Rear Brakes
The rear brakes had been refurbished and new pads, handbrake shoes and discs had been sourced. As part of the rear suspension overall, the parts for the handbrake system had also been cleaned, zinc plated and built back up.
The calipers on the 944 have some crazy anti vibration shims that sit inside the caliper pistons. They come in various sizes, 44mm, 40mm, 36mm, 34mm and 28mm and cost between £8 - £10 quid each and you will need 16 of them in total, four per caliper. There seems to be no logic in trying to calculate the size that is required based on the size of the piston or the hole inside the piston. The 944 parts catalogue lists 40mm and 36mm for the fronts and 30mm and 28mm for the backs. Rather than buy new I figured I would use what I had, however, the front brakes did not have any fitted so I had to get these new. After a few purchases and returns I figured out my setup had 40mm and 28mm at the front and 30mm & 28mm for the backs.
I used a tiny bit of sealer to bond the back of the pads to the anti vibration shims and built the items back up on the bench. With the calipers back in place the hard line brake pipes and the ABS & brake wear warning senior could be routed and clipped in.
With everything back in place was time to address the hand brake cable routing. The broken piece that comes out of the driver-side back seat floor well had been poorly welded and broke off while pulling out the handbrake cable.
After a hours of scratching my head and a cuppa I figured out how the handbrake cable worked. It’s really confusing as there is only one cable that comes out the car and therefore only one direction of force is applied to the cable. The Porsche 944 catalogue image of the handbrake cable is below:
The diagram is not up to date as the two cables do not require item 21 as they have stops that seat against the swing arms built into the cable. My understanding of the cable mech is below:
Long Cable Composition:
- Metal cable (inner wire)
- Plastic sheath crimped to the metal cable
- Rubber sleeve encasing the plastic sheath
Connection to Short Cable:
- The plastic sheath of the long cable connects to the metal cable of the short piece.
Force Transfer Mechanism:
- When force is applied (pulling the handbrake), the plastic sheath compresses.
- This compression of the plastic sheath pulls the short cable's metal wire in the correct direction (opposite direction)
Once I understood the handbrake mech, it shed some light on the 5 points the cables use to apply the required force (one on each swing arm, two on the axle carrier and the one that enters the car) The one that enters the car had snapped, as this take all the force applied to the long cable and all the handbrake cable adjustments. I bought a Porsche 911 - 1978 -83 handbrake spacing tube cut it down drilled it out 2mm to 15mm to take the handbrake cable end and had it welded into place and routed the hand brake cable in and adjusted until it felt good.
Re-assenbleing the in car handbrake mechanisum was difficult as I coudn't find any infoirmation online about how it all came togather, it is not complicated enough to document, but too complicated to remember a year later. I took some pictires just incase I had to take it apart again.
Next was the brake pipes, the long pipe from the front of the car to the rear had already been replaced with some stainless pipes with PTFE cores. So it was just a case of replace the rear pipes with the same. The brake pipes where ordered made to measure by Hosetechnik as the pipes from the rear callipers are hard lines, I only needed two flexi pipes one from the drivers side trialing arm to the T-Junction at the back on the same side and another long one from the same T-Junction to the trialing arm on the passenger side.
