Series 2a new brakes spongy

I like to think that I'm an experienced mechanic, but the solution to this problem has eluded me.
I've bought my lad a 1962 2a 88" for his 16th birthday, something for us to work on together as he learns basic engineering skills. The car has been off the road for 16 years, so we've replaced the complete braking system, partly on safety grounds, and partly as a learning exercise.

So, new master cylinder, reservoir, kunifer pipes, wheel cylinders, shoes and drums.

The system is well and truly bled, but to achieve any sort of pedal feel takes four or five pumps, then the brake pedal moves up and down considerably when the wheels are rotating.

I suspect that there is not enough displacement of fluid in the master cylinder to take up the free play in the system, before the brakes start to act, and also that one or more drums are running eccentrically. Checking the drums, which appear to be well made, they are not oval, but the hub mounting hole is a couple of mm larger than the old ones, which may allow it to fit non-concentrically. Looking at the brake shoes, they aren't touching uniformly, but I'd expect this to some extent, before they bed in. Or are they the wrong radius and having to flex excessively before they work?

Has anyone else experienced similar problems, and how did you fix them? The parts are from a combination of manufacturers mostly via R&C 4x4.

Thanks!

When you say hub mounting hole, do you mean the hole in the middle of the drum? If so, this shouldnt make any difference if the shoes are adjusted properly and the drum retaining screws are in place. Unfortunately, a lot of replacement master cylinders are useless. If you still have the old one, take a.good look at it to see if its worth refurbishing. Also you may have fitted the shoes or retaining springs incorrectly.

Col

Clamp each brake hose one at a time to see if you can figure out where the problem lies.
Pedal height is pretty important, followed by pedal free play.
CV or CB master cylinder? CV type is the same as the clutch master, CB is larger.

I take it they are standard 10 inch drums with just the one cylinder per wheel? nipples at the top of the cylinders ie fitted to the correct side of the vehicle? iirc wheel cylinders front and rear have different bore sizes.

I find adjusting them tighter than the manual suggests works best, ie adjust them until the wheel is locked then back off until the shoes are still lightly rubbing, if you de adjust them so they are totally free you will never get any brakes.
Are the adjusters keeping their set adjustment?

Pics of the under bonnet set up might help people diagnose your issue.

Have you adjusted the matter cylinder push rod and have you adjusted the snail cams on each wheel?

Thanks for the replies. To answer the questions,
Standard 10" drums, one cylinder per wheel, CV type master cylinder. Free play in the pushrod minimal and the pedal travel is complete. The snail cams have been set just rubbing, but I will have a bash with them set on harder.

I've kept all the old parts, which presumably were OK but untested as the car was not on the road. Swapping out against the new ones to find the fault will be another next step.

Does sound like too much travel in shoes. I’d be tempted to give the snail cams another click.
Just don’t compare the stopping experience with a modern vehicle

Adjust the snail cams right up so the wheels don't turn, then try the pedal again.

If all else fails, try wedging the brake pedal hard down (I use a hammer) and leave it like that for 24 hours. That finally cured my recalcitrant brakes.

Col

Colthebrummie said:

If all else fails, try wedging the brake pedal hard down (I use a hammer) and leave it like that for 24 hours. That finally cured my recalcitrant brakes.

Col

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I use that trick on my bikes as standard, works every time. Not the hammer bit though

kermit_rr said:

Adjust the snail cams right up so the wheels don't turn, then try the pedal again.

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That's be where my money is too.