Thread: 80in brake bleeding?

If you have trouble with regular bleeding, you could try reverse bleeding, by using a syringe and forcing fluid back through the master cylinder.

Start at the most distal cylinder, which in the 80" is the front left, then front right, followed by rear left and finally rear right. Lower the level of the reservior between each cylinder.

Still not happy with mine either so bought a hand vacuum bleeder on ebay. Should be here soon.

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A few of further suggestions -

Clamp off all three hoses - should have a rock solid pedal. If not investigate why, remembering it is possible to bleed it at any union.

Release rear hose, bleed rear brakes, LH first. Reclamp the hose (gives more flow for other cylinders). Repeat for the two front wheels.

When pumping the pedal, do so vigorously - faster flow will carry the bubbles out better.

If the brake shoes are cocked sideways at all, this will make it impossible to get a decent pedal - see manual.

Hope this helps,

John

When doing my 86" brakes some years ago the father-in-law (who worked in the brake industry) helped.

2 techniques he used were
Really stamping on the brake pedal (me underneath undoing the bleed nipples), seems to get the air bubbles moving.
Pumping the system up. He pressed the pedal hard to pressurise the system then I opened the nipples.

Still couldn't get a firm pedal so we clamped off the hoses one at a time and tracked it down to the rear brakes. Turned out the linings didn't fit the drums properly and were only making contact on a very narrow area at one end (shoes were trying to bend). Filed the linings to suit the drums and finally a firm pedal.

One tip he received later on was to be careful when reassembling the master cylinder. There are 3 (from memory) small bleed holes in the piston, make sure one of them is at the top when assembling as this allows the air bubbles an easy way out....

All the above was on an 86", not sure how different the 80" brake system is.



Colin

Good advice Colin - I have used the stamping-on-the-pedal technique to good effect on S2 and 3 as well,

Cheers Charlie

Charlie,

I remember when researching bleeding the brakes on my Series 1 I got a bit concerned. I read that you had to lift the front of the car in the air (or park it on a steep incline), vacuum bleed etc. turned out a bit easier than I thought.
Mind you the FIL's bother in law is Jack Pearce's son (PBR director) and they worked together in a small brake business so brakes are in his blood.

The FIL told me a story of rebuilding a 3 leading shoe system on an early race car. Spend days removing all the lost motion in the linkages, set the backplate up in the lathe with the shoes held in place, machined the linings to match the drums. Customer phoned up once they were installed and complained that the brakes juddered and were worse now that they had been overhauled.
Quick trip out to the customer, agreed there was a problem, got him to drive along slowly and apply the brakes while someone walked alongside the vehicle to see what was happening. Turned out the brakes were better than they had ever been, the problem was.......the chassis was twisting then releasing causing the judder.
Father-in-law took the brakes back and fitted 'cardboard' (dead) linings and the customer was a happy chappie....

The FIL ran an 80" series 1 back in the 60's. He suggested fitting adjusters to the shoes was a good idea because as standard as the linings wear the pedal gets closer to the floor. Pedal touches the floor under panic braking, time to re-line the brakes...


Colin

I made up a fitting that replaces the tube from the remote reservoir to the master cylinder to which I then connect a garden pressure spray unit,put in some brake fluid and pressurise then go around each wheel cylinder and bleed,works well and very little wasted brake fluid.I also found that pumping the brakes when first starting to bleed sometimes doesn't produce enough pressure to lift the bleed nipple ball off it's seat and allow bleeding as the ball has a tendancy to stick.