mk1 rear disc conversion

[Golf Loon]

New springs would be interesting. 1400 Seat Ibizas have the number 35 valves but I'm not sure if they're openable to swap the spings over.

The Ibiza 1.4 has drums so no good. I think an early Ibiza GTI without ABS has the valves and rear disks.

There is also one in Mk3s, I wonder what they are rated at?

[jasonO]

256 ml discs same as little drums he reckons.

[VdubEd]

Hi dado, I'm picking up a whole lot of this stuff in uk to do the same to my cabriolet. If you can wait I can get extras for you. PM me to let me know what you still need, I leave tomo!

[cartertronic]

Sorry to dig up an old thread, but have come across another type of proportioning valve and thought it best to keep the info in one thread...

From previous posts in this thread:
3/15 = rear disc valves
3/35 = rear drum valves

I've come across another set of valves while doing a Mk1 rear disc conversion (Mk3 rears to go with Calibra 16v/256mm fronts) that I was hoping someone could identify and make a recommendation on whether they are worth running or not.

3/25 proportioning valves


I'm guessing these will be somewhere in between drum and disc pressure, so more likely to lock-up than 3/15's.. but by how much & what did they come off?!

Anyone seen these before?

[dado]

A stamp of 3 .25 would indicate the break at 300 psi and a slope of .25.
Most proportioning valves fall between a slope of .25 and .50. after the break point.
there is some talk that they may be from caddy but not 100%
this e-bay seller sell some, maybe worth checking out
GOLF MK1 MK2 REAR BRAKE PRESSURE REDUCING VALVE FOR MASTER CYLINDER 1.8T 20V | eBay

[roccodingo]

Markings indicate a 30% drop in pressure starting at 25 bar for the valves you have Simon.

[cartertronic]

Ahh I get it now.. so 3/15's drop the pressure earlier at 15 bar

So what's the consensus, reckon these will be safe to use?

[Dub Toffee]

personally i wouldn't risk it, its better to pay a bit more for something that their is no question mark on
and to not have to worry about brakeing issues

[roccodingo]

3 /15's are available from VW new. VW classic parts did a production run a few years back. pricey at just over 100 Euro each but safety costs. or go the other way and purchase a pair of adjustables and plumb them in.

16V = VW # 533 612 151A
Drum brakes = vw# 533 612 151

check on heratige vw site.

Those valves may cause the rear disc pressure to be to high under emergency stopping or in the wet = car doing a 180 turn... not cool if your on the freeway.

[cartertronic]

Cheers guys, as enticing as 180 degree spins sound I'd better give them a miss!

If anyone has some 3/15 valves I have cash waiting...

PS - found this interesting white paper on proportioning brake pressure for those interested in learning more...
Brake Proportioning Valves; The True Story of a Misunderstood, Misused and Misnamed Brake System Component