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Model 91 Brakes


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The front hub on my M91 Sherpa has the **** chrome lining which is pitted and peeling but the rear hub is the conventional type, is this correct for this model.

Does any one have any recommendations for sorting out the front hub problem, I read some time back that it's possible to have the hub metal sprayed and machined, is there other options I could take ?

Regards

No balance.

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Bultaco UK do exchange hubs with liners. I don't know anything about the metal spraying technique but I think it's costly and I heard someone saying it didn't last. I've had a few converted to liners and they work fine.

Yes your rear hub is correct, the rear hub wasn't chrome lined until the 1976 bikes.

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Speak Dave at your show as he no longer does them but the person that did them will do your own one with the steel liner

Woody My 175 Sherpa has a steel liner from new built in 79 and I bought it new (A Parts bin build ???) The front is still alloy

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Woody

Do you think the steel liners are as effective as cast iron?

Regards

Sparks

I honestly haven't a clue. I've heard it said from people who know about this stuff that cast is better but they also say it depends on the grade / type of cast as if it is the wrong type it's no good. I've no engineering background so personally I have no idea.

Mine are steel and they work ok but I've no idea what type of steel. A friend did them. The biggest problem on the Sherpa rear brake is the mechanism, not the brake itself, which can lead you to think the brake is no good. I have a linered Sherpa rear wheel in my BSA with left hand brake pedal and it works perfectly.

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Speak Dave at your show as he no longer does them but the person that did them will do your own one with the steel liner

Woody My 175 Sherpa has a steel liner from new built in 79 and I bought it new (A Parts bin build ???) The front is still alloy

You mean an earlier type wheel with the non-chrome hub? Or the later conical hub which was fitted with a liner from the factory?

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They are the later hubs the rear has no chrome liner The rear brake is poor The alloy brake pedal looks to small to get good purchase on it the front is brilliant

Are you sure it's not just that the chrome liner has completely worn off, disintergrated, etc.

I've seen this more than once.

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One easy improvement is to install as soft brake pads as possible and het rid of decade old brake pads. This is easy done.

Second machine the brake pads (mounted to the brake plate) so they are aligned to the drum.

Third use the longer steel brake arms front and rear, they don't flex and hive more torque = more braking power, (don't show up very often in craiglists but sometimes).

Fourth the lining with steel inserts, standard steel quality SRJ 235 is completely OK. Or new hard chrome linings, but this is the most expensive way to do. You need a professional hardchrome coating company that is specialist for chroming machine components, Wissing-Hartchrom is the only company I can name here, €€€!

I would first do 1. then 2. ... until you are satisfied with the outcome.

lf you want a perfect result you have to spend a likewise effort in the project which means time and money that has to be named too ...

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Hello Pschrauber, appreciate the input, your second suggestion regarding the shoes (in England pads are for disc brakes) is one that I have been giving a lot of thought, but not sure if this is something that could be achieved in the home workshop or can it only be done by a specialist. It makes sense to have more surface area of the shoe making contact with the drum.

Many thanks

No balance.

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Send your shoes to Villiers Services who will get them relined with a softer material. They'll make them oversize if you like so that you can skim them to fit the hub better but just the linings themselves will improve things.

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Hello Pschrauber, appreciate the input, your second suggestion regarding the shoes (in England pads are for disc brakes) is one that I have been giving a lot of thought, but not sure if this is something that could be achieved in the home workshop or can it only be done by a specialist. It makes sense to have more surface area of the shoe making contact with the drum.

Many thanks

No balance.

if you have access to a lathe it's simple enough to turn down to size.
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My 199A has about half of the chrome left in the rear hub.Does this mean that if I ride it in a trial or two before having it fixed that I will chance ruining the hub to the point of no repair? I can have my hub re-lined here for about 250.00 if I break it down and then re-lace it.I just can,t spend it right now and would like to ride it in the first trial coming up,but if it will make the hub non-repairable it will have to sit until I can have it done.

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