17 replies to this topic

[WanaGo]

Hello,

 

Just got to the point in my build of our 1978 Morris Mini 1000, and filled the brake system with fluid, bled the system (mostly) and are now adjusting the drums, and have an issue with the Drivers side (RHD).

Its Drums front and rear obviously. All new lines, hard and rubber, and rebuilt the master, new slaves, new springs, new shoes (minitex), new drums.

 

No matter what position the 2 adjusters are on the drum (twin leading shoe), the wheel is really tight and binding. Managed to turn the wheel a number of times and its a little better, thought initially it was just a high spot on the new shoes or something, but I think its more than that. 

 

Anyway, I made a video showing the pressing part of the issue. 

 

Can you have a look and hopefully let me know what you think?

 

Compared what we have with diagrams in the Haynes manuals and various other online resources, and the shoes are the correct orientation, springs are in the right spots etc. I cant work out what might be wrong.

 

Thanks in advance

 

https://youtu.be/NgDJXuDjCH0

 

 

[Spider]

Great clip there, shows what you've done, checked and the issue - quite helpful.

 

Having said that, while I can see and understand well what's happening, I'm not sure I can suggest why.

 

One thing I have found with Rear Shoes in recent years is that the frame of some of the replacements can be short. Perhaps try another set of Shoes, even old ones.

[WanaGo]

Great clip there, shows what you've done, checked and the issue - quite helpful.

Having said that, while I can see and understand well what's happening, I'm not sure I can suggest why.

One thing I have found with Rear Shoes in recent years is that the frame of some of the replacements can be short. Perhaps try another set of Shoes, even old ones.

Thanks for the reply
I managed to figure out my mistake.
The front passenger side was fine, just the front drivers side was not. Compared and didn't spot the difference. Tried old shoes and springs and still same issue. Then I clicked what it was.
The springs were upside down. So the coil part was hitting the adjuster.
Rediculous now I see it.

Appreciate the reply.

Issue now is the bleeding. I get half a pedal even with brakes adjusted. Tried manual bleeding with 2 people. Tried one system that uses a spare tyre and forces fluid into the master and though. Also tried a vacuum hand pump on the bleed nipples. All got fluid coming out and air but the pedal either gets worse and goes to floor or manages to go half way. Pumping it up gets it pretty good but not much. Must be introducing air somewhere but not sure where yet. No leaks.
Fun times.

[mbolt998]

If you set all the adjusters much too tight so everything is locked, do you have a firm pedal? If so then the issue isn't bleeding. With the spare tyre system I recommend using a bit more pressure than it says (maybe 20psi or so), leave it connected, and pump the pedal a bit before opening any of the bleed screws. Don't know if that really makes much difference but it worked for me.

 

If you rebuilt the MC I believe there might be a special procedure for getting air out of there. Somebody more knowledgeable will probably explain what it is.

[bpirie1000]

If you suspect the master cylinder you can remove the hard pipe and just put a bleed nippleminto the master and bleed the shortest system. That will show you what the best pedal will ever be like ruling out any air causing the soft pedal.

Will also test to make sure the master cylinder holds pressure..

For full system bleed some say It is best to elevate the rear and work from furthest away from master and so on... then raise the front, etc.....

[gaspen]

It should be a good idea to bench-bleed the Master Cylinder before install it to the car. Somehow the air can trapped in the MC

 

You can find many videos on YT how to do it

[WanaGo]

It should be a good idea to bench-bleed the Master Cylinder before install it to the car. Somehow the air can trapped in the MC

 

You can find many videos on YT how to do it

 

Thanks. I would have thought using the spare tyre kit and forcing fluid through from the master, would have purged the master itself of all air. 
The only bench bleeding videos I can find on YT do not relate to the classic mini, but it just looks like you pump the fluid around and around from the outlet back into the reservoir. So not really going to gain much over what I have done already I dont think.

[WanaGo]

If you suspect the master cylinder you can remove the hard pipe and just put a bleed nippleminto the master and bleed the shortest system. That will show you what the best pedal will ever be like ruling out any air causing the soft pedal.

Will also test to make sure the master cylinder holds pressure..

For full system bleed some say It is best to elevate the rear and work from furthest away from master and so on... then raise the front, etc.....

 

This is a great idea and I will try it.
I did manage to get a better pedal. Just not sure what it 'should' feel like as I have never had a mini with drums all round before. When I got this mini, the brakes were shot and leaking everywhere, so I have no reference point.
After leaving what I have done already, a few days, I still have a pretty solid pedal about half way down.
I did the furthest to the closest, bleeding, despite what the Haynes manual says, which suggests do front passenger first etc. Ended up just doing more bleeding, and might have got it, but really not 100% sure.

The design of these masters is not great, with the loop of hard line coming out the top of the master, if anything that is the highest point and unless the shot from the pedal and move the air from there in one push, it seems like a place for air to get trapped. I would hope though that the 20psi tyre kit would have forced any air out, so potentially I am OK.
Time will tell when I get it rolling and see how it performs.

[Spider]

You can bleed the lines at the tube nuts on the hard lines in the same way as you can from bleed nipples, just crack them open 1/4 turn, pedal down, lock off, pedal up.

When you had the bleed nipples in the master cylinder ports, the pedal should have gone just about rock hard with about 20 mm pedal movement or less. If was moving more than that and / or wasn't very solid, then either there's air trapped in the master (which I doubt by now) or it's not right for what ever (internal) reason.

Is it single circuit or tandem on this car ?

Have you also tried isolating the brakes ? You can get line lock tools that close off on the flexy lines each brake - beware though, you can only use these with rubber lines, not braided. These tools are inexpensive, if you have 4, lock off all brakes and see how the pedal feels, then check each brake, 1 at a time. This will help you isolate where the issue is if it's related to 1 particular wheel.

[WanaGo]

You can bleed the lines at the tube nuts on the hard lines in the same way as you can from bleed nipples, just crack them open 1/4 turn, pedal down, lock off, pedal up.

When you had the bleed nipples in the master cylinder ports, the pedal should have gone just about rock hard with about 20 mm pedal movement or less. If was moving more than that and / or wasn't very solid, then either there's air trapped in the master (which I doubt by now) or it's not right for what ever (internal) reason.

Is it single circuit or tandem on this car ?

Have you also tried isolating the brakes ? You can get line lock tools that close off on the flexy lines each brake - beware though, you can only use these with rubber lines, not braided. These tools are inexpensive, if you have 4, lock off all brakes and see how the pedal feels, then check each brake, 1 at a time. This will help you isolate where the issue is if it's related to 1 particular wheel.

 

Thanks, will certainly give a few more things a try

 

This is a single circuit. Original Lockheed metal master. The bore seemed fine, and used the refurb kit from Minispares.

The pedal is still at about half way a few days later. Maybe i'll take a quick video and post that and see what people think of it in action

[Spider]

The pedal is still at about half way a few days later.

 

I did read that earlier, but is that with the nipple fitted to the master or the brakes plumbed in ?
 

[WanaGo]

 

The pedal is still at about half way a few days later.

 

I did read that earlier, but is that with the nipple fitted to the master or the brakes plumbed in ?
 

 

 

Brakes plumbed in. Havent tried a nipple on the master yet

[gaspen]

 

It should be a good idea to bench-bleed the Master Cylinder before install it to the car. Somehow the air can trapped in the MC

 

You can find many videos on YT how to do it

 

Thanks. I would have thought using the spare tyre kit and forcing fluid through from the master, would have purged the master itself of all air. 
The only bench bleeding videos I can find on YT do not relate to the classic mini, but it just looks like you pump the fluid around and around from the outlet back into the reservoir. So not really going to gain much over what I have done already I dont think.

 

 

You can not push the piston all the way up in the car with the brake pedal

[WanaGo]

 

 

It should be a good idea to bench-bleed the Master Cylinder before install it to the car. Somehow the air can trapped in the MC

 

You can find many videos on YT how to do it

 

Thanks. I would have thought using the spare tyre kit and forcing fluid through from the master, would have purged the master itself of all air. 
The only bench bleeding videos I can find on YT do not relate to the classic mini, but it just looks like you pump the fluid around and around from the outlet back into the reservoir. So not really going to gain much over what I have done already I dont think.

 

 

You can not push the piston all the way up in the car with the brake pedal

 

 

Ah, right. Maybe I can just pop the pin out then and push it up and down without the pedal, if I can acheive that. Rather than taking it out.

So using the Spare Type 20psi forcing method, wont get that air out like pushing the piston all the way up, you think?

[gaspen]

 

 

 

It should be a good idea to bench-bleed the Master Cylinder before install it to the car. Somehow the air can trapped in the MC

 

You can find many videos on YT how to do it

 

Thanks. I would have thought using the spare tyre kit and forcing fluid through from the master, would have purged the master itself of all air. 
The only bench bleeding videos I can find on YT do not relate to the classic mini, but it just looks like you pump the fluid around and around from the outlet back into the reservoir. So not really going to gain much over what I have done already I dont think.

 

 

You can not push the piston all the way up in the car with the brake pedal

 

 

Ah, right. Maybe I can just pop the pin out then and push it up and down without the pedal, if I can acheive that. Rather than taking it out.

So using the Spare Type 20psi forcing method, wont get that air out like pushing the piston all the way up, you think?

 

 

Meanwhile I read that you have a sinlge circuit MC, I am not sure that it will need bench bleed

 

( In a dual-circuit MC there is two pistons "connected" by a spring only. So the second piston will move all the way up if you push it in a bench )

 

Did you replced any other components in the brakes ?

 

On the old MiniSpares website there was a chart about the brake components which I can not find now. Anybody knows where it is ?

 

From that chart you can find out which diamater wheel cylinders you can install for a given MC. 

Edited by gaspen, 13 January 2025 - 10:37 AM.