Brakes won't bleed up.

[PeterTR7V8]

Frist of all, #$*&($@#$#&@%!!!!

Right then. I had the calipers from my front brakes serviced before Christmas & when I put them all back together I couldn't get a firm pedal. After a lot of bleeding I could get it to firm up but only near the end of the travel & the test drive was not a happy experience. To get the car to stop I had to pump the pedal 4-5 times each time.

I got a length of clear plastic 5mm tube & ran it from the caliper back to the master cylinder (the fuid in the system was completely new by now) & pumped the brake pedal. The driver side coughed up a couple of bubbles then ran clean. The passenger side produced a bubble with every pump for several minutes & never ran out of bubbles.

These calipers are Austin Princess type each with 3 bleed valves (I bled from all 3).

So could there be something up with the caliper that is allowing air into system? Would it be entering through the piston seals? There doesn't seem to be any obvious leak.

I'd appreciate any wisdom before I take the caliper back to the reconditioners.


Never say die. At least not while you're still breathing.

[Jolyon39]

I have the Austin Princess Haynes manual. Do you want me to send you a copy of their references to this calliper and bleeding?

These callipers have two inlet hoses. Do yours still have two or have they been cross drilled?

Jolyon

[saabfast]

I assume that you bled all brakes including the rear (stupid question I know, but to eliminate the obvious). I always use a pressure bleeder (Gunson Eazibleed) to chase the fluid through and get rid of air. It still tends to take several bleeds to completely clear the rear (original with cross tube and single bleed nipple). Also remember to take the failure warning switch out from the bottom of the mastercylinder before bleeding.

Alan
Saab 9000 Stg 1
Saab 9000 2.3 FPT Auto
'81 TR7 DHC

[PeterTR7V8]

The inlet is on the inboard side with 2 bleed valves at the top. On the opposite side of the caliper positioned slightly higher up is the 3rd bleed valve. I assume from this that they are cross-drilled. Using this old picture as a reference it's all plumbed up the same as it was before.



If you are able to beam the info then I'd be very grateful.


Never say die. At least not while you're still breathing.

[Marko]

peter could you describe your bleeding technique?

[PeterTR7V8]

Method 1: connect short tube to bleed valve, get lovely assistant to pump & hold brake pedal (although sometimes clutch - don't ask!) while I direct flow of oil into bottle & co-ordinate open/close of bleed valve.

Method 2: connect long tube to bleed valve & stick other end in master cylinder reservoir then I pump pedal while watching the stream of bubbles in the tube.

Both produce the same, inadequate result.

Today I have connected the tube to the solid brake line ie, before the caliper & still get bubbles so I've removed the master cylinder & will investigate replacement or repair. FWIW it has a bunch of numbers on it then it says 7/8 but it looks like the pic below.




Never say die. At least not while you're still breathing.

[Marko]

thats ok , try to see if the system holds pressure? ,


just press on the brake , try to hold it down as long as you can, if it gets to the floor you ether have a leak or master cylinder is on its last breath

[saabfast]

Peter, Method 2 is not ideal as you are putting aerated fluid back into the system. Also note that the failure warning switch is still in position (not sure why but you are supposed to remove it for bleeding, I assume it allows the little piston in the bottom of the m/c to move). The bleeding did start from the rear brakes? Looks like a non standard adjustable compensator fitted, might be worth setting it to full front (counting turns)to flush any air out?

Alan
Saab 9000 Stg 1
Saab 9000 2.3 FPT Auto
'81 TR7 DHC

[PeterTR7V8]

Both methods produce the same result but method 2 is a lot faster. I have done some research & might look at building a pressurising gizmo for future bleeding efforts. My intelligent [:p] use of the Search feature on this forum suggests I have a worn master & that with dual pot calipers I should upgrade it in any case. The pedal travel had always been a tad longer than ideal. The No.1 choice would be a Sherpa but is not practical due to unavailability in NZ (did you ever find one Jolyon?) but the No.2 choice, SD1, should be easy to find. The problem will be finding someone who can rebuild them over the holiday period as most places are closed until Jan 5 & I have a club run on the 3rd.

Does the Volvo conversion require much work?


Never say die. At least not while you're still breathing.

[Jolyon39]

Hi,

I never did find a Sherpa in New Zealand.... they used to be here but they do not exist here now.

I have a rebuilt MK1 SD1 master sitting here, it has to match with the correct Booster so some mods to the firewall holes are required I think. I also thing that the pushrod needs work, lengthening I think.

I will have to dig around for it but I think I have both the master and the booster.

Send me your new address and I will ship it all to you now so you have a few hours before the 3rd... bit of a push I bet but we could do it. Sort me out later for it all.

I also have a brand new Mk2 master and booster (Booster might be second hand). I am not sure if the Mk 2 fits easily and purchased this first.

Email me or call

Jolyon

[john mc nulty]

I have fitted a MK2 SD1 booster to my car had to cut and weld the push rod to fit onto the brake pedal its about 40mm to long Dont know how well it works as yet as the car is a project and not up and running yet.The booster is big just fits in but no work required to alter the firewall. I have done the volvo upgrade also hardest part getting someone to make the spacers. Peter look at the post about the guy putting soarer V8 in he has done a conversion using VT commodore callipers and WRX disks looks very easy.It explained in the V8 section.

[PeterTR7V8]

A reconned master cylinder from Jolyon & a proper bleed has restored my brakes to their usual peak efficiency. Thanks for all the help.

I didn't put the SD1 booster that Jolyon sent me on because I wasn't able to shorten the pushrod in time & it looked like it needed a bit of work. The SD1 booster is nearly twice the size of the standard Triumph booster.

Conclusions:

One-man bleed kits are not as good as the 2 person method.
If you are going to go to the effort of reconditioning your callipers then do the master cylinder at the same time.
Make sure you have twice as much brake fluid than you think you'll need when you start.


Never say die. At least not while you're still breathing.