I have 1972 911 Boge struts on the front of my 914 and I am still trying to figure out what brakes I will use front and rear. I know many people think the 1974 and later 3.5 inch struts are better but I have these and I'm gonna use them. My question is can you run rear Carrera ( 1984-1989 ) calipers on the front? If I understand this correctly this would give me a 24mm front rotor with caliper pistons that would work well with M calipers in the rear with a adjustable proportioning valve, anyone running this setup? I am going to install a 19mm master cylinder. This will be a street/autocross machine with occasional DE's thrown in. Oh yea I'll be throwing in a 911 engine too!! Any thoughts on this brake setup?

That does not make sense. They are only 42mm pistons, the same as a 914/4 front. Offset may also be wrong. I would just stay with the stock 914/6, 911T front calipers and the 20mm rotors. A lot also depends on engine power.

davep any suggestions on what caliper/rotor combo to run on the rear if I stay with the stock 911T front brake setup? My plan for engine power is a 2.4,3.0 or 3.2 so horsepower will be in the 150-225 range.

basically for now all you can run are the 3" M calipers.... with a good pad such as the porterfield R4-S it will stop just fine.

wheel size dictates what brakes you can fit, not a whole lot of choices for 3" struts, but a few exist.

Run M-Calipers up front as suggested.

Run 914 "rear" calipers in the rear and adjust your factory P-valve.

You can run 911 calipers in the rear without the spacers (for the 914 solid disc.) but you will have no hand/parking brake. I don't recommend that.

You can purchase 914-6 calipers and they would be a perfect match for the fronts but not a perfect match for your wallet.

You can purchase Ferrari calipers for the rear and they would be a perfect match for your M fronts as well, with or without the spacer (with for vented, without for solid).

Dave is spot on... putting carrera rears on there would be a downgrade.

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If you're in the 150 range the set-up you have should be fine with 914 rear calipers.

If you go beyond that I would recommend what others have with the 3.5" struts and either A or S-Calipers. I would then look for a Ferrari caliper for the rear (needs a bleeder mod).

Eric if I go with the OEM 911 front M caliper with 20mm rotor is your V-Caliper with a 911 20mm rear rotor a good match for brake bias?

And what size pistons are in the rear calipers on a 1975 914?

all 914/4 had 33mm pistons
all 914/6 & the suggested Ferrari calipers are 38mm

That's "basically" what a 911 of that era had. I would think you could work the p-valve a bit to get a little more rear brake at that time but, that would be a workable solution.

911's did have the 38mm pistons that the 914-6 and Ferrari calipers enjoyed which is why I kind of like that combo but, for most 914's, a V-Caliper in that situation would be perfect. Still better to have a bit less rear brake than a bit too much

33mm vs. 38mm in the rear is the question.

The basic 911 setup (from 110 to 190 HP) was the 48mm front & 38mm rear. With the lowest HP, the rotors were not vented, and they used M pads. Mid-range power got the vented rotors added. Higher power they went to the S & A calipers with the larger pads on the front. Even the first two years of the 930 they stayed with the S setup. From the 1978 turbo they changed radically with 4 piston calipers. With the Carrera about 1985 the rear calipers went to 42mm pistons and the rotors went from 20mm to 24mm thickness.

So the 914 rear caliper has 33mm pistons. The 911 calipers have 38mm pistons. The Ferrari calipers have 38mm is the advantage to the Ferrari calipers that you retain emergency brake? What model Ferrari calipers do you look for? Or is it easier/cheaper to adapt 911 emergency brake? Or how about hydraulic E brake?

I would not recommend hydraulic:

Line locks are usually applied with the system is hot (after you've been driving the car). When the system cools you car will roll down the hill and into the neighbors house. Your neighbor will not be amused as well as your insurance agent. Your wife will then probably get mad at you, question your overall intelligence and she'll eventually want a divorce. You will then view this as a failure in your life and your work ethic will begin to sprial. Your boss will begin to notice that you're spending too much time on 914World looking for a new car to replace the one that went careaning through your neighbors living room and you'll eventually be fired. You won't be able to make the mortage payment and your house will go into foreclosure and soon you will be looking for comfortable overpasses to sleep under.

I do not recommend the hydraulic brakes

Ferrari 308 and Dino calipers will do the trick. 914 calipers will do the trick. Just look at Daves' caliper progression. That's my MO when I build a "system" for a car. Every component needs to be looked at as to how it relates to the system.

The 914 FOUR has 33mm pistons in the rear calipers.
The 914 SIX has 38mm pistons in the rear calipers.
The Ferrari 308 has 38mm pistons in the rear calipers.
All three have the same parking brake arrangement.
The Ferrari 308 has the bleed nipple on the 'bottom' when used on a 914, so the caliper has to be modified for a second bleed nipple. The Ferrari 308 caliper is already set up with spacers for a vented rotor.
The 914 SIX caliper can be spaced for vented rotors with parts from the 911 caliper.
The Ferrari 308 caliper may or may not be cheaper than a modified 914 SIX caliper.
They are off of a Ferrari, what do you think?

The 914/6 GT used vented rotors with a modified 914/6 caliper up to about 250HP. The vented rotors on the 914/6 GT are similar to the 911 vented rear rotor, but do not have the drum for a parking brake (and cannot be modified to do so), they are slightly smaller in diameter (to fit the caliper and pads of the 914/6), and they have a different offset (so no hub spacer is required to center the rotor in the caliper)

The 914/6 GT used the front calipers off of the 908. These calipers are very similar to the 911 'S' aluminum caliper with a few modifications for racing use.

.. Been sitting on a set of 70T struts and M calipers that I bought a few years ago before I knew that I should have bought 74+ with 3.5 spacing. Thinking about a small six in the near future 2.2 or 2.4, and I have wondered what I will need to do for the rears. Don't want to be a hi-jacker.

If I go with the early Ms on the front and stick with stock 33mm, non-vented on the rear, can I replace the P-valve with a T?

Secondly, if I wanted to go with a 911 setup w/parking brake, which years should I look at. I would not want to overbrake the rear, and I would also like to do away with the P valve.

Thanks,
Ken

You could but I recommend setting up the factory adjustable proportioning valve. You'll have to chip off some epoxy and loosen the lock nut, then adjust with the hex.



1969-1973. These have the proper spacing for the bearing retainer.

A factory -6 has the M-calipers up fron and the 38mm pistons in the rear like the 911 but it retains the proportioning valve.