61 replies to this topic

[adam_93rio]

My dads mini is an early '64 which had single leading shoe front brakes.
After a few butt clenching moments he's decided to upgrade to twin leading shoes.
We went to mini spares and got new back plates, 4 wheel cylinders, with associated bolts etc, new shoes and the link pipes between cylinders.

We have them fitted, in which I believe to be the right way round.
Adjusted them up, and no matter how much we bleed them, there is no pedal.

Between yesterday and today, we've bled probably getting on at 2 litres of new fluid through the system. Still nothing.

We've tried starting furthest from the master and working towards it, and visa versa. Also tried bleeding where the pipes join at the top of the system near the master. Still to no avail

There is literally no resistance in the pedal what so ever. If we try to pump it up, it eventually gets a slight bit of feel, but almost at the floor.

This would indicate that there is air in the system but can only get clear solid fluid out of every bleed nipple.

I'm really at a loss with what to try next, all the brakes were working before we fitted these new ones. Albeit fairly poorly.

Can anyone suggest why we can't get a pedal other than that there is air in the system? I'll attach pictures of each side too in case the plumbing or figment isn't right.

Everything points to there being air in there I know, but I can't see any way of getting the air out if there is.

Also, I think the little springs near the cylinder are wrong, but this was built up as per a picture in the Haynes manual and seemed correct to that

These are pictures of the drivers side






Passenger side (left)






The bleed nipple is on the back cylinder, at the top. The fluid goes in through the top of the front cylinder, then through the link pipe from bottom to bottom, the bleed nipple is at the top. Is this correct?

[Stiggytoo]

From the first picture it looks as though the top adjuster been turned the wrong way? They should all be turned in the direction of wheel rotation. I am confident that adjustment is your issue as it comes up so often with drums.

Firstly make sure the rears are adjusted properly.
The front adjusters are very sensitive to adjustment, try to make the shoes drag slightly. You should be able to both feel and hear this. It is really important that you do this otherwise they will be imbalanced and ineffective.

Edited by Stiggytoo, 30 May 2016 - 08:22 PM.

[kyle9832]

My dads mini is an early '64 which had single leading shoe front brakes.
After a few butt clenching moments he's decided to upgrade to twin leading shoes.
We went to mini spares and got new back plates, 4 wheel cylinders, with associated bolts etc, new shoes and the link pipes between cylinders.

We have them fitted, in which I believe to be the right way round.
Adjusted them up, and no matter how much we bleed them, there is no pedal.

Between yesterday and today, we've bled probably getting on at 2 litres of new fluid through the system. Still nothing.

We've tried starting furthest from the master and working towards it, and visa versa. Also tried bleeding where the pipes join at the top of the system near the master. Still to no avail

There is literally no resistance in the pedal what so ever. If we try to pump it up, it eventually gets a slight bit of feel, but almost at the floor.

This would indicate that there is air in the system but can only get clear solid fluid out of every bleed nipple.

I'm really at a loss with what to try next, all the brakes were working before we fitted these new ones. Albeit fairly poorly.

Can anyone suggest why we can't get a pedal other than that there is air in the system? I'll attach pictures of each side too in case the plumbing or figment isn't right.

Everything points to there being air in there I know, but I can't see any way of getting the air out if there is.

Also, I think the little springs near the cylinder are wrong, but this was built up as per a picture in the Haynes manual and seemed correct to that

These are pictures of the drivers side






Passenger side (left)






The bleed nipple is on the back cylinder, at the top. The fluid goes in through the top of the front cylinder, then through the link pipe from bottom to bottom, the bleed nipple is at the top. Is this correct?

have you adjusted the shoes so they are binding the drums a little?

[Stiggytoo]

Saying that, usually with poor adjustment you'd still be able to pump up the pedal. If there is no resistance for the entire pedal travel, perhaps there is an issue with the master cylinder?
Also it might just be me but the spring fitment looks bizarre?

[Spider]

For the sake of getting a peddle it won't matter which way the front adjusters are turned, as long as the shoes are adjusted up. There are two adjusters on each side for the fronts (so 4 in total on the front end).

 

However, before driving it, as Stiggyloo has suggested, be sure they are adjusted the right way.

 

If you are getting fluid out of each nipple - front and back - on every stroke and no peddle, that tends to indicate to me that the master cylinder maybe the issue. The fluid is only being pumped out by the secondary seal and not the primary (pressure) seal.

 

Try clamping off all 4 flexible hoses at each wheel to see if you can get a peddle. if it's well bleed (and it sounds like it) and there's still no peddle, then it can only be the master cylinder.

 

One other thing to keep in mind here too, especially if changing the master cylinder is the original bore size was 0.75" and the ones that were fitted to the twin leading shoe cars was 0.70" dia.  The bigger bore cylinder would actually make the peddle 'higher' but harder. I don't think this has anything to do with your current issue, but something to consider if replacing it.

[minimat]

The red springs should be hooked into the little hole in the side of the piston although i cant see this causing the problem,maybe the op has de adjusted the shoes to make it easier to take the drums off and take the pictures?

If you are 100% sure you have adjusted them correctly ie turning the adjusters in the direction of the wheel i would suspect the master cylinder on a single line system if it failed you would loose all brakes and old cylinders can sometimes be damaged by bleeding brakes if the pedal was pressed all to the bottom it could flip the seals inside,rare but can happen.

[adam_93rio]

Just to answer a few of the posts above

I've since realised the springs should be hooked into the little holes in the wheel cylinder, so that will be rectified anyway.

The adjusters in this pic had been wound back a touch to get the drums off.

We weren't adjusting them correctly before (could've been but unsure) however since the photos were taken I have put the drums back on, and adjusted them all rotating toward the front of the car, clockwise on the passenger side and anti clockwise on the drivers side.
I started with the front adjuster, wound it forward until the drum locked, then backed it off a little so that I could spin the wheel by hand and made sure it stopped itself writhing 1 rotation. Then did the exact same with the back adjuster.

Back brakes are adjusted correctly, I rechecked this at the same time as adjusting the fronts, but they only required the slightest little tweak.

With all brakes double checked for adjustment, still have no pedal. So I'm fairly sure that adjustment isn't the problem.

I'm 99% certain there is no air in the system. So I guess it does point to the master,

The master cylinder is about 4 years old and hasn't seen many road miles at all. But I think the next job is to pull it off and check the seals.

With the master being so new I wouldn't have suspected it, especially as it was working perfectly before taking the brakes to bits

[adam_93rio]

For the sake of getting a peddle it won't matter which way the front adjusters are turned, as long as the shoes are adjusted up. There are two adjusters on each side for the fronts (so 4 in total on the front end).
 
However, before driving it, as Stiggyloo has suggested, be sure they are adjusted the right way.
 
If you are getting fluid out of each nipple - front and back - on every stroke and no peddle, that tends to indicate to me that the master cylinder maybe the issue. The fluid is only being pumped out by the secondary seal and not the primary (pressure) seal.
 
Try clamping off all 4 flexible hoses at each wheel to see if you can get a peddle. if it's well bleed (and it sounds like it) and there's still no peddle, then it can only be the master cylinder.
 
One other thing to keep in mind here too, especially if changing the master cylinder is the original bore size was 0.75" and the ones that were fitted to the twin leading shoe cars was 0.70" dia.  The bigger bore cylinder would actually make the peddle 'higher' but harder. I don't think this has anything to do with your current issue, but something to consider if replacing it.

The car won't be driven until everything is perfect, it's not worth the risk at all. It will have copious amounts of testing on the driveway to make sure everything is in order.

I will clamp the flexis tomorrow night after work to check the master and report back.

Is there a way of telling which size master is fitted looking at it externally? it was changed like for like so got exactly what was on there when we got the car before we restored it. I would believe it was the correct part as it hadn't really been messed with, but of the later smaller bore master had been fitted, I suspect that would make the pedal lower so could be part of the problem?

[Spider]

 

Is there a way of telling which size master is fitted looking at it externally? it was changed like for like so got exactly what was on there when we got the car before we restored it. I would believe it was the correct part as it hadn't really been messed with, but of the later smaller bore master had been fitted, I suspect that would make the pedal lower so could be part of the problem?

 

 

Some MCs have a groove in the lower body, just above the mounting flange to identify them, but in the case of replacements, I've found this can be unreliable, so it's best to remove and measure the cylinder.

 

None the less, I can't see the wrong size MC alone being the issue here, it wouldn't cause a 'no peddle' condition, only a wrong height / soft or hard peddle condtion. You would get some peddle.

[nicklouse]

As above, if wrong size they would still work but feel of travel would be off.

I would say shoe adjustment is off.

Also the tie bar to lower arm bolts are fitted the wrong way around.

[gazza82]

"clockwise on the passenger side and anti clockwise on the drivers side. "

Doesn't sound right .. They all adjust the same direction surely? I must admit I've not seen that type ... (Need to check my manuals)

[nicklouse]

The adjusters should be adjusted in the forward wheel rotation direction.

[timmy850]

Are the rubber hoses in good condition? If they are old it'd be worth replacing them now while you are bleeding the system to eliminate them as a problem. 

 

If you fill the system up to the top in the reservoir, are you getting any fluid loss over time?

 

Whoever designed the link pipe to go around the hub obviously never thought about it very much, it's a pain if you want to take off the hub uprights as you have to rebleed the brakes...

[adam_93rio]

This morning all hoses were clamped and the pedal was solid. So the master is doing its job.

As far as I'm aware I've adjusted them correctly, multiple times. I've even tried adjusting them too tight to test, still nothing.

I guess it is leading towards air in the system again, although I have no idea how, I'm going to invest one of those suck through bleeding systems and give that a go.

All the hoses are only a few years old, still looks and feels like new rubber.

Tried bleeding again today with a new easy bleed kit, still not luck. Could it be that there is too much wheel cylinder capacity for the small master cylinder?

[adam_93rio]

With the front brake flexis clamped we get a good pedal.
If the back flexis are block off there no pedal.

While I was at work today my dad had taken his master cylinder off and checked it, all still like new