Brakes don't work

Post by **tingo** » Sat Mar 14, 2009 10:08 pm

Hi all,

My brakes have been steadily getting more spongy for the last month until the pedal was going almost to the floor in order to get a fairly weak braking action.

I thought the problem was either air in the lines or the master cylinder - so bleeding the brakes couldn't make things worse could it?

I have bled the two back brakes today and ran out of time before I could do the front two, but now the brakes don't work at all on the first press of the pedal. If I pump it once I get really good braking on the second press. Thirty seconds later I can do the same thing. Repeated braking gives very good results, but nothing on the first press.

The car is off the road until I can get it sorted, it's too dangerous to have to double-brake every time.

Any ideas please? Have I got an airlock by just bleeding the back brakes, or have I finally finished off a dodgy m/c?

Post by **bmcecosse** » Sat Mar 14, 2009 10:27 pm

First move is to check if any of the wheel cylinders are leaking oil into the drums. Also - check to see if there is sufficient lining on each shoe - and are the cylinders free to move, and do they move when an assistant gently presses the brake pedal.
Next check - refit the drums, slacken off the handbrake cables and adjust all the brakes up until they are rubbing on the drum - barely able to turn the drum by hand. Then - start bleeding - start at the back and move forwards to the passenger side then finally driver side. You can bleed 'by gravity' using a rubber tube and a jam jar, but probably easier to have the assistant pump up the brake pedal - then you open and close the nipple sharply - then they release the pedal on your command of 'UP'. Repeat around the car - the pedal should become more or less solid. Remember to keep topping up the master cylinder as you go. Finally - slacken off the adjusters slightly to the point where the drums are just lightly skimming the shoes, and retighten the handbrake cables so the brake locks the wheels on about the 3rd or 4th ratchet. While at the brakes - observe the flexi pipes (one each front and one at rear axle) - if these become damaged (or just old!) they can sometimes swell up when pressure is applied - and this is of course v dangerous - and will give a v spongy pedal.

Post by **jonathon** » Sat Mar 14, 2009 10:34 pm

Then - start bleeding - start at the back and move forwards to the passenger side then finally driver side.

Sorry Bm this reads slightly confusing to me. Bleed the brakes n/s/r, o/s/r,n/s/f, o/s/f.
Why do you adjust the brakes right up before bleeding, we slacken everything off,bleed, then adjust the foot brakes followed lastly by the handbrake.

Post by **bmcecosse** » Sat Mar 14, 2009 10:41 pm

Well - I find it works best if the cylinder is held closed by the adjusted up brake - we've had this discussion before ! Doesn't matter which side is bled first at the rear - they both are fed by common pipe.

Post by **tingo** » Mon Mar 16, 2009 7:18 pm

Thanks for the advice, I've also done a bit of research on Wiki.

It looks like I had the bleeding technique wrong! I was opening the nipple before asking my lovely assistant to press the brake pedal so I was probably sucking air back into the system.

From what bmc said above and what's on Wiki it looks like you need to apply pressure to the system before opening, and close whilst there is still a bit of pressure left.

It also seems that you should bleed about 250ml through each brake to make sure all the air has gone, even though the system only holds 250ml in total. Have I got this bit right?

Post by **bmcecosse** » Mon Mar 16, 2009 9:06 pm

Yes - build up a bit of pressure - then open/close nipple briefly. You won't need to bleed anything like that amount through each nipple - maybe through the whole system, yes. The Wiki must have been written by a Brake Fluid Salesman!

Post by **tingo** » Mon Mar 16, 2009 10:46 pm

Never ask a barber if you need a haircut!

Post by **tingo** » Sat Apr 18, 2009 2:23 pm

I'm delighted to announce that I have fixed my brakes !!!

It has taken four long days work over the last month. I had a seized cylinder at the back. I have renewed both back cylinders and the brake pipes which I had to hacksaw to remove from the banjos.

This morning I fixed the final problem which was to replace one of the front bleed screws - it wouldn't come loose without a great amount of persuasion that broke the old one.

Total cost for the job was about £30 in parts - and yes - I did use a whole litre of brake fluid as part of the learning process. Could probably do it with half that next time.

Thank you to everyone who provided advice on this thread and the other recent threads about brakes.

Now that the car is back on the road, our next adventure will be a trip to the garage for our first MOT together ...

Post by **bmcecosse** » Sat Apr 18, 2009 7:42 pm

£30! Consider what it would have cost for parts etc for a modern car! Likely nearer £300. But well done getting it fixed - does it now pull up in a nice straight line? And the handbrake should lock the rear wheels at 20 mph.

Post by **tingo** » Sun Apr 19, 2009 6:59 pm

Thanks bmc
Not only does it stop in a nice straight line, the nose of the car dips if I brake sharply. It has never done that before.
I haven't tried applying the handbrake on the move - is it generally approved as a test? I've tried pulling away with the handbrake on and I can feel that it is doing something - but not enough to stall the engine. Do I need to tighten the cables more? I expect the MOT will show if it is not working well enough.

Post by **bmcecosse** » Sun Apr 19, 2009 7:56 pm

Well - it should lock the rear wheels at about 20 mph if you dip the clutch and pull it on hard! But that's just a pre-MOT test, they do of course test it properly on the rollers, although some places still seem to manage to get away with the Tapley meter test, which is much easier!! handbrake cables should only be tightened AFTER you have fully adjusted the rear brakes, and then only if you feel the handle is coming up too far inside the car. I like 3 clicks - some like more, some less.