uncoupled brake balancing - old forum thread

[JonE]

Russell - how were drums considered for your strategy for Chummy and Apex? Did you feel the need for cast items that have been advocated by others as being the best improvement for braking (just because of the worn nature of many original drums)?

[AustinWood]

I like the uncoupled brakes on my 1929 saloon. When approaching junctions, traffic lights, roundabouts etc I usually pull on the handbrake a couple of notches because I know it's likely I shall have to stop. I can then use the footbrake to come to a standstill or release the handbrake if I don't need to stop. It also balances the wear between back and front.
I have got good balance on the footbrake by bracing the cross-shaft. It's very instructive to look under the car when an assistant presses the brake pedal. The cross-shaft moves forwards on the offside because of the force from the pedal and moves back on the nearside in reaction to tension in the brake cable.
I have made a bracket at the nearside bracing the cross shaft to the chassis cross member to stop it moving back. On the offside I fitted a bolt in the cross member that bears against the cross shaft bracket to stop it moving forwards.
The improvement is very marked and the brakes can be balanced with little trouble.

["Slack Alice" Simon]

I like the uncoupled brakes on my 1929 saloon. When approaching junctions, traffic lights, roundabouts etc I usually pull on the handbrake a couple of notches because I know it's likely I shall have to stop. I can then use the footbrake to come to a standstill or release the handbrake if I don't need to stop. It also balances the wear between back and front.
I have got good balance on the footbrake by bracing the cross-shaft. It's very instructive to look under the car when an assistant presses the brake pedal. The cross-shaft moves forwards on the offside because of the force from the pedal and moves back on the nearside in reaction to tension in the brake cable.
I have made a bracket at the nearside bracing the cross shaft to the chassis cross member to stop it moving back. On the offside I fitted a bolt  in the cross member that bears against the cross shaft bracket to stop it moving forwards.
The improvement is very marked and the brakes can be balanced with little trouble.

I am working very slowly on my '34 tourer, having re-lined the rears but not the fronts.

To simplify things (ie. balancing) I have run it with the brakes uncoupled for a while now.

I am used to this anyway because "Alice" has uncoupled brakes and I have done many miles in that car.

The tourer has a low top speed, and I have found that driving around with a 2 + 2 system is quite adequate.

It helps in diagnosis:  there is a often terrible groaning noise when I brake using the rears, which appears to come from the front of the car.

I am sure this is vibration due to braking feedback through worn out rear spring pins, but if the brakes were coupled, I would have dismantled the front axle to find the source of the noise.

I will re-couple the brakes eventually, but at present rate of progress it will in be a month or two.

Simon

[squeak]

Russell - how were drums considered for your strategy for Chummy and Apex? Did you feel the need for cast items that have been advocated by others as being the best improvement for braking (just because of the worn nature of many original drums)?

Jon the 28 chummy brakes have had an upgrade in the past to semi girling fronts.
 In MY ownership I treated it to 4 cast iron drums from the spares pile, and new bonded soft linings. The standard early radius arms were boxed and sundry bushings replaced,  the uncoupled cross shaft was beefed up by adding (welding) a steel connection piece from the shaft bearings forward to the chassis crossmember.  THEN, I paid careful attention to  play in the linkages and achieving a 90 deg angle at the junction between cable and lever, at point of maximum braking effort.
The results were quite good, probably as good as the aforementioned 38 ruby, so I have not sought new drums. 
The Apex is not on the road and will get similar brakes to the chummy.
Recently my wife and I toured the UK in a 27 top hat and the brakes were RUBBISH despite my replacing the linings, cables and on road adjustments. We DID feel the need for Tony's new cast iron drums and fitted a set, the brakes are still uncoupled and still  rubbish.
 I'm sure now that I'm home with the saloon and access to a hoist, I'll be able to make the cross shaft support connections, and fine tune the braking and suspension condition. I will keep Tony's new drums on and pay more attention to the linings contact area. 
We use the top hat weekly and in common with other seven owners, we have a well developed sense of anticipation.
Anticipation of a pleasant outing.  cheers  Russell

[Tony Press]

Russell - how were drums considered for your strategy for Chummy and Apex? Did you feel the need for cast items that have been advocated by others as being the best improvement for braking (just because of the worn nature of many original drums)?

Jon the 28 chummy brakes have had an upgrade in the past to semi girling fronts.
 In MY ownership I treated it to 4 cast iron drums from the spares pile, and new bonded soft linings. The standard early radius arms were boxed and sundry bushings replaced,  the uncoupled cross shaft was beefed up by adding (welding) a steel connection piece from the shaft bearings forward to the chassis crossmember.  THEN, I paid careful attention to  play in the linkages and achieving a 90 deg angle at the junction between cable and lever, at point of maximum braking effort.
The results were quite good, probably as good as the aforementioned 38 ruby, so I have not sought new drums. 
The Apex is not on the road and will get similar brakes to the chummy.
Recently my wife and I toured the UK in a 27 top hat and the brakes were RUBBISH despite my replacing the linings, cables and on road adjustments. We DID feel the need for Tony's new cast iron drums and fitted a set, the brakes are still uncoupled and still  rubbish.
 I'm sure now that I'm home with the saloon and access to a hoist, I'll be able to make the cross shaft support connections, and fine tune the braking and suspension condition. I will keep Tony's new drums on and pay more attention to the linings contact area. 
We use the top hat weekly and in common with other seven owners, we have a well developed sense of anticipation.
Anticipation of a pleasant outing.  cheers  Russell

A club member who was a brake man at GMH during his career ventured the opinion that the original light drums were better able to conform to the shoes as they pivot, giving full lining contact. 

Any new linings should be ground to the radius of the drum inside diameter when applied and not rounded at rest.

Cheers Tony.

[squeak]

A club member who was a brake man at GMH during his career ventured the opinion that the original light drums were better able to conform to the shoes as they pivot, giving full lining contact. 

Any new linings should be ground to the radius of the drum inside diameter when applied and not rounded at rest.

Cheers Tony.
[/quote]

Tony did you mean a "brave" man at GMH, I can't get the image of the drum performing a Mexican Wave out of my head.
Is he saying the shoes should be ground to the shorter radius of the stretched drum's elipse? cheers Russell

[Tony Press]

A club member who was a brake man at GMH during his career ventured the opinion that the original light drums were better able to conform to the shoes as they pivot, giving full lining contact. 

Any new linings should be ground to the radius of the drum inside diameter when applied and not rounded at rest.

Cheers Tony.

Tony did you mean a "brave" man at GMH, I can't get the image of the drum performing a Mexican Wave out of my head.
Is he saying the shoes should be ground to the shorter radius of the stretched drum's elipse?    cheers  Russell
[/quote]

Russell,

If you were brave I suppose you could line the drum with emery cloth and do a run around the block with light application, although I expect this wouldn't stretch the drum enough !

Cheers, Tony.

[JonE]

Rob’s modification used one long brake cable which went through the centre of the cross shaft, exiting through smooth brass cups then up over a wheel on an arm, from memory.

Can't 'quote' the picture again, but just came back to this thread in light of all the uncoupled chat. How in practice would one make a cable? - I'm not sure how the lever fittings attach at the backplates and how would one factor adjustment in the single line... a stainless turnbuckle?