Cosmo Kramer

The USA "S" brake cars from 82 - 86 are all the same as far as I know. the 78 - 81's have a different spindle, hub, rotor and caliper. Good work Mark, watching the progress with great interest.

mark kibort

now, there is an idea! 14" rotors for the early buggers!
what do those things cost each?

xschop

That 35.2mm dim is the Early 944 rotor, it mounts to the back of the hub.

I have read here that the 928 "S" spindles are 89mm caliper bolt centers. I'm tring to confirm the Early 928 spindle ears are 76mm? I've made adapters before that didn't require changing spindles out because Porsche made the spread widths 94mm on the 944 compared to when they went 89mm on the 928 S spindles. There's more than one way to kill a cat.

mark kibort

no pics of the S brake spindles so i can plan out my attack?

Mark Anderson

You can get Cayenne rotors which also fit the GT3 for about $175 each

BigAl1

From my 1980 Euro S spindles, the bolt pattern for the calipers is 104mm.

xschop

That's odd, I assumed the earlier 79-82 spindles had smaller spreadwidths than the 89mm (83-86 "S") spindle/calipers.

slate blue

I think it is 78 to 79 MY and then 80 to 86 MY inclusive. Then 86.5 to 95 MY.

However the conversion I am doing...................err slowly, is GT2/3 2005 calipers = 6 pistons and 355 mm and it uses the EVO 72 vane rally disc. Weighs around 20 pounds plus the alloy hat. I think it is a 32 mm disc as their may be a clearance issue with the thicker disc.

The calipers are $675 each new from Porsche. You can get Pagid pads in any compound too. Annulus of the disc is around 64 mm from memory, I can look it up if needed. The bolt spacing is 142 mm and because of that I think the 80 to 86 spindles can be used.

Greg

hacker-pschorr

US 80-81 have the same spindles, which is why they are needed for this brake upgrade:

https://www.928gt.com/ps-657-15-big-...77-860998.aspx

xschop

So to confirm, the 79-82 spindles have the same AXIAL mounted caliper ears....
and what is the center to center measurement?

The 83-86 "S" are also AXIAL mount and their C2C measurement?

87-up S4, GT, GTS are radial 130mm?

Also according to BigAl1 the 80 Euro S is different?

hacker-pschorr

US 78-81 are the same
US 82-86 are the same
EuroS is the same as US 82-86

Can anyone remember why the "big brake" adapters don't work with the 82-86 spindle? IIRC had something to do with the location of the mounting tabs being lower, putting the caliper right on the ball joint.

BigAl1

1980 Euro S spindles and rotors.

xschop

Either BJ interference or the radial bolts from the radial calipers interfere with the axial bolts in the brackets. I read from other posts that the "S" spindles were 89mm center to center. A strong adapter bracket can be made with 89mm axial spindles and they would be weaker with 104mm C2C axial throu-bolts (that's assuming you went with 130mm radial calipers).
This was the reason I didn't make adapters for the 86T-944 (94mm).....A porsche afterthought on the front brakes that made the hubs weaker to get the offset for off-the-shelf calipers.

xschop

Are the mounting bolts M12 x 1.5 on those spindles?

mark kibort

Here is the plan

a flat piece of steel, 9mm thick to mount the calipers to, as well as to the spindle.

any pictures of the calipers themselves. I forgot what they look like, to see if a flat plate will work or get in the way of mounting.