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I have a friend with a 1931 boat tailed tourer which he has used as everyday transport since the 1950s. He relined the brakes in the summer and soon after when he brakes the brakes grab there is no gentle braking. So he relined the brakes again with linings from another of our cherished suppliers, these have now developed the same problem and with winter approaching and possible icy roads he needs to find an answer. His car has coupled brakes and 1.25" brake shoes and drums. I've gone through the usual loose brake shoe pivots, broken brake shoe springs, oval drums, worn king pin bushes and or shackles. Help, have any of you got any ideas as to the cause. 
Joined: Mar 2015 Posts: 5,180 Threads: 222
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Location: Scotchland
I had a similar problem and tried all the remedies you suggested without success - until I noticed the radius arm ball joint rivets were loose. Rectifying this cured the problem, in my case.
Joined: Aug 2017 Posts: 605 Threads: 18
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Location: Sheffield South Yorks
Car type: 1932 RN saloon
10-11-2017, 10:16 AM
(This post was last modified: 10-11-2017, 10:17 AM by Dave Wortley.)
Dave,
Has he tried putting a chamfer on the leading edge of each brake lining? If asbestos he must take health precautionsbefore gently hand filing.
Dave.
Also how about play in rear spring pins and bushes
Joined: Aug 2017 Posts: 16 Threads: 1
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I had this on an older car after fitting new shoes. It always happened on the first application of the brakes after the car hadn't been used for a few hours. It was particularly bad on cold, damp mornings.
I chamfered the leading edge of the shoes and continued to lengthen the chamfer to little effect.
I put it down to the removal of asbestos in the friction material and would apply the brakes as soon as it was possible to do so safely at the start of each journey, expecting them to snatch. Once they had a tiny bit of heat in them the problem wouldn't recur.
Joined: Aug 2017 Posts: 848 Threads: 22
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Location: Near Cambridge, UK
Car type: 1928 tourer (mag type), short chassis Gould Ulster
10-11-2017, 11:22 AM
(This post was last modified: 10-11-2017, 11:28 AM by Robert Leigh.)
(10-11-2017, 09:53 AM)Dave Mann Wrote: I have a friend with a 1931 boat tailed tourer which he has used as everyday transport since the 1950s. He relined the brakes in the summer and soon after when he brakes the brakes grab there is no gentle braking. So he relined the brakes again with linings from another of our cherished suppliers, these have now developed the same problem and with winter approaching and possible icy roads he needs to find an answer. His car has coupled brakes and 1.25" brake shoes and drums. I've gone through the usual loose brake shoe pivots, broken brake shoe springs, oval drums, worn king pin bushes and or shackles. Help, have any of you got any ideas as to the cause.
Apart from what has been suggested, ie the slightest bit of play in suspension fixings which should be rigid, I remember having the problem and it turned out to be a peculiar coating on the drums. It may be worth removing the drums and ensuring that the braking surface is completely clean of any trace of oil or a varnish like surface which is what I found. Labouring with emery cloth until I had a clean metal surface was the answer.
(10-11-2017, 09:53 AM)Dave Mann Wrote: I have a friend with a 1931 boat tailed tourer which he has used as everyday transport since the 1950s. He relined the brakes in the summer and soon after when he brakes the brakes grab there is no gentle braking. So he relined the brakes again with linings from another of our cherished suppliers, these have now developed the same problem and with winter approaching and possible icy roads he needs to find an answer. His car has coupled brakes and 1.25" brake shoes and drums. I've gone through the usual loose brake shoe pivots, broken brake shoe springs, oval drums, worn king pin bushes and or shackles. Help, have any of you got any ideas as to the cause.
Apart from the suggestion of ensuring that all fixings which should be rigid are rigid, it may be worth removing the drums and ensuring that the braking surfaces are all scrupulously clean of oil and any other contaminant. I once found a varnish like coating had developed and neededvery thorough cleaning off with emery cloth, and this cured the problem.
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Location: Darkest Bedfordshire
Brake grab is often the result of contamination on the friction surfaces - as Robert suggests, give them a good clean up using some brake cleaner spray. It sounds counter-intuitive, but oil on linings can cause this. Otherwise something loose or sticking, either within the brake itself, or externally (as Ruairidh suggests). The shoes must move freely and smoothly, and return firmly when released.
Joined: Aug 2017 Posts: 1,664 Threads: 46
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Location: Auckland NZ
Car type: 36 Nippy, 31 RM, 38 Special, 24 Works Rep
I agree with almost all of the above and like Ruairidh have found this issue linked to the radius arm ball, in my case the brass cups, through wear, were a poor fit in the radius arms allowing movement, rectifying this cured the problem.
Black Art Enthusiast
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I have the same problem on my RN, it's not going forward, its going in reverse I get the juddering. The problem I get going forward is the N/s locks up on full lock. It's in the garage now on stands so I can investigate the problem.
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Location: Auckland, NZ
On my car I bedded the cups in solder but more refined remedies can presumably be devised.
If the front levers are excessively forward the problem worsens. The direction of cotters is one influence.
With Sevens it is difficult to adopt a short pedal travel without incurring various drag problems.
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Many thank for all your comments, I spoke to my friend last night, this all started after his car hit a 13" deep pot hole breaking 1 kingpin and the radius arm ball mount bolt. He replaced these and is definite that the radius arm mount is nice and tight, the linings leading edges are chamfered and brake drums cleaned.
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