15 replies to this topic

[evl666]

The fronts just won’t bleed down
Back bleed easy as with the vacuum bleeder
Reco big nut master rebuild calipers and new lines
Vacuum bleeder just won’t draw fluid
Master cylinder was bench bleed and flowed well
Calipers are on the right way
It’s doing my head in!!!!!!

[bat 53]

try the old way ' pump pedal hold down crack bleeder 

[dron]

If the old way will not work (and it should) try a tom thumb pump and fill the resovor by pumping fluid in an empty system from the bleader on the calipers. Works when most other wasy to bleab a system fails.

[dattoman]

Check master to booster clearance

[evl666]

Ok guys here is an up date....so I’ve got brakes, rears feel strong as they should but the fronts grab weak but I can still just turn them with the wheels on and the pedal still goes to the floor. So is there air still in the system or is the master cylinder stuffed?

Edited by evl666, 03 March 2019 - 04:24 PM.

[S pack]

Ok guys here is an up date....so I’ve got brakes, rears feel strong as they should but the fronts grab weak but I can still just turn them with the wheels on and the pedal still goes to the floor. So is there air still in the system or is the master cylinder stuffed?

Pics of your calipers please show us your nipples.

Edited by S pack, 03 March 2019 - 05:02 PM.

[evl666]

Calipers are right and so are those nipples!!! I clamped the rubber brake lines and there was no change in pedal so tell me if I’m wrong but that means my bignut is stuffed?? I just pulled it off to have a look and it was leaking a tad from the rear. I put new seals but looking at the piston I think they are slight flat so I’ll hone the sleeve and replace the pistons and seals again and have another crack. Dattoman what’s the part numbers I’m after? I’m sure you know them!

[S pack]

OK, I shouldn't have doubted you about the calipers. Sound like you are on the right track, however, you said in your 1st post the M/Cyl has been reco'd so I ruled out a m/cyl problem.

 

Cheers

Dave.

Edited by S pack, 03 March 2019 - 06:45 PM.

[evl666]

Well it has...it’s been resleeved with new seals. It’s been sitting like that for about 3 years before I put it on the car. Like I said the pistons look worn on one edge so I’ll replace them and go again. It’s be very frustrating as this is the last mechanical part of the build I need to sort then I’m on the home straight with the interior. Can’t figure why it’s being so difficult to bleed the system then getting good flow at the nipples, getting some brakes at the front but pedal still won’t take up pressure

Edited by evl666, 03 March 2019 - 07:03 PM.

[RallyRed]

Datto knows brakes....did you check that clearance mate.

Edited by RallyRed, 03 March 2019 - 07:33 PM.

[evl666]

I checked the clearance...the rod is the right lc length....about 10mm past the booster face. I think that’s correct. Just seats nicely in the inside of the master cylinder when it’s bolted up

[rexy]

Try adjusting it shorter. It’s easy to get wrong. Ask me how I know...

[evl666]

I would have thought that if I went shorter it would give the pedal less throw therefore less pressure in the cylinder to push the brakes?

[S pack]

I believe the correct measurement for the LC pushrod is 7mm protruding past the face of the booster canister (Neil correct me if I'm wrong). If the pushrod is too long it may be activating the primary piston when the m/cyl is bolted up to the booster.

Edited by S pack, 04 March 2019 - 06:05 AM.

[evl666]

Alright guys....I honed the master cylinder bore and it appears one of the seals had a cut in it....replaced seal, bench bleed master, adjusted booster rod (out by 3mm) and re installed. I have a pedal that’s works/doesn’t go to the floor and it appears my brakes are now working. It’s a miracle!

[S pack]

Alright guys....I honed the master cylinder bore and it appears one of the seals had a cut in it....replaced seal, bench bleed master, adjusted booster rod (out by 3mm) and re installed. I have a pedal that’s works/doesn’t go to the floor and it appears my brakes are now working. It’s a miracle!

Coo el