bassam

car is 964, c4 to c2 conversion. I can turn abs off, but I want to clean up my trunk, abs pump, 4wd solenoids and electronics. there are only two lines out from the master cylinder to the pump and 3 lines out from the pump. wonder what's the best way to bypass ABS pump.

Larry Herman

964s have 3 channel ABS. The 2 fronts individually and the rears as a pair. What you have to do is to tee the two front lines together and connect the front master cylinder line to it, and then connect the one rear line to the rear master cylinder output. The rears tee off in the back of the car (hence only one line).

bassam

will that have any effect on brake bias ? Thank's.

Larry Herman

No, the brake pressure limiting valve is in the line to the rear brakes, located in front of the trans axle IIRC. Removing the ABS unit will not affect this.

bassam

thank you.

Dad911

I seem to remember that 1991 & newer the speedometer is controlled by the abs brain.

bassam

lost my speedometer when I went with 993 transmission, just replaced it with a gps speedometer that looks almost similar to stock and fits perfect! my car is a 1989.

Tom W

You can take it a step further and remove/replace the original pump and MC and go to a Tilton dual MC with cockpit adjustable bias. No 'power' brakes and no ABS. It's what I have.

bassam

I might end up doing that. how do you like your brakes compared to before? how often do you lock your tires if at all? If I remember correctly from one of your posts, you have big reds? Thank's for the advice.

Tom W

It definitely takes effort to apply the brakes, but I like the feel/ability to modulate more. It took a few sessions to get used to the great increase in force required but after that I was very happy with the "feel" and ability to modulate the braking.

I run bias ply slicks (11" in front and 13" in back) and can lock them up if I try. Lately I've started collecting MoTeC data from 4 wheel speed sensors to look more at lock-up and the pressure sensors for bias.

Yes, I have 'big reds' in front and the appropriate matching rear calipers. They were done early on when I though I had an over-heating issue and wanted bigger rotors. I don't think that brakes that big are really needed for my car's current weight (about 2350 lbs with me in it).

It took a while, but the folks at Jerry Woods figured out a good way to get me dual MCs and the cockpit adjustable bias (doing it with the existing fuel cell was a bit of a chore as the space was restricted).

38D

Why are you getting rid of the ABS? Sure 4 channel is better, but it's better than nothing IMO.

Matt Romanowski

If you are going with a Tilton or Wilwood pedal assembly, go with Wilwood or Alcon brakes and save yourself some money and get better brakes. Plus, you'll find it much easier to get the bias right.

bassam

on bumpy areas of the track and other situations, when abs kicks in, car doesn't decelerate as fast as it would without it. A little scary.

38D

I raced 964s for a while, so I know the feeling you're talking about. However, you eventually do learn to work with this and you'll be faster with abs than without. If you are in the abs frequently, then the braking technique is flawed. There is an abs push thru switch that was used on the cups (mine has one). It allowed you to turn off the abs in panic situations by applying more pedal pressure.

Glen

I think adding adjustable bias would be good. By default since the 80's the bias has been to the front in the us. You could override it by going into abs but without abs and stock bias I believe you will find you lockup the fronts while the rears still rotate if you keep the stock bias valve.