964RS brakes

[Bill Verburg]

Lots of interest in upgrading 964 brakes lately

The 964 RS front used one piece 322x32 rotors and mid/large size 44/36mm radial mount calipers which use a 132x48mm pad. Same as 964 3.3t and America Roadster. The calipers use the same pads as the 993/928S4 mid/large size front caliper but w/ a built in boss that raised the caliper for use on 322 rotors trather than the usual 304x32 rotor.

964RS 322x32, mid/large caliper

964RS raised mounting boss



Big Red on a 2 piece 322x32, 44/36mm pistons, 132x58mm pad

notice how deep the caliper is compared to the smaller 964RS caliper

The 993, 964RS and 964t uprights have the correct monting bosses built in, the normal 964 does not, but rather uses axial mounts. To use the bigger calipers and rotors a caliper adapter is thus needed.

964 axial to radial caliper adapter. The height of the adapter varies depending on the rotor caliper combinations chosen.


The easiest up grade is to use a 993/928S4 front caliper, caliper adapter and 928S4 rotor. in nthe back you use 993 30/34 small body axial mount calipers on stock rotors. they look the same as the 4 piston 964 rears and use the same rotors but have larger pistons which help keep the bias in line when the front is upgraded. It all bolts on.

If you want to use the larger 322mm RS rotors and don't have the RS calipers w/ raise mounts then the caliper adapter needs to be thicker to move the caliper ~10mm further outboard.

Instead of a caliper adaptor the RS/ turbo or 993 uprights can also be used. Though this is more expensive.

[Bill Verburg]

For comparison, here is a powder painted 993 front caliper

and a better view of the raised boss version


and rotor comparison

993RS one piece 322 left 993tt two piece 322 right, you can see the pad wear pattern on the 993tt rotor when the smaller 993/928S4 size caliper is used on it

[Bill Verburg]

Measuring the boss
993/928S4 is ~10mm

[ilko]

Great info Bill, thank you for sharing these pictures!

[Bill Verburg]

Another and I think better way to go is to ditch the iron 964 uprights and use aluminum 993 uprights or aluminum 993RS/GT2/EVO all three are the same. The lower the car the better the more expensive EVO uprights are.

To do this you need the 993 uprights, 993 front struts(you were going to buy JICs or Motons anyway, right?), tie rods matched to the upright and ball joints.

This the easiest way to replicate the 964RS/964T uprights plus you use much lighter aluminum components.

Here is a Cup car w/ correct 964RS 1 piece 322x32 rotor and 964RS/964 3.3T caliper, the 993tt 322x32 is 2 piece, is lighter, is cheaper, is easier to get and can be made lighter w/ an aluminum hat yet has all the thermal capacity of the 1 piece version


if the 993 pieces are used then stock 993 1 piece 304x32 rotors and caliper bolt on w/o having to use any adaptors or the bigger 322x32 993RS/tt front calipers and rotors can be bolted on instead.

[Bill Verburg]

964 Cup upright, (thanks to Geoffrey R for the pics.)





like the 993 and 993RS/EVO uprights the calipers bolt to the upright, no caliper adaptor needed

[Bill Verburg]

964 stock and 993RS/EVO uprights


993RS/EVO upright and 993RS/tt 322x32mm rotor on a 964

[Bill Verburg]

In the back 964RS used the same small body 4 piston calipers as n/a 964 but w/ larger pistons
964n/a 28/30mm pistons, 98x44mm pad, 24x299mm rotor
964RS 30/34mm pistons, 98x44mm pad, 24x299mm rotor

to update a n/a 964 to RS spec use '95up 993n/a rear calipers
993 n/a 30/34mm pistons, 98x44mm pad, 24x299mm rotor

for any of these calipers use
951 352 041 02 plain stock 964n/a rear rotor
or
951 352 041 91 drilled 968 M030 rotors

Both of these rotors are the same in all respcts except one is plain faced the other drilled.

here is a painted 993 rear caliper on the 968 M030 rotor

[Bill Verburg]

For those 964 owners upgrading to 964RS the C4 cars have 23.8mm m/c stock, not change is necessary for those cars

For C2 and RSA a 993 booster and 23.8mm m/c or the 25.4mm electro-hydraulic 964RS/turbo system needs to be t/ped in.

The 993 sytem is easist to t/p

993parts needed
m/c 993.355.910.00
vac can 993.355.023.10
gasket 993.355.301.00
m/c support 993.355.163.03

you will also need to address the issue of 12mm 993 fittings vs 10mm 964 fittings, either new lines or 1x10mm adaptors are needed.

lastly, just remember, anyone that asked me my opinion re 964 or 993?, I responded 993 are much easier to modify and deal w/ in general.

[Don Plumley]

Great Info for the Archives Bill. Thanks!

[Bill Verburg]

Don, that's why I'm doing these kind of threads, I get on avg 4 pm's a week on what to do.

[Bill Verburg]

Another possibility to upgrade 964 brakes is to use 993 n/a front calipers on ''86 - 91 304x32 928S4 vented rotors, these are available solid, dimpled and slotted or 968M030(/L 965.351.041.01 & /R 965.351.042.01) front rotors which are also 304x32 drilled & vented

again as decribed above 993 n/a rear calipers are used w/ either stock 964 rear rotors or 968 M030 rear rotors which are drilled to match the front drilled 968 M030 rotors.

and again as above 993 m/c and booster

[BlackWidow964]

Bill - where might I find measurements for rotors for 964 3.6 Turbo's? My RSA was supposedly fit with '93 C2 Turbo brakes front and rear by the previous owner, and now I need to determine what are the correct rotors now that they are cracked to the edge and in need of replacement. I'd like to verify all of the dimensions first, however. It's possible that some version of 993 brakes had been used too, from what I understand. Any spec sheets available that you could steer me to that would include the diameters, hat heights, pad surface widths, etc?

[davisriley]

Check his pelican page, at the bottom with his signature. Has a lot of brake info, including all of the measurements. I have it bookmarked.

[Bill Verburg]

Originally Posted by BlackWidow964

Bill - where might I find measurements for rotors for 964 3.6 Turbo's? My RSA was supposedly fit with '93 C2 Turbo brakes front and rear by the previous owner, and now I need to determine what are the correct rotors now that they are cracked to the edge and in need of replacement. I'd like to verify all of the dimensions first, however. It's possible that some version of 993 brakes had been used too, from what I understand. Any spec sheets available that you could steer me to that would include the diameters, hat heights, pad surface widths, etc?

3.6t used the same 1 piece 322x32 front rotors as 964RS and 3.3t. But used the large body (Big Red) calipers. Look closely at the first 2 pics in my first post. The black calipers are RS or 3.3t the Red is 3.6t, the difference can be seen in the top of the caliper and the gap between the hub and bootom of the caliper.

In back the 3.3t & 3.6t used a 28x299mm rotor that cannot be used on a n/a 964 rear trailing arm, with small body 30/34 calipers. So what RS and RS clones do is use stock 964 or 968M030 rear calipers which are 24x299 w/ 993 rear small body 30/34 calipers.

[Bill Verburg]

The Pelican brake page isn't being maintained
this one is
http://members.rennlist.com/1976c38/brakes.htm

one of these days i'll update w/ the 996 -997 specs

[BlackWidow964]

Much appreciated Bill!!

Dave

[Bill Verburg]

to use the RS 25.4mm m/c the entire electro-hydraulic booster set up needs to be t/ped


964 20.6mm m/c, too small


964 & 993 m/c, the 993m/c uses 12x1.0mm fittings, 993 use 6mm line

964 uses 10x1.0mm fittings on 4.75mm line



to use the 23.8mm 993 m/c you also need
993 vac can 993.355.023.10
gasket 993.355.301.00
bracket 993.355.163.03
and either 993 lines or adaptors.

lines and adapter sources
Classic tube

Plews-Edelman

Fedhill

[davisriley]

As always bill, thanks for the info!

[Bill Verburg]

Originally Posted by davisriley

As always bill, thanks for the info!

Hope it helps, too bad it's so disorganized. I posted as questions came in.

one more piece of the puzzle
p/v
use
964.355.305.10 55 bar stock on all 4 piston rear C2 & 964RS
or to get a little more rear bias
964.355.305.01 60bar