UNI casing rear brake issue

[Topgearskin]

Having swapped out all of the internals from my SIL casing into a new UNI casing, everything has gone well until I got to the rear hub. I've fitted the pins, shoes and pivot lever from teh oringal engine and used the same rear hub. The layshaft is the same, gearbox etc all the same. Even refitted the same rear hub bearing.
And yet...the brake shoes are binding on the hub. I've rubbed down the shoes to take off a bit of meat and its no better.
I've stripped the gearbox (again)and the hub bearing to make sure the layshaft was fitted correctly, and that the bearing was true. The bearing does sit proud of the case on the hub side by about a millimetre.
But I'm stumped.
The only thing I can think is that the pins are bent or the holes for them are drilled too far apart?

I've tried different shoes (although the shoes are specific to the hub?) and no better. Tried a different pivot lever - no better.

any help?>

[al pushpak]

Have you tried a different hub ?

[Topgearskin]

Have you tried a different hub ?

Yes - I tried the original GP style hub (indian) that was on the engine, then tried the S2 hub that I had. Neither work, both bind.

[ste s one]

Have you tried torqueing down the hub without the shoes fitted ?
I had the same issue and found the inside edge of the hub rubbing on the casing, not the shoes .
10 minutes dremel and sanding drum ( on the casing ) and all good .
Worth a try

[Fast n Furious]

To give us a better chance of advising you. Try using some tracer paint or tippex on the edge of the shoes, to determine if the binding is in the middle of the shoe(s), or more toward the hinge side of the shoes or more toward the actuator side?
Is the cam actuator shaft the thin GP type or the thicker Ser3 type?

[Topgearskin]

the plot thickens.

I've looked at where the shoe is binding - it appeared to be on the edge closest to the pins. I replaced the pins and tried again - although there is very slight binding it felt like the issue was more layshaft/ gearbox related, since without any shoes on the hub would turn but had a lot more resistance than my other engines. The resistance is still there when I removed the chain (so that's not rubbing). I then removed the clutch - no difference, then loosened the end plate and the resistance reduced significantly. I checked the float/ shim and its within tolerance. Pulled the bearings from the cluster gear and from the layshaft (clutch side) - still not great with new bearings.

I swapped the end plate with one I had from another engine - not better.

Will look again tonight but I'm being led toward the NEW gear cluster.

[Storkfoot]

What gearbox is it and why did you replace the gear cluster?

[Topgearskin]

its got an indian GP 200 box in - has been fine for years but when I stripped it to go in the new casing I found the lower bearing face was mangled. I'd have considered "whatever mangled it" (bearing/ endplate) as a possible root cause but as I've replaced both I had hoped that I'd ruled that out. There is some belief that the cluster (new) could be out of tolerance (Its a new indian from SR) -I'm going to check that tonight.

[Fast n Furious]

It could be that the endplate dowel holes in your new case have not been machined in the correct position. I've seen this a few times and "no end" of endplate changes could correct it. Usually this is the result of poor dowel repairs to old casing where the holes have been welded up and redrilled incorrectly but it can also happen with a new aftermarket casing.
Try assembling the gearbox but leave out the endplate dowels and only lightly tighten the endplate nuts. This should now allow the the gearbox shafts to self centralize within their bearings. The shafts should all now spin freely by hand without any binding. Tighten down the endplate nuts and check again. Now fit the hub and see if there is any improvement and get back to us with your findings.

[AL BARKER]

If the brake shoes were originally trimmed to suit the Indian casing which are known to have the pivot holes in the wrong place.... then I would be surprised if they fit uni casing. Might be worth trying new brake shoes from a reputable dealer before replacing any gearbox parts...... worth a try? Also make sure the brake shoes match the brake cam..

[Topgearskin]

thanks Folks

I had another play tonight. Pulled the endplate out again and had a good look at the contact surfaces for the bearings. Ended up removing the one that sits above the layshaft with new. Significant improvement. Put in new shoes - still binding so trimmed them a fair amount (particularly around the "tips" by the cam end, again - much improved.

I think this may have cured it. There is still a tiny amount of resistance on the shoe but another go with some sandpaper should free that up.