Brakes: Pedal Travel

Post by **rsawatson** » Thu Jul 30, 2009 10:21 pm

Opinions please...

I've replaced every part of the braking system, including pipes, apart from the master cylinder. Even when correctly adjusted, the pedal travels almost to the floor before strong braking action is realised (although travel can be improved by pumping the pedal). I've always got by with them in this state, in fact the brakes are perfectly strong enough and I've never had any problems stopping. The system does not leak fluid. I've bled the system umpteen times and no air has come out.

I assumed a replacement master cylinder would be required. However, is there air trapped? On advice, I have wedged the pedal on with a block of wood overnight to see if this allows any air pockets trapped to come out into the reservoir.

I should be grateful if anyone who has had similar problems could share how they sorted it out!

Thanks.

Post by **LouiseM** » Thu Jul 30, 2009 10:24 pm

Moved to 'mechanical' from 'general discussion' as more appropriate forum.

Post by **mike.perry** » Thu Jul 30, 2009 11:30 pm

It sounds as though you need a new master cylinder
Meanwhile you can take up some of the pedal travel by adjusting the rod on the front of the master cylinder but don't overdo it or you will lock the brakes. Make sure that you have a bit of free play on the brake pedal

Post by **d_harris** » Thu Jul 30, 2009 11:54 pm

Sounds like there might be a small leak in the MC

When you press the brakes to the limit and hold them, does it slowly start to sink further? That would be indicitive of a seal failure

Post by **rsawatson** » Fri Jul 31, 2009 10:31 am

Dan_Harris wrote:Sounds like there might be a small leak in the MC

When you press the brakes to the limit and hold them, does it slowly start to sink further? That would be indicitive of a seal failure

No, it holds firm where it is. There is no fluid loss whatsoever.

Post by **8009STEVE** » Fri Jul 31, 2009 10:45 am

Has been said before (not by me). Try pumping the pedal, get a good pedal, and somebody releases the bleed nipple. Do this on all 4 corners and, if there is a bubble, it seems to shift it.

Post by **bmcecosse** » Fri Jul 31, 2009 10:47 am

Sounds simply like brakes needing adjusted up - although I'm sure you have tried ! Try again - adjust each brake up so it is rubbing hard on the drum - how does the pedal feel now ? If it's not sinking to the floor - then the m/c is ok - don't rush into changing it! As others have suggested - there is an adjustment on the m/c push rod - but you must leave a little 'free play'. If the pedal is much better with brakes adjusted up - then back each one off just one click - even if that leaves it slightly rubbing - and try that.

Post by **rsawatson** » Fri Jul 31, 2009 12:08 pm

Why does pumping the brake pedal make it feel harder?

Fri Jul 31, 2009 12:18 pm

Why does pumping the brake pedal make it feel harder?

because you will have pushed the brake shoes out with the first pump (and not hit anything) the second pump moves them the final little bit to hit the drums and hence why they go firm \ hard.

Assuming you have adjust the shoes "out" have you taken the car for a quick spin, braked a few time and adjusted them out again. When you remove the shoes it is very difficult to centralise them so when you adjust them the first time they seem to be ok but in fact they are not when they get centralised.

As for removing air bubbles when bleeding the brakes i tend to remove my hand quickly from the peddle to "bump" air bubbles out of the system.

having said all that i would go with the other posters I think it sounds like a problem with your master cylinder.

Post by **stevey** » Fri Jul 31, 2009 2:50 pm

sounds like the brakes on mine, new cylinders and master cylinder all round. pedal travels nearly to the floor then brakes hard. all adjusted up correct and all no idea what it is but it brakes straight and well very time.

Post by **PSL184** » Fri Jul 31, 2009 3:03 pm

I had a similar problem after renewing everything - I was convinced there were no leaks as the level in the MC never dropped, however, after much frustration and searching I found a very slight weep from the rear brake pipe at the MC connection. Might be worth just checking over every joint again to be certain all is air tight.

Post by **bmcecosse** » Fri Jul 31, 2009 5:05 pm

Air - or leaks - or faulty m/c - will show as slowly sinking pedal. It's adjustment!

Post by **nslocomotive2** » Sun Aug 02, 2009 10:27 am

just to add, i had the same problem, and for me it was adjustment, lock all the adjusters up tight so the wheels wont turn, then try the pedal, if you get instant pedal everything is fine, and slacken the adjusters just one click so when the wheel turns but its slightly rubbing, It took me a few days of tinkering to work this out and under stand the advice.

If the pedal still sinks with wheels locked up then it rules out adjustment.

Post by **rsawatson** » Tue Aug 04, 2009 1:29 pm

Thanks for all your comments.

However, problem is now solved! The issue is the front brake drums - they are a tad tired basically. This meant that when adjusted correctly, the snail cam was at its highest point and was liable to pop down - meaning that the brakes were effectively out of adjustment. A shim has been fitted so as to stop this happening.

Another thing that was not helping was the handbrake - the rear levers on the slave cylinders were sticking right out. Disconnected, pushed levers in, adjusted, reconnected.

Now the pedal is like new!

Post by **8009STEVE** » Tue Aug 04, 2009 1:34 pm

Good to hear it is sorted.

Post by **rayofleamington** » Tue Aug 04, 2009 1:47 pm

A shim has been fitted so as to stop this happening.

If the front adjusters roll round, you may have the wrong adjusters (early minor 1000 with 7" brakes had different adjusters).
If the problem is actually very worn drums then it's MUCH safer to replace them than to shim the adjusters!!
If the drums are not excessively worn then it is likely to be just badly made shoes - I've had this at least once myself

Another thing that was not helping was the handbrake - the rear levers on the slave cylinders were sticking right out.

best idea is to disconnect the handbrake cables from the cylinders when bleeding and adjusting. This is a bit overkill but it does make sure that there is no interference and that the hydraulic piston is then pushed back home properly.

Post by **mike.perry** » Tue Aug 04, 2009 6:07 pm

Apply a couple of squirts of oil to the inner cables at the back where they leave the outer casing and work the cables in and out a few times. Also don't forget to grease the cables if they have grease nipples

Post by **bmcecosse** » Tue Aug 04, 2009 7:08 pm

It's pretty much essential to release the handbrake when doing any significant work on the rear brakes - then re-set it when the foot brake is all correct.

Post by **alainmoran** » Tue Aug 04, 2009 8:25 pm

I have to say I agree completely with BMC, every single time I've tried to get away with leaving the handbrake connected it has stuffed things up royally.

Disconnecting it is the only way of knowing for sure that you have things adjusted right.

Post by **bmcecosse** » Tue Aug 04, 2009 9:21 pm

" stuffed things up royally " - I like it -
considering my name is Roy All------!