zerMATT951

My car doesn't have a brake proportioning valve - should it? My car is an 86 body with Turbo S brakes including M030 big blacks. Would adding a proportioning valve help the brake balancing at all? They feel fine at this point, but I haven't had much track time in the car so I haven't played too much with trail braking to know how the front/rear balance feels.

Scott H

Was ABS transplanted with the rest of the M030 suspension? If so, the regulator resides on the ABS module in the passenger fender.

zerMATT951

The reluctors and wires are at the hubs, but no plumbing or other ABS parts were added. The passenger fender well is empty.

lart951

yes you need a 5/33 brakes pressure regulator

zerMATT951

I wonder if my brake line is long enough to add the regulator... and it figures that I just bled everything 3 weekends ago when I put the new brake lines in.

67King

Yes you need one, and it looks to me like your current line was stressed to install without the valve. Should be easier WITH the valve.

My first time at a DE was at Road Atlanta. The longest straight ends with a big hill going down (so the rears were less loaded than normal). My rears locked up on me (there was an issue with the car). The car ended up hitting a wall. Straight line, or very close to it, it isn't just a trail braking thing.

FWIW, mine is leaking so I just ordered a new one. Cheapest place I found was www.porscheoemparts.com for $68.

zerMATT951

It's interesting that I haven't noticed any brake balance problems without it. I did a track day a few weekends ago, and while I'm not driving as deep into corners yet as I used to with the 924S, I didn't ever feel like the rear was braking too much.

I'm going to take another close look at the rear brake lines to make sure there isn't a valve located elsewhere...

Bri Bro

I am pretty sure I still have a factory valve if you need one. Drop me a PM. I also agree that the angle on the brake line is incorrect, the factory unit should go right on to the existing brake line.

You will see the effect if you brake hard on a wet surface and it will not be a nice feeling.

zerMATT951

As luck would have it, I already bought a 5/33 valve when I was collecting parts for my rebuild, but I didn't realize I was missing the stock valve until I investigated a little more. I'll get it installed soon... I definitely don't want that "feeling" in the rain!

JBreckeen

I know this sounds stupid, but by the picture it appears you already have one installed . . .

It is hard to tell, but it is the small silver cylinder inline between your rear brake line (the forward line) and the master cylinder -- in a non-abs car.

But, the angle of the picture may be playing tricks one me.

Also, for what it's worth, I am running without a valve. I have big blacks up front, and the original turbo fronts moved to the back. I still get too much front lock up - even with an adjustable valve set full rear . . .

Great looking car, btw . . .

Scott H

I thought there was one there too at first, but I'm pretty sure that's just the boss where you screw in the bias valve. If you look at the line you can see it bent a few degrees toward the master cylinder like the bias valve isn't there.

Bri Bro

It stands out.... when attached.

zerMATT951

Sorry for the bad angle of that pic... I took that a while ago for another reason, but trust me, it's not there. My master cylinder is that bright shiny thing (and no, I've never polished it ).

racerxrick

I run the 928 valve Matt...if i recall that's the 5/33

jasonlp

I've got Turbo S calipers in front and Turbo fronts in rear and the 5/33 prop valve caused rear lock up during threshold breaking