Brakes not right

[mickl]

Folks, I had the back brake cyls of my 2 litre Berlina project redone professionally along with the master cyl under the drivers floor. After installation I renewed the brake fluid and bled the brakes. After a bit of pumping etc there seemed to be pressure on the pedal and so they were left about 6 months while I did other work.
I just backed the car out of the shed and the brake pedal had no pressure and but for the handbrake i would not have pulled up.
I have pumped the brake pedal another 30 times and there was pressure again and under slow movement the brakes took up and stopped the car...but with much less effectiveness than would be expected.
I bled the back brakes and they were fine with no air.
The front brakes would not expel any fluid despite much pumping from inside by Mrs Mickl.
I am guessing that the front cyls might now also need work, and possibly the 2 vac assists as well.........but I am new to this.
looking for help from the forum members please.
Mickl

[AikenDrum105]

I feel your pain - I had to change the master cyl on a dual circuit GTV a few months ago, lying under the car on an angled driveway...  I love making a hard job harder for myself.

The best way to troubleshoot them is to work from the master forward - loosening the brake pipe unions a little until fluid weeps out (and air usually too) just like bleeding the calipers - pedal down, loosen, tighten, pedal up etc..   

If the master has any bleed nipples, start there (mine has a large bowl built into the top of the master with a nipple protruding) otherwise start with the front circuit output pipe from the master - once you get fluid coming out there - trace it up to the booster input pipe - bleed the fluid / air out there,  then the output pipe - then the union of the hard line to one of the front flexible lines,  then the flexible line to the caliper, and finally the bleed nipples.

I think most of the mechanics use a pressure feed system to force the fluid down from the reservoir bottle - keep the pressure on and bleed through at least to get the master primed...  I think someone on the alfabb or here bought a cheap garden weed sprayer bottle/pump  and managed to use that to pressurise the system.  This of course applies pressure to the rubber hoses from the bottom of the reservoir which normally only have gravity working on them - watch for leaks if you do this.

A quick check too - if the Berlina has a pressure-driven brake light switch - they run off the front circuit - if so and the brake lights come on ok - then it starts to point to collapsed flexible lines or gunked up calipers in the front.

If you just can't get that front circuit to prime down at the master end - it's possible the master has been assembled incorrectly inside.. - there's some great diagrams of both the bonaldi, benditalia and ATE master cylinders on the alfabb that I used when rebuilding the one for the GTV...

I hope that helps a little at least   Other more knowledgeable folks may chip in with a much simpler way to go through it that I've missed....  I hope so !

[mickl]

Thanks for the detailed response Scott. I have been in the shed today to work it out but this is what I found:
  Master cyl: No bleed nipple but there is a screw on the top of the unit facing out. I loosened it and tried some brake pressure but no fluid or air was coming out so I retightened it and went elsewhere to:
  The vac assist unit which is nearest the firewall appears to be for the rear brakes and there is fluid at both inlet and outlet.
  The vac assist closest to the front had no fluid at either the inlet or outlet however, when I pressed the pedal with the pipe which connects to the body of the unit removed (not the pipe which fits to the circular end) then a very small squirt of fluid was emitted when the pedal was released quickly. There is no fluid expelled when the pedal is pressed down, only when it returns quickly, and just a very small amt emitted.
  Tee piece attached to firewall....this fitting has two elec wires on top and takes the pipe from the circular end of the forward vac assist, then splits the fluid into two pipes with one pipe to each wheel. Nothing in these connections either..no fluid.
Back Brakes: after bleeding the back brakes the pedal pressure is nil. On pumping the pedal a few times the pressure builds and the pedal gets harder...........but the back brakes both lock on and the only way to release them is to rebleed some fluid from each wheel. This doesn`t sound right at all.
   I haven`t removed the front calipers to see if they are Ok but there seems no point if fluid is not getting anywhere near them.
Any suggestions on whet to do next?

Regards Mickl

[AikenDrum105]

That is weird...

I guess - if you can't get the master to pump fluid around the front circuit it's probably not worth worrying about the rear circuit locking on until the master is sorted.

For the front circuit of the master cylinder - loosen the hard line coming from the reservoir where it screws into the master and check fluid can run out there under gravity,  then tighten that up, and loosen the hard line on the master that leads to the T-junction and let any air out of that just like bleeding a caliper.  If you can get fluid coming out there under pedal pressure  then the master might be ok -  then move up to the input port of the front booster again and see if you can get it up there.  If you remove the pipe completely - remember to block the end with your finger when releasing the brake pedal - so you get suction just like bleeding the caliper.

If you can't get fluid coming out of the front output port of the master then you're probably going to need to take it out and pull it down to check it.   I've had *two* new aftermarket master cylinders from different suppliers fail to bleed in the last 5 years - they just needed a very quick light hone to get them to work perfectly - some of the protectant they spray them with had hardened inside the bore creating a little lip/ring that the seals had to bump over - letting pressure past in the process - if you pull it down and it's nice and clean inside, and the assembly order is correct  - perhaps try a quick hone with some 800 or higher grade wet/dry wrapped around a pencil in a cordless drill (works like a flappy sander)  +  WD 40.  Clean it all out with brakleen after of course. 

Oh -  The bolt you loosened on the side might be the lock-bolt that holds the pistons in place between the front / rear circuits,  it might be possible to tighten that and jam the piston if it's not centered (but the bolt won't go all the way in if so -I think-  )  which might cause the rears to jam if they didn't before you started testing.

Re the locking back brakes - if it's not the master misassembled / seized inside - you could check the booster - pump the brakes up so they lock,  then loosen the *input* port of the back booster and see if that lets a little pressure out  and unlocks the brakes.   if not - try the *output* port of the booster.

If the input releases it - the master is likely at fault, if the output releases it - the booster isn't releasing pressure and is likely at fault.

If neither make a difference - try letting the pressure out where the rear flexible brake from the body to the diff meets the T-junction on the diff - if that releases the brakes the the flex line has swollen inside so much that hard pedal pressure will get through, but light return pressure will not.  I had one on the Duetto that was like that - they would drag for 20 seconds or so after releasing the brake.

I hope that helps - I remember stuffing around with the duetto on the first odd master I got,  and bleeding it so often I was just pouring the clean fluid out of the bleeder straight back in the reservoir - rather than keep wasting it.

The worst bit is trying to keep that fluid off the engine bay paintwork ....  nasty stuff.

Cheers,

[mickl]

Thanks again for some great help Scott.........I have been getting very dirty and frustrated these last couple of days. Progress on suggestions is:
1 There are two hard lines from the reservoir, (both lines are bigger diameter than the pressurised lines out of the master) and i loosened each (not removed) at the master and both leaked out brake fluid so retightened. The lines from the reservoir go into the furthest forward part of the master and the third one back from the front. Now, the furthest back line leaving the master (smaller diam) leads directly to the front brakes vac booster and enters it from the side and there is fluid there when loosened off at the booster.. so hopefully the master is OK? (the line from the master does not go to the Tee junction in this car). The outlet from the front booster which exits at the end of the unit leads to the driver side top of the Tee junction where there is only a small squirt of fluid coming from the loosened Tee inlet on release of the pedal. The passenger side of the Tee (fluid present at Tee) goes to the left wheel where there is no fluid.  The bottom outlet from the Tee also has some fluid at the tee but again there is no fluid at the right wheel.
Sooooo does this all mean that the lines between the Tee and each wheel are gummed up? How should I clean them out if so as the manual says not to use compressed air?? Or is there some other problem?
2 The back brakes locking on: I pumped them up and the pedal is hard and then i loosened the input on the booster...fluid leaking out much more than it had previously with the front booster in  above. Retightened and brakes still locked on.
I loosened the output of the back booster and again fluid leaked out readily so I retightened and sure enough the back wheels were now turning freely and the pedal was able to be pushed to the floor with negligible resistance.  So I guess I am up for a new back booster at least.

3 I think that is all nowso maybe I am getting close?
best regards
Mickl

[AikenDrum105]

Thanks again for some great help Scott.........I have been getting very dirty and frustrated these last couple of days.

No problem - you'll laugh,  but I'm chasing some air in the front brakes of the super at the moment -  my ATE karma must be low...

Progress on suggestions is:
1 There are two hard lines from the reservoir, (both lines are bigger diameter than the pressurised lines out of the master) and i loosened each (not removed) at the master and both leaked out brake fluid so retightened. The lines from the reservoir go into the furthest forward part of the master and the third one back from the front. Now, the furthest back line leaving the master (smaller diam) leads directly to the front brakes vac booster and enters it from the side and there is fluid there when loosened off at the booster.. so hopefully the master is OK?

Yep - sounds like it's doing it's job.

(the line from the master does not go to the Tee junction in this car).

You're absolutely right - my mistake - the T junction is fed from the booster output - sorry to muck you about !

The outlet from the front booster which exits at the end of the unit leads to the driver side top of the Tee junction where there is only a small squirt of fluid coming from the loosened Tee inlet on release of the pedal.

fluid coming out on Release is odd...  however ...

The passenger side of the Tee (fluid present at Tee) goes to the left wheel where there is no fluid.  The bottom outlet from the Tee also has some fluid at the tee but again there is no fluid at the right wheel.
Sooooo does this all mean that the lines between the Tee and each wheel are gummed up? How should I clean them out if so as the manual says not to use compressed air?? Or is there some other problem?

If you've loosened the join between the right and left T lines and their flexible lines in the wheel arch and get no fluid there - a spray tin of brakleen and some thin wire to poke through the hard lines might get them moving again, once you can get fluid through - maybe fill them with brakleen and plug the ends and leave them overnight - you could probably take them off and nip into a brake place and have nice new ones bent up to fit instead... - the one under the carbs is a bit hard to get in out with the carbs installed

If that join is ok, and the blockage is in the actual flexible lines - They're a consumable - they're not expensive.    If you were desperate - you could try unblocking them as above - but I'd replace em.

If the flex lines are ok - perhaps the front calipers are completely rusted / seized inside - can you retract the pistons / push the pads away from the discs ?

I loosened the output of the back booster and again fluid leaked out readily so I retightened and sure enough the back wheels were now turning freely and the pedal was able to be pushed to the floor with negligible resistance.  So I guess I am up for a new back booster at least.

It sounds like it - the booster shouldn't hold pressure against the brakes once the pressure is relieved on the input.  A friend of mine had a little pipe made up at a brake place to bypass the boosters when he was troubleshooting - cheap way to make sure... you could swap the front / back boosters too I guess.

You can also undo the large clip around the booster and separate the halves to reveal the rubber diaphragm and it's pushrod.  see if that rod is seized in it's bore.  (if you pull it all the way out you'll probably get brake fluid coming out - just fyi - there's a good exploded diagram on the alfabb I think)

3 I think that is all nowso maybe I am getting close?

I hope so   whomever is assistant pedal - pusher must be owed a lot of beer / sweets / backrubs by now....

I hope that helps and I'm not running you in circles !

Cheers,

[mickl]

Scott
You have been a great help with this problem..sincere thanks.
The front pistons are stuck solid so they will be removed and professionally refurbished. The guy at the brake place also agreed that the back brake booster was in need of an overhaul which was likely to cost about $275 or maybe $500 for a new one but he would need to see the unit on his bench. Needless to say i will be taking the cheaper option if it is repairable. Just hope the front brake booster is not shot like the rear........it will double the value of the car once these things are fixed!
Best regards
Mickl

[AikenDrum105]

Hi mate - no probs,  glad you got to the bottom of it !

I know Milano Spares offer reconditioned boosters on a change-over basis (with warranty)  so that might be an option for you (The one on my Super is a reco from there) - They come up well - and are re-plated (I think cad plating is illegal now, but they look the same...). 

Let us know how you go !