I have a '73 914/4 that was converted with 2.7/Webers, 911 front suspension, 16 x 7/8 Fuchs(replicas), fiberglass fenders and stock rear brakes with studs.

I have installed 911SC front calipers and would like to upgrade the rear brakes to vented rotors. What are my options?



I tried investigated 911SC rear calipers and rotors and discovered a couple of problem areas:

1. The outer diameter of the rear hub is greater than the inner diameter of the brake rotor.

2. The offset (negative) of the caliper mounting bracket is too little.

By using a spacer between the hub and rotor, I believe the 911SC rear brakes will fit.

Has anyone done this?

Thanks in advance

Eddie

'73 914/6 2.7

 

Most people don't bother switching because you lose the ebrake. If you want vented rotors get the spacer block and bolts off the vented M calipers and space the 914 calipers so you can run a vented rotor.
The 914 rears do soo little that its a waste of time other than to upgrade to a better pad depending on the use of the car. Street use don't bother.

You can use early 911 hubs, axles and CV's and use 911 caliper too.
Ask on the 914club.com forum for people who have done it.

Hey, would like to see your car sometime. Not too many Seattle guys around.
Geoff

 

Have you ditched the stock proportioning valve and fitted an aftermarket adjustable one yet?
My experience has been this makes a HUGE improvement reqardless of what brakes are fitted to the car.
Check out the article on brakes in the latest Grassrootsmotorsports. at the end they cite their project 914 went from 150+' from 60 to zero down to 121 feet with the replacement of the proportioning valve.
I would fit the new proportioning valve before you do anything else.

Kelly

 

Proper bleeding of the brakes helps the most. Buy and install Speed Bleeders and then the job is easy. Its almost impossible to get the air out of the pvalve unless you use the Speed Bleeders.
That makes rock solid brakes even with stockers.

Geoff

 

Proper bleeding of the brakes helps the most. Buy and install Speed Bleeders and then the job is easy. Its almost impossible to get the air out of the pvalve unless you use the Speed Bleeders.
That makes rock solid brakes even with stockers.

Geoff

 

I never tried the speed bleeders. Sounds like you may want to try that first.

Kelly

 

The 914/6 had rear calipers that looked the same as the /4 but the diameter of the cylinders was bigger.

There were also kits on the market at the time for splitting these calipers and spacing them out enough to fit ventilated discs.

Other options involved the calipers from 3-series BMWs

There was always an ongoing arguement about the proportioning valve. Some people swear this is the secret and some say it doesn't affect anything. My opinion is that fitting an adjustable gives you choices. Setting the ideal front rear balance depends on the weight distribution of your car and the weather !!

 

Geoff,

Talk to me about the spacers for vented rear rotors a bit if you could. I'm assuming the M calipers you are referring to are 911 fronts. Correct? These would be used in conjunction with 911S rear rotors. Correct again?
Thanks for you help.

Kelly

 

I added a bleed nipple to my stock prop valve and still have the typical soft pedal. I also have added front calipers with larger piston area than the stock -6. Braking is still not stellar.

Maybe removing the prop valve is the next step.

Art

 

Thanks for everyone's help!

We made the 911SC rear brakes fit the '71 914 with only one caveat ... no e-brake!

Solution:

1. 5-lug conversion of the 914 1.7 rear hubs - done by previous owner.

2. Space the 911 SC rear rotor 5mm outboard from the hub with a wheel spacer (note: longer studs were required).

3. Space the caliper inboard from the mounting bracket approximately 0.050".

I used the stock 914 metal brakelines and 911 SS flex lines. I have retained the OEM proportioning valve for the time being. After the pads are bedded in, I'll be able to test the balance. Since swapping to the 2.7 six, installing fiberglass front fenders, bumper, and hood most likely shifted the weight balance to the rear, I might be able to get away with removing the proportioning valve. But the weight balance must still be more forward than the 911SC from which the brakes were designed.

Only testing will tell.

Thanks again.

Eddie