo setup. i looked into brake upgrades for ages then went brembo with ds2500 pads and ebc ultimx discs best setup for ££s i could find any where
 
nice thread, usefull info as i just ordered some EBC redstuff brake pads
and superblue brake fluid

cheers
 
you'd be better off with the brembo setup to be honest better stopping power and also replacement parts are cheaper have you seen the cost of discs for r32 setup?? brembo stuff is as chaep as oe stuff really so no hidden costs come replacement also it will cost much the same to do a 2nd hand r32 setup with new discs and pads as it is to do a complete new brembo setup. i looked into brake upgrades for ages then went brembo with ds2500 pads and ebc ultimx discs best setup for ££s i could find any where

Yes, maybe you're right. It's just that the MOT in Belgium is realy strict en most upgrades are illegal, even a 10 times better BBK.
The R32 brakes look a bit more OEM but if it's that expensive then it's maybe worth changing them every year.
 
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good post Jojo, I've been following this thread for AGGGGGGGGGGES on ukmkivs, and I've recently bought my porsche brakes from the above mentioned DaveB.

I'll be fitting my controversial (Bill and Tufty say they don't work) Porsche 996 rears next weekend, so I'll let you know how they are!
 
Good information that! That Porche upgrade looks cheap, is 250 the bottom line or do you have to buy different size discs and pads?
Do you also get increased braking power when compared to standard? Or is it just better to keep standard and buy ds2500s?
 
Just spotted this thread. Great timing as I will be doing my breaks in June ready for a trip to the ring. I've already purchased braded lines and motul dot 4 racing fluid, just need discs and pads.

I was always going to get some DS2500's but I was going to get some fancy grooved discs which I will probably forget and buy some cheaper plain discs now i've read the above. What do people recommend as a plain disc upgrade?
 
I know it says DO NOT use the Porsche Boxster rear calipers but it doesnt say why? I have done some research and asked some questions on here and on other forums and it appears the metal lugs that are there to retain the pad are too long so you cant fit the 312mm 25mm thick disk into the caliper. It would appear that machining them down so the gap is 27mm, the same as the 996 rears makes them ready to use exactly the same?

Can anyone else shed any light on this?
 
I know it says DO NOT use the Porsche Boxster rear calipers but it doesnt say why? I have done some research and asked some questions on here and on other forums and it appears the metal lugs that are there to retain the pad are too long so you cant fit the 312mm 25mm thick disk into the caliper. It would appear that machining them down so the gap is 27mm, the same as the 996 rears makes them ready to use exactly the same?

Can anyone else shed any light on this?

Pistons are too small making the pedal effort too hard with no pedal travel... essentially means you have to stand on the brake pedal to get any braking effort with very little assistance from the servo as it needs to travel to be able to actually 'assist'... net result is brakes that feel worse than OEM... based on the findings from the pair fitted to a customers Leon (his request) they are dangerous IMO, you would get vastly superior brakes just using DS2500's on the OEM setup.

The customer has since stated he is going to change the calipers as he agrees with Bill's findings now he has had a chance to live with the new brakes...

<tuffty/>
 
Great thread! i have bought some leon brembo brakes for my S3 the discs and pads were included as were the red painted rears which i will probably fit at the same time even though they are the same part, it will tie in the colours. does anyone know of someone who makes the carriers up to fit to an audi? (i have not got them yet an assume i will need one?)

on another note my old 312mm fronts and 256mm vented rears may be for sale soon (full S3 standard set up) pm me if interested.
 
I don't know if this will be the correct place to ask but... recently the solid line on the rear brakes has corroded (the part that is on the rear swing arm and goes into the rubber line)
My question is... is there a braided steel option out there that replaces both, the solid line and the rubber line?
hope this makes sense.
cheers
Liam
 
i currentlye have ebc red stuff pads with grooved dics on my s3but they are shot so i need new front discs and pads.

do people not reccomend ebc red stuff??

after reading through here i have fiound some brembo max grooved discs on ebay for 120 and the ferrodo ds2500 pads are around 100 from venom as the link further down the page.

im not looking at spending too much does anyone reccomend any other set ups? cheers
 
I've just fitted a set of 996 fronts to my A3, and they're AMAZING!

Forget the 996 rears mentioned above, these are ****. I know Bill and Tufty said it, but I was being stubborn and not willing to accpet it. I've not seen the light and gone for something decent, and it was SOOOOOOOOOOOOO worth it.

Piston sizes in the 996 fronts are 36 and 40mm, and the pedal feel with them fitted is brilliant. I bled the whole system, replacing teh fluid starting on the rears then doing the fronts, and I've got a really nice high stiff pedal.

THey're nowhere near bedded in yet at all, but they're already feeling very good indeed. I'm just off out to put a few more miles on them, then later I'll do a little fitting write up with more pics.

Very happy all in!

37340_421051131776_501476776_5028551_8239640_n.jpg
 
I've just fitted a set of 996 fronts to my A3, and they're AMAZING!

Forget the 996 rears mentioned above, these are ****. I know Bill and Tufty said it, but I was being stubborn and not willing to accpet it. I've not seen the light and gone for something decent, and it was SOOOOOOOOOOOOO worth it.

Piston sizes in the 996 fronts are 36 and 40mm, and the pedal feel with them fitted is brilliant. I bled the whole system, replacing teh fluid starting on the rears then doing the fronts, and I've got a really nice high stiff pedal.

THey're nowhere near bedded in yet at all, but they're already feeling very good indeed. I'm just off out to put a few more miles on them, then later I'll do a little fitting write up with more pics.

Very happy all in!

37340_421051131776_501476776_5028551_8239640_n.jpg

So what you running now then, the 996 front's? Did you try the rears then?

Where did you get the adaptors for the breaks from?
 
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NO FOR SALE POSTS IN THIS THREAD PLEASE!

Thanks.

Joe
 
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A basic question, but i couldnt find the answer here. What quantity of brake fluid do i need for a complete fluid change (s3)?
 
BRAKE FLUID

If you want to improve your braking power on a budget, try using a Performance brand of Brake fluid and bleed your brakes. it makes alot of difference!
Chances are your fluid now is old and has absorbed some water and air and is not as good as it should be so the pedal will feel spongy. Sort this by bleeding your brakes and use a decent brand of fluid, ATE Super Blue Racing sounds good, and it's blue! how cool is that! anyway, it does make it easier to see when the new fluid has come through, and it has a low viscosity, it resistant to absorbing water, and has a boiling point of 200°C, which means less brake fade. another one is Castrol SPF Racing, it's expensive though!

I would not use the ATE Super Blue Racing fluid as its known to stain the inside of the reservoir and if you try next to swap it will be a right pain in the butt. They were a few chaps i know who did swap their fluid to the blue stuff then the next year to red stuff and the fluid that came out after swap was a really manky colour and you could not tell when the old fluid was out ! Just use ordinary stuff as its much easier to read... Also, i would add that upgrading fronts might worsen the way the car brakes, especially if the car had small brakes to start with and one just fitted massive brakes up-front, they will get the brake bias out of balance-hence the car will stop worse. I have 4 pot calipers on me a4 and i had to change the ABS pump codding because the car would brake in a weird way on a hard brake at high motorway speeds. I did blame-it at first on the ****** rear tyres but that had nothing to do with it. As soon as i codded the brakes like for rs4 models, the feel changed and the car brakes straight and true without the tramlining feel like the back will take over... I do not know if every car will behave the same way though !
 
how do i get hold of daveb then anyone need some of them porshe calipers
 
What is the bolt spacing dimension on an A3 8L front hub?

Does anyone know?

Thanks
 
My 8l S3 to R32 conversion

Stripped all these down and shot blasted / powder coated them red and here is the result sorry i didnt take any pictures but there isnt much to it really just unbolt and bolt back on. The upgade is unbelivable these are what should have been on the car when it came out the factory, i also changed all the fluid and rebled the system, a surpising amount of ar came out the back calipers so they cant have been doing much, very very happy with the result though. Still awaiting a wheel refurb so excuss the mis match in colour between the center cap.

Before :


IMG_0093.jpg



IMG_0203.jpg



After :

IMG_0205.jpg



IMAG0253-1.jpg







A basic question, but i couldnt find the answer here. What quantity of brake fluid do i need for a complete fluid change (s3)?

I bought 2.5l worth of AP racing dot 5.1 and i still have a 500ml bottle left.
 
What are peoples views on the following combination in terms of performance, noise and brake dust:

Black Diamond grooved discs and Ferodo DS pads

or

OEM discs and Ferodo DS2500 pads

Both used with standard S3 calipers.
 
Hi, may be a silly question but is there an adapter to run 996 carrera fronts or boxster s fronts with the original/leon cupra discs?

Tom
 
This thread is advocating the extremely dangerous practice of fitting porsche rear calipers to the front of your car.

This is a ****** stupid thing to do due to the porsche caliper having a MUCH smaller piston area than the standard calipers.

For anyone who doesnt understand hydraulics, your leg pushes a piston which generates pressure in the brake pipes. This pressure acts on all surfaces of the sealed hydraulic system, including the caliper pistons, forcing the pistons against the disk, generating the clamping force that stops the car.

Simple highschool physics gives us the formula Force = Pressure x Area. Given that the pressure is constant for a given leg input, reducing the area will clearly reduce the force clamping the disk.

As a worked example, lets assume that with us shoving the pedal as hard as we possibly can, we generate 3000psi in the pipes:

Standard A3 caliper has a single 54mm piston. This has an area of 22.89cm^2 or 3.55 square inch. Applying our simple physics, 3000psi x 3.55 sq inch = 10650lbs of clamping force.
A Porsche rear caliper has a pair of opposed pistons, one 28mm and one 30mm. These have an area of 6.15cm^2 and 7.1cm^2 respectively, giving a combined area of 2.05 square inch. As above, 3000psi x 2.05 = 6150lbs

This shows that the porsche caliper will squeeze the disk nearly half as hard as the original OEM caliper, for a given leg input, and as a result will give half the wheel torque.

As another analogy, it would be like taking a standard A3 288mm brake setup, retaining the standard caliper, but swapping the disk for a 164mm item, such is the reduction in total brake torque.

996 Front calipers on the other hand have a pair of 40mm pistons and a pair of 36mm pistons giving an area almost identical to the original A3 caliper, and so are actually a proper upgrade.

I really hope the Moderators/Admins of this forum heed this, and remove the suggestions from this "definitive" brake thread about a practice that actually reduces your braking performance by nearly 50%.
 
I really hope the Moderators/Admins of this forum heed this, and remove the suggestions from this "definitive" brake thread about a practice that actually reduces your braking performance by nearly 50%.

I don't think anyone has actually used Boxster/996 rear calipers as a brakes upgrade on this forum, not that I'm aware of anyways. The information provided at the start of the thread was copy and pasted from a thread from UK-MKIV's forum with permission from the OP over there. The information in your reply though is good info, so hopefully, anyone using this thread for information for choosing their brake upgrade will read the whole thing and take it in.
 
Not everyone is sensible enough to read the whole thread, infact the whole point of a definitive posting is that its definitive... Not half definitive and only fully definitive if you read down thru 37 replies and stumble across the important information...

You say no-one on here fitted rear calipers, but looking at the above "Prawn" seems to have fitted 996/Boxster rears to his car, and even spent a while denying that they were hopeless/dangerous before eventually "seeing the light" and swapping them for fronts.