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DickyM

Sherpa Brakes

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Hi All

Hoping to benefit from your collective experience.

Getting on OK restoring my Sherpa 198A and am currently working on the wheels/brakes. Front wheel all sorted and rebuilt.

On the back wheel though the steel brake liner pressed into the hub has a highly polished, almost mirror like finish. I thought this should be roughened up a bit with some wet and dry before reassembly. Problem is the surface is beyond glass hard and wet and dry doesn't seem to touch it. I've never personally come across this before. Any ideas on how to get under this hard glazed surface, or should I just leave it as is? The bike was a non runner when aquired so never ridden so no idea if the brake worked properly or not. Brake linings look fine and nothing obviously wrong with them.

Whilst I'm asking for the benefit of everyones experience anyone got any recommendations for black paint for the motor? It was originally black so I want to refinish the same. I'm thinking mostly for the barrel and head as obviously they get the hottest. Never had a painted motor before so no experience. Any suggestions welcome.

Thanks in advance

Rear brake drum.jpg

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I think you will find that is hard chrome plate, you won’t remove it with ‘wet and dry’ !

Rebuild the bike and try the brake performance before you try modding those hubs.

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When the bike was new both hubs had a chrome braking surface but with time the chrome finish sometimes came away. The fix was and is still to machine in a metal liner often cast iron but sometimes stainless steel which has a surface like you describe.

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It's been a long time since I saw chrome as good as that on a Bultaco hub

Have the shoes relined with modern material and have them done oversize so that they can be machined down to fit the hub for full contact. Off the shelf shoes like Newfren / EBC have quite thin linings and only a small patch of the shoe actually contacts with the hub.  Villiers Services or Safetek can reline your shoes

For engine, I've just tried RHT engine paint which is resistant to petrol and gives a nice finish, I got it from ebay. PJ1 used to be a popular paint with a nice finish but petrol melts it faster than boiling water takes butter of a knife now, they've changed something to meet emissions probably. Some people use barbecue paint but I'm not sure how well that resists petrol

Edited by woody
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I remember when i bought a Bultaco to give Trials ago after 20yrs of MX, & i rode it through the edge of the dam, i then went to use the brakes & they weren't working plus they were squealing. They were squealing that much & for sooo long my Wife came out & said what is that noise ;) Then i pulled the wheel off & saw the beautiful chrome brake liner :(

To this day, i still ask myself why would you put chrome liners in a bike that has a very good chance of seeing water ?

Edited by eagle8

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16 minutes ago, eagle8 said:

I remember when i bought a Bultaco to give Trials ago after 20yrs of MX, & i rode it through the edge of the dam, i then went to use the brakes & they weren't working plus they were squealing. They were squealing that much & for sooo long my Wife came out & said what is that noise ;) Then i pulled the wheel of & saw the beautiful chrome brake liner :(

To this day, i still ask myself why would you put chrome liners in a bike that has a very good chance of seeing water ?

They did it to create the lightest wheels possible at the time. I'm not saying I like the idea of the plated brake drums either, but you did ask

 

Edited by feetupfun
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5 hours ago, feetupfun said:

They did it to create the lightest wheels possible at the time. I'm not saying I like the idea of the plated brake drums either, but you did ask

 

They used to be advertised as the lightest production wheel in the world

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Chrome then.

Wasn't expecting that but obvious now you've all said. Leave alone and rebuild the wheel then.

This bike is full of odd surprises. I'm pretty sure that drums and wheels are original fittings as in fact I think were the tyres. Date codes definitely pre 1990 anyway.

So front wheel no sign of chrome plate and a magnet sticks to the liner. Rear brake chrome plate and the liner is completely non magnetic so makes me wonder what they actually put the chrome plate on to135465943_Frontbrakedrum.thumb.jpg.481107831f0bcda6cd2d432610297314.jpg. Also front wheel had all aluminium spoke nipples whereas rear wheel all steel.

Using up stock as they got towards the end I guess.

Picture of front wheel hub posted for comparison.

Thanks for all the replies on the subject and to Woody for the paint info.

 

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Front wheel has had a steel/cast iron? (ferrous, anyway..) liner inserted. This is the usual means of salvaging hubs which have suffered deterioration of the chrome plating.

Hard chrome originally applied direct to alloy casting.  If your chrome is as intact as it looks, keep it unti it fails.

Rear spokes stainless butted, or steel galvanised ?

Edited by lorenzo
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Hi Lorenzo, thanks for your comment.

I think you're right about the front hub being sleeved with a ferrous liner. It is in good nick anyway.

The rear chrome is very good and as you say I will keep until it fails.

Both front and rear wheels had galvanised spokes but front had alloy nipples and the rear steel.

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