930 front calipers and carrera rear

[dede911]

Hi,

I have been searching last evenings regarding an affordable brake upgrade for my SC (1100kg and 250HP)
Until now I run carrera front and SC rear. Stopping power is OK (trackdays on Toyo 888) but lifetime of pads, rotors and caliper seal is rather limited.

What looks affordable is 930 front calipers and carrera 42mm rear calipers.
The theoretical hydr bias is not to bad.

Does anyone has real live experience?

What about pedal feel with a 20.6 mastercilinder?

Thanks

André

[wildcat077]

Andre,

There's a guy on Rennlist selling a complete 930 brake kit including calipers and rotors with a new 23mm master for $3900.00 dollars.I think it's all new and unused ...

You might want to check it out !

Cheers !
Phil

[McLaren-TAG]

Phil, I wonder if your definition of affordable is the same André's.

[dede911]

Yes, I have to admit that my definition is different. On the other hand it is correct that 3900USD is not a bad price at all.

I can get here in europa front calipers for 450€ each. Disks could be wilwood with custom hats.
The complete conversion should be feasable for under 1500€.

[wildcat077]

My 996TT conversion cost me a lot more than that and i still didn't factor in the cost of my Fabcar dual master unit to tame the heavy front bias and all the Tilton mounting hardware ... so yes $3900.00 for a true bolt on setup is a good deal !

Definitely affordable in my books

Cheers !
Phil

[TRE Cup]

Pedal feel will be a little softer, but that's ok as you will be buying new front tires from flat spotting them under hard braking.
Not a good combination

[Mahler9th]

A number of us in Norcal have run 930 rear calipers in front with a lightweight Wilwood vented rotor that sells for about $30 US. And in the rear, a modified Carerra caliper on SC trailing arms with a modified alu Wilwood hat and a lightweight Wilwood rotor.

These are racing cars weighing about 2100-2200 pounds with driver and with about 350 - 400 bhp.

In front we have a simple alu "hat"/adapter for the rotors to attach to the SC hubs. It is about 1/4 inch thick. The caliper needs to be centered over the rotor with washers/shims. This is easy to achieve.

For the rear, the Wilwood hats are no longer made, but I know where there is some new/old stock. The mod required is trivial-- 2-3 holes need to be drilled to match the hub bolt pattern. For the caliper, material needs to be carefully removed for proper clearance of the rotor.

Some of us have recently switched to a rear Boxster caliper instead for the rear. In this case, an adapter is required. I have just installed this set up on my car. The adapter is not commercially made, it is pretty easy to whip up on a Bridgeport. No ebrake tho.' We don't need an ebrake for our application.

And we use the ubiquitous larger master cylinder.

[TRE Cup]

Mahler is correct with using a turbo 930 REAR caliper on the front. The bias is restored and even braking is present.
Re: The boxster rear caliper adapters- we have sold over 300 sets world wide ;-) and still continue to do so

[Bill Verburg]

Physics must work differently in California

[Bill Verburg]

930 fronts on 304x32 and wide Carrera rears on 299x24 are a tad front biased but nothing to worry about
930 rears on 304x32 and wide Carrera rears on 299x24 are way rear biased, that isn't opinion it's pure Physics

[winders]

Bill,

I have 930 rear calipers all the way around on my race car. The rear rotors are currently stock 930 rotors. On the front, I have Wilwood 11.750" x 1.250" on the front. I have a non-boosted master cylinder...I can't recall the size.

By the way, the guy that is configuring these brake systems knows what he is doing. My car is incredible on the brakes....

Scott

[winders]

Originally Posted by Bill Verburg

Physics must work differently in California

Have you thought that maybe there is more to a braking system than bias ratios?

Scott

[ivangene]

Bill V has thought about it - and done the research and put it out there for us - he's a good guy and he know ALL the numbers for these "conversions"

[winders]

Originally Posted by ivangene

Bill V has thought about it - and done the research and put it out there for us - he's a good guy and he know ALL the numbers for these "conversions"

Apparently not......

Scott

[Bill Verburg]

I'm not going to get into a pissing match w/ you.


If you like it great!! However you are failing to include other crutches that you are using in your braking system.

I can give you the torque at each wheel for a given pedal input for any brake configuration that you care to dream up.

There is certainly way more involved than just basic hydraulic bias but you need large difference is rotor sizes, pad coefficients f/r m/c and or bias bar geometry to over come 1:1 hydraulic bias.

The average guy just bolting r 930 calipers all around is going to find his butt in a sling w/o the other modifications.

[winders]

Originally Posted by Bill Verburg

I'm not going to get into a pissing match w/ you.


If you like it great!! However you are failing to include other crutches that you are using in your braking system.

I can give you the torque at each wheel for a given pedal input for any brake configuration that you care to dream up.

There is certainly way more involved than just basic hydraulic bias but you need large difference is rotor sizes, pad coefficients f/r m/c and or bias bar geometry to over come 1:1 hydraulic bias.

The average guy just bolting r 930 calipers all around is going to find his butt in a sling w/o the other modifications.

Bill,

Actually, you are wrong. There are no crutches in my braking system. I have the same brake pads (Hawk Blue) front and rear. I have no bias valve. I run a single master cylinder. The calipers are mounted in the stock locations (930 trailing arms). The front rotors are 11.750" x 1.250" while the rear rotors are 12.18" x 1.10".

I was at Sonoma Raceway a little more than a week ago racing and my car behaved extremely well all weekend. Edit: I am a big time trail braker too!

If my car had as big a problem with the bias ratio as you suggest, I would be either dog slow or off the track into a wall. I was neither.

As I said, there are more things that need to be taken into account than just bias ratios.

Scott

[winders]

Originally Posted by Bill Verburg

The average guy just bolting r 930 calipers all around is going to find his butt in a sling w/o the other modifications.

TRE Cup and Mahler9th are not "the average guy" and you rolled your eyes at what they said. That is why I commented. I knew my brake setup was all contrary to what your spreadsheet says should work so I threw it out there. I am not "the average guy" either.

Your numbers are good starting points, but they don't take the entire car into consideration. So, just because something works, or doesn't work, on one car doesn't mean it applies to all cars.

Scott

[mfyoung1086]

pssshh there's a reason the 993 was built!

To give the 80's carrera guys better brakes!

[Bill Verburg]

hmm lets see
lets take take a '73 RSR as a base,
front/rear brake torque at 70bar line pressure 3356/2050 ratio 1.637



Scott's super recommendation at the same line pressure
2050/2091 ratio .98

good luck!

hmm who to emulate, Weissach or Scott

[ivangene]

you cant reach them all Bill - hopefully the OP uses the old kind of math and will end up OK