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master brake

Posted: Fri Mar 02, 2007 5:57 am
by rein
I have a 13/16" master brake cylinder that I want to use for my 1961 saloon. I noticed the bolt for the banjo connection doesn't fit. The 7/8"m/c from the saloon uses an 3/8" 20 TPI thread and the 13/16 m/c uses an 7/16" 20 TPI thread. Is the 13/16" m/c modified by a previous owner or did the m/c have 7/16" thread for the banjo connection? Is the banjo from the 7/8" m/c able to be used for the 13/16" m/c? (The 7/8" m/c is still in the car. I used another 7/8" m/c to check things out first).



Posted: Fri Mar 02, 2007 10:28 am
by bmcecosse
I guess you will need the complete correct banjo and bolt for that new cylinder - but someone who knows will be along in a few minutes - I'm just popping it back to the top for you!

Posted: Fri Mar 02, 2007 10:55 am
by 57traveller
I can't give a definitive answer about the sizes unfortunately. However, a few years ago I replaced the existing 7/8" MC on my saloon with a 13/16" MC. I don't recall there being a difference with the banjo bolt, I'm sure I just re-used the original. My memory could be wrong though! It gets like that at a certain age. :( But as bmc says you may have to order a new fitting from a parts supplier. Why not contact one of them and enquire?


Posted: Fri Mar 02, 2007 4:46 pm
by Willie
I confirm that, I changed from the 7/8"to the 13/16" and did not have to
change any fittings.

Posted: Fri Mar 02, 2007 6:43 pm
by rein
Thanks all.
I supplied a brake company with a 7/8" m/c with the question to resleeve it to 13/16". I didn't mind I was given an overhauled 13/16 " m/c instead. But if the thread on that particular m/c is not standard they have to come up with a solution. I will contact them on Monday. I will have to keep an eye on the brake fluid level for yet another week.



Posted: Sat Mar 03, 2007 5:56 pm
by bmcecosse
May be that 'pattern' parts have been made with wrong thread.

Posted: Fri Mar 09, 2007 5:49 am
by rein
The company that supplied the m/c gave me another m/c with the correct thread.
This weekend I want to change the m/c over. I already changed the bolts that fix the m/c into the chassis. So I don't have to remove the torsion bar.
Do I need to remove the floor panel? Although the workshop manual tells me I do, I am not sure why. Is there a shortcut?


Posted: Fri Mar 09, 2007 8:37 am
by Willie
As long as you have secure access to the underneath of the car then you only need to removed the small plate over the Master Cylinder.
If you have reversed the bolts then do ensure that they do not protrude
enough to contact the torsion bar. If necessary grind the end of the bolts
if adding washers on the inner side doesn't do it.

Posted: Sun Mar 11, 2007 7:59 am
by rein
Thanks Willie.
I was able to get the m/c in without removing the floor panel. At the same time I replaced the pipe running from the m/c to the stop switch.

I have bled the brakes on the Morris before without to many problems.
This time I am not able to get the air out. I read some threads on the forum on this subject. Still I am not sure what could be wrong with the system. There is so much air in the system that the fluid sometimes looks like foam. Already 2 litres brake fluid past thru the system, so I am assuming somewhere air is entering the system.The funny thing is that the rear brake line fluid looks good (without air).
Could there be a problem with the overhauled m/c? The pedal is not slowly sinking to the floor.
I am at a loss and now I need to take the train to work.

Suggestions are very welcome.


Posted: Sun Mar 11, 2007 8:43 pm
by les
Put the m/c bolts in the right way round, that's your trouble!


Posted: Sun Mar 11, 2007 8:46 pm
by Willie
LES what on earth is that supposed to mean?


Posted: Sun Mar 11, 2007 8:50 pm
by Willie
Rein, the clue may be in that you changed the pipe from the MC to the brake light switch?? I take it that you have air coming through the front bleed nipples which,of course, are supplied with fluid via the same pipe which feeds the brake light switch!

Posted: Sun Mar 11, 2007 8:52 pm
by les
Sorry, the devil made me do it. That bolt trick is one of my pet hates!

Posted: Sun Mar 11, 2007 10:01 pm
by rein
Today I will get some more brake fluid and follow up all the suggestions and tips I read on the forum on this subject. I have been thinking about the replaced pipe, but I don't understand that so much air is in such a short pipe. Perhaps I allowed the brake fluid level in the m/c to get too low a few times? I will make sure this can not be the case when I again start bleeding the brakes.


Posted: Sun Mar 11, 2007 10:04 pm
by les
On a serious note, if you have let the m/c get too low and sucked in air, that is surely the problem.

Posted: Mon Mar 12, 2007 5:39 am
by rein
I bled the system with a close look on the fluid level to no avail.
I isolated the problem to the front brakes. I think that the front wheel brake cylinders draw in air (if that is possible) because, when I bleed one of the front wheels as good as it gets, close the nipple and bleed again after a few minutes a lot of air entered the system again (at the first pedal movement!).
I will check the cylinders and see if I can see anything wrong with them.


Posted: Sat Mar 17, 2007 7:06 am
by rein
I think I found the problem. The valve in the master m/c wasn't working at all because the rubber washer was warped. I am not sure, but it looks like a washer for a 7/8 m/c. So the system didn't have any remaining pressure after returning the pedal. This caused the intake of air at the wheel cyinders. (I should have read the workshop manual more closely to understand why this remaining pressure is needed!).
I put back the old 7/8 m/c for now and will go back to the place where I bought the m/c. She is back on the road again.




Posted: Sat Mar 17, 2007 7:48 am
by Willie
Glad you are mobile again Rein but i cannot see how the system could suck in air at any point(without also leaking) so please tell us your final outcome for future reference.

Posted: Sat Mar 17, 2007 8:48 am
by TeHoro
I've had hassles in the past bleeding the Morris' brake system - its one of those easy in theory/tricky in practice things.

My current method is to use a special fitting on the M/C cap that I can attach a compressed air line to. I set the regulator at about 20psi then open each bleeder in turn.

I have to be careful that the M/C level doesn't drop too low, but it works well otherwise. I wish I could easily make adapters for some of my other cars :P

The adapter for the Morris is simply a quick-release air fitting threaded into a spare M/C cap, and the existing vent hole plugged with a nail.

I think someone in the US sells a system that uses air pressure in the spare tyre in a similar way. I doubt you'll find one in NZ though.


Posted: Sat Mar 17, 2007 9:14 am
by alex_holden
TeHoro wrote:I think someone in the US sells a system that uses air pressure in the spare tyre in a similar way. I doubt you'll find one in NZ though.
I think you mean the Gunson Eezibleed kit. It comes with caps suitable for most makes of reservoir and there are more available by mail order, but unfortunately they don't do a Morris Minor one (you have to modify an old cap yourself). The advantage it has over your method is that it has a large plastic fluid reservoir and as fluid drains out of the car's reservoir it's replaced with new fluid from the Eezibleed bottle. They're not heavy so I wouldn't have thought postage to NZ would be prohibitively expensive.