Carrera Calipers

Superman · 02-11-2003, 08:47 AM

As usual, I'm too lazy to fish through old posts, especially when I'm sure someone knows the answer. Yesterday I scored a pair of Carrera front calipers for my favorite price ($0). I think they just bolt on my SC, but I'd need the thicher Carrera rotors. As far as I know, the rotors are all I'd need to put these brakes on my front end. True?

Also, I wonder whether my current front calipers could, or should, go on my rears. Advice?

Chuck Moreland · 02-11-2003, 08:50 AM

To question A - yes, bolt on.

To question B - No. Wrong bolt pattern, wrong piston size, hosed up bias.

Superman · 02-11-2003, 09:08 AM

Thanks, Chuck. Follow-up question: If all I do is bolt on some Carrera rotors and calipers up front, won't that result in a bias problem? I guess I'm probably asking whether the Carrera pistons are the same diameter as my SC pistons (if I understand brake hydraulics, which is not a good assumption).

KennyG · 02-11-2003, 09:22 AM

You can have my rotors if you want

Early_S_Man · 02-11-2003, 09:23 AM

Jim,

No bias problem, as both use 48 mm pistons ...

The bias problem Chuck alluded to would be if all four corners had the 48 mm pistons!

Chuck Moreland · 09:53 AM

Both calipers are A with identical piston sizes. The Carreras just have a thicker spacer between the caliper halves. So no change to bias, no worries.

edit: Calipers are A not M

Superman · 02-11-2003, 09:34 AM

Most awesome!

Chuck, you're a fountain of information. Warren, it's always nice to hear from you. Kenny, I'll take those rotors. I wonder why you don't want them.

KennyG · 02-11-2003, 09:45 AM

I just put new rotors on, and I have no need for the old ones. I don't know what they measure, but they worked fine on my car.
Also, weren't you the one who wanted the Swepco gallon ?

Superman · 02-11-2003, 10:04 AM

Indeed I was. This sounds like a reasonable excuse to meet for a beverage somewhere. In fact, events are taking place (job stuff) that would have me appearing regularly in Seattle starting as early as the last part of this month. I'll probably be there sometime later this week as well, for a meeting.

KennyG · 02-11-2003, 10:21 AM

hmmmm, freinds are at Redhook brewery on Fridays........
I'll hold the rotors and oil for you.

Superman · 02-11-2003, 10:24 AM

Thanks, Kenny. I'll see about Friday.

Wil Ferch · 09:30 AM

Some cautions, unless this is known already:
- Carrera fronts are "wide A" calipers ( with spacer) using 48 mm pistons
- Carrera rears are "wide M" calipers ( with spacer) using 42 mm pistons

Carrera in this case is 3.2L 1984-89. "A" caliper use 3.5" bolt mount spaing. "M" uses 3" bolt mount spacing.

- SC fronts are "A" with 48 mm piston.
- Sc rears are "M" with 38 mm piston.

SC's as a rule didn't use a proportioning valve. When the 3.2's came out, the increased piston diameter of the "unchanged" M rears ( from 38 to 42 mm)...would have brought with it too much rear brake bias...and this caused Porsche to use a brake proportioning valve that limited pressure to the rear wheels when brake line pressure exceeded 33 bar.

So yes...if all that is changed is the front from "A" to "wide A"...then the piston diameters remain the same..the bolting pattern is the same...and the heat sink is improved for the fronts. Brake bias remains the same. If, however, you want to match the increased heat sink for the rear, then you would go wide "M"( Carrrera) for the rear...but the increased piston size would now also require the Carrera bias valve...whew! ( clear as mud?)

--Wil Ferch

ChrisBennet · ChrisBennet's Garage

Wil,
I could swear Carrera brakes just bolted on SC's. I know someone who did just that even. I sold my Carrera brakes to someone who put them on his '73 so I think that is a bolt up too. Are you sure SC fronts have a different bolt spacing?
-Chris

Bill Verburg · Bill Verburg's Garage

I'll just echo what has already been said, Carrera brakes do just bolt on to the 3.5" SC struts they are "A" calipers w/ a thicker spacer between the halves(do use the thicker Carrera rotors), they do use the same 48mm pistons as the SC and brake balance remains unchanged. Since most of the braking is done at the front and overheated rears are rarly(if ever) a problem there is no need to change the rears.

Superman · 02-11-2003, 01:21 PM

Thanks, folks. I think I get it. The calipers I scored are old, dirty and were reportedly 'sticking.' If I need to replace pistons, where would I look? If Pelican, then nevermind, I'll look there. If not, then who sells them (48mm pistons)?

KennyG · 02-11-2003, 03:35 PM

I could always sell you my whole setup and then buy me some Big Reds

Superman · 02-11-2003, 03:59 PM

Well, here's my observations. Someone recently said that their SC brake heat problems went away with the Carrera calipers and rotors. The brakes on my car right now can probably stop the car as well as any brake system could. I can lock them up if I want, or just brake HARD. In fact, the brakes on my car are ferocious. Three+ years ago the insurance lady asked me some questions about my car. One was "Does it have antilock brakes?" Of course, I said no. In thinking about it afterward, I almost wish I had said that my car could win a braking contest with virtually any modern antilock brake car (by virtue of its lower weight, fat tires, weight bias, etc.). It wouldn't have made a difference of course, but my point is that the braking system on your car is hard to improve upon. When I show off my brakes to a passenger, I have to warn them first. After the demonstration, their eyes tell a story, and they verbally admit that cars generally just cannot stop nearly as fast as ours.

So, I'm sure that Big Reds are better, but gosh you have good brakes now!

Greg S · 02-12-2003, 08:58 AM

Super,
I swapped my SC front brakes for the Carrera version last year. With the SC brakes, I could definitely feel the effects of heat buildup toward the end of a run in a DE or track day. The brakes didn't go away, but the braking distances were becoming longer. After swapping to the larger Carrera rotors, there was no perceptible fade or heat buildup effects. With both setups I was running ATE Blue & MetalMaster pads. IMO, the Carrera brakes are a nice, cheap upgrade from SC rotors.

Wil Ferch · 02-12-2003, 09:35 AM

My mistake:
I've edited my earlier post to recognize that SC's use the same 3.5" bolt spacing and "A" caliper as does the "wide A" of the front of 3.2 Carrera's. Mistake is noted and I went back to edit my first post. Should now read correct. My point was to highlight that the rears would not have the same heat sink upgrade..and many have said that isn't a big matter anyways..probably true.
Sorry for the confusion...
-Wil Ferch

Superman · 02-12-2003, 09:50 AM

Thanks very much to all. I knew what you were teaching me, Will. I asked for, and received, everything I need to know about this upgrade. You guys are the place to shop for truth about Porsches.