Cross-shaft bearings: how much clearance is OK?

[Ron Hayhurst]

I am overhauling the cross-shaft and bearings on the coupled brakes on my 1934 Box Saloon. With all parts cleaned and measured, it can be seen that there is little wear on the N/S bearing and some wear on the centre bearing, which measures 1.181 inches diameter. If I guess that this was an inch and three sixteenths when new (1.1875"), then there is about 6 thou wear. 
The O/S bearing, next to the foot brake connection, is at the end of a long length of inch and five sixteenth shaft (1.3125") and would have been this same diameter when new. It is now slightly oval with diameters between 1.301" and 1.304" diameter. If a new bearing sleeve was to be slid up the shaft it would need to be (say) 1.314" inside diameter, so there would be 10 to 13 thou slogger. 
Before I consider machining the 1.3125" part of the shaft to match the cleaned up part of the O/S bearing (and maybe cleaning up the centre bearing) it begs the question: is it worth it?
In other words, would this amount of slogger affect the braking efficiency, or make it harder to correctly adjust the brakes? I would be pleased to know if anyone has previously commented on this.
Ron

[Bob Culver]

I don’t have the answer but the centre and rhs are pulled forward, the lhs back. Adjusting the brakes with the footbrake somehow applied would seem to sort much of the lost motion. Mechanical perfection is satisfying but not always critical! I would not contemplate reducing any tubes over length.
I dunno how experienced you are but the (intended) concentric operation of the rhs tubes is far from obvious, is mentioned in few or no publications, escapes most, and is likely seized. Was eventually covered at length on the old site

[Hugh Barnes]

My feeling on this is you actually need a certain amount of 'free play' in this set up. Too 'good' a fit will see the shaft bind in the bearings as the chassis flexes...

[Ruairidh Dunford]

Spot on Hugh.

[Martin Prior]

Does anyone stock the largest (offside) cross-shaft bush?

The usual suppliers have the other two, but I need to replace the full set.

[Ruairidh Dunford]

I bought suitable tube from John Barlow for this Martin.

[Hedd_Jones]

My test after an overhaul (and painting) is that the return spring returns the shaft itself when youve finished (minus cables etc). If it doesnt its too tight.

A little play is if no consequence, the brake efficiency is defined by the angle of the levers rather than how much play you have. When set up the springs on the shoe end of the cables keep them taght. The play in the pedal is taken out by a spring etc. The lost motion is generally only the cables srtetching and the bearings flexing.

[Ron Hayhurst]

Thanks to those who replied on this thread. It would appear that the wear indicated in my original post will be OK; so no plans for any machining etc. Amongst my spares I have a new sleeve for the O/S bearing which is couple of thou under the unworn shaft size. Application of a little heat has enabled that to rattle down to the far end of the shaft so that at this point there will be about 10 thou clearance.
I was puzzled that this thread no longer appeared on either "New Posts or "Today's Posts" which is where I normally go (probably nobody else does!!). Not any longer! The package appears to only allow one screen here so the preferred route, especially if you are not in here every day,  is to click on Forum Chat and start to explore the 70 odd pages where all the topics are listed. 
Incidentally, there is quite a bit of chat about cross-shafts on the Old Forum q.v.
Ron