ok so heres whats happened...about 4 months ago we replaced my master cylinder, we had it resleeved and all. we bled the brakes and all was well.

but then... i dinged up the front and since then it hasnt been the same. there is a photo in my photobucket if you want to look. so anyway since then my brakes have been ****. we keep bleeding them, and they come good, but about a week later they are gone again and need to be re-bled.

so we decided to see what the problem was, it turns out the master cyliner is sucking air. so we got a brand new one and put it in today, and it still didnt work, there is still no pedal. so we changed over that next bit, im not sure what its called but it's hiding bhind the windscreen washer reservoir. and its still not working. the front is working apparently but not the back. also, we dont seem to be able to get much fluid out of the back???

what is wrong with my brake system???

perhaps its haunted? i have never had good brakes...

EDIT: i forgot to add a poll...so i did...

edit: there was supposed to be another option in the poll..."turning the brake lights on only" but it didnt work and now i can't edit the poll. poo

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78 Leyland Mini - Prince

Might be time for new rear hoses, they swell with old age, then fluid won't go thru them as the bore gets blocked by the swelling.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

i was thinking something along those lines, maybe an old hose or possibly a blocked hose?

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78 Leyland Mini - Prince

How hard did it get dinged??....you may have split a brake line or cracked loose a connection on the side that got hit.

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"Show me the Mini!"

You may need to take a total look at your system.

By fitting a new master cylinder to an older system it may have accelerated other problems.

Start with a full inspection. Make sure none of your lines are kinked or squashed, make sure the wheel cylinders arnt leaking and the rubber seals are not perished.

Clean it all. This means cleaning the drums by deglazing them with emery paper. Do this to the pads as well. You can wash all this down with metho. Adjust up the pads in the drums once youve done the deglaze. By spinning the drums while adjusting the shoes you'll find if any of the drums are egg shaped as the wheel spins it will catch the shoe on part of the rotation and spin free for the other. If egged then get them machined.

Greasing the brakes is for the hand brake mechanism, make sure all the pivot points under the car are greased and free to move as this will ensure the return point when released doesnt change to give you a good pedal sometimes and no pedal the other. Then adjust up the slack in the wire to 3 ratchet clicks on the hand brake for full lock.

Now the master cylinder needs to be an exact replacement for the original and the pipe clamp ferrule that you swewed the pipe into the master cylinder with need to be clean (wire brushed) and tightly fitted. If this leaks back air then as you said your ****.

Finally the bleed is really important. Its easy to froth the fluid and have micro bubbles in the line when you adjust them. This gives you the feel of good brakes but as the micro bubbles join and make a singular big bubble then you got a spongy pedal again. You really need to suck the fluid through the system and completely change the fluid instead of pumping the pedal and lock/unlock the nipple. If your like me a tight on cash and dont want to use a brake shop then make a vacuume brake flusher out of an old fridge motor/compressor.These suckers can create a really strong vaccume on the compressor inlet side and draw through the brake fluid completely no bubbles. Make sure you connect a glass jar inline between the brake bleed nipple and the compressor so you can see the fluid come through and you dont fill the compressor with brake fluid. You will be amazed how much crap comes out, then amazed how the hell you could ever stop.

So by this point you should have a firm pedal with a high engagement point. On first application I hope you dont go through the wind screen with the new found braking acceleration.

If in a weeks time the brakes are low engagement then readjust the shoes (I do mine 1-2 months as I brake hard) If the pedal is spoungy then the wheel cylinders are probably shot. Why do they become shot? well normally because the brake fluid absorbes water then leaves micro traces of it on the wheel cylinder walls and this starts to rust then wear the surfaces....so....change the fluid every 12-24 months and if youve got the tight guys sucker still it'll only take you a saturday morning to fully refresh the whole system and have that perfect pedal feel and importantly avoid the rust.

My 2c worth

Fine...so long as the shoes are centred....

I usually, centre the shoes by eye, do the brake adjustment, fit the drum with no retaining screw then go and tap the brake pedal a couple of times...then check the adjustment by sliding on and off the drum....tiddly up the the adjustment if needed.

If your drums are trully oval..that too will soon become apparent....although don't expect new shoes to be perfectly round either.

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"Show me the Mini!"

Really just follow as I suggested you need to fit the drum with screws fitted before adjusting as I suggested.

The drum may have wear on them so need to be correctly fitted to make sure your adjusting the shoes is tightest it can be and they are not sitting up on the lip created by no wear.

Dont worry about the shoes being "round" as they dont rotate so the highest point will touch first and last regardless of location. as you tighten the adjusting square lug the shoes will automatically centralise but you can pump the brakes to assist.

Your information has come in handy. I'm also having problems with the braking system on my mini.

Untie those knickers Besser...my comments aren't about having a go at you.....


"Besser" Really just follow as I suggested you need to fit the drum with screws fitted before adjusting as I suggested....Good suggestion

The drum may have wear on them so need to be correctly fitted to make sure your adjusting the shoes is tightest it can be and they are not sitting up on the lip created by no wear....Drums and disk rotors can develop ridges which need to be watched and treated over the life of the unit. If you start developing a ridge than get some emery paper and carefully remove the ridge....of course there is a limit to this...sometimes machining is required, sometimes (undersize) you go and buy new ones or ones that are less worn....drums have wear bevels on their leading edges...disks have a minimum thickness.

Dont worry about the shoes being "round" as they dont rotate so the highest point will touch first and last regardless of location. as you tighten the adjusting square lug the shoes will automatically centralise but you can pump the brakes to assist.....the problem here is that some shoes have high furry spots which can make contact first when adjusting...for this reason.....you usually need to make several adjustments over say a period of a month with new shoes to maintain good braking (more frequent dust removal is also required)

2c

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"Show me the Mini!"

I think between 9 and myself you have most angles covered. I missed the regular dust removeal

ok awesome thanks guys! we shall give it a whirl, see if i cant fix these damn brakes!

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78 Leyland Mini - Prince

oh i forgot, we are re-shelling so i dont know how much point there is spending lots of cash on the brakes when we are going to be transferring some/all of it into a new shell in the next few weeks anyway...

oh 2 of the drums are 5 months old... they are on the front...

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78 Leyland Mini - Prince

just out of curiosity did you bleed the master cylinder first ????
makka

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