Fitting Boxer rear brakes to 911

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jimsrs
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Fitting Boxer rear brakes to 911

Post by jimsrs »

Is it possible to fit Boxer rear brakes to a 1975 alloy rear arm I will be running 11x15
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Re: Fitting Boxer rear brakes to 911

Post by fetuhoe »

Tricky on a 15" diameter wheel.

If you are leaving the front calipers standard you will move the bias significantly towards the rear which could be a problem.
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Re: Fitting Boxer rear brakes to 911

Post by sladey »

I *think* you can - only because you can replace the brakes on a 3.2 carrera with boxster front and rear and that they fit under 15s. However most people (including me) just do the fronts so not really had any interest in doing the rears
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Re: Fitting Boxer rear brakes to 911

Post by fetuhoe »

It seems as if TRE make an adapter that works with 15" and 16" wheels and works with a standard rotor - may be from a 3.2 Carrera.

I would be interested to know how the brakes behave when you only change the fronts to Boxster.

Did you keep the caliper with the 42mm rear pistons?

If you remove the pressure restrictor used on later cars with the larger pistons then the extra front braking will

you leave the pressure reg in place the balance will shift strongly to the front.
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Re: Fitting Boxer rear brakes to 911

Post by jimsrs »

The fronts are sorted with 4 pot calipers its just trying to find a 4 pot for the rear I have a bias peddle box
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Re: Fitting Boxer rear brakes to 911

Post by Bruce M »

Fwiw

2.7 boxster rear discs are 20mm thick & the "S" discs are 24mm thick.

I think the 2.7 calipers can be modified to work with 24mm discs (by moving or shortening the pad "pins") but you'd need to check that.
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Re: Fitting Boxer rear brakes to 911

Post by sladey »

fetuhoe wrote:It seems as if TRE make an adapter that works with 15" and 16" wheels and works with a standard rotor - may be from a 3.2 Carrera.

I would be interested to know how the brakes behave when you only change the fronts to Boxster.

Did you keep the caliper with the 42mm rear pistons?

If you remove the pressure restrictor used on later cars with the larger pistons then the extra front braking will

you leave the pressure reg in place the balance will shift strongly to the front.
Not sure if you were asking me there Chris

I think I did the change to boxster fronts only about 6 years ago - been fine.

I did read about the changes that could be made to change the balance but I can't remember the outcome except that it wasn't a definite "DO THIS" - -some people were saying change other stuff and others not so. I think it was also a factor depending on what year car you had as the master cylinder size changed (I'm now furtling around in the back of my brain and that last bit could well be a dream) - perhaps I'm overbraked at the front, perhaps not, but it doesn't feel unbalanced at all
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Re: Fitting Boxer rear brakes to 911

Post by corner shop »

Rebel racing do a rear boxster adaptor kit - I bought their front adaptor kit for my 87, and like Mark, didn't bother with the rears.

http://www.rebelracingproducts.com/Brakes.html

I think the theory is if fitting fronts only, you remove the bearing from the proportioning valve at the front to make it redundant.
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Re: Fitting Boxer rear brakes to 911

Post by jimsrs »

Thanks corner shop I have sent them a e-mail to see if there conversion will work with 15 inch wheels,if it does at $250 plus buying the calipers the conversion should come in under £500
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Re: Fitting Boxer rear brakes to 911

Post by jimsrs »

Just heard back you have to use non S calipers with there kit for 15 inch wheels
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Re: Fitting Boxer rear brakes to 911

Post by sladey »

Yep - same on the front - S calipers don't work
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Re: Fitting Boxer rear brakes to 911

Post by jimsrs »

A mate of mine looked at the photos of the brackets and said they would be very easy to reproduce on a CNC machine and about half the price if I could get several guys interested anybody interested,
Jim
PS he says he could do the front ones also
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Re: Fitting Boxer rear brakes to 911

Post by smallspeed »

corner shop wrote:I think the theory is if fitting fronts only, you remove the bearing from the proportioning valve at the front to make it redundant
This seems like a strange thing to do if it is a proportioning valve - it would lead to quite a lot more rear brake pressure (%) at higher braking forces
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Re: Fitting Boxer rear brakes to 911

Post by KS »

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Re: Fitting Boxer rear brakes to 911

Post by jimsrs »

Thanks KS they only do the fronts
I have just bought the brembo rears and am taking the arm , disc and caliper to a engineering company to get the brackets made
Jim
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