Morris Minor Owners Club

I am in the process of removing my faulty brake master cylinder but am having problems removing the 2 bolts which secure the unit to the chassis. I have a good selection of spanners but cant seem to locate one which fits the nuts properly. As many members will know access is limited and accurate spanner size is essential to obtaining a good purchase to shift 'stubborn' nuts. Any advice would be greatly appreciated.

Are you using metric or A/F imperial spanners? Stick to imperial... leave the metric to one side. Once undone the bolts will be particularly difficult to get over the torsion bar... a handy tyre lever is usually required at this point.

1/4 Whitworth. You will need two, one for each end.
1/4, 5/16, 3/8, 7/16 Whitworth spanners and sockets are essential for working on a Morris Minor

Hello Mike, Many thanks for your advice, will obtain Whitworth spanners in recommended sizes.

Hello Dean, many thanks for your swift response. Very helpful

from memory tyhey are bigger than 1/4 Whit - however if you get the sizes recommended by Mike you'll be much better off for a lot of the jobs on a Minor.
I also have Whitworth sockets for this range, although the only one used regularly is 1/4" Whit.

Many of the head sizes are Whitworth, even on the later Minors as they didn't update a lot of the fasteners, e.g. when the bolt goes into a captive nut on the body - this would have made the shells different and that would have caused all kinds of issues. Some threads and heads are AF.. It becomes even more difficult when some nuts and bolts are replaced in metric sizes and/or AF during servicing and repairs.
This will lead to needing Whit, AF and Metric spanners / sockets. That itself can frustrate people, but if you're prepared with the right tools, any job becomes possible.

E.g Seat bolts, wing bolts, door hinge bolts are 1/4" Whitworth. This is just over 13mm and only a Whit spanner or socket will do the job properly. If you can get a 13mm spanner to fit, then either the head has rusted undersize or the spanner is poor quality and made outside of tolerance!
e.g.2 It's common to find 1/2" AF heads on wing bolts .
e.g.3 Wheel bolts are a Whitworth size, but close enough to 18mm socket size not to cause any problems.


Depending on size, the threads can be similar, but not identical. Using a bolt with not quite the right thread can cause more problems that it's worth.

[Certainly those who are inclined to do so would make sure there are no metric fasteners on their car to avoid the 3rd set of tools being needed. If you're on a journey and take tools with you, having to take lots more is not ideal. On the early cars you need just one size and imagine being able to do most things on the car with just a couple of spanners?! That was how they designed cars in the good old days.]

As for the brake m/c - I use a long lever and a long block of wood to lever against to move the torsion bar for bolt removal and replacement. Just make sure your finges can't get trapped if something slips and then there shouldn't be too much to worry about.
Putting the bolts in the wrong way round is common but often causes the torsion bar to get damaged when it flexes under load, as it can rub on the bolt/nut even if it had clearance when the car was stationary.

I physically checked the master cylinder bolt size on my spare = 1/4 Whit. We used 5/16 W on the oil filter bolts and it also fits the nut and bolt on the lower suspension arm. The 3/8 W socket fits the nut on the back of the tie rod forks on the lower suspension arm and of course fits the wheel nuts. 7/16 W is on the other end of the 3/8 W spanner.
The Series MM engine is even more complicated with mostly Metric fine threads on the bolts which have Whitworth sized heads

Thanks to MIke, Dean & Ray for all your help. I appreciate the time you have all expended in providing advice on this issue., and will let you know the outcome. I have A/F, Metric spanners and am expecting the arrival of a Whitworth set in the next few days.

Certainly won't be 5/16 Whit on the 'oil filter bolts' - ALL the engine and gearbox nuts/screws are 'AF' sizes.

The oil filter mounting bolts on the Series MM which Ray and I were working on are 5/16 W.

Aaaaahhh - the MM....... Metric threads with Whit heads!!

Metric fine threads to be exact ;-)

Have finally managed to remove the 2 bolts securing the master cylinder, - quite a struggle and had to resort to using a length of tubing over the spanner to provide extra leverage. Having disconnected both brake pipes I thought my problems were over. Not so! It appears that the transverse shaft which is part of the clutch pedal and on which the brake pedal pivots, is the later version, (non cotter pin type) and is secured through the chassis member with a locating washer and 'castellated' nut. I removed the latter but was unable to withdraw the shaft. I resecured the nut with a few turns and gave it a few cautious taps with a rubber faced mallet, but no success. I welcome any advice/recommendations to enable me to proceed.

Telpet

Hi

You will find that there is a spacer tube on the shaft which will have rusted in place. Hold it with some pipe grips or a stilson wrench and after a good soak with penetrating oil, rock the pedal up and down to loosen the spacer on the shaft. Use heat from a blowlamp if neccessary.

Should then be possible to get the pedal shaft out

Good Luck

Taupe

Hello Taupe,

Many thanks for your prompt reply and advice. I'll proceed as suggested and let you know how I get on.

Telpet

mike.perry wrote:1/4 Whitworth. You will need two, one for each end.
1/4, 5/16, 3/8, 7/16 Whitworth spanners and sockets are essential for working on a Morris Minor

Agreed! and sometimes a 3/16 Whitworth.

Trying to "make do" with metric and AF will just lead to rounded nuts, skinned knuckles and a lot of wasted time!

Hello Taupe,

Your advice was invaluable, likewise all others who have kindly helped me deal with my brake problems. Many thanks.
Now here is another curiosity, or maybe not. The castellated nut securing the hub unit ( offside front axle) is removed anti-clockwise as is normal. However, when removing the nut on the nearside front wheel axle I was surprised to find it was a left hand thread, ie., removed clockwise. I am wondering whether this is a normal feature of Minors.

Telpet

Yes - that's correct.

Thank you bmcecosse.

I am relieved to learn that in respect of my left hand thread ( nearside front wheel), my Minor is not unique

Thanks again,,


Telpet