121 replies to this topic

[sibhs]

Hi Guys,

Trying to sort my brakes out. All original specs, as near as possible anyway.

Recond booster

Recond Big nut Master, with new pistons and seals

New rear brake shoes and slave cylinders.

Skimmed drums

New pipe work

Proportion valve cleaned and new o rings

Brakes bled from furtherest to closest. 3 times

 

Fronts seem to grip tight but only slight pressure on rears, can still turn wheel by hand with max pressure on pedal.

Took drums off and pressed pedal gently and they work but after the pedal has been depressed a couple of inches.

Adjusted handbrake star dial thingy so brakes just gripping with handbrake off.

 

Also when bleeding rear brakes with the lid off Master cylinder there is a squirt of brake fluid shooting straight up from front reservoir.  Is that normal?

 

Any ideas.

My guess is master cylinder, something wrong in there.   

After it was assembled I did remove big nut to fix a leak, use a smear of gasket goo on new aluminium washer to fix. then re fitted big nut.

 

Cheers

Marty

[S pack]

I suspect you have a seal installed the wrong way around in the M/cyl however Datto may be better able to pinpoint the problem.

 

Cheers

Dave.

[Kevrev]

A friend of mine had a similar problem with his Monaro, the rubber brake hose to the diff had collapsed internally and was blocking the flow of fluid to the rear brakes. 

Cheers Kev

[xu2308]

My GTR did that, where u top up the fluid for the rear brakes was low on fluid, so might be that, but Daddo is a Brake Guru, so he will know more

[UCSLE]

Maybe the wrong slave cylinders , too big ? . Do you know there part numbers ?

[73SUNBURSTEXYOUWON]

make sure you have no line clamps on. . Hahaha, i had a mate had some rear brake work done on his car, and the rears were not working, so i go have a look for him, and found a black line clamp, left on by the repairer, being black too, it was hard to spot.

[sibhs]

Ok, no clamps on.
New rear hose, so that should be good.
Rear slaves are smaller than what used to be there when car was drums all round. Datto got those for me so they'll be right.

When I use handbrake wheels lock up tight so pads are gripping.

[dattoman]

Shoes standard , drums oversize ?

[sibhs]

Did think of that but thought cause the handbrake worked they are ok. But I think handbrake pulls out bottom of pads and hydraulics push out top.
How do I check?
Spose measure drum but how to check pads?
Cheers
Marty

[hanra]

Not sure if it would effect anything but is the brake fail warning switch out when your bleeding?

[UCSLE]

when you converted it from drum to disc was it the same master cylinder , if so did you remove that valve thingy and did you remove it from the correct brake line ?

[rodomo]

Pull a shoe off again and see how it fits in the drum radius wise. Smaller wheel cyls will give less brake effort. And what ^he^ said too.

 

Er and the other bloke re brake switch..........................do they bleed normally?

Edited by rodomo, 23 October 2014 - 09:23 PM.

[sibhs]

I Left the brake fail warning thingy IN while bleeding. Should it be out?
When converting master to drums I fitted spring valve to rear and no valve to front, both then had the brass/copper fitting pressed in.

Disregard what I said about new rear slaves are smaller than what used to be there. I don't know the answer to that. I was comparing them to the old front drum slave cylinders( they're massive)

Thanks for all these replies and ideas, bit hard to check some things while no son or wife to help.

Marty

[sibhs]

Looking at this spare valve and trying to understand it.
Wouldn't fluid piss out if warning unit removed while bleeding?

[sibhs]

Bit more studying, looks like the warning sender is protected from fluid by the two "o" rings.
What triggers the warning, does it just earth out somehow?

I think if sits in this position.

[sibhs]

Can't work out what this slot on end of thingy is for? Where the screw tip is.

[rodomo]

It works on pressure difference between the front and rear circuits. If the front  had pressure, eg no leaks, and the rear has a leaking wheel cyl, the shuttle valve will move and trigger the brake warning light. (Piston moves and dick on switch drops into annular groove on piston and turns light on)

 

So...................................While you are bleeding the brakes, you will have a pressure difference, the shuttle should move (if it's not seized) which will trigger your light AND trap the shuttle in that position until the switch is removed and the pressure difference neutralized after bleeding is finished (providing all is well at the wheels)

 

Basically? Bleed brakes with switch removed.

[sibhs]

Thanks R.O.B. that makes sense. So that dick thing must be spring loaded.

I'm washed up and inside the house so will check and bleed without that sensor tomorrow or Sat.

 

Cheers

 

Marty

[hanra]

Yep. The little end of it is spring loaded.

[S pack]

Also when bleeding rear brakes with the lid off Master cylinder there is a squirt of brake fluid shooting straight up from front reservoir.  Is that normal?

 

 

Cheers

Marty

I don't believe that is normal. Well I've never experienced fluid shooting straight up from a reservoir during bleeding however I always sit the lid on during bleeding but it isn't locked down. If fluid was squirting up and hitting the rubber seal I would expect some fluid to escape and run down the outside of the m/cyl but it has never been a problem.

[jd lj]

I recently fitted a reco big nut master cylinder on my car and while bleeding the system there was fluid squirting up from the master cylinder, I also wondered if it was normal or not. It's a bit of a concern when you've just resprayed the engine bay, even though everything was covered up.

[sibhs]

Thinking about this warning prop valve. Before I waste another half bottle of fluid.
I don't think removing the warning sender is going to make any difference. It doesn't change pressures to fronts or rear. IMO.

Can anyone confirm outright that having warning sender in when bleeding could cause any problems?
All I think it could cause is the warning light to come on.
Cheers
Marty

[gad05]

Just reading my Gregory's repair manual, no mention of removing warning switch when bleeding .

Cheers Graham .

[S pack]

Thinking about this warning prop valve. Before I waste another half bottle of fluid.
I don't think removing the warning sender is going to make any difference. It doesn't change pressures to fronts or rear. IMO.

Can anyone confirm outright that having warning sender in when bleeding could cause any problems?
All I think it could cause is the warning light to come on.
Cheers
Marty

Removing the warning light switch or not won't make any difference to brake line pressures or fluid flow. Removing it during bleeding simply prevents the warning light coming on and consequently having to remove and refit the switch to reset it.

 

BTW, it isn't a proportioning valve, it is simply a brake line junction block designed to contain a brake fail warning switch.

Edited by S pack, 25 October 2014 - 09:28 AM.