Saturday, October 30, 2021

Broken brakes back

 OK so they weren't 'broken' really but they were in need of attention through the passage of time. Because top quality components were used with silicon fluid and the car had been stored well, the brakes were in amazing condition although the pedal did hit the floor and stay there - a minor issue :-)

Here's the set-up. We have a Tilton "over hung" pedal box with three master cylinders. Twin masters for the brakes (front and rear) with an adjustable bias arrangement - that's the red cable on the left of the picture above. This red cable leads to a knob on the dashboard and means that you can alter the front/rear bias from the drivers seat. The clutch pedal is also part of the pedal box arrangement - this leads to a Saab annular release bearing, the bleeder you can see near the right hand master is a remote bleeder for the clutch . All this is all fitted into the pedal box which is in turn fitted into the reworked bulkhead. Master cylinders are Girling and although I couldn't tell until I had disassembled it all, they are all identical 0.7 bore - same as GT6 brakes.

Pedal box stripped out of the car (above) it's a nicely made thing, cast alloy and vert durable. The only thing I'm a little unsure of is that there's now trace of any return spring on the brake pedal, it relies on the internal master cylinder springs. A test drive is a long way off but that will tell me for sure if this is acceptable. It was not the easiest of things to get out due to space limitations in the driver's footwell!

Three times the fun, here are all the masters stripped and ready for new rubbers. The actual seals were fine but the little valves at the opposite ends were knackered, basically they were the consistency of a wet wine gum. All replaced with new now. The bores of the masters were perfect, no corrosion, scoring or any marks at all. These are proper Girling components, not Chinesium copies. It's worth pointing out that in the above picture, I have just dismantled, not cleaned anything.

The front callipers are Alcon with alloy hubs and grooved discs, again all good quality stuff. I've de-rusted the discs and expected to find them pitted and unserviceable but they are great. The callipers and pads have not seen much action
My plan is to take the pads out and see how the pistons are, they should operate OK after I bleed the brakes - if all is OK then I'll reassemble and run with it like this. I should be able to tell/see if the seals are OK but bearing in mind the quality of the components and the lack of work done I'm confident we'll be fine.

Rears are standard stuff but all new when the car was built, I intend to flush it through with fresh silicon fluid and go from there. The wheel cylinders are available (I haven't seen seal kits for a while now) so at the first sign of any issues, I'll replace them all. The brake lines are all Aeroquip Teflon lines with stainless couplers so they are fine. The only thing I might change is the brake light switch - it's currently fitted into a bracket that covers the pedal - I can't see how to remove the bracket so I had to remove the pedal from the pedal box in order to get the box out. It's also quite exposed and I think would be prone to damage. If I do put a hydraulic switch in, it would only work on one circuit, which is fine but I'm not sure if that's legal - I guess if I put it on the front brake line that would be OK. That would mean I could put the switch in the engine compartment and hide the wires -would make for a tidier installation and easier removal of teh pedal box (not that I intend to do that again!)

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