964RS

Hi all!

It might not be the right forum category for me, but I'm a turbo wannabee.

Anyways I have this 944 N/A -86 that is upgraded with a turbo engine of sort.
The turbo engine has a Borg Warner EFR turbo on the exhaust side, steel sleved cylinders, forged pistons, forged connecting rods, solid lifters, on off designed camshaft, Motec and some more.

Chassie is a bit different and is designed for trackday use only.

Now to my question, the brakes.
I have a full setup of the 996 GT3 calippers and rotors mounted, a 968 master brake cylinder. There is of course no ABS since it is a -86 car.

The problem is that the brakes tend to lock up instantly even with original oem pads (textar) and with semi race pads like carbotech xp8 I cant even look at the pedal before they lock up.

I can of course get some brake power before they lock up, but it's very modest.

Has any one made this conversion or similar and if you have, is it working better than mine?

Darryl H

I've got 996 GT3 mk1 calipers, so might be valid? I too have a 1986 n/a converted to Turbo.

I use a 740i master cylinder and a bias valve, I can give them quite a lot of grief before they lock up, it may be the tyres you are using? I'm using NS2R track tyres and 225/255widths.

Darryl H

I forgot to add that I have custom discs. 330x34 from memeory but I can double check that if needed

V2Rocket

which tires are locking up? rear, front, all?
what proportioning valve do you have

Adonay

i think you are more than qualified to post in the turbo section . Perused this conversion a few years ago and came to the conclusion that i should change for the later offset hubs and controlarms etc. best for you would be a adjustable brake bias valve

JustinL

Great looking car! what is your front tow hook attached to? As far as brakes, I would agree that the proportioning is probably off as I assume you are locking the fronts. If you're locking up all 4, then a different master cylinder or pedal setup might solve that.

964RS

Great input all. I have no proportioning valve, but a brake bias adjuster. It only locks up in front.

On the brake testing rolls , if that is the word, i have brakepower on all wheels.

I use Pirelli Teofeo R, 235 front and 265 rear. I'm shortly upgrading to BBS E88 with 265/285.

964RS

How the tow bar is attatched,

964RS

From what body, the one that James Bond drove from the backseat?

V2Rocket

any chance you have a larger version of that first photo?

964RS

As requsted...

thingo

Got any pics of the turbo install?

MAGK944

Some of the best builds and fab work I have seen on this forum has been from Sweden, Finland and Iceland. What do they put in the water in that dark and cold part of the world?

333pg333

Might need to play around with the bias but I'd also say you've got a faster car than the tyre sizes were designed for. 235/265 is a bit on the small side for what must be a quick car. If you run say 275 all round or wider still, you will have more mechanical grip and lock up less. Bigger brakes may only lock up those small front tyres more.

964RS

You are correct and that's why I'm upgrading to wider tyres and that will help, at least partly. There was a notable difference when I upgraded to new tyres. But I think the question is still valid since I lock up even in 70kmh (40mph). It's like the rear brakes are not there to help. Compare with a motorcycle, if you only use the front brake you will most likely stand on your head. You need som rear brake action to balance it up.

And I think that is the culprit, the rear are to slow to activate or has less bias than needed.