I am in the process of installing a 1971 911 front suspension. I think its a 71, anyway, I put all new bushings, bearings, brake lines, rotors, and I am using Volvo 240 brakes witht he 3 inch spacing with spacers behind them to correctly position it on the rotor. It bolts right up and I am sure it will work but my question is, it doesnt look like it sits down on the rotor like it should. The factory calipers that came with everything are the M calipers and they dont even fit over the rotor. Am I missing something here? Were the rotors for earlier cars thinner? These were for a later model car I think. I had them cross drilled. But I ordered factory vented rotors and this is what I got. How come the factory M Calipers dont fit over them? Or am I making a mountain out of a molehill? I want to be able to stop. Help!

The important piece is whether or not the PAD is contacting the rotor.

Carrera rotors are 24mm wide (IIRC)
and SC rotors are 22mm wide.

The diameter is the same (it appears)

I'm not sure who made your adapters.. but it looks like they left some on the table.


B

What adapters are you referring to? I didnt use any on this. The only thing that is different from what I got all as a set, is the calipers, and of course the rotors are new. I still have the orginal calipers but they dont fit over the rotors. The calipers have a 1/8 washer behind them to center them on the caliper. I know Bernbomb has then on his car.

I wont swear to it.. but I think Rich Johnson moves the bolt pattern in his calipers that he sells (like we do with the 944 Turbo stuff) Basically offset the holes.

Sorry about the adapters comment. I *thought* they needed an adapter.


B

Thanks Brad, I appreciate the advice especially from you. When you say move the bolt pattern, what does that mean? Can I change these to move in on the rotor? That is really all I would need to do. But would it be safe?

Every 944 Turbo caliper sold for use on a Carrera strut has the holes moved to locate it on strut/rotor properly.

I see NO issue with you changing them and moving them closer to the rotor. It will have to be done on a good mill and the old holes welded up (to do it properly)


B

So do I modify the caliper or the strut? Is there a way to put the big reds from a 944 on a strut with 3 inch spacing? Or would I have to change the struts?

Sounds like you got "Carrera" rotors. M-Calipers should slip right on a standard vented rotor, drilled or not.

Another question; what calipers are you using on the rear?

If you're staying with stock 914 calipers then I'd match them up with the M-calipers and some "awesome" pads. If you plan to go larger then by all means modify your existing calipers to fit in closer to the hub.

In choosing a rear caliper (if you're going that route) I'd check the overall pad area on the Vulva pads and match them up with a Porsche equivilant and then use what Porsche used opposit that. E.G. If it's the same pad area as a 944 Turbo then find out what caliper they used there and make it work.

Drop the proportioning valve in favor of the "T" fitting or go the adjustable route.

Larger rears also mean parking brake issues... it does end at some point.

Well, I havent made a decision on the rear yet, I have several sets of stock rear calipers with the E brake but would like to go larger. I am doing a V8 conversion on this car and the extra weight will need bigger brakes. I am installing the T in where the rear proportioning valve goes. And upgrading the master to the 19mm. I got the 6 rear rotors and have been told to run the stock caliper, I will have to shave them down. I would like to run one that I dont have to do that with but would also like a rear E brake too. Suggestions?

Here are some pics of the front calipers that came with the set.

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I agree with upgrading the entire "system" with your V8 plans.

Keep the Vulva's and get them set right on the rotor.

Get larger rears to team up with the fronts based on the the front pad area and use the "T".

For parking brakes... "basically" one option at this point:

This...

Or you could carry a rock to put under the tire

Those look like good clean M-Calipers...

I havent shaved any 9146 rear rotors for use with stock calipers. I have *heard* this also but havent found a need to do this yet. I have also heard that the rotors "grow" with heat (I know they do) but havent had an issue yet. A stock rear caliper doesnt do much of anything so heat isnt my concern.

I am HIGHLY concerned that this braking system will be 100% out of whack when it comes to bias. Your playing with fire. I had Andy running around with stock Carrera fronts and stock 914 rears... it was WAY out of balance with the stock Carrera fronts.. I cant even imagine what you will end up with in this case.

And it is not a matter of adding a brake bias.



B

Ok, What if I run the M calipers on the rear with no E brake for now and see how it goes? Would this work? Can I run the M calipers on the rear? I think I read somewhere that somebody did that.

Depends. That's fairly common on the board and that's the setup the factory used on a 76 930 Turbo "if" you think the pad area on those Vulvas is close to the size of an A-Caliper or an S-Caliper.

What both Brad and I are trying to say is... brake combos are tricky. I would only question the "unknown" aspect of the Vulva pad size. It's not a great idea to stick mongo calipers up front without addressing the backs. Try to go with what the factory engineers provided us with. Hence, my recommendations of pad size ratios. Brad's "Andy" experience best tells the story.

My set up is S-Calipers up front on Koni struts and M-Calipers on the rear. 911 handbrake and a "T" fitting. I haven't run the combo yet so I'm keeping my fingers crossed on the bias issue. I know it will be close (again, this is what the factory supplied on all S's, RS's and 930's through 76) but worst case I'll need to get an adjustable valve.