Decided to take a risk ...

[kwlw]

OK, we will see, what result it will be at the end .

Purchased set of 996 rear brake calipers ...

It seems that it is possible to fit 30mm diameter disc on those, if grind some meat from the pads. Now it is time to find someone who can properly calculate (don't want to kill myself) and make adapters for these things to fit typ85 struts. Also someone who can drill discs for 4 bolt pattern which I'm currently using on my coupe.

BTW is it possible to purchase american audi a8 rotors in Europe ? Maybe Zimmerman makes those ?

Long way to go, wish me luck

Sau

[nervas]

you can get Zimmerman here in Lithuania cheap, and you can even get to try to fit them, and if don't fit you can give them back. So like that I have Audi S8 from and from MB 500 Coupe in the rear..

[Alistair C]

Hey -

Don't take this as absolute fact - but this is what I worked out when I considered putting 996 rear calipers on my S2.... based on a previous post by Lee.


S2 master cylinder =507mm

--------------------------------------------------------------------

Standard calipers have 2 pistons on each caliper 1x36mm and 1x44mm
total surface area = 2538mm^2 for both pistons.

to move both pads 0.5mm, the pistons have to move 1mm due to sliding caliper design:
So, master cylinder travel would be (1.0 x 2538 / 507) = 5.0mm

--------------------------------------------------------------------

The 996 rear calipers have 2x28mm and 2x30mm pistons
total surface area = 2645mm^2 for all 4 pistons.

to move both pads 0.5mm, all 4 pistons actually have to move 0.5mm:
So, master cylinder travel would be (0.5 x 2645 / 507) = 2.6mm




Whilst having 4 pots will certainly increase the clamping force,
the fact that these calipers will close with almost half the fluid as the original Girling calipers would suggest to me that the front / rear bias would be quite badly out.

Anyone care to discuss ????

[kwlw]

Hey -

S2 master cylinder =507mm

--------------------------------------------------------------------

Standard calipers have 2 pistons on each caliper 1x36mm and 1x44mm

So, master cylinder travel would be (1.0 x 2538 / 507) = 5.0mm

--------------------------------------------------------------------

The 996 rear calipers have 2x28mm and 2x30mm pistons

So, master cylinder travel would be (0.5 x 2645 / 507) = 2.6mm

Whilst having 4 pots will certainly increase the clamping force,
the fact that these calipers will close with almost half the fluid as the original Girling calipers would suggest to me that the front / rear bias would be quite badly out.

Anyone care to discuss ????

I've cut unneeded stuff out. I go from the following assumptions:

1. Stock rear brakes on my car is almost no brakes at all. I've even drove this car for an year without rear brakes at all. Everyone who took my car for a ride - made smoke even when gently breaking . So I'm used to it.

2. Removing stock brake balance regulator (there is such on typ85), it makes more fluid go to the rear. Probably I'll do that.

3. My front brakes are single piston ones. Like on golf ... A problem now, however it can be benefit when using porsche rears on the front.

4. If it will be bad, maybe something like tilton brake bias proportioning valve can help me. My friend, which was running slalom prepared car - used one. He was satisfied with the results.

However there is one very serious question - how to bias brakes properly? As far I understand - rolling brake stand will not help there. I mean absolute measured meanings will not help. As far I understand I will need to measure time and effort which makes front and rear to lock.

Sau

[Sir Buff]

@nervas

What disc do you have in the rear exactly?

[nervas]

@nervas

What disc do you have in the rear exactly?

I must find my papers, and then I will write here part numbers.

[nervas]

@nervas

What disc do you have in the rear exactly?

I use those in rear:



from MERCEDES-BENZ 500 SL (R129) Rear

[Sir Buff]

Thank you for the pic nervas.
Is it not too thick?
Which caliper do you use?

[nervas]

Thank you for the pic nervas.
Is it not too thick?
Which caliper do you use?

mine is from 911 turbo, or 928 S4. Stock brake disks in porche would be 304x32 front and 309x28 rear
Brake pads from ferodo is for those calipers FCP560 front and FCP 451 rear