Front Pulley Issues

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swooshdave said:
Overly complex compared to shoving crap in the gap or getting a blank pulley machined to the right taper.
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I don’t agree. Any competent machinist with a lathe could do that in 15 mins. Way way way better that jamming bits of tin in there. Machine it back, put some engineers blue on it to identify the problem area, grind it with some valve grinding paste. Install a proper fitting key and if necessary pack out the pulley to increase the width.

Job done in way less time than this thread has been running
 
johnm said:
I don’t agree. Any competent machinist with a lathe could do that in 15 mins. Way way way better that jamming bits of tin in there. Machine it back, put some engineers blue on it to identify the problem area, grind it with some valve grinding paste. Install a proper fitting key and if necessary pack out the pulley to increase the width.
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I thought he was joking....wasn't he?
 
Ah!!! Your absolute right should have woken up earlier this morning
 
swooshdave said:
Is there an advantage to brass over aluminum in this case?
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There are advantages to the aluminum. The can costs the price of deposit, is easy to source and can be cut with scissors. It will provide feedback on how much material is missing from the shaft. It will give you insight into how much of a pain in the ass it is to cut a shim for a tapered shaft and get it fit into place. AND you get to drink the beer before deciding if the idea of shimming has any merit. Then you can decide on what material is best suited or move to another idea. Seems to me the feedback would be useful before you start machining away material on your pulley. And did I say, "you get to drink the beer"?

Cheers
 
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johnm said:
I don’t agree. Any competent machinist with a lathe could do that in 15 mins. Way way way better that jamming bits of tin in there. Machine it back, put some engineers blue on it to identify the problem area, grind it with some valve grinding paste. Install a proper fitting key and if necessary pack out the pulley to increase the width.

Job done in way less time than this thread has been running
Click to expand...

You obviously don't understand how the front pulley fits. Did you even watch the video? There isn't room to move the pulley inboard no matter what you do. You can't remove anything from the pulley to reduce the width.

The only option is to get the taper to fit better with the pulley in the original position.
 
swooshdave said:
You obviously don't understand how the front pulley fits. Did you even watch the video? There isn't room to move the pulley inboard no matter what you do. You can't remove anything from the pulley to reduce the width.

The only option is to get the taper to fit better with the pulley in the original position.
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Interesting. Must work differently to the ones on my bike. Friends make their own pulleys for their race bikes and you can machine them to sit wherever you want.

Just trying to help but all the best.

But I do agree you might have an issue with the hardening coating.

Cheers John
 
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johnm said:
Interesting. Must work differently to the ones on my bike. Friends make their own pulleys for their race bikes and you can machine them to sit wherever you want.

Just trying to help but all the best.

But I do agree you might have an issue with the hardening coating.

Cheers John
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But just to be clear.

What is the problem? You machine the back. The pulley can then sit further up the taper. How is that fundamentally different than machining a new taper on a blank?

and yes I did watch the video. The set up is exactly as my race bike I ran for years.
 
@swooshdave i think you may be the one that doesn't understand what is being suggested here - please don't get shitty, people are only trying to help you.

The keeper on the pulley is removable.

Take it off, and machine off a couple of millimeters from the back face of the pulley.
This will take anyone with a lathe about ten minutes, and cost you a beer.

The RGM pulleys are 27mm wide to fit a 25mm belt.

Put the keeper back on after the machining work.

This will allow the pulley to use a tighter part of the taper, so will be a snugger fit on your crankshaft.
2mm is quite a lot in these terms.

You could even take a larger cut, say 4mm, then put a shim between the pulley and the alternator rotor to give you plenty of clearance for your belt.

The good thing about this, is you may get away with not shimming the crankshaft, plus you don't have to wait for parts to arrive, plus you must know someone with a lathe.

Removing the hard anodize from the back of the pulley won't compromise it's strength in any way.


I think this is a great idea, and is very simple to do.
 
How thick is the backing plate? It should be pretty easy to pull it off and see if that thickness is enough to keep the pulley from hitting the case. It would give quick feedback as to how much would have to come off the pulley.
 
gtiller said:
@swooshdave i think you may be the one that doesn't understand what is being suggested here - please don't get shitty, people are only trying to help you.

The keeper on the pulley is removable.

Take it off, and machine off a couple of millimeters from the back face of the pulley.
This will take anyone with a lathe about ten minutes, and cost you a beer.

The RGM pulleys are 27mm wide to fit a 25mm belt.

Put the keeper back on after the machining work.

This will allow the pulley to use a tighter part of the taper, so will be a snugger fit on your crankshaft.
2mm is quite a lot in these terms.

You could even take a larger cut, say 4mm, then put a shim between the pulley and the alternator rotor to give you plenty of clearance for your belt.

The good thing about this, is you may get away with not shimming the crankshaft, plus you don't have to wait for parts to arrive, plus you must know someone with a lathe.

Removing the hard anodize from the back of the pulley won't compromise it's strength in any way.


I think this is a great idea, and is very simple to do.
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I was just concerned the anodising may make it hard to machine the back with normal tooling. Maybe necessary to grind it ?

And I’d use the engineers blue to see what’s going on with the shaft.
 
Front Pulley Issues


As I mentioned already the width of the pulley = width of the belt.

Remember this RGM kit is 10 years old. They may use a narrower belt now.

So, the only way I can see that machining the existing pulley would be to use a narrower belt and machine the pulley down.

On race bikes they don’t use the cast chaincase so there is a lot more room to play with.

If I didn’t have the chaincase I would be ok except the belt is already running to the inside of the clutch. Any more and I’d have to move the clutch inboard too.

Unless I’m completely dense (this is plausible) the pulley taper needs to move inboard and the only way to do this is to machine a new taper in a new position.
 
Ok. So that belt is exactly the pulley width. Every other one I have seen has several mm of extra clearance.

It would still work but you would have to pack out the outer guide and yes you would lose a few mm of belt engagement. I would probably work fine but for peace of mind in the long run the best fix is a new pulley and remachined taper.
 
johnm said:
Ok. So that belt is exactly the pulley width. Every other one I have seen has several mm of extra clearance.

It would still work but you would have to pack out the outer guide and yes you would lose a few mm of belt engagement. I would probably work fine but for peace of mind in the long run the best fix is a new pulley and remachined taper.
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Or a shim. :D

Or a new crank.

Probably what I should have done is take the crank from the blown motor and had the bearing material removed and use that crank instead.
 
swooshdave said:
Depends on who you know.
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They show up when you don't need them. I had a Harley guy pepper me with questions about some unknown crankcase he had been given (part of a barn parts stash). Turned out to be a Combat serial number range Commando.
 
I think I may have solved my crank problem but havnt seen it yet so not certain at present
 
Front Pulley Issues


I started by putting painters tape (low tack) and carefully trimming with a razor blade.

Front Pulley Issues


The tape came off and I stuck it to a piece of paper. Now I had my first template.

Front Pulley Issues


Then traced it onto a pop can. No beer for me these days. Gin and tonics please.

Front Pulley Issues


A little bit stuck out. I used a sharpie and traced around.
 
Front Pulley Issues


Then I could just trim the marked part off.

Front Pulley Issues


Test fit with the aluminum. No key at this point.

Front Pulley Issues


It took a puller to get it off. I knew I was shimmed correctly because the inside of the pulley was flush with the shoulder on the crankshaft.

Front Pulley Issues


The brass came in different thicknesses. I measured it at .0025, same as the can. Again I traced it and trimmed as needed. This time I made room for the key. It went on relatively easy, the shims didn’t need anything to slide on and stay where they needed.

Front Pulley Issues


The old key was buggered a bit but since my package from Old Britts showed up today with a new key I was golden. The new key fit much better. Without tightening it down it was much tighter. Just the tiniest little movement. I reassembled and will try it out tomorrow. I don’t expect any issues.

Thanks for all the suggestions and the banter.

One less thing to worry about.
 
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