OBehave

Im getting the Hanson car ready for a run at Lime Rock and want to replace the brakes and other various things. I was told by everyone I spoke with that the rear brakes on this car were S4 front brakes and even the article in the 928 Forum Magazine from back in the day says the same thing.The mounting of these calipers are not the same as any S4 I have worked on but the physical size is close to an S4 front caliper.Does anyone know for sure or can tell by the pictures below? Thanks in advance!
Ed

auzivision

Boy those mountings sure look identical to mine. I have an early 87 S-4... maybe that's the difference.






But then again I have the raised letter. I believe they flatten them out in the later years.

auzivision

One more before photo that almost shows the mounting arrangment.

OBehave

Thanks Kurt for responding. The caliper mount is the same as S4 but the caliper is physically the size of a front caliper. The brake pads on this caliper are physically the same size as the GTS pads I have up front but have a different shape.All the pics of different Porsche calipers that I could find have the front style mounting.

atb

Take a pic of the pistons, if they are smaller than the stock S4 rear pistons as shown in the photo above, they are 993TT rear calipers.

hacker-pschorr

I thought front S4 calipers used a radial mount.

atb

The information from the 928 Forum article came from Don Hanson. We didn't do a close inspection on the rear caliper, just presumed (as Don probably did) that DEVEK had made an adapter bracket. It wasn't common knowledge at the time that a modified 993tt rear caliper could fit. DEVEK was very tight lipped about the source of its mods, so I'm not really suprised that they didn't point out this mis-information in the article. Since it looks like its using an OEM rotor, the caliper mounting "ears" would have had to have been machined to center the rotor in the caliper. It you see the milling marks, that's another indicator of a 993tt rear caliper.

BC

That looks like a big red-sized brembo but with axial mounting ears.

xschop

94mm Bolt Centers?
The Red caliper is a later caliper. Brembo cast the ribs out of the body to add strength when going to larger pistons.

993.352.426.10

Leon Speed

Looks like a rear caliper. Brake lines of front calipers on a S4 (and later ?) are attached with a banjo fitting, rears screw in directly like in your picture.

xschop

Those are small pistons also at 28mm

OBehave

Thanks for the help Adam and everyone else who responded. When I tear it down I will measure the pistons and look for machining marks and report back what else I find. Ed

IcemanG17

Those brakes sure looks like "big reds" or GTS front brakes, but with the different mounts..... The easy way to tell GTS Big Reds vs S4 style is the flat surface with a "Porsche" sticker vs the raised "Porsche" lettering in the casting on the S4 front and rear brakes....

Benton

Those are either 1) 993TT rear calipers, or 2) 993RS rear calipers. Same basic casting, RS has larger pistons. Once you know the piston sizes, we can determine which of the two.

Vilhuer

There are three different version of S4 front caliper. Latest has flat surface with sticker so its not 100% sure sign of GTS vs S4 caliper.

993TT rear caliper is larger than S4 front. Its same size as GTS front but pad isn't as large.