Joined: Dec 2017 Posts: 49 Threads: 26
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I have an Austin seven special using Morris minor cylinders and drums. This is how it came so I am not sure of the specifics .The brakes are very poor. On inspection I note the only the leading and trailing edges of the shoes are contacting the drum.
Are there different size drums and shoes? Could I have a set of shoes for a larger sized drum?
Any ideas? Please see attached pic.
Best Wishes
Shane
Joined: Aug 2017 Posts: 226 Threads: 9
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Location: Edinburgh/Lothians
Car type: Seven Special
Hi Shane,
Most conversions use the original Austin cast iron Girling type drums not MM ones.
Suggest you measure the inside dia. of the drum. Should be 7".
Often the reason for the wear you describe is there are high spots on the shoe due to it not being a matched curve to the drum. Most shoes bed in. Some of us have home made devices that assist in doing this. The leading edge of the shoes may benefit from some dressing back.
Some photos would be helpful.
Paul N-M
Joined: Aug 2017 Posts: 926 Threads: 22
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Location: Near Cambridge, UK
Car type: 1928 tourer (mag type), short chassis Gould Ulster
The picture seems to be missing, but in my opinion there is no way the 8" shoes would fit in a 7" drum. If the shoes and linings are from a drum which has been skimmed but you have a drum which has not been skimmed this could give you the symptom you describe.
Robert Leigh
Joined: Aug 2017 Posts: 926 Threads: 74
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Location: Essex
Firstly is the problem with fronts, rears or both and is the contact mark both ends of one shoe? A simple test would be to put the shoe inside the drum. If the centre sits off the drum an appreciable amount, draw an 8" circle on paper and offer up the shoe..
Joined: Dec 2017 Posts: 189 Threads: 8
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Location: East Yorkshire
Car type: Ruby sports trial special .
Just been doing my brakes there's no way 8"
Shoes will fit take shoes off and hold them in
The brake drums to see how well they fit
Have come across badly modified
Backplates were cylinders are off centre!
My problem I ask questions that other people don't like?
Like have you got that for an investment or for fun?
Joined: Aug 2017 Posts: 926 Threads: 74
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Location: Essex
Could be the wrong wheel cylinders then... the fulcrum may be in the wrong place.
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most reasons for bad brakes on hydraulics have been listed above.
but you will to check to see if you are running on new or used parts.
brake shoes are easy, and for £15 most people will fit some new shoes.
but many systems were built up on used drums as new were not available. so your drum could be 100 thou oversize to the standard 7 inch. or even more when scimmed.
with an oversize drum, only the edge of the shoe will touch when the cylinder is open.
it has the same effect with standard brakes, which is why the old myth that austin 7s have poor brakes is put around.
tony
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
As above if it is each end of each shoe either a lining bedded or ground for an oversize drum or a packed or thick oversize lining which were/are available. If the MM system does not allow the shoes to completely positon themselves as on moderns then if made up the fulcrum location critical, although would not expect to give the pattern described. If fitting the linings beware NOS and others likely asbestos.
Joined: Oct 2017 Posts: 1,504 Threads: 54
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Knowing the propensity for the MM wheel cylinder pistons to seize are you sure they are all free?
