Still got brake problems!

[Geoff Butcher]

Geoff.....thats not how I shortened my pedal (and double welded as its a critical component).

Mine is shortened on the vertical plane. so that the pedal has further travel before it hits the floor. Clutch is shortened to match (on one of my cars).

Your pedal appears to be shortened on the bottom section up to the rubber pedal. It will not make any difference in travel there and will hit floor in roughly the same point.

I can't see or feel any signs of cutting and shutting

[manifold]

Sorry geoff I was looking at you clutch pedal....my error.

Your brake pedal (middle) has not been cut. Its as factory. It needs reducing by 2 inches in depth to allow the pedal to swing further....you will be running out of floor.

Cut in the vertical plane..where it is narrower (by the steering column) by removing an inch from the bottom of the verticle and an inch from the top.

Unfortunately its a bastard to remove the pedal to work on as you need to undo the pedal box.

[Hans Efde]

Okay, I have taken a few pics and measured up a few things.
First, the pedal. My pedal is modified. In resting position the rubber part is 12cm from the floor. It is rock solid when it is 8cm from the floor, so a maximum throw of 4cm, say 1.6 inch.
Here's a pic. of the pedal:

brake pedal.jpg (151.49 KiB) Viewed 12706 times

If you look up in the foot area, you can see the m/c sticking through the base plate (silver), the primary piston is the black cylinder sticking out:

primarypiston.jpg (104.08 KiB) Viewed 12706 times

There is not much room for the clevis and the locking nut, but I could shorten the clevis or primary piston, or half the nut.
Another pic. shows the clevis

clevis.jpg (107.42 KiB) Viewed 12706 times

By the way, in issue 59 of the club mag. I described this mod.

Under the bonnet the lower position of the m/c is visible. The plate is 45 degr. angled and uses the original brake servo holes. The rear brake limiter is almost pointing straight forwards. I had to angle it slightly to the right to prevent the reservoir interfering with the clutch reservoir:

mc01.jpg (151.96 KiB) Viewed 12706 times

mc02.jpg (163.41 KiB) Viewed 12706 times

mc03.jpg (155.81 KiB) Viewed 12706 times

As you can see I carefully rebend the brake lines. They may become brittle when they get old, so be careful with this.
The plate is 11x11cm, the bolts pointing downwards are 9cm apart. I used a piece of cardboard and bolts to make a prototype and then took it to a metal shop for them to recreate. The bolts for the m/c were welded in and then the heads were ground off because the plate has to sit flush on the baseplate.
I hope this helps.

[Geoff Butcher]

Thanks very much, David and Hans, some food for thought there.

[Geoff Butcher]

Latest episode in this ongoing saga: I've found that if I clamp off all four front hoses the pedal hardly moves and feels solid, so that appears to rule out the master and the rears as the source of the problem. If I only clamp the primary circuit, i.e. lower pistons the pedal goes down further than with only the secondary circuit shut off. Therefore the air or most of it must be in the secondary circuit (upper pistons). Question is, how to get it out? My pads are nearly new so the pistons are pushed right in. Would it make any difference to bleed with them part way out? Don't know why it should, but there's only one way to find out.

[Stuart]

Here's a daft question.... You have got your calipers on the right sides of the car with bleed nipple at the top?

[mikeeskriett]

that's a good point I did that when I very first starting playing with cars, you learn very quickly!!!

[Geoff Butcher]

I know I wouldn't be the first, but yes, they are the right way up!

[Hans Efde]

And the bleed nipple is higher than the brake pistons? I.e. you have not positioned the car or suspension in a way that the bleed nipple is lower than the pistons?

[Geoff Butcher]

I wonder if this is anything to do with my sagging pedal problem. These pistons are from the recon caliper I fitted a few months ago after shearing a bleed screw.





It doesn't show very well but there is a distinct witness mark where the seal sits. It doesn't go round the whole circumference but it's on all four pistons. I've seen plenty of rusty pistons but never one with a wear mark, if that's what it is, and not after a few months. I've also never seen this dark grey surface finish, they're always shiny, which I take to be electroless nickel, unless they're stainless of course. Could this somehow be acting as a one way valve and letting air in? Time will tell if the pedal starts dropping, but I don't think I'll be using these pistons again.