Brake bleeding after MC replacement - Conflicting procedures

[peteracs]

Hi

Given the orientation of the bleed screws and the pathway to them, it would be very unusual to have air trapped in them.

If you have already tested the m/c on its own, you must have some blanks to block the ports. Try using them to isolate each circuit in turn to see if you can isolate the problem circuit.

You may find it is just one circuit that is causing the problem.

Peter

[JASPER_40]

Thanks for all the good info Guys......appreciated

Regrettably still not solved the problem and still have a longish pedal travel and spongy brakes.

Since my last update, I have added brand new discs / Pads front and rear at a staggering cost !!!! (These items are enormously expensive in Australia and sourced internationally the cost of shipping is almost prohibitive).  The reason for the expense is that the discs, especially rears had a substantial lip and have been machined by the previous owner to well below minimum thickness. I had previously put new pads in the rear and had noticed that the wear on the pads suggested that the contact area was compromised by the lip....hence the new discs.
The discs will definately improve the efficiency of the brakes and may possibly improve the pedal travel...yet to be tested.

One thing I am getting obsessed with is the rear brake compensator valve....which is also new. I had someone operate the pedal whilst I was watching the compensator action and can see that the plunger / piston moves out about 2 - 3 mm with the action of the pedal......surely this will impact the pedal travel ??
Could be I need to adjust it better so that the resistance offered by the "torsion bar" is far greater such that it doesnt allow the plunger to move when the car is level and unloaded. Not sure how much force the plunger exerts upon braking.

My plan is to bypass the compensator valve altogether using a nifty little bypass connector I got and this will tell me for sure if the compensator action is the issue.

I am hoping that the above fixes will get the brakes into an acceptable operational state such that it will pass an inspection. A lot of me thinks that the young lads in the tester station expect that the brakes should be every bit as as good as a modern car....should they be  ?

The saga continues .....

[SanRemo78]

Have a look at the state of all the bushes in the linkage. The ones on my car were falling apart when I dismantled it and are being replaced with new on the rebuild. If they have failed on your car then that might allow the piston to move as the actuator bar can move within the bushes and cause the symptoms you're seeing? You could eliminate the compensator and it's linkage by removing it and joining the in and out pipe feeds together. If that created a solid pedal you're closer to sorting it?

Guy

[WestonE]

Beta Brakes are respected, were very good in their time and normally good for spirited road use. They should comfortably pass MOT testing standards but are not what you get with current generation German Autobahn designed machinery.   

Eric

[JASPER_40]

Have a look at the state of all the bushes in the linkage. The ones on my car were falling apart when I dismantled it and are being replaced with new on the rebuild. If they have failed on your car then that might allow the piston to move as the actuator bar can move within the bushes and cause the symptoms you're seeing? You could eliminate the compensator and it's linkage by removing it and joining the in and out pipe feeds together. If that created a solid pedal you're closer to sorting it?

Guy

Thanks Guy....yep, I found that too that the bushes disintergrated when I tried to remove them so all have been replaced. even then, the piston / plunger in the compensator still moves a couple of mm when the pedal is pushed. I even tried adjusting the compensator to its max tension and the movement of the plunger under braking is still enough to move it a couple of mm.

I wonder if the PO has moved the connection arm from the sway bar to the compensator torsion bar....and so not allowing enough tension to be applied when the car is level. I am 100% convinced that this plunger movement Must surely affect the pedal travel so I need to engineer this movement out by applying more tension on the torsion bar at the compensator or by elimination altogether.

Regardless, my next move is to introduce the simple compensator bypass pipe to conclusively tell me if the 3mm of plunger movement is enough to cause the longer pedal travel and create the spongy feeling.

[WestonE]

One thought if your car is RHD is to look closely at the cross links and pivots from pedal to servo for excess play. The center of the link is LH and RH threaded to allow play to be adjusted out and the pedal ball joint has a cap that can be adjusted in to remove play.

Enjoy!

Eric
PS the Haynes Beta manual has a description on how to adjust the Bias valve for load.

[JASPER_40]

Beta Brakes are respected, were very good in their time and normally good for spirited road use. They should comfortably pass MOT testing standards but are not what you get with current generation German Autobahn designed machinery.   

Eric

Thanks Eric,

The problem is also that I have nothing to compare this to which has this brake compensator valve. It could be that this is how Lancia beta brakes are supposed to be as I am used to the my German daily driver. (as you said)

I need to put the wheels back on and get this thing on the gound for a road test. I am certain that the new discs/pads will make a massive difference and also the loading of the rear suspension could help the tension on the rear compensator.

watch this space....

[JASPER_40]

One thought if your car is RHD is to look closely at the cross links and pivots from pedal to servo for excess play. The center of the link is LH and RH threaded to allow play to be adjusted out and the pedal ball joint has a cap that can be adjusted in to remove play.

Enjoy!

Eric
PS the Haynes Beta manual has a description on how to adjust the Bias valve for load.

Just to address your questions....I am confident the linkage has no play as I have taken a video of the fluid in the reservoir when I very very lightly touch the brake pedal and the fluid is disturbed suggesting to me that the pistons in the MC are sensitive to movement of the brake pedal.

As for the Haynes manual.....have followed that to the letter.

Maybe I need to get the car on its wheels and allow the suspension to settle to see if it lays lower that how I have the brake compensator set up for......might make a difference. My expectation is that the piston in the compensator should not move at all when he brakes are applied when stopped hence you should get a 50/50 brake distribution. When the nose of the car dips under braking then this is when the piston in the compensator should move to lessen the distribution to the rear.

Will test and report back....

[JohnFol]

Are the banjo bolts 10mx1.25

I spotted a link to this in another thread

https://www.ebay.co.uk/itm/131817736572

If so I might replace these bolts rather than risk snapping the bleed nipples.

[peteracs]

Hi John

There is no down side to trying to loosen off the bleed nipples, if they break, they remain sealed. These banjo bolts are a good solution if you do not want to have the calipers refurbished and one does break.

Normally when I have bought replacement break hoses I have received new banjo bolts and crush washers.

Mark also has these banjo bleed bolts on his site, but current showing as sold out.

In answer yes, M10x1.25, go for stainless ones if you can.

Peter

[Nigel]

When I first approached the brakes on my car, the bleed nipples felt very tight.

I used a plumbers torch to warm the caliper, just around the nipple.
All the nipples came free after that. I then replaced them, adding some copper-slip on
the threads.

I'm not sure the banjo bolt bleed option would get all the air out.

Nigel

[peteracs]

Hi Nigel

Yes the banjo bleed option is not ideal as the bleed nipples are direct from the cylinder, however the orientation of the banjo bolts being at th top of the calipers should allow the oil to fill the cylinder and allow the air to escape.

Peter

[JASPER_40]

Hi Guys,

I regret to report that I am still no further on with my issue of spongy pedal with too much travel....lost my mojo a bit with this thing and need to get stuck back in.

My wife is telling be to take it to a brakes specialist and this is killing me as I have replaced the MC, new discs, new braided brake lines, new discs/rotors & pads (originals were contaminated), new rear brake adjuster, tried a bypass pipe for the brake adjuster aswell.....and have spend an embarrassing amount of money on brake fluid as well as a reverse bleeder and also a pressure bleeder. I have zero confidence that a specialist will do anything that I havent done already and I could end up with a bill for thousands with no result.

Anyway,enough of the sob story...

I did have a thought that the symptoms that exist could well be caused by the MC somehow still having air in one of the circuits despite me having bled this on the bench twice. One thing that ocurred to me is when bleeding the brakes uing the 2 man method, the pedal travels all the way to the floor when I open just one of the nipples. Surely this duplex system is a safety feature which still provides braking if one curcuit fails. In this case then I would expect and open circuit to result on the pedal travelling further but still able to operate and stop the car without the pedal going to the floor.

Could it be that there is in fact air still in the front circuit that I wasnt able to purge via bench bleeding ?

Is there a procedure for bench bleeding the MC. I am thinking of leaving the mixed circuit open and dry such that I can put all the effort into fully bleeding the front...

Any advice greatly appreciated....

[peteracs]

Hi

You should not need to bench bleed it. I replaced all items on mine incl hard lines and simply filled with fluid, pressure bled (as on my own) and not had to do anything to them since. Did you ever try isolating individual circuits to establish where the problem is? It may be you have a faulty new MC of course….

[Nigel]

As Peter suggested, the MC may be faulty.

Does your current one match up to either 82293524 or 82369266?

Both these part numbers appear to be exact matches, the latter number
succeeding the former,  and are 22.2mm bore.

The Beta braking system didn't change throughout the years and models so
you can be reassured these numbers are ok.

Nigel

[JASPER_40]

Hi

You should not need to bench bleed it. I replaced all items on mine incl hard lines and simply filled with fluid, pressure bled (as on my own) and not had to do anything to them since. Did you ever try isolating individual circuits to establish where the problem is? It may be you have a faulty new MC of course….

Hi Peter, I got as far as making some capping adaptors to isolate all of the circuits but didnt attempt anything as I realised that i could not bleed the curcuit. However, I have since thought better of this and decided it will bleed ok by loosening the cap and closing it when under pressure. It was about this time my Mojo disappeared !

Need to resume the crusade.

One thing that was curious was that I decided a while ago to securely attach pipes the both bleed nipples on the nearside front and pump the brake pedal with the aim of cycling the fluid around the shortest circuit and then back into the reservoir. The mixed circuit worked fine and the returning fluid was clear and no bubbles whatsoever but the Front circuit had almost a constant stream of tiny bubbles (almost froth like). I took this to be simply air being drawn into the system from the bleed nipple thread.....hmmmm

[JASPER_40]

As Peter suggested, the MC may be faulty.

Does your current one match up to either 82293524 or 82369266?

Both these part numbers appear to be exact matches, the latter number
succeeding the former,  and are 22.2mm bore.

The Beta braking system didn't change throughout the years and models so
you can be reassured these numbers are ok.

Nigel

Hi Nigel,
The part supplied to me by Betaboyz was LM29584 (Delphi) and I have seen that this cross references to the Lancia part number 82369266. The Delphi MC was slightly different to the original Lancia MC that I removed in the respect that it did not have a "piston stop screw" to limit the movement of the piston in the front circuit. I just assumed that the part had been superceeded by a better design maybe ? . The rest of the MC was externally exactly the same as the original. I didnt dismantle the new one as...why would I ?

[JASPER_40]

Hi Guys,

question still stands ....

Using the 2 man bleeding method, the pedal travels all the way to the floor when I open just one of the front nipples. Surely this duplex system is a safety feature which still provides braking if one curcuit fails. In this case then I would expect the open circuit here to result in the pedal travelling further but still able to operate and stop the car without the pedal going to the floor.....On my car, the pedal goes to the floor every time and so not saved by the other entirely seperate circuit......what am I missing ?

I do hear you all and your feedback about a faulty new master cylinder but the brakes actually do operate albeit they are spongy, not responsive and the pedal travel is too long....as in it is not leaking fluid out of the cylinder nor is the pedal sinking to the floor....

Another thing to add is that when I got the car in the first place the brakes were every bit the same as they are now, even after all the work I have done. The oly thing I have not done anything with is the calipers themselves (all operate and the pistons are not seized or leaking)

I can hear Peter screaming at his PC (and I live in Australia) telling me to isolate everything as he suggested.....gotcha...on it

Cheers,

Steve
Cheers,

Steve

[HFStuart]

Using the 2 man bleeding method, the pedal travels all the way to the floor when I open just one of the front nipples.

Is this the case no matter which nipple is open front or rear?

[JASPER_40]

Using the 2 man bleeding method, the pedal travels all the way to the floor when I open just one of the front nipples.

Is this the case no matter which nipple is open front or rear?

Yes, when bleeding the brakes, the rear brake nipples and both the front cause the pedal to go to the floor when open. I would have thought that with this super duplex system that the pedal should never go to the floor regardless of which nipple / circuit is open unless one nipple from both circuits was open.

Hypothetically, if either circuit fails then the pedal should travel further resulting in a mechanical stop for the MC piston in the failed circuit allowing a hydraulic action in the good circuit to apply the brakes. In my situation, the symptoms of long pedal travel and weaker brakes suggest that one of the circuits isnt working which could possibly be be air in just one of the chambers in the master cylinder, rendering it inoperable.