Series 2a brake problems... Again

For the purposes of bleeding, if you have the shoes adjusted hard up against the drums , it does not matter what size slave cylinders you have , it should bleed & you should get a hard pedal, if it does not you have assembled the brakes incorrectly or have a faulty master cylinder .

I hear you when you say you adjusted the snail, m both ways, Are the wheels locking up when you adjust the snail cam , ( must be on a jack so you can turn the wheels to know this) if not theres your problem.

If you can't bleed the whole system in 20 minutes, one person , by pressing & holding the brake pedal with a stick against the seat box then there is something wrong. Should not take more than half a 500ml bottle .

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Originally Posted by goingbush

For the purposes of bleeding, if you have the shoes adjusted hard up against the drums , it does not matter what size slave cylinders you have , it should bleed & you should get a hard pedal, if it does not you have assembled the brakes incorrectly or have a faulty master cylinder .

I hear you when you say you adjusted the snail, m both ways, Are the wheels locking up when you adjust the snail cam , ( must be on a jack so you can turn the wheels to know this) if not theres your problem.

If you can't bleed the whole system in 20 minutes, one person , by pressing & holding the brake pedal with a stick against the seat box then there is something wrong. Should not take more than half a 500ml bottle .

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All four corners are up on stands, snail cams adjusted until brakes bind on drums and wheels cannot be turned. Even had the drums off at one stage and used a ratchet strap to hold shoes together nice and tight to see if that made any difference while bleeding.

I’m pretty confident I have all the air out of the system tried every way possible bleeding through and pushing fluid back through aswell. Never had this problem before on any of my other vehicles after full brake system overhaul just strange.

I suspect that in some cases at least, people are getting it bled - in the sense that they have got all the air out, but are keeping at it in a vain attempt to 'fix by bleeding' what is actually a mechanical or hydraulic fault, not air in the hydraulics. And one cause of this could be the use of larger front wheel cylinders without the larger master cylinder.

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Originally Posted by JDNSW

I suspect that in some cases at least, people are getting it bled - in the sense that they have got all the air out, but are keeping at it in a vain attempt to 'fix by bleeding' what is actually a mechanical or hydraulic fault, not air in the hydraulics. And one cause of this could be the use of larger front wheel cylinders without the larger master cylinder.

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JDNSW I have just put through an order for 1 1/4” front cylinders as recomended by Steve at British auto parts Australia in Bayswater so will have to wait till they come through the post and see if it fixes the issue. Fingers crossed!

Sounds like a dodgy master cylinder .

That is the other possibility of course. It would be nice to be able to say that this never happens with new parts, but unfortunately, that is not the case.

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Originally Posted by goingbush

Sounds like a dodgy master cylinder .

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Is there anyway to narrow the problem down to the master cylinder? Or will it be a case of just replacing it

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Originally Posted by jessec96

Is there anyway to narrow the problem down to the master cylinder? Or will it be a case of just replacing it

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its all it can be, as I said before if your shoes are adjusted up hard again the drums it does not make any difference what size the slave cylinders are because the pistons don't have any room for movement so no fluid is being displaced.

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Originally Posted by jessec96

If I clamp off front lines the pedal feels good. So I’ve bled almost a litre through the front also pressure bled with pump bottle.

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As already mentioned, sounds like it's not air in the system.
From the above comment the problem lies with the fronts.

Remove the front drums, rub chalk over the linings, re-fit the drums, adjust the shoes till they rub, rotate the drum several times, back off the adjusters and remove the drums.
Now have a look at the linings and see where they make contact, you may need to remove & file the linings then repeat the above till you get good contact between shoes & drum. I mentioned this in another thread and someone suggested holding emery cloth in the drum & rotating the shoe against the emery to get the radius correct.

Pattern parts, worn drums etc. mean that you may have the lining only touching in one spot. When you press the pedal the pressure forces the shoes out and they flex. This procedure also means you get the best contact area between shoes & drums and therefore the best braking force.

This technique came from my Father-in-Law (no longer with us) who was in the brake business for years (co owner of Neville Pearce Brakes, Hallam). I had the same problem with my Series I, the rears OK but fronts spongy, filed until I got about 70% contact area on the linings and problem solved. Also learnt some bleeding tricks that got the air out of the system whereas everything else had failed.

Fitting the correct cylinders to the fronts will reduce the pedal travel but worth doing the above anyway.


Colin

I once had a 2A land rover. It had a forward sloping master cylinder and to bleed the brakes I had to jack up the front of the vehicle so as to have the master cylinder body on a level plane.
If this was not done it was impossible to remove the air from the back of the cylinder.