BRAKES WHAT'S NORMAL

[AllAlloyCup]

I Thank Ruairidh, I was hoping it would be 1 1/2” to
2” travel on a maximum of 3”, leaving 1” to 1 1/2”
Before the pedal floored.

The brakes are uncoupled and have new linings
Cables, yokes and clevis pins.

Neil is coming over tomorrow to help have a first go at setting
The rear brakes up. Hard to adjust the balance though?
As I reckon you need the floors up to do them?
The side to side rear balance might need readjusted
once the car can be driven?

Regards

Bill G

[Ruairidh Dunford]

Adjustment will be needed several times whilst everything settles in Bill. Set the N/S to come on slightly before the o/s and you will be a in a good starting position. Ensure the cross shaft levers need to be all the way backwards at rest.

A famous A7 builder always used to put his body weight in old cylinder blocks in the car before adjusting the brakes - as you have no engine in and the car is not completely built up - consider this and the effect the extra weight will have on the semi elliptic springs...

[AllAlloyCup]

Hi Ruairidh

We’re putting the engine and gear box in too
Plus I’ll put the spare block on the drivers side
as you kindly suggested, or just use the mass of Neil!

Regards

Bill G

Ps I’ve only ever had hydraulics to deal with before!

[AllAlloyCup]

Just found a section in my 1928 Nicholson red book
that says once the pedal travels 2” you need to readjust your
Rear brakes( on an uncoupled system)

So will try to set up for 1” or thereabouts.

Regards

Bill G

[JonE]

John Barlow lists new 1-1/4" shoes with linings at £15 each.
I have them on my front brakes.

Jim - so is it true you are running 1  1/4" drums on rear with 1" brakes to improve an uncoupled system, as per a thread from years ago. Or have you revised your thought on that? Do they fit straight on?
And what is your strategy re the wider shoes on front brakes... but presumably not rear?

[AustinWood]

I have 1-1/4" brakes all round with Tony's CI drums, they fit straight on. Fronts have John Barlow shoes, rears Austin shoes with woven linings.
Brakes are uncoupled.
On the front I have longer levers and I've made modifications to the handbrake to increase the travel. Often the handbrake is limited by lack of travel and the lever hits the end of the slot before maximum effort is reached.
For the rears I've added a bracket/bearing on the nearside connecting the cross shaft to the cross member To prevent the shaft flexing back under load. Also a stop on the O/S to prevent it flexing forward. This improves the brake balance which is normally biased towards the O/S. With the standard set-up the N/S rear brake needs to start to work before the O/S to get reasonably straight braking. That wastes travel.
It is very instructive to watch from below while someone presses the brake pedal. The amount of flex on the cross shaft is surprising!

[JonE]

understood. thankyou Jim. But at the time of that long ago post, you'd posted

"However it wouldn't lock the wheels until I changed from 1" to 1-1/4" drums. I think the latter are more rigid. Still with 1" shoes".

I'm interested to know about the difference in the feel from 1" to 1 1/4" as it sounds like you have completely gone over now? Also, did you try Austin 1 1/4" drums before moving to Tony's, and were they an improvement in rigidity (assuming their condition was rounghly the same)?

[AustinWood]

Don't think there's much difference in feel, just work better.
Assuming everything else is correct such as good bushes & cams, levers at the right position, no oil on the linings then they should work pretty well.
My modifications to the cross shaft have made a big improvement. The standard setup means that the O/S brake gets more of the effort because the cross-shaft flexes. The N/S brake has to be set up to come on well before the O/S. What then happens is that as the footbrake is applied the car pulls left but as the pressure is increased this evens out then starts to pull right.
Uncoupled brakes.

[JonE]

Thanks Jim - was looking at how to do those bits today.

Ref my photo in post #29 of rear brake lever position. I now feel it's impossible for a diagnosis of cams being wrong sided for that scenario. I've been faffing for a couple of sessions and of course, you learn best whilst doing that. But what becomes clear is that when the shoes are resting, full on cam flats, there are 4 possibilities from the cam pair. Two result in the lever facing upright so obviously incorrrect, so that leaves one potential position on each of the cam pair to investigate. The correct one put the lever approximately downward, whilst the incorrect puts it over the top of the axle tube, so it would be impossible for it to move when actuated, despite it being nicely far back.
The factors [that lead to that angle of lever photographed] were solely lack of shimming and wear on the drums, meaning that the cam was adjusted up for pedal travel, but with hardly any slack left before the cam would flip dangerously.

This thread has been fabulously helpful (thankyou all), and the real thing I've gradually learnt is that you need to do ALL the in-drum stuff (3 shimming positions, drum choice) to minimise clearance before even thinking about the cams.

[Bob Culver]

Despite all this any newcomer is likely confused. Despite the  listing by major supplier it is clear the pre Girling rear cams differ front to rear and the rear side to side. 

I have asked several times but no answers. I do not have enough accessible parts to verify. But from various pictures the rear cams on (some?) Ruby hubs seem to be more forward than previous, the whole "backplate" effectively rotated forward. If so this would seem to require yet another pair of cams. Is that Jon's problem?

Maybe someone could list all the cam  part numbers.