75 911 with 3.5" caliper spaceing 17" wheels, advice please

[andy s]

Hey all, just picked up a 75 chassis with a 3.6 and all the goodies, but the car still has stock brakes on it....

Its been a while so I have forgotten (and or may not know new combinations), so what can I put on for Big Red (or similar) calipers and rotors.

The car does have 17" wheels and I will be putting on a Fiske, Fuch style 17 wheel.

looking for something on the larger side as I will be tracking the car.

It does have 930 flares on it

There are some '04 996 turbo calipers I can get my hands on, but I' open for some education and options

Thanks!

[Sboxin]

Originally Posted by andy s

Hey all, just picked up a 75 chassis with a 3.6 and all the goodies, but the car still has stock brakes on it....

Its been a while so I have forgotten (and or may not know new combinations), so what can I put on for Big Red (or similar) calipers and rotors.

The car does have 17" wheels and I will be putting on a Fiske, Fuch style 17 wheel.

looking for something on the larger side as I will be tracking the car.

It does have 930 flares on it

There are some '04 996 turbo calipers I can get my hands on, but I' open for some education and options

Thanks!

Since not much response, I will share our experience . . . we race a 1978 911 w/3.8L and 17" wheels 245 and 315 Hoosiers . . . with stock calipers - but, race pads and slotted rotors . . . car weight is 2500 w/driver and fuel . . . pads are Raybestos ST-43 front and Pagid Black rear . . . fluid is Motol 600 . . . front brake air cooling ducts . . .

There are many Pelican Forum threads on larger brake calipers and rotors . . . Bill V is the resident expert on these and has posted many times . . .

If you do decide to change to larger calipers Bill usually can help with a complete brake system change - because that is what you may need for such a conversion . . .

Wish you the best on your new car and project,

Regards,

[andy s]

Thanks Roy;

I have a big Red set up on my race car and being a very late, hard braker wtih experience, I know stock brakes, even with pads and fluid will not work for me.

And yes, I am hoping Bill weighs in..... Always learn from his threads.

Globally yes, partly about wantnig hand of GOD brakes, partly style.... (come on, we all have a bit of vanity in us...LOL!!)

along those lines, and I'm guessing i'll put it in another thread, the chassis has the hole for the power brake booster and I think I have one in my P part building.... where and how to get vacuum will be my next quesition, if I go that way. My race car does not have PB, but my other street/track day car (modified 90 C2) does... that C2 is the best stopping car I have ever owned and I own cars...

[Bill Verburg]

As always you are limited by the available rotors that fit the chassis and wheels

w/ 17s you will generally not have any clearance issues w/ any reasonably sized rotor
so the field of whats available
stock 282x20 f & 290x20r
C3.2 282x24 f & stock 290x20 r or C3.2 290x24r
930 304x32 f & 309x28 r
993RS 322x32f & w/ a lot of work 322x28 r

some folks have fitted various 996 rotors 318x28 f & 299x24 r 05 996tt 330x34 & 330x28 (I've never done either of these so have no idea of what's involved)

easiest and most straightforward is 930s all around, these have great stopping power and great thermal performance and are all you really need

If you want more than that 993 calipers on 930 rotors are fairly straight forward and not too difficult to implement, bias is very close to the 930s thermal performance is the same because they use the same rotors

Hand of god and the best thermal performance and bias comes from full 993RS
I have them on both of my cars, The issue here is that though the front is straight forward and all bolt on w/ the proper adaptors the rear is not


These used to be available in bolt on kit form from Race Technology but as far as I know they are no longer offered. You could contact them and ask though

W/ 930s the main is issue is that the rear calipers need to be modified

Here you cans see a modified rear, the mounts need to be 3" OC for 911 use


some of the late 930s(87 up) need the feed modified as seen here




The 993RS rear calipers need major mods
from left stock 993RS axial mount caliper, modified 993RS caliper radial mount & adaptor for 911, stock 993RS front radial mount



in addition the 322x28 993 RS rear rotors need to have the parking brake modified as seen here on the left, a 9111 parking brake is pinned into the 993RS rear rotor, on the right is a stock 993RS front 322x32 rotor w/ a flat hat for use on 911, they come form the factory w/ a bolt on o/s hat that is removed an discarded.

[1979-930]

I'm lazy. I would just get the Brembo kit Rebel Racing sells and bolt it on.

[Bill Verburg]

Originally Posted by 1979-930

I'm lazy. I would just get the Brembo kit Rebel Racing sells and bolt it on.

You could do that the front rotors are 323x28 just slightly less effective thermally than the 993RS fronts, they spec the rears but they appear to be 309x28 930s so again just a bit less effective than 993RS and whole lot easier to put on the car.

[andy s]

OK, Bill;

I have a line on a set of front and rear '86 944 turbo calipers.... Will they work and what do I need for rotors and adaptors?

Thanks!

[Bill Verburg]

Originally Posted by andy s

OK, Bill;

I have a line on a set of front and rear '86 944 turbo calipers.... Will they work and what do I need for rotors and adaptors?

Thanks!

Those are the same as 964

front
swap the bleeds and feeds on the calipers
make or buy a caliper adaptor, the specs of the adaptor depend on the rotor used. I used 930 32x304mm rotors w/ flat hats when I used these. The big issue is that the stock mounting ears need to be machined off and then tapped to accept the adaptor.
964 modified for front fitment on a 911, This is the main reason that i prefer 993 fronts on the 930 rotors, the 993s are radial mount oe


stock 964 w/ axial mount ears


stock 993 front & rear


stock '79-80 2 piece 32x304mm rotor w/ flat hats, these are floaters but non floating is also available, you can use the later 930 32x304 1 piece if you have 930 front fenders


rear
I like the 993 rears much more than 964 or 944. The 993 have bigger 30/34 pistons which move bias back towards where you want it. The 944 need the bleeds and feeds swapped. All of them work w/ 930 28x309 rear rotors w/ minor mods.

the mods are
slight opening of the throats and fill the oe mounting holes and redrill to fit the rotors

you can see here the holes were plugged and redrilled


throat opening


Installed 964s, 993 would use the same rotors but front would be a bigger easier to install caliper

[Duc Hunter]

I did the same thing on my 75. I went, as a temporary thing, to get the car on the road, Carrera front brakes and '75 rear brakes. My car is a street car and that turns out to be plants of brakes for my car, 17's or even when I tried my 18's. I am eyeing some super secret brakes for it this summer, but that upgrade will be for show, not because it needs better brakes.

I have in a box bigger brakes. I think they re 928S4 fronts and 944 Turbo rears, or something. They were apparently a "cool upgrade" back in the day.

[3rd_gear_Ted]

This months Excellence magazine, Tech Tips, Best of Q&A, Page 75
911 SC Brake Upgrade
First off, there is no "right" rotor per the article

BUT, for those like me that can't afford 930 brakes for their 911 SC track car this is a great article about the mods required for a 1986 Turbo 944 brake set up with 28 mm thick rotors. This front brake mod along with some Carrera rear brake calipers & 24 mm rotors with a 930 M/C has served me well many years.

[Bill Verburg]

Originally Posted by 3rd_gear_Ted

This months Excellence magazine, Tech Tips, Best of Q&A, Page 75
911 SC Brake Upgrade
First off, there is no "right" rotor per the article

BUT, for those like me that can't afford 930 brakes for their 911 SC track car this is a great article about the mods required for a 1986 Turbo 944 brake set up with 28 mm thick rotors. This front brake mod along with some Carrera rear brake calipers & 24 mm rotors with a 930 M/C has served me well many years.

Specifically what rotors are used in front

here's the issue
stock 911 20x282s have a height of 35.3mm
stock 911 24x282 have a height of 35mm
stock 930 flat hat 32x304 have a 13mm o/s and w/ the hats added have a height od 35mm
stock late 930 32x304 have a height of 57mm and can only be used w/ 930 fenders
stock 964 28x298 have a height of 80mm
stock 993 32x304 have a height of 72mm
stock 996 28x318 have a height of 67mm
stock 944t h28x298 have a height of 74.2mm or32x304 have a height of 76mm
etc etc
none have the low height needed for a 911, which means you need custom hubs for any of them to work