sprie

I am refurbishing the brakes and brake lines on my 928. I have had to purchase a second-hand replacement calliper for the rear drivers-side (as it was damaged), which has 968 scrawled on it.

Both the replacement calliper and the existing one on the other side have me confused.

The callipers go on the front of the rotor (so going forward the wheel rotates downward through the calliper).

I know it is important (essential?) to have the 2 bleed screws at the top.

For both of these callipers, this means the arrow is going the wrong way.

I can’t tell for sure, but I am wondering if the Porsche 968 has the calliper on the rear of the rotor – in which case these could have been installed on a 968 (swapping my driver’s side one with the passenger side) with the arrow pointing in the right direct (upward) and having the bleed screws at the top.

If that means I have 968 callipers, is it reasonable to have them on my 928 with the arrow pointing the wrong way or must I move the bleed screws and the connecting pipe to the other end i.e. swap their ends. I am not keen on doing this, as I did try to remove the connecting pipe as part of the refurbishment, but it showed no sign of wanting to come off, and was starting to strip the head.

p.s. i know the rotor is rusty, but i don't believe it is particularly worn, so i am hoping it will clean up once the car brakes have been used a bit.

Gary Knox

The F and R calipers could be used on different vehicles. The arrow doesn't really mean much - I don't think. The bleed screws and the crossover tube can be changed from end to end to accommodate mounting in front of or behind the axle.

Speedtoys

If there are different sized pistons in the caliper, location matters.

I believe generally the small piston is before the larger one, rotation wise.

Mrmerlin

swap the bleeder screws with the crossover pipes,
and swap the calipers to other side.

puyi

+1 pistons have different sizes

davek9

The rust will clean up, however some of it will embed in the pads resulting in poor performance. take them off and have them cleaned up/turned also a great time to check the wheel bearings re-grease.

sprie

thanks for the replies everyone.
i am doing the job properly - so that means swapping the connector and the bleeder valves on one of the callipers, and moving that to the other side of the vehicle
For the other one, i have had to swap my second-hand replacement for the "opposite" one, and am doing the same swapping.
end result is arrows pointing the right way and the bleeder valves at the top.
All good fun!

GregBBRD

Not completely clear what you are doing.
If you are installing 2 968 calipers from the same car, you will have no issues.

But if you are mixing and matching pieces, depending on what 968 calipers you received, the piston sizes might not be the same as the piston sizes on your 1990 model.

Mixing piston sizes from side to side can give "different" front braking....dangerous.

sprie

Hi Greg. thanks for the reply, i appreciate your safety comments.
The good news is that the pistons are the same size on both sides (i.e. they have the same size small piston and the same size bigger piston) - i have a set of new seals that are the right sizes and these fit perfectly. So all good.
all the best

Speedtoys

Will you be changing the orientation of the piston sizes relative to the rotation of the rotor?

Because..this is what I was getting to...the leading pistons are smaller in diameter in order to combat uneven wear of the brake pads. The arrow is authoritative for rotor direction, not simply pointing to the bleeders.