upgrade rear calipers on SC to Boxter

[thechiller]

Now the time has come to upgrade my brakes, i have changed the head studs, upgraded chain tensioners, new Dansk exhaust (realy nice sound) and converted to 964 cam profile.

I now have a pair of Boxter rear calipers and disks that i want to use on my 1981 SC. I think i have see a drawing on this forum that shows how to adapt these calipers, but i can't find it. Does any one know how to do this?

I will use 964 brakes in front as i have been informed i can put them right on.

Thanks
Kjell R



My god i love this car

[rlh930]

I installed mine with a kit that included an L-shaped bracket that mounted to the original brake mounting holes on the bannana arm and allowed mounting the Boxster caliper on top of the axle as shown. Unfortunately I don't have a picture of the bracket. You will need to fabricate new brake hard lines to go from where the flexible lines terminate to the new caliper. It is possible to bend the old hard line if you are very careful and brave.

['76 911S 3.0]

Originally posted by rlh930
I installed mine with a kit that included an L-shaped bracket that mounted to the original brake mounting holes on the bannana arm and allowed mounting the Boxster caliper on top of the axle as shown. Unfortunately I don't have a picture of the bracket. You will need to fabricate new brake hard lines to go from where the flexible lines terminate to the new caliper. It is possible to bend the old hard line if you are very careful and brave.

Holy spacer BAtman!!

[WPOZZZ]

Originally posted by '76 911S 3.0
Holy spacer BAtman!!

isn't that stock on the 930s?

[jstgermaine]

The 930 does have spacers, but not to that extreme. 28mm in the rear if I remember correctly. It looks like there are two different spacers being used in this application.

[MotoSook]

No need to put the Boxster brakes in the rear, just get the Carrera rear caliper and rotor (no adapters, not hassel). I'm running 964 front caliper and Carrera rear caliper on my '89. Works well so far with a track weekend of testing

[Rich76_911s]

Not that I am an expert on Brakes or anything. From what I understand Boxster brakes have greater clamping force than carrera brakes. But becasue the stronger caliper is being used on the same size rotor the heat energy builds up faster in the rotor and actually makes the problem with frequent track braking worse. Is this wrong?

[Bill Verburg]

Originally posted by Rich76_911s
Not that I am an expert on Brakes or anything. From what I understand Boxster brakes have greater clamping force than carrera brakes. But becasue the stronger caliper is being used on the same size rotor the heat energy builds up faster in the rotor and actually makes the problem with frequent track braking worse. Is this wrong?

You are correct sir. As is Souk. Using Boxster calipers on Carrera rotors is not an improvement, if you like the look, go for it. If you want better performance go to 930 minimum

[Mahler9th]

Here we go again... Sounds like thechiller already has the parts so he just needs to get them on. I think TRE in SoCal makes the adapter referred to here. I am pretty sure that Smartracing Products have obtained some and put them on some customer cars, and a few of our Porsche Racing Club Spec 911 racers have them.

I have a friend with a GT car and Boxster rears with a homemade bracket-- I will see if he has a drawing.

For my car ('75 race car at ~2000 lbs and ~360 bhp), 930 rears would be a little foolish. Not worth the weight. Car stops fine with the itty bitty Carrera calipers in the back. The only reason I might put Boxster calipers on is the save money on rear pads...

Anyway, try googling +TRE +Porsche-- I think they have a kit, also try VCI in NJ.

And remember, how "much" brake you need depends on weight, HP, and tires. Bigger and heavier may actually increase your lap times.

[Bill Verburg]

Originally posted by Mahler9th

Bigger and heavier may actually increase your lap times.

But the probability of that being true is <2%

If you want to use Boxsters you should at least use some bigger Wilwood rotors

[Mahler9th]

Disagree completey depending on the factors involvded. For example, if I put 930s or bigger on the rear of my car (where all of the wieght is) I am sure I'd go slower. My point is that regrading brake choice, one must consider the car and the tracks and...

A good resource on brakes is the Puhn book.

[Bill Verburg]

hopefully we are not including doing something dumb like only addressing one end of the car

[Mahler9th]

Oh no. This is what I am referring to:
"Intermediate steps which are cheaper and have fewer negative side effects should be tried first as the principal design goal should be to use the smallest lightest combination which will do the job."

That is my point (and yours I presume).

- MM

[KTL]

Originally posted by thechiller
..............I will use 964 brakes in front as i have been informed i can put them right on.

Thanks
Kjell R

Make sure you have been informed correctly. The 964 front calipers are not a simple bolt-on. Some have gone the route of allowing them to bolt on by widening the mounting holes. This is not the appropriate way to fit them.

Cutting off the mounting ears and affixing caliper adapters onto the calipers is how it's done properly, along with using the appropriately offset 28mm or 32mm rotor. Using a 24mm rotor with caliper that is designed to use a 28mm rotor is dangerous, as the pistons can actually fall out if the pads are allowed to wear far enough!

[KTL]

Originally posted by Mahler9th

Anyway, try googling +TRE +Porsche-- I think they have a kit, also try VCI in NJ.

Yep. It's TRE Motorsports in California.

http://www.tremotorsports.com/product.cfm?Node=1329



Another adapter source

http://www.timmonsbillet.com/Porsche.html

VCI doesn't do anything with the Boxster/monoblock calipers (yet).

[Bill Verburg]

Originally posted by Mahler9th
Oh no. This is what I am referring to:
"Intermediate steps which are cheaper and have fewer negative side effects should be tried first as the principal design goal should be to use the smallest lightest combination which will do the job."

That is my point (and yours I presume).

- MM

Yes, brake cooling, pads, and fluid. The next baby step is Carrera rotors at least in the front. But you get the same bang as the Boxsters on Carrera as you do from Carrera on Carrera(in front). Lots cheaper.

the next step would be Boxster on ~310x28mm rotors(front) then 930 then 993 then 993tt/RS. This last is overkill for almost any stock car, the others it depends on all the other factors. The fact is that just changing the front calipers and rotors to Carrera is a nice and sufficient step for many cars. The Boxsters on Carrera isn't enough better to warrant the steep price differential, if you like the looks fine.

[Noel]

Bill,

Do the Boxster calipers need to be machined to fit a 28mm wide rotor? I've never heard of this before (always thought they only fit the 24mm Carrera rotor), but may be interested with using stock carrera rears with the 24mm rotor.

Thanks

[Bill Verburg]

Boxster S used 28x314 front rotors and 24x299mm rear.

AFAIK the regular Boxster can also use the 28mm rotors w/o issue, but I don't go there so am not sure.

[Duckworth]

Mahler - you held your own pretty good there with Bill on this thread... Then he kind of laid 4 queens down and you ought to 'tip your hat' as they say.



_____________

'82 Targa - sold
'80 928

[Hetmann]

I've always thought SC brakes were quite good.