Author Topic: SRM Dynamo belt drive  (Read 3757 times)

Offline england kev

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SRM Dynamo belt drive
« on: 19.09. 2008 22:32 »
I have just ordered a belt drive kit from SRM, have any of you guys fitted one. I have also ordered an alloy clutch plate too, oh and some other little bits but we wont go into that yet ;)

Offline dpaddock

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Re: SRM Dynamo belt drive
« Reply #1 on: 20.09. 2008 19:42 »
Just ONE alloy clutch plate?
David
'57 Spitfire


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Re: SRM Dynamo belt drive
« Reply #2 on: 20.09. 2008 20:42 »
pressure plate we assume!
re belt drive, gearing up is good and so is toothed belt which seems to hold its tension very well. But I don't like the alloy pulley centres - my drive pulley failed in under 500 miles and slipped to the point where the taper wouldn't and couldn't ever mate with the shaft again. Had to take steel centre and taper from original sprocket by unriveting it, and re-machined pulley to accept it. No prob in several thousand miles since. Could have been my intermediate shaft taper, but I doubt it as all has been well with steel on steel. And it was certainly done up properly upon initial installation. My experience was not typical I am sure, as the kit is decent quality otherwise, but there were a few comments here on the topic a few months back and I wasn't the only person to have had a prob with one or other pulley.
Bill

Offline england kev

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Re: SRM Dynamo belt drive
« Reply #3 on: 20.09. 2008 23:19 »
Yes I did mean pressure plate! the stuff is all here too, although I was out today, so I have to grab it from the post office Monday morning. Ordered Friday lunch time, delivered Sat morning.

Online bsa-bill

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Re: SRM Dynamo belt drive
« Reply #4 on: 21.09. 2008 12:20 »
I fitted one of these when I restored the bike, Can't say anything bad about it at all and the result is a much lighter clutch action
and less drag  if you follow the instructions, I screwed the springs up a tad to much and got a bit of drag I slackened them of  bit and it helped but it needs to have a bit more tension off.
you have to cut the clutch pushrod down a bit a tip I didn't try is to cut the rod in the middle and insert a ball bearing in between the two halves, the thinking is that this allows the rod a degree of flex so it remains straighter in operation, I haven't done this but it sound feasable, if anybody out there has tried it I loved to know how it works out.

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline england kev

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Re: SRM Dynamo belt drive
« Reply #5 on: 12.10. 2008 22:37 »

Online RichardL

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Re: SRM Dynamo belt drive
« Reply #6 on: 18.03. 2014 14:33 »
New issue in this topic, I think.

Has anyone fitting the SRM dynamo belt drive kit found that the underside of the large pulley/sprocket comes in contact with the bump that is cast into the timing cover for oiling the idler bush? I believe I need to grind it down a bit but I don't want to break through to the drilled oilway.

Advice and thoughts appreciated.

Richard L.
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Online bsa-bill

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Re: SRM Dynamo belt drive
« Reply #7 on: 18.03. 2014 16:29 »
pardon if this is obvious Richard but are you using the cork or felt washer that goes on before the pulley
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online muskrat

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Re: SRM Dynamo belt drive
« Reply #8 on: 18.03. 2014 18:55 »
G'day Richard. I have two and neither rub anywhere. I'd say the shaft has moved inwards causing your problem. The shaft is only a light interference fit in the idler gear so a light tap or two will push it back through a tad.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
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Online RichardL

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Re: SRM Dynamo belt drive
« Reply #9 on: 18.03. 2014 18:57 »
Bill (and all),

I was using the felt washer, but tried the cork, following your question. It seems that this is a case of the taper is going to seat where the taper seats. If I try to compress the cork far enough to seat the taper, I will be at the same point of rubbing against the casting. I did speak to SRM a bit about this and Gary suggested that the idler gear may may need to be moved on the shaft. This would seem to make sense considering that the shoulder at the bottom of the taper does not reach the end of the bush. That didn't matter with the chain sprocket, which doesn't ride as close to the inside timing cover.  You'll see that I already tried a bit of grinding but decided I'd better ask the questions before getting in trouble. The black arc on the bump area shows where the pulley is contacting.   

Richard L.

Posting, even though someone has commented in-between.
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Online RichardL

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Re: SRM Dynamo belt drive
« Reply #10 on: 18.03. 2014 19:01 »
Well, Muskrat, great minds think alike (your's  and Gary's, that is). The sad bit about this is having to reopen another already sealed joint.

Should I heat the perimeter of the gear a bit (while trying to avoid the spindle) before trying to move it?
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Re: SRM Dynamo belt drive
« Reply #11 on: 18.03. 2014 19:04 »
Yep that's the problem. Inner cover off, tap shaft till shoulder on shaft is just proud of the bush. I don't think heat is necessary but it won't hurt.
Cheers
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Re: SRM Dynamo belt drive
« Reply #12 on: 18.03. 2014 19:58 »
Ah yes, well done lads I had forgotten about the idler shaft, I had to move mine right enough - wonder when they'll get Cloud for the elderly
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline duTch

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Re: SRM Dynamo belt drive
« Reply #13 on: 18.03. 2014 22:12 »
 Richard, I had exactly that issue too. Also the outer rim of the pulley interfered with the bottom of the casing, but won't talk about that here.
  From memory, I considered realigning the idler gear/shaft but it would've affected the alignment of the pulleys, so just carefully sculpted some off with the Dremel, and also bevelled the corresponding inside corner of the pulley a bit.
  Also from memory, I ended up with~ 0.020" side-float on the idler which I decided wouldn't matter too much as, and be 'self centred' by the belt/pulleys, having decided too risky to use a shim that thin on something spinning.
 Felt/ cork washers were too thick, so left them out.

 Have only done about 3K miles since, but all seems ok so far.......next oil change will try remember to have a look-see.
 Have photos buried somewhere, I think I posted them in a different thread at the time .....!
 
Edited- To free the taper, I slipped a couple of strips of flat bar behind the pulley to pull it against the case, before tapping the loose nut on the shaft...works a treat- no heat needed

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Online RichardL

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Re: SRM Dynamo belt drive
« Reply #14 on: 18.03. 2014 23:37 »
All,

I think the problem could have been easily avoided if SRM had turned a champher into the backside of the pulley. Once again, I'm hampered for lack of machine tools. I am pretty certain the taper in the pulley would work with the taper on the shaft, even with the spindle sitting a bit low in the bushing. Like I said, it was fine with the chain sprocket.

Yep, about 0.020" of float is what I have, as well. It looks like I will need to move the gear about 0.045" toward the crankcase just to get flush with the bushing when the spindle is in the pulled-up position. There is a groove just behind the gear which seems like it is marking the stopping point and I will be overlapping that groove, just a bit.

The timing cover seems very thin where the idler oilway is and, you guessed it, I don't have the right caliper to get in there to see how mcuh meat there is to play with. That I can work out, if I decide to go back to grinding.

Richard L
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