Questions on brakes upgrades

jriera · 04-14-2002, 03:21 PM

I did a search on the board but I cannot find the answers..

I'm planning on buying a set of calipers from an 89 C4 (front an rears) to 'upgrade' my 73 911, I will have Koni S struts up front.

Questions: will the calipers mount properly front and rear? what rotors to use (I was thinking on 930 rotors)? what tire size will I need 15", 16"?

Any advice will be greatly apreciated.

Thanks in advance.

Jim Smolka · 04-14-2002, 04:11 PM

Not sure of the caliper mounting spacing.
Measure to see if the caliper spacing on the strutt you are going to install has the 3.0" or the 3.5" center to center.
This well help us to answer you question.

jriera · 04-14-2002, 04:44 PM

Jim, the front strut is 3.5" bolt spacing (fortunately!!)

DByers · 04-14-2002, 05:15 PM

Jordi, Please post a thread on how things turn out along with some pics and such. I am looking to do a brake upgrade in the near future and would love to know the outcome for you.

Jack Olsen · 04-14-2002, 06:00 PM

Our own Bill Verburg has put a lot of information about this subject here.

jriera · 04-14-2002, 06:26 PM

Thanks Jack, for some reason I miss that reference.. way too much info.. need to read carefully..

BDyers, I do plan to document the rebuild of the front suspension and brakes, it may not happen for a while, but it will be fully documented.

slakjaw · 04-14-2002, 06:43 PM

i want to put big brakes on my 71 911 T but i have the 3 " bolt spaceing i read some where i can upgrade to 74 or later struts what is the deal with this. anyone out there ever done that before??

thanks
Kyle

Jim Smolka · 04-14-2002, 08:14 PM

Kyle,

From about '76 to 89, the struts had 3.5" spacing. You can swap to the later struts and it is a relatively easy project.

Another option is that a friend of mine mfr an adapter to mount Willwood 4 piston calipers with 944 turbo rotors on 3" spacing 911 struts. IMHO, not a bad way to go...

katigbr · 04-15-2002, 10:44 AM

Kyle,
I recently finished upgrading my 72T 3" spacing strut to the 3.5" struts and 930 brakes. I was able to use my old hubs with some custom 930 rotors. The only thing that I didn't plan on was the need to purchase new washers and clamp nuts for the new spindles on the struts. The old spindles used a different sized nut. Other than that, it was a straightforward "Remove and Replace".

The washer and clamp nuts are part numbers 30 and 31 on this diagram.

Regards,
Rick

Bill Verburg · Bill Verburg's Garage

Jack posted a link to a general info page. This is the one you want;

964 brakes to 911

gfly · 04-16-2002, 07:48 AM

I did an upgrade last year, and here's what I learned:

The bolt spacing of your calipers may not match your strut bolt spacing. You can have new holes milled so that they bolt-on. You probably can't use 930 front rotors; the offset and "hat" of the rotor won't work with a narrow-bodied car. Figure out how thick the rotors are that work with your new calipers. I think that your new front calipers are intended to work with a rotor with a 28mm thickness, and your new rears with a 24mm. The OE rotors that go with your new calipers also won't work on your car (I think) because they are intended to work with a wheel with a 52mm offset. Confused yet?

You will also need to upgrade your master cylinder, and likely remove or change your brake proportioning valve. All the extra weight from the brakes and rotating mass of the larger wheels may spoil the lightweight nature of your car. My two cents is that you should find some '84-'89 Carrera brakes and put them on instead. Good luck.

jriera · 04-16-2002, 08:23 AM

Thanks for all the answers.... I forgot to mention that I will be installing 9" flares front and rear (I'm making an ST 'look-alike'), so that will help with the offsets.

Thanks for the tip on the brake master cylinder. Right now I'm 'collecting' the parts and pieces, and I will start this project late June to mid-July.

Thanks again.

PS. Wayne, thanks for keeping the board up-and-running despite all the technical challenges you are suffering. Let us know how we can help.

slakjaw · 04-16-2002, 01:04 PM

yes thanks for all the help you guys make this too easy

thanks

Kyle

71 911

Mifintifin · 06-15-2002, 05:24 AM

Little more input for you. I researched using 944 calipers on my 82 SC earlier this year. They will work, but not without extensive machining. Good explaination is here Caliper modifications

I decided it wasn't really worth the effort when there are others available that will work. The company with the above link wants $500/PAIR to machine them and provide the still required adapters. Thats $1,000 plus what you paid for the calipers, and you still need to get wider rotors!

I also found that, after all is said and done, the unequal piston diameter in the 944 calipers is really not right for a 911 to begin with.

Mifintifin

82 SC Coupe
83 SC Cab

Bill Verburg · Bill Verburg's Garage

Previous discussion

Previous discussion

there are a lot of previous discusions on this topic the above are 2.

The differential bores as used in the late Brembo calipers are a desireable feature, which more proportionately distribute pressure on the pad, this will result in increased braking efficiency and more even pad wear than that available form older non differential bore calipers(930).

The matching of front to rear calipers is far more difficult with the Brembos due to the fact that external appearances are no longer sufficient to determine the piston sizes which are variable form caliper to caliper depending on original use, there are many different calipers that look the same. There are 3 basic sizes of the 4 piston Brembo caliper, 2 of the sizes are available in radial or transverse mount with at least 6 different piston combinations. If I were you I would buy a kit of caliper and rotor from some one that has already done the leg work.