Rear brake imbalance MOT fail

[cookie79]

After 9 years off the road & a 2 year restoration project I finally got to the stage to take my G for her 1st MOT since 2005 & more importantly was buzzing to be able to get back behind the wheel, unfortunately it failed on a rear brake imbalance across the rear axle. Everything on the rear is new, drums, shoes, braided hoses, wheel cylinders, & I had to make up new rear brake lines back to the compensator because they had corroded.
As far as my mechanical ability goes I'm ok at removing old stuff & putting on new stuff so really I wouldn't know where to start with rectifying this problem.
Could it be the compensator, or as far forward as the master cylinder? Or perhaps could it be my homemade copper brake lines? Maybe the flaring on their ends not allowing fluid though.
Goes without saying any help is greatly welcome, & if it's in the form of a step by step idiot guide then that's even better.
Cheers

[Andy]

Without knowing the exact details of the failure (what were the measurements?), I'm guessing - but most likely just the rear shoes need adjusting/bedding in on the new drums. Reverse at speed and slam the brakes on usually sorts them. I had a similar issue as I'd only done 2 miles to the MOT station since renewing the entire braking circuit.

[cookie79]

Very up helpfully it doesn't say on the MOT fail sheet what percentage the imbalances were.
What your saying does make sense, so I'll try bedding some wear in on them.
Cheers

[PeteG40]

Could be one side hasnt bled properly?

[GR40]

The rear drums are adjustable via a little wedge, are you sure you adjusted them correctly after replacement? If one is further away from the other it will cause uneven braking! Had that problem before!

[cookie79]

With regards to bleeding I was satisfied that I had bled them properly, but I did notice a little leak before the MOT, just needed a tighten to stop leak, so I thought I'd bleed it all again & I had very little luck bleeding the rear, I did read on here somewhere about cable tie the compensator in order to assist with bleeding the rear so I also have that to try.
When I put the drums back on I made sure that the shoes were adjusted so that the drums just about push on. Is the adjustment wedge the part I've circled in this pic?

[cookie79]

Forgetting my manners, thanks for all you help & suggestions 

[Andy]

Yep, that's the adjustment wedge - but they are little bastards for moving when you re-assemble things! You can lever them with a screwdriver through the wheel bolt holes in the drum, but I find the reverse-at-speed/slam-on method works fine too.

If they were a pain to bleed, always worth checking that the brake line unions are all good - if any of the flares are very dodgy that could be restricting fluid flow.

I hate flaring pipes, and was too tight to buy a proper flaring tool (at circa £450) - so tried in the past with one of my two motor-factor cheapo special flaring kits. They were fine for making a one-off repair, but I chickened out in doing a full new set of lines and bought an off-the-shelf kit from these guys: http://www.automec.co.uk/.

[cookie79]

Yes I also used a cheapo flaring tool I borrowed without any experience of using it so I am a little worried that my homemade brake lines could be part of the problem. The leak was on the union between one of my copper lines joining the braided hose to the drum, I tightened it up which stopped the leak, & now I'm thinking maybe my caveman approach has just mashed the flare & stopped it passing fluid appropriately.

Cheers