Not-so-Big Brake Kit - Porsche Brembo 4-pot callipers on VRS

[muckipup]

First off, a big thanks to DaveB1970 and some of the guys on the mk5golfgti.co.uk forum whose ideas and wisdom I stole for this write-up

Despite having added a bunch of modifications to my Mk2 VRS over the past 18 months, the only thing which has really bugged me was the OEM brakes. I guess it is each to his/her own but I have never felt happy with them and the final straw came when another buttock-clenching braking moment made me realise that this was one of the first mods that I should have looked at instead of chasing power-enhancing mods. So off I went to look at the options in more detail…

Of course, there are a bunch of options to look at from big Brembo or AP kits, etc coming in at £1200++ to getting the rear callipers of a Porsche 996 and sticking them on the front with a fitting kit or the tried and trusted R32 setup. I didn’t want to part with £££s so was sniffing around for some second hand R32 callipers on the various forums and ebay was the obvious choice.

That’s when I stumbled on this thread over on the MkV Golf GTI forum: http://www.mk5golfgti.co.uk/forum/index.php?topic=13985.0

where it is described as a not-quite-so-big-brake-kit (“NQS BBKâ€)

In short, DaveB, the resident forum break guru (or did he self-confess to being a “brake geek�) had come up with an idea for putting 4-pot Porsche callipers on the MkV / VRS / etc. OK, nothing mind-blowing there…but…these callipers could be sourced for sub-£250 second hand and would use the standard 312mm discs!! Moreover, there is a whole range of pad choice including some respectable but pocket-friendly options.

The callipers in question are those from the front end of a Porsche 986 / 987 Boxster / Cayman. The part number is 986.351.421 and 986.351.422 for the other side (those from the 996 Boxster and beginning with the 996.xxx part numbers are not what we are looking at here nor 986.352.XXX which are rear callipers). These callipers can even be picked up new from a (non-rip-offing) Porsche dealer for £395 for a pair!

Each calliper has the 4-pistons coming in at 36/40mm each side which is the same as the 996 Carrera 2 so they promised to be a performer even at the planning stage. This is opposed to the single piston (albeit a very big one) on the standard MkV/VRS or R32 setup.

I am not taking away from the benefits that can be gained from the R32 set-up but in addition to the 4-pots, another advantage is that these things are 1-piece alloy and are way lighter than the OEM or R32 callipers; you will have great difficulty doing this with a pinky on the iron VRS or R32 callipers:

DaveB can supply the fitting kit and brake lines for £225 so this set-up can be done for £250 for the callipers +£225 for the kit and then whatever cost for pads (say £50ish) and fluid should you need them.

NB: Don’t pay more than £250 for the callipers and try to make sure that the dust seals on the pistons are in good condition and definitely make sure the pad-retaining pin and spring come with the callipers. Otherwise the dust seals are £11 a pair (and it could be up to 4 pairs if in bad nick although that would be very unlucky) and pad retaining kits are about £30 each or something daft like that. Knock that off the target price if it is an issue or walk away. The single pad wear sensor for the passenger side may be a bonus if thrown in if you wanted to splice that in the existing circuit but they are about £9 new. Another big bonus would be the anti-vibration (‘anti-squeal’) dampers if you can get them as these are also about £11 each from Eurocarparts and you’d need 4 of them – some folks have been OK with the usual copper grease or 3M anti-squeal stick on backing pads but I wasn’t; the Porsche anti-vibration dampers however, work a treat.

If you are painting or getting the callipers refurb’ed, the external appearance is probably not that important. I learned the hard way with the dust seals which was painful as the whole point about this project is keeping the cost down so, if in doubt, ask the seller!!

Despite the tin of Hammerite and best intentions, some work commitments and impatience meant that I took the easy route and sent my callipers to DaveB for a refurb. Here are the before and after pics:

One thing to note is that the Boxster callipers are to the rear of the disc on a Boxster but to the front of the disc on our vehicles i.e they will be upside down. This means that the bleed nipples would otherwise be at the bottom if simply moved around 180 degrees which ain’t ideal. To fix this, the fluid pipe on the left calliper must be removed and repositioned to where the bleed nipples are on the right and vice versa (the geometry and bends of this bridging pipe mean that simply swapping the bleed nipples for the pipe on the individual calliper is not the best way). Getting them off was a bit tricky with the soft bolts but DaveB recommends mole grips and brute force rather than a spanner to crack the bond initially (although he will do this if you send to him for a refurb’); it is still easy to chew the bolts for the calliper bridges but I filed them back to a respectable look.

Swapping left calliper to the right on the car isn’t the answer either as the smaller piston would be to the bottom and it should be the one that ‘sees’ the disc before the larger piston i.e. it should be the leading piston to give a more progressive pedal feel.

The only other thing that needs to be done to the callipers is for a couple of mm max of the pad-retaining pegs in the callipers to be filed / Dremelled / ground down to accommodate the 25mm thickness OEM disc rather than the 24mm Porch disc. This should be easy with the soft alloy metal ( pic above and below courtesy of DaveB1970):

OK, on to a simple ‘How to’ guide:

In addition to the usual jack / axle stands, you’ll need a decent socket set and preferably a torque wrench or something to give a bit of leverage as some force is needed to remove the existing calliper carriers. iirc it is a 21mm socket for those bolts. A large (Size 10 iirc) socket hex bit is needed to bolt the new callipers on and a combination of 15mm and 17mm spanners to remove the old brake line and 14mm and 17mm to attach the new ones I may have those spanner sizes a bit wrong as doing this from memory). The only other spanner is that to loosen the bleed nipples (and the small torx bit to remove the screw that holds the disc in place if you plan to change the discs). Plus a screwdriver to prise off a couple of clips that secure the OEM brake line to the car.

My Halfords socket set had everything I needed although the larger torque wrench came in handy. I chose to do my discs at the same time as the old ones had seen better days:

With the front of the car up in the air and secured by axle stands and the wheels off, the first thing to tackle is the two bolts holding the OEM calliper carriers as these can be removed with the existing callipers still attached.

The new calliper carriers supplied in the kit can now be attached with a bit of muscle (and a bit of Loctite if you feel inclined; I didn’t) with the bolt going from the disc side (rather than the back as per OEM carriers). I found that the layer of powdercoating on the new carrier combined with the rust/muck on my hub made the interface between the new carrier and hub (red arrow on piccy) a fraction of a mm out for a perfect line up with the bolts on one side – a bit of a file sorted this in a few seconds

Next is to disconnect the OEM brake line. Before starting this, I wanted to minimise the loss of brake fluid on to my drive way. I did this by putting some doubled-over cling film over the fluid reservoir and securing with a cap (in my case the cap for the Gunson Eezibleed which I use later to bleed the new callipers) to create a vacuum. I also found that the cap from a car/bike Schrader valve produced a nice fitting cap to plug the new braided lines supplied by DaveB. I don’t expect it would pour out but this kept the fluid loss to a minimum.

All that needs doing is to use two spanners to remove the unclipped brake line and a quick swap-over to the new braided line.

If you are swapping the disc for a new one, it needs to go on now as they can’t be installed / removed with the callipers attached.

Make sure the calliper pistons are fully pressed in (you’ll see why later). The callipers then bolt on with the hex socket. Note that there is plenty of space between the previously filed down pad-retaining pegs in the callipers and the disc!

Now connect the new brake line to the calliper and tighten up when you are happy that it is all pointing where you want it to go and clip the line back at the point where the new line connects with the car (there is a second clip down nearer the hub that is used to clip-on the OEM line at a second point but that is no longer needed).

Assuming your disc is nice and clean with no oil or whatever on it, the brake pads (and anti-squeal dampers and wear sensor on U.K. passenger side if you chose to use one) can be fitted. I found it easier to loosen the disc-retaining screw to give a bit of slack on the disc and squeeze the new pads into place. Given that these callipers and pads usually go on a 24mm wide Porsche disc, it is quite a tight fit with our 25mm discs thus the reason for ensuring those pistons were fully pressed in. However, the disc should travel reasonably freely and just be ‘skimmed’ by the new pads.

The pad retaining spring is pushed on to the pads and the cotter pin slid through with an ‘R-clip / pin’ fixed through the cotter pin to hold everything in place.

Job done!

All that needs to be done now is to move on to the other side and repeat the process and then bleed the new callipers before the wheels go on. Bleed the callipers inside nipple first and push sufficient brake fluid through; tapping with a mallet helps ensure that air bubbles and bits are pushed out. There are plenty of guides on bleeding brakes (and clutch nipple if you want to while you’re at it) so I’ll leave the details out.

Just one bit of advice for those with newly repainted / refurb’d callipers – keep some soapy water handy and wash off any brake fluid that gets on to the calliper…Here's what happened when I was stupid enough not to tighten one of the bleed nipples before attaching the brake line and didn't notice for a few minutes

The callipers have plenty of clearance with 18†Octavia Zenith alloys without the need for any spacers although I can’t be sure with others. Interestingly, the new pads have a very similar contact area with the discs but leave the inside 10mm of the disc untouched.

This set up may not compete with the massive 6 or 8-pot big brake kits used by some of the serious track-day enthusiasts but I don’t think that it would be too far off it. It has been tried on the track by a few of the MkV Golf GTI boys and they rate it highly. Furthermore, this set up isn’t intended to compete with the racing BBKs, it is intended to give an excellent alternative to OEM callipers and do it at as low a cost as is possible. I couldn’t honestly say how it compares with the R32 set-up as I haven’t been able to do a direct comparison. What I can say, is that this set-up with decent pads is leaps ahead of the OEM brakes and I am a very happy bunny!

Edited 3 January, 2012 by muckipup

[boomsly]

i myself have just got some brakes off dave and i must say his kits look good quality and im glad i went with his stuff to be honest

[rob_e]

great write up - thanks!

[Wardy]

Nicely done. Well done for the decent write-up and high standard of photos

[john999boy]

I doubt that I'll be doing this mod but nice to see such a comprehensive write up.

Edited 3 August, 2010 by john999boy

[Brimma]

I unfortunately had to pay a man who can, but it's nice to see what he would have had to do

[Hedge]

I must admit everytime I read something about DaveB's work I am impressed.

To be honest the standard brakes are poor on the vRS and the same setup is used on the Golf GTI and also my Edition 30, which with the right mods is 300hp +.

I went the R32/Cupra R route but had I known about this it would have been a cheaper more effective alternative.

Nice write up as well.

[Hauptmann]

It is a very good write-up. But has anyone worked out the implications of using these calipers?

The swept area is the same, so the braking torque for a given pad pressure will be the same as the standard set up.

The multi-pistons will give improved pad stability and limit taper-wear of the pads. The pedal feel may well be better.

Has the hydraulic advantage (with respect to the rear brakes) been worked out?

I'm an ex braking engineer and know that modifying the manufacturer's set up has to be done with caution, especially when changing the brakes at only one end of the car.

[daveb1970]

It is a very good write-up. But has anyone worked out the implications of using these calipers?

The swept area is the same, so the braking torque for a given pad pressure will be the same as the standard set up.

The multi-pistons will give improved pad stability and limit taper-wear of the pads. The pedal feel may well be better.

Has the hydraulic advantage (with respect to the rear brakes) been worked out?

I'm an ex braking engineer and know that modifying the manufacturer's set up has to be done with caution, especially when changing the brakes at only one end of the car.

You make a good point, theres been quite a bit of research done into balance. The Mk5 / Octy 2 platform doesnt suffer from a lack of options in the same way that the Mk1 did.

Theres not really a major amount of maths to do with this particular setup. The reason for it is that theres aftermarket OEM supplied kits within the group that between the stock setup and the OEM upgrades "bookend" the Porsche setup.

To put a bit more meat on the bone:

Theres a Kit available from the accessory catalogue for the Seat Cupra which comprises the old Brembo GT Junior Caliper - piston sizes are 36/40mm which is based around a very heavy and expensive 28mm wide 330mm disc so by utilising the Boxster caliper we were able to be very confident that the balance from utilising the same rears would be similar but not exceed the bias change from using the bigger 330mm disc from seat.

Despite the fact that the Brembo GT junior caliper is not only used on the Leon Cupra R Mk1 and Ferrari 360 when you start to upgrade the pads to give a bit of heat headroom for track days etc, they get very noisy as theres very little options for quieting them down without the typical installers method of lashings of copperslip which I despise as it ruins the dust boots on most brembo calipers. The Porsche caliper has over 30 different compounds in production for it and its possible to pursche anti squeal shims from Porsche which give them impeccable road manners.

Whilst the Octy isn't a Cupra - parts bin engineering wins with the calipers /hubs/mastercylinder/ABS system all being the same part numbers - whilst vertical CofG obviously plays a part the Octy has a longer wheelbase which assists with anti dive .

Not withstanding all that...... to see the setup do 6-7 laps of the Ring back to back and in front of a stock braked car of similar performance with no fade nor vibration and then drive home was bloody impressive, the other thing to consider is whats worse.....leave the stock brakes as they are whilst running 50% more power than stock or increase the total sum total brake torque figure albeit not where the numbers might be (front/rear) in an ideal situation. Some of these highly modded cars are regularly stopping from 160mph speeds at which Im not sure the OEM ever had them to, I'm not surewhat the technical term in a vehicle design office is but in aerospace circles we call it V_mbe !!- I'd be interested in hearing your thoughts.

Its a "Clubman" setup not necessarily the very best braking, but affordable to buy with cheap consumables using OEM spares, the fact that theres no negative in terms of road manners and noise is a big bonus, its very easy to have great braking with an unlimited budget....... to do it quietly is also a priority for brake engineers

I've personally driven a number of VAG models with the 310mm rears together with 350mm front discs with 4/6 pot calipers with around 49-50 sq cms of piston surface area and setting the maths to one side for a second its simply feels very very good.

If you consider a Mk4 R32 Golf with 334mm front disc with lucas twin 43mm pistons with stock rears at 256mm and a single 38mm piston caliper - its way fom optimum something like 72/28%, its no coincidence that the 256x22mm rear disc shares exactly the same casting as the Mk1 & Mk2 golf front disc - again parts bin engineering at its worst at the cost of brake efficiency and stability in my humble opinion. My point being is that the manufacturers dont always punt them out of the factory at optimal and there is room for considered improvement

Very green on here isn't it?

Edited 3 August, 2010 by daveb1970

[Brimma]

Very green on here isn't it?

With just a hint of red

And congratulations on such a helpful first post

Edited 3 August, 2010 by Brimma

[Hedge]

Very green on here isn't it?

Hello and welcome Dave, it brings a whole new meaning to going green.

[muckipup]

Thank you for the kind comments chaps!

...and thanks DaveB for providing some further info

Brimma - do you have to go showing off like that?

[Brimma]

Thank you for the kind comments chaps!

...and thanks DaveB for providing some further info

Brimma - do you have to go showing off like that?

Sorry, I'll happily delete it if it detracts from your thread :yes:

[D@z]

DaveB, what would you suggest for my Dirty Derv daily driver, not doing any track days?

was going to got down the VRS brake route, but may as well see what else there is, just in case I can save some ££! which is important!

[muckipup]

Sorry, I'll happily delete it if it detracts from your thread :yes:

Naaarr, I was only joking mate

[Nick P]

Great write-up that.

I've been following Dave's NQS BBK for a while on the mk5 forum and I think this has convinced me to go for it (when I get some work).

[muckipup]

Great write-up that.

I've been following Dave's NQS BBK for a while on the mk5 forum and I think this has convinced me to go for it (when I get some work).

You won't regret it, Nick...bit of a fun project too! :yes:

[ollybroad]

Does DaveB sell these directly or only refurb them?

Muckipup if you dont mind me asking how much did you pay for the adapters and lines?

[muckipup]

Does DaveB sell these directly or only refurb them?

Muckipup if you dont mind me asking how much did you pay for the adapters and lines?

He only refurbs these calipers (should the seals be in poor condition and/or if you don't feel like painting them yourself). Otherwise the calipers can be got second hand from ebay or a Porsche breaker taking care to get calipers with the part numbers that I mentioned above.

DaveB does supply the adapters, caliper bolts and HEL brake lines - these are £225

[rob_e]

TBH if i was going for this (and i AM tempted..!) i'd just get some new calipers from a porsche dealer. 395 for the pair apparently according to that gti thread.. no need to have them re-furbed or rebuilt.

[muckipup]

TBH if i was going for this (and i AM tempted..!) i'd just get some new calipers from a porsche dealer. 395 for the pair apparently according to that gti thread.. no need to have them re-furbed or rebuilt.

Yup, that is an option and it would be better to go this route than pay £250 for a used set and find that you have to replace all the seals and get a new pad fitting kit thus my 'buyer beware comment in my OP.

Be aware that there are Porsche dealers and there are Porsche dealers - I was quoted £295 each by my local dealer whereas DaveB knows a 'hand-tamed' dealer who charges £395 for the pair.

Also the stock colour is a dark grey look and not too exciting to look at.

[rob_e]

Also the stock colour is a dark grey look and not too exciting to look at.

that's a good point - i'd need red to match the rears, and a brembo logo to replace the porsche script

[muckipup]

that's a good point - i'd need red to match the rears, and a brembo logo to replace the porsche script

A tin of Hammerite Smooth Red (or any calliper paint) with the Brembo decals available on ebay would sort that one out!

[Timmyboy]

Mmmmm, tempting. I've been toying with the idea of a brake upgrade for a while now.

[dan_the_v8man]

Hmm be interesting to see if these would fit under my 17" BBS CO's on the Jetta without spacers