I have a 1971 and I need a rear caliper or ideally a repair kit and piston, can anyone assist?
Original Post
Replies sorted oldest to newest
The stock rear caliper actually has two +/- 43 mm pistons acting in one bore. The open ended bore casting is what's actually bolted to the caliper mount. Brake fluid enters the bore between the two pistons and acts by forcing them apart.
The direct piston has the groove in the face that engages the tang on the back of the brake pad. It applies force directly to the pad that bears on the inboard side of the rotor.
The indirect piston includes the e-brake actuator arm. It applies force indirectly through the big stamped steel piece to the pad that bears on the outboard side of the rotor.
The action of the two together allows the caliper to float.
I believe the direct pistons are all the same. Left, right, no matter. They are an assembly, but they cannot be taken apart. Be sure the piston is not pitted or banged up, then look really hard at the tiny threads on the cross shaped piece on the inside. If those tiny threads are blurred in any way, someone tried to force the piston back into the bore without turning it the 45 degrees required for disengagement of the internal mechanism. The mechanism will now slip on the damaged threads and the e-brake will not take up on that side.
I don't think the tiny threads are actually threads, but they look like it. I think they're grooves, like the teeth on a very fine file.
I believe the indirect pistons themselves are the same too, but after incorporation of the parts for the e-brake actuator mechanism subassembly, they become handed, based on the orientation of the e-brake actuator arm. The subassemblies are not interchangeable from right to left.
The indirect piston subassemblies can be broken down by putting the piston in a vise and slightly compressing the hat shaped piece and digging out a rather sturdy 'C' clip, but it's not easy, and most don't bother.
If you do go for it, you will find about fifteen pieces in the subassembly. One of those is an o-ring seal deep inside. It seals a short, small diameter pushrod that reaches into the pressurized bore to apply e-brake force the direct piston.
I think I have a couple of used pistons. Are you sure of what you need?
The direct piston has the groove in the face that engages the tang on the back of the brake pad. It applies force directly to the pad that bears on the inboard side of the rotor.
The indirect piston includes the e-brake actuator arm. It applies force indirectly through the big stamped steel piece to the pad that bears on the outboard side of the rotor.
The action of the two together allows the caliper to float.
I believe the direct pistons are all the same. Left, right, no matter. They are an assembly, but they cannot be taken apart. Be sure the piston is not pitted or banged up, then look really hard at the tiny threads on the cross shaped piece on the inside. If those tiny threads are blurred in any way, someone tried to force the piston back into the bore without turning it the 45 degrees required for disengagement of the internal mechanism. The mechanism will now slip on the damaged threads and the e-brake will not take up on that side.
I don't think the tiny threads are actually threads, but they look like it. I think they're grooves, like the teeth on a very fine file.
I believe the indirect pistons themselves are the same too, but after incorporation of the parts for the e-brake actuator mechanism subassembly, they become handed, based on the orientation of the e-brake actuator arm. The subassemblies are not interchangeable from right to left.
The indirect piston subassemblies can be broken down by putting the piston in a vise and slightly compressing the hat shaped piece and digging out a rather sturdy 'C' clip, but it's not easy, and most don't bother.
If you do go for it, you will find about fifteen pieces in the subassembly. One of those is an o-ring seal deep inside. It seals a short, small diameter pushrod that reaches into the pressurized bore to apply e-brake force the direct piston.
I think I have a couple of used pistons. Are you sure of what you need?
Beaver, those toy rear calipers were also used on some models of the French Peugeot sedans in the '60s & '70s, according to the Pantera Interchange List. IMHO, they're very small and uses pads smaller than on the rear of a 914 with far less weight. So not worth fiddling with, but most of the vendors have many, many of these laying around as take-offs. Some may be free; call around.
Many thanks for the replies, I have found out it is related to the handbrake and the handbrake mechanism is required not the actual calliper. So if anyone has one lurking about in their shed please let me know.
Ian@straight6.com
cheers Ian
Ian@straight6.com
cheers Ian