Advice / help with brake upgrade

[jomalkay]

I bought a set of what i thought were 993tt brakes, front and rear with rotors. Plan was an upgrade to a 81 SC that i am setting up for both street & track use. Will rebuild the set and refinish. during cleaning, i checked the rear set part numbers, rotors are definitely 930, calipers look to be as well, part number as best as i can tell is 930.352.542.OR, caliper is also stamped on inside "11" "78". I checked 930 and 993 parts lists and could not find a match, but visually they do look like late 70's 930 calipers. Need some help and advice;
- identifying the rear calipers
- i think i will have brake bias issues as the set does not appear to be a full 993tt set up?
- now i am wondering if it is better to try to find front 930 set, or will this set up work fine (from reading some posts, 993tt & 930 are not a good mix).
I did get a set of 17" Kinesis wheels, the stock wheels were 16' Fuchs. Do the 930 calipers fit under 16" Fuchs, i know if i use the 993tt will need the 17" wheels.
One more, what is best method to loosen the 10 mm socket head cap screws that bolt each side, these are extremely tight had a 2' breaker and could not break them free, backed off as i did not want to trash anything.
Thanks in advance. Maybe Bill V can chime in as well.
John

[Flieger]

930 calipers will fit under 16inch Fuchs (or even 15 inch). Those do look like 930 calipers to me but I am no expert. I have heard that 993TT setup is the most heavily front biased (mechanically) setup ever installed on a 911. So with the rear weight bias of a 911 you might want to go for a full 930 setup with more rear bias.

[wildcat077]

Flieger,

The 996TT front calipers are THE most heavily front biased brakes installed on a 911 ...
Ask my two flat spotted front tires ... lol
I'm using Pagid RS19 front and RS14 rear on top of that !

Cheers !
Phil

[Flieger]

OK, I could be mistaken.

I thought I had seen Bill Verburg say that it was 993TT, but the hydraulic bias can fix that, I suppose, if you have a dual master cylinder setup.

[Bill Verburg]

Originally Posted by jomalkay

I bought a set of what i thought were 993tt brakes, front and rear with rotors. Plan was an upgrade to a 81 SC that i am setting up for both street & track use. Will rebuild the set and refinish. during cleaning, i checked the rear set part numbers, rotors are definitely 930, calipers look to be as well, part number as best as i can tell is 930.352.542.OR, caliper is also stamped on inside "11" "78". I checked 930 and 993 parts lists and could not find a match, but visually they do look like late 70's 930 calipers. Need some help and advice;
- identifying the rear calipers
- i think i will have brake bias issues as the set does not appear to be a full 993tt set up?
- now i am wondering if it is better to try to find front 930 set, or will this set up work fine (from reading some posts, 993tt & 930 are not a good mix).
I did get a set of 17" Kinesis wheels, the stock wheels were 16' Fuchs. Do the 930 calipers fit under 16" Fuchs, i know if i use the 993tt will need the 17" wheels.
One more, what is best method to loosen the 10 mm socket head cap screws that bolt each side, these are extremely tight had a 2' breaker and could not break them free, backed off as i did not want to trash anything.
Thanks in advance. Maybe Bill V can chime in as well.
John

That's a 930 caliper pictured in your post, it should have 30/30 pistons and be used on a 309x28mm rotor w/ p/b. The mounts will need to be modified for use on a 911 rear.

It will be an OK match for 993tt fronts on 322x32rotors.

You will need 17" wheels for the 993tt fronts, hopefully at least 8x17.

You will want to use a 23.8mm 930 m/c too.

The fronts should look like this

[wildcat077]

Originally Posted by Flieger

OK, I could be mistaken.

I thought I had seen Bill Verburg say that it was 993TT, but the hydraulic bias can fix that, I suppose, if you have a dual master cylinder setup.

No dual master yet ... although i'm looking around for a bolt on unit !
They're pretty hard to come by in the used section ...
Bill is THE reference when it comes to brakes

Cheers !
Phil

[jomalkay]

Bill,
Front rotors do measure 332x31. Attached pics of front rotors and calipers. They have adapter blocks for 911. 17x8 wheels up front
The rear 930's have 30mm pistons, mount bolt spacing is around 76/77 mm,
3 1/16". They were off an SC, is this correct spacing?
Regarding caliper rebuild kit, were all 930 calipers pretty much the same for pistons & seals?
So, in your opinion, ok set up / good set up with 993tt front / 930 rear? Running 225 / 255 tire combo.
Any clues on removing caliper bolts?
Thanks for input from all.

[Steve@Rennsport]

JMHO, but the rotor's slots in that bottom pic were incorrectly machined and are quite dangerous.

Many years ago, I saw a 911 with such rotors that cracked, offset themselves and locked the wheel sending the car into a cartwheel. Wasn't good at all.

I'd replace them.

[Bill Verburg]

Originally Posted by jomalkay

Bill,
..., mount bolt spacing is around 76/77 mm,
3 1/16". They were off an SC, is this correct spacing?
Regarding caliper rebuild kit, were all 930 calipers pretty much the same for pistons & seals?..

yes, all '69-89 911s have the same trailing arms mounts, the measurement should be 3" even, the 930s used 3.5" oe.

Yes, all 30mm pistons and seals used in 930 calipers are the same.

Try some heat(~150*C) on the bolts, they were assembled w/ Lok-tite on them

[jomalkay]

Steve,,
The slots "appear" to be part of the cast, the surface of slots has that rougher cast finish. What do you see regarding the incorrect slot machining?
Bill,
Based on your depth of brake system knowledge, you think this is a good set up, 993tt front & 930 rear?

Again, thanks to all.

[Bill Verburg]

Originally Posted by jomalkay

Steve,,
The slots "appear" to be part of the cast, the surface of slots has that rougher cast finish. What do you see regarding the incorrect slot machining?
Bill,
Based on your depth of brake system knowledge, you think this is a good set up, 993tt front & 930 rear?

Again, thanks to all.

You generally don't want any slots or holes or cracks going to the edges of the rotor annulus

It will be ok, but I do prefer more rear bias. I used 965 30/34 rears or 993RS 30/36 rears on mine, 993tt 28/28 rears will give you too much front bias, the 30/30 rears will have less front than the 993tt but more than 965 and much more than 993RS.

To use all that the 993RS can give requires special attention to the cars setup which can be expensive

[RoninLB]

Originally Posted by jomalkay

Any clues on removing caliper bolts?

My 930's were such a bear tearing down that I bought all new bolts. Threads were beat due to the steel bolt vs alloy threads

at one time the calipers were rebuilt and no loctite, lube or never seize used to re-assemble. I used nickel never seize and painted the heads with Por-15 Pelucid 400F degree clear so they don't look like crap in a year

these rebuild prices are from March 2009 and a full set of new bolts weren't cheap either






ps: I soaked bolts in PB Blaster for a week... didn't help

I was flaky about using too much heat but a little heat and an good quality IR air hammer got them out in wrecked condition