Hi all. I'm building a Mk2 VR6, and have put all the running gear from a mk3 on the car. It was from a VR6 mk3 with ABS, so doesn't have a brake bias valve on the rear axle. After searching on this forum, I'm going to be using a Wilwood bias valve in the car, and am running the lines through the car - nothing on the bulkhead at all due to smoothed engine bay. What diameter brake line do I need to order? I'm thinking of trying the Cunifer type (Copper/ Nickel/ Ferrous), as it's supposed to be stronger, but easier to work with. 3/16th seems to ring a bell, but can someone confirm this for me? Also, I'm not sure about layout of the lines - do I need a master cylinder with 2 outputs (blank some off?), then use a t-piece on each of those? Any better way of doing it? Thanks. Matt.
Hi Matt - layout looks fine. Wilwood bias valve on a Mk2 should be ok. Be wary of Mk4 calipers which for reasons I never got to the bottom of, seem keener than Mk2/3. Bias valve can easily be changed if you need to at a later stage. People will be tired of reading it by now, but search on "Mini bias" and check my comments. Pipe diameter? Don't actually know - get it from the factors, it's standard cunifer, which the usual fittings take. Use cunifer, not copper (too soft). One outet or two on the m/cyl doesn't matter as far as I know - it's continual pressure that it needs, so it gets it either way - so the t-piece plan should be ok. But for the fronts, it's often easier to get a 4 outlet m/cyl, us one for the rear and two for the front, which saves the front t-piece and so on. Blanks can be got - GSF for the extra rear hole. When you say large master cylinder, you mean 23mm?
been to Earls in silverstone today as luck would have it and we were chatting about doing a similar thing im my racer. I'm using a 24mm m/c with 2 outlets. 1 outlet will be T'd off for the fronts and the other will run a single line to the bias valve which continues to the rear beam where it T's off to either calliper. for ease of fitting and to reduce overall cost and time (brake pipe buildings a swine ) I'll be using braded lines for everything. no solid lines anywhere! only 6quid per metre + the fittings! and they make it all to order while you wait
Thanks for your reply Chris. I've got all the lines now - just got to get fittings for the ends, and then a master cylinder. Which one would people recommend for 288mm brakes? I was thinking of using the one from my mk3 donor car, but it has a much wider pipe going to the ABS unit that I'm not going to be using, so probably no good. Which car are the 23mm/ 24mm cylinders from? I thought that 22mm was the biggest - from the G60 IIRC? Matt.
Ah, maybe we can solve this They take the same piston windback tool - which makes them 'appear' the same... Where've you seen the data?
I cant remember where I read it, if anyone has one to hand if you check the number cast into the caliper this tells you how big the piston is! Lookin at ETKA not all MK4 rear calipers are created equal! I have several using the same seal kits as a MK2/3 rear caliper, and others which have a different part number for the seal, suggesting the piston is different. Strangley one of the caliper sets using the same seal kit as the MK2 are for 256x22 rear discs, theres another set with 232x9 discs using the different seal kit. I'll try to break it down. Calipers using MK2/3 Seal kit, 8D0 698 761: 8N0 615 423C and 434C - 256x22MM (4-motion PR-2EE & FWD PR-1KY) 1J0 615 423D and 424F - 239x9MM (PR-1KK,1KS & 1KV) 1J0 615 423E and 424E - 256x22MM (Painted caliper, PR-E54) Calipers using different seal kit, 1J0 698 671: 1J0 615 423B and 424B - 239x9 (4-motion PR-1KE & 2EG) 1J0 615 423B and 424B - 232x9 (PR-1KP,1KT & 1KX)
can u put the bias valve on road cars as ive stripped brake pipes off car and thinkin of doin it 4 the crack. will it pass mot with it and could i use same setup as the 1 at top of page 4 road use. cheers also where do u get the caliper repair kits. its a mk2 gti 16v 1988
Good thread , going to be doing this soon on mine (been on about it for 5yrs now) From TallChapsmk2 Well built mk2 track car.
mk4 rear calipers have larger pistons, some are 36mm (or poss 34 i cant remember) and later ones are 38mm.
not with limiters in the system so I can adjust the pressure and with the correct wieght set up which I will have by the summer when more of the mass will be in the back. give me a few weeks and Ill get the car on the pads at work and tell you the corner wieghts if you like? I will also be able to tell your the decel and the stopping distances and energy disapated by the system too, fronts only and rears if you so wish....
all the aluminum rear calipers have the piston size cast on the calipers body polos are 34 and 38 mk4 are 38 as far as i know
i am with chris on this one Mini bias valve moded to make it adjustibal and works much beter than a Wilwood bias i just sold one with some mini sub frames and 1275 gt hubs last week
Not true, see my post further up. if the piston was larger on ALL of them then some wouldn't have the same seal kit as MK2/3 calipers would they