Series 2a master cylinder.

[army2a]

Hey guys, before I take my 109 to a brake shop I thought I'd just check that I haven't missed something. I've rebuilt all four drums ( new shoes and wheel cylinders), and replaced the master cylinder. The first cylinder I put in bled up fine and had good brakes, but after about 5 kms of driving, there was no freeplay left in the pedal at all. Countless adjusting has made no difference and even with the shoe adjusters all the way out, the pedal is hard right from the top! If the car sits for 15 minutes the brakes free up and then spin freely????? Adjustments on the master cylinder pushrod have changed nothing either. After buying another cylinder (nos), it has taken about 3 hours to finally bleed all the air out? With all wheels adjusted there is only pressure on the brakes about an inch from the floor. The pushrod on the cylinder is adjusted correctly. Any ideas? Could I have the wrong mcylinder? (88')?

[isuzurover]

Sounds like your first MC had an issue (something inside was sticking and not releasing pressure.

Your 2nd MC sounds fine, it just sounds like there is still a small amount of air in the system.

There is a difference in bore between 88" and 109" MCs, and there is a noticeable difference in size. You couldn't have the wrong MC unless your previous one was also incorrect.

When I bought my 109" IIA it was fitted with an 88" CB-type MC, and the brakes worked well, and the pedal stopped about 33% of the way down. The smaller bore of the SWB MC meant the brakes required much less effort! However ajustment was finicky.

[JDNSW]

Check where the problem is by clamping off the three hoses, and bleeding each section separately. With all hoses clamped, pedal should be solid with only the free play on the rod.

For each front wheel (and the two back wheels) separately, if you adjust the shoes till they are locked against the drum, then any additional free play must be air, but if it is solid but you get free play when you adjust the shoes correctly, then the problem is not air, but with the brake shoes or springs incorrectly assembled, drum out of spec etc.

And remember that you can bleed at any union.

John

[ezyrama]

Try using the clamp method as suggested by JD and make up one of these, it works like a charm.

[army2a]

I'll give it a try, I did make up one of those vacuum bleeders like in the pic, and it did work well but it must still have air somewhere, with the three flex hoses clamped the pedal is good. So there must be air somewhere. Does anyone bleed the brakes with the shoes adjusted up against the drum? Thanks for your help guys!!!! Much appreciated. I was thinking the only answer was a box of matches!! Ha ha

[ezyrama]

wind them out so they are against the drums, that way and movement in the pedal should force air out. One thing I had with smeg was the master cylinder was on a slight angle and the line off the MC was at the other end so I had to lift the car quite high to release any trapped air through to the brake lines and then bleed it out/ draw it out, with the vac pump.