17 hours ago, R_U_AFA said:

Anyway today I found a slight drip from one of the unions that I had disturbed, so that could have been sucking in a little air.

Yes it won't help with brake pedal feel or braking.

 

17 hours ago, R_U_AFA said:

Seen this trick done before, must admit I had forgotton about it, but again it shouldn't be necessary with a pressure bleeder

Could be used with two man method.  Do you know the one man 'sealed' jar method it's the way I've done my brakes and clutch (far too) many times and with  two person method.

 

17 hours ago, R_U_AFA said:

But also I heard somewhere that if you trap air in the master cylinder it's hard to get rid of.

I'm not sure about that, I've also heard and even suggested bench filling and purging(?) a master cylinder but I've never had to do this even when I stupidly let the fluid run too low when flush bleeding.

 

17 hours ago, R_U_AFA said:

Just as a test along this line I could place some shims between the shoes and wheel cylinder it see if it locks up the wheels. Also I will point out that the handbrake does lock up the wheels.

No point in putting shims in as it negates what is being tested.  Presumably the handbrake moves the shoes to the drum somehow so takes up any distance between the shoes and drums.

 

I wonder about the obvious stuff but also at the back of my mind there's a previous issue that someone had with a less obvious cause and I keep thinking it was the shoes but as there have been so many threads on the subject I doubt I'd ever find it - or remember what it was.

 

Good luck, let us know how you get on perhaps nipping up the union will help a lot.

 

Been at this again today, and I have managed to get some better action on the rears, by doing the following:

1. first was to nip up the dripping union(I had to tighten the hell out of it to get it to stop)

But this didn't actually seem to make the issue any better

 

2. I changed the front pads and discs(I ony had about 3-3.5mm left on the pads and discs were worn below minimum thickness)

This just shows how hard the front brakes have been having to work

This did help with the rears a little, not a 100% sure why. (Mabey less fluid in system to have to be pushed around?)

 

3. Started engine

Now this might sound stupid to some of you, but up to now all my tests have been with the engine NOT running, and all the vacuum exhausted from the servo.

This really helped in fact it made the rears go from an estimated efficency of around 15% to 75-80%, This is quite interesting because I shouldn't need the assistance of the servo to actuate the rears, I don't know what this might signify? (slightly blocked lines to the rears, or mabey a servo fault) Any ideas on this one, and why it should be happening?

 

So now I am at least a little better off, I know the rears are a bit better. I'm going to have another fettle around with with it because I still not fully happy with it as it is, and there still seems to be another issue somewhere. And I haven't actually even done any work on the rear brakes today.

As it's so easy and quick to do you might as well test check the servo. -