17 replies to this topic

[Norris73]

Hi All,

 

Have been taking advantage of this lovely weather to try and get my brakes sorted ready for L2B.

 

Some back ground the brakes had been working fine (drums all round), however when cleaning out the drums the other week I noticed that 2x front wheel cylinders were leaking. So Yesterday and today I took the opportunity to replace all the front wheel cylinders (minispares genuine ones) and fit new brake shoes all round. Everything has adjusted up nicely. I bleed the system with my eezibleed kit (I last used this when I converted my other mini to disk brakes), everything seemed to go ok some air came out then the fluid ran nice and clear with no air.

 

However the pedal feels dreadful! I can push it down about half way through its travel then it goes rock hard! I went out for a quick spin to confirm my suspicions - It appears only the rear brakes work, which promptly lock up. I have since tried to bleed the system again, with no joy the pedal is still rubbish, at this point I have pushed nearly 2l of fluid through the system with no joy! I just need to get some front brakes to work, the rears are fine!

 

Does anyone have any tips or advice before I go crazy and take it to a garage!

 

Thanks,

 

Olie

Edited by Norris73, 01 May 2016 - 08:07 PM.

[Stiggytoo]

Adjustment. Top and bottom adjusters must be turned in direction of travel as close as you can get them without dragging. Should be able to hear slight rubbing between shoes and drums.

Edited by Stiggytoo, 02 May 2016 - 04:49 PM.

[carbon]

+1 for tightening up the four snail adjusters on front brakes.

 

Sometimes these need to be tightened up to point where wheel is getting slightly difficult to turn.

[russo]

How old is your brake master cylinder? Because normally you only use the top half of your master cylinder for normal braking and when you bleed brakes you use a full travel of your master cylinder, the unused portion of the master cylinder quite often of gets corrosion in the bore. When the old rubber cups slide over this corrosion it can sometimes damage/cut rubber cups and cause it to suck in air and or leak. I'd be checking the master cylinder.

[Norris73]

Master cylinder was replaced by previous owner in 2006, fingers crossed its ok as I didn’t much enjoy replacing the clutch master cylinder the other week.

 

Going to try the front shoe adjusters this morning and will report back.

 

Thanks

 

Olie

[Norris73]

Hi Guys,

 

Im at my wits end now with this!

 

Thanks for everyones suggestions so far. I checked the adjusters, no joy. On a whim after reading another post where Shifty mentioned the flex hoses working as a one way valve I clamped them off up high near the union, straight away the pedal went rock hard right at the top of its movement! does this mean the master cylinder is OK?

 

Anyway as I had new flexies I replaced both of them and checked all unions were nice and tight.

 

I then rebleed with my eezibleed, and there was no change exactly the same as before. On a whim I tried the two man approach to bleeding the brakes, this improved the pedal very slightly and lots of air came through, now if you pump the pedal twice the car pulls up perfectly. However the pedal is still very low and when pressing the brake pedal once the rear brakes lock up (as I have no front brakes)

 

I think air is still getting in somewhere (or isnt being removed) - but I literally spent another hour and 1.5l of fluid this afternoon trying to bleed the brakes.

 

There must be someting im missing? - please any advice welcome before I use the UKs supply of DOT4 trying to bleed this thing!

 

Thanks,

 

Olie

Edited by Norris73, 02 May 2016 - 05:19 PM.

[russo]

I've also found that air gets trapped in crossover pipe between top and bottom cylinder. It seems the only way I've found to get rid of this is to open the bleeder and give the pedal a sharp sudden stab as tough you've just made an emergency stop, while the pedal is still down get, close off the bleeder. Repeat this process several time. Best of luck.

[timmy850]

When you say you checked the adjusters, what do you mean by that?

 

With the front wheels off the ground you should be able to hear both the shoes dragging very slightly on the drums. You need to adjust both the square adjusters up tight so that they are right next to the drums. If they are not correctly adjusted when you put your foot down the shoes will move out but not contact the drum.

 

When you pull the shoes on and off they aren't necessarily in the centre of the drum, so you need to pump the brakes a few times to get them centred and then adjust them again. 

[Norris73]

Thanks for the replies so far.

 

When bleeding the brakes with the two man method we tried the traditional open the bleed valve press the pedal, close valve release pedal. Later on we tried open the valve then 4x sharp pumps of the pedal then hold, and close valve release brake. Non of these have worked.

 

Regarding the adjusters, I was fairly confident the first time that I had them right as I had studied the Haynes manual prior to adjusting, however I rechecked and adjusted from the drum being fully locked each adjuster requires maybe just slightly more than 1/8th of a turn backing off in order to allow the drum to spin with a slight rubbing heard of the shoes. I then reconfirmed this my fitting the road wheel, the wheel spins but not freely there is a light resistance to it.

 

After all this and still not getting a good pedal I removed the drums and watched the shoes as someone pressed the brake, on both sides the wheel cylinder connected via the linking pipe has far lest effect on the shoe than the wheel cylinder connected to the flexi hose.

 

I have someone going to Minispares today to collect every conceivable part I may require. I am going to start by replacing the two wheel cylinder linking pipes (my theory being really that they are the only part I have removed/touched and not replaced!)

 

Still I am starting to panic now!

 

Olie

Edited by Norris73, 03 May 2016 - 06:55 AM.

[midridge2]

If you are having to pump the brake pedal you still have air in the system, clamp up both rear flexi brake pipes and bleed again.

[Ethel]

Are you sure you've got the shoes in the right way round, all the springs fitted correctly?

 

Nobody had mucked and fitted 1 1/4" shoes previously?

[Norris73]

Thanks for the replies in trying to help me track this down!

 

See photos below of how I have the shoes and springs fitted:

 

 

 

 

The shoes I removed were definitely 1.5", I took photos of how they were in before I removed them and fitted them back based on my photos. I also replaced both front drums as a precaution.

 

Thanks,

 

Olie

[Norris73]

The mystery deepens

 

This evening I have replaced the link pipes between the two wheel cylinders, and tried to re bleed the front brakes. Unfortunately still getting the same pedal only firms up half way through it movement. You can bleed the system until no more air appears then 5 minutes later you go and check by re bleeding the fronts and loads more air appears! The pedal firms up while bleeding only for a few seconds then sinks again.

 

Im finding this very strange as the brakes worked well (for drums) prior to me changing the wheel cylinders and shoes on the front. If I clamp of the front brake flexy hoses the brake pedal goes rock hard. Would my symptoms suggest a failed master cylinder? I don't mind changing it if this is the suspect part, however I would rather not change it unnecessarily. The master cylinder was last changed in 2006 however the car sat from Feb 2012 - Dec 2015.

 

Thanks,

 

Olie

[carbon]

Olie,

 

Looks like the brake shoes and springs are all correctly fitted.

 

Sounds like air is somehow getting into the system. I would recheck all of the recently replaced hydraulic components.

 

I think it's less likely to be the master cylinder as this was working fine before you changed the wheel cylinders.

[cambiker71]

Lock the adjusters up solid and check the pedal movement again, if it's ok and hard then it's bled and needs adjusting correctly, if not leave the adjusters locked up (all of them, front and rear) and bleed using the old fashioned BMC two man method..

 

fill the reservoir.

get an assistant to help

open the furthest from the master cylinders bleed nipple (start at the rear from scratch) and get your assistant to press the pedal SLOWLY down and hold it.

count 10 seconds 

tighten the bleed nipple and get your assistant to release the pedal.

count 10 seconds

check the reservoir level

 

Repeat until you have fresh fluid and no air bubbles then move to the next nearest bleed nipple and start the above procedure again then repeat until all is bled and the pedal is good, then readjust the brakes all round, check the pedal travel after adjusting each brake, if it goes away, you then know which one is the problem

 

Adjusting the front ones is the most difficult, to me it sounds like you may have only one shoe adjusted correctly on each side but not the other one (gives a long pedal but still feels like its slightly binding and adjusted correctly when you turn the wheel by hand) also remember there will always be a bit more pedal travel with new linings until they have run in a bit, readjust them again after a couple of hundred miles of normal use and then they will stay adjusted for longer.

 

it's important to count ten seconds each time as above, after pressing the pedal the ten second pause allows line pressure to subside, the pause after releasing the pedal allows the reservoir to fill fully together with allowing the lines negative pressure to subside.

 

This method has never failed me with bleeding drum brakes (not just on minis either!) you just need a little patience though