I think this has been asked before but can't seem to find the thread so does anyone know where I can get one of these? Like the one fitted to the reeves mk1?
Here you go: http://www.clubgti.com/forum/showthread.php?t=193657 http://www.clubgti.com/forum/showthread.php?t=175951 http://www.clubgti.com/forum/showthread.php?t=173542 The Mini one enables up to 100% lock out, which is quite handy for tapering off the performance of over-eager rear discs on Mk1s. The reason this mod came to prominence was in 2001, when the Reeves Mk1 tagged a tyre wall at Combe, after the rears locked up: http://www.clubgti.com/forum/showpost.php?p=1844806&postcount=547 It was put on some MOT rollers, and the existing bias lever wasn't taking enough away from the rears. The Mini units now have to be obtained from Mini specialists and modified. Previously Demon Tweeks used to sell a kit, which was actually sourced from Aldon Automotive. When the ready supply of new ones from Lockheed(?) temporarily dried up, Aldon stopped doing the modified ones, and so they were no longer available off the shelf. They're quite easy to modify - strip one and it soon becomes apparent.
What brakes are you running? Bias pedal box? If you cannot reduce the line pressure enough with one of the Willwood or AP valves to stop the rears locking up that sounds like something is mismatched a little.
My Rocco track car has G60 fronts and Mk2 Golf rear discs. The Willwood valve is fine on that, with a 22mm M/C.
It's the discs & calipers. I had this on mine the same time as the Reeves Mk1 had issues. In fairness, I'd put Mk4 calipers on the rear, which are much more eager, but my AP bias lever was having no effect and IIRC (edit: following another thread here, there are 38mm and 41mm pistons - avoid the 41mm ones like the plague which are the ones I had!!). The Reeves one was a Tilton. Both were on 22mm master cylinders and 16v servos, piped front-rear. My bias lever was on the Jetta saloon in my sig, so translate that to the rear of a Golf with no weight in the back... Tricky to get one's head around I'll admit, but 2 cars were doing the same. I've purposely left my Mk1 ex-racecar on the drums it raced on at the rear, at least for now, for this reason.
I have had the same type of Willwood bias valves on my mk2 rally car and scirocco. Various brake setups, 239 f + std discs r, 256 f + std discs r, 280 f + std discs r and 288 f + std discs r. I was always able to eliminate rear brake lockup with a couple of clicks to spare even in the wet, and could add more when it was dry. It is a most simple setup with a single girling master cylinder off the pedal mounted on the bulkhead. I ran std rear pads as they do so little. Possibly performance pads with a higher coefficient of friction may cause a problem.
Difficult to make a call, differing experiences. Tarmac/gravel? Where did you tend to use it? I'd agree with the standard rear pads. I've shamfered the edges off them before, just to reduce the surface area.
239 and 256 were loose broken tar and gravel. 280 and 288 are circuit. There are two different piston sizes in the rear calipers. 36 and 38 IIRC. Smaller ones would reduce locking tendancy.
I am running 22mm master and 16v servo. Front disc's will prob end up being wilwood 4 pots either 280 or slightly larger (depending if I can fit them inside the wheels I have). Rear disc's and calipers are standard mk2 golf. This will only be used on trackdays and as a weekend car so no serious racing.
If you are using the original type master cylinder it is designed for a dual circuit system with one front and one rear on each of the circuits. If you run the rears off one circuit and the fronts off the other you are trying to displace different volumes of fluid from the 2 master cylinder circuits due to the different front and rear caliper piston sizes. As fluid does not compress this is far from ideal and may be the reason some have difficulty in getting a correctly functioning system.
If it is not for out and out racing I would think fitting 280 discs and calipers with decent pads on the front and std discs, calipers (36mm) and pads at the back should be adequate. If you plumb the system to be dual circuit, diagonal split and put it through the oe load valve (at rear axle) this should work fine. If there is not enough adjustment on the oe load valve to reduce rear brake locking, reducing the rear pad area slightly could be done. The master cylinder I use is just a single circuit girling mounted on the bulkhead with no servo. This may infringe on construction and use regulations if used on the road however as the original system was a dual circuit and I have converted it to a single circuit system.
Yes, it is a safety thing, in that if there was a hydraulic failure in one of the circuits there would still be one good circuit to retard the car. Hence the diagonal split to offer some kind of control and balance as the car comes to rest. Think it is in the blue book depending on what the car is built for too. Tends not to be looked at by scrutineers too much and in some circumstances braking is "free" anyway.
I'm more thinking of the Road Traffic Act. Re-reading though, you're saying single circuit, as it not diagonal and not piped front-rear. Aren't old cars single circuit? There must be an exemption up to a certain date
I was meaning with regard to road traffic act but it is also applicable in motorsport. More to do with altering the car from how it was originaly designed. Engineers reports etc. True that early cars were single circuit though, back in the days before the words health, safety and liability were invented.
I'll have a look. (I'm sure you know this, but) where the Blue Book refers to road issues, it effectively has a brief layman's summary of what's already sitting in C&U statute (albeit doing nothing to stop hydraulic handbrake-equipped newly-registered cars rolling out M-sport and Prodrive, all day long!).
