atb

So here's the S4 booster and mc I picked up today.



So I test fit the booster, no fitment problems. I wonder if my OB got the 9" booster with 10" firewall? I was expecting to have to do some pounding to make it fit.



The S4 mc only has two ports, where the OB mc has four. I'm not planning on adding ABS, so any suggestions on a way to T or Y off the mc to get a line to each caliper?

Mark Anderson

Looks like a nice find

atb

Bought from a local Volvo mechanic (no joke).
I've got an order coming your way Mark for the clutch MC, gaskets, and other bits.

atb

Looking on the PET, I came across this blow up of the S4 brake system:



It is interesting that it shows the bias valve (#21) bolted directly to the master cylinder. Since I won't have ABS on this car, does anyone see any problems associated with using the OEM bias valve in this location?

BC

Thats exactly where it goes normally. I'd say since its for a race car (right?) that you should put an adjustable bias valve in though.

Rob Edwards

I know you know this, but hold off on actually mounting the booster until the clutch MC is in.

Tom. M

were there ever S4's without ABS?...could it be the non-abs location?

My GT has the bias valve after the ABS unit up near the PS reservoir on the drivers fenders..nothing but lines coming off the booster

atb

Colin had mentioned and adjustable valve by Wilwood, this would be the ticket:



As much as I like the idea, I'll have to think about this one. Time taken out to tinker with brake bias is time lost behind the wheel - a flagrant violation of the Mark Anderson code of race car building. Basically, use OEM "install it and forget it" components where ever possible.

Rob, appreciate the heads up. Nothing bolted down yet.

BC

That's the one I bought and installed, but I ran line to inside the car.

Lizard928

Adjusting the brake bias is very quick and easy, and can be set to stock pressures as a baseline as a starting point.

There are good gains to be had from adjusting it though.

atb

Pics?

Also, any input on what kind of brakeline to use?

A search shows its 3/16", but I'm not sure what material. The stock lines look like they are copper clad, but there is also copper alloy, steel, and stainless steel in the aftermarket. Any suggestions?

atb

The Wilwood says its range is 100-1000psi.

How does that translate to an OEM bias valve that is rated from 18 - 55 psi?

Is there a lower range pressure adjustable valve that Wilwood makes, or are the PSI measurements not apples to apples when comparing Wilwood to the OEM bias valves?

Rob Edwards

The factory bias valves are 18, 33, 45, 55 and 60 _bar_. Multiply by 14.51 to get psi.

261, 478, 652, 798, and 871 psi.

From a post by Roger:

https://rennlist.com/forums/928-foru...to-33-bar.html


Brake Bias Valve 60 bar 965 355 305 01
Brake Bias Valve 55 bar 964 355 305 10
Brake Bias Valve 45 bar 964 355 305 00
Brake Bias Valve 33 bar 928 355 305 02
Brake Bias Valve 18 bar 951 355 305 01

BC

I used new brake line, I think its 3/16 steel. Yes, the stock lines are copper. I do not think copper is used any longer in production cars. Stainless would be cool.

I used AN fittings and then some adaptors to get from the stock system to the new pieces. It was an enjoyable job.

Rob Edwards

Since Adam is going to get rained on once in a while , perhaps cunifer might be a longer-term solution than steel? We're not all blessed with San Diego weather......

http://www.fedhillusa.com/