Author Topic: SRM dynamo belt drive  (Read 2112 times)

Online lillygunny

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SRM dynamo belt drive
« on: 13.06. 2012 23:27 »
I am installing this kit on my RGS and I would like to know if others have used the cork gasket or the felt gasket provided. I understand the pulley must be tight on the shaft but I am not sure how to best determine this.

Thanks,
Ron

Online bsa-bill

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Re: SRM dynamo belt drive
« Reply #1 on: 14.06. 2012 09:35 »
Hi Ron
The cork gasket would be my first choice, it is quite thick though and sometimes will not allow the pulley to be drawn up onto the shaft taper far enough to grip, in this case use the felt one or as my mate did slice a bit off the cork washer.
Best of luch with it - a nice bit of kit
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Offline alanp

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Re: SRM dynamo belt drive
« Reply #2 on: 14.06. 2012 12:19 »
Hi Ron
The cork gasket would be my first choice, it is quite thick though and sometimes will not allow the pulley to be drawn up onto the shaft taper far enough to grip, in this case use the felt one or as my mate did slice a bit off the cork washer.
Best of luch with it - a nice bit of kit

I tried it with a compressed cork washer and also a sliced cork washer and they both broke up! I now run without a cork washer since the bush behind the pulley has a spiral cut into it which has proved to keep the belt chamber free of oil. The bushes should have the spiral, I think, and those fitted by SRM definitely have. You might want to check this before bothering to fit a cork washer and risk bits getting under the belt teeth and ruining the belt (been there, done it!) or fitting the cork washer with a slack fit which is a bit of a waste of time. So, the key to this is, is there a spiral or not, hopefully yes. If not, good luck.
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Offline duTch

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Re: SRM dynamo belt drive
« Reply #3 on: 14.06. 2012 16:00 »
Hi Ron,
          I have the kit semi fitted, have elected to not use the washers at least initally, as mine never had them before and has the spiral bush, and as the idler gear has about 20thou end float am working on the theory will allow the belt pulley to self align, although  I had issues with clearance back and bottom of pulley. Hopefully yours'll be sweet

cheers, duTch
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Offline jjbsa

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Re: SRM dynamo belt drive
« Reply #4 on: 16.06. 2012 11:05 »
Hi, I've had the same problem (cork washer breaking up) and didn't fancy bits of the washer getting caught in the timing belt drive used for the dynamo, so I bought a garter seal and milled out the cover to accept it.  It's working fine.  The photos show the job (use quill feed and the quill stop to determine the depth.  Job is done with bush in place.) and the size of seal I used.  The seals cost about £1.40.  HTH, Jon

Offline a10gf

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Re: SRM dynamo belt drive
« Reply #5 on: 16.06. 2012 14:26 »
^^^ excellent work!

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Online lillygunny

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Re: SRM dynamo belt drive
« Reply #6 on: 17.06. 2012 15:04 »
I installed the belt drive yesterday. The cork gasket was way too thick so I used the felt. There was not a gasket of any type on the sprocket, and no oil in the case, so I think it will be fine.
Thanks for all the help.

Ron

Online RichardL

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Re: SRM dynamo belt drive
« Reply #7 on: 31.07. 2016 20:56 »
May as well use this existing topic, rather than starting a new one.

What happened to my SRM dynamo belt? The dynamo turns freely. I didn't find any orange bits. It's done at least 700 miles.

In retrospect, maybe I didn't use enough grease.

Richard L.
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Online mugwump

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Re: SRM dynamo belt drive
« Reply #8 on: 31.07. 2016 21:14 »
I can appreciate the reasons for a belt conversion on the primary drive, but what is the advantage of a belt over chain for the dynamo. Seems its caused some problems with you guys and there is the cost too.

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Online RichardL

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Re: SRM dynamo belt drive
« Reply #9 on: 31.07. 2016 21:26 »
Lots less noise and dynamo spins faster for more output.

Richard L.
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Online morris

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Re: SRM dynamo belt drive
« Reply #10 on: 31.07. 2016 21:45 »
I'm not sure but it seems most having this kind of trouble seem to be the SRM conversion kits?
I'm running a Dynamo Regulators setup on both the SA and the plunger.
They're on for at least 1500-2000 miles now, and a recent check on the SA (oldest conversion) showed it still as new.
Don't want to point a finger here, just curious if my suspicion is true.
I can appreciate the reasons for a belt conversion on the primary drive, but what is the advantage of a belt over chain for the dynamo.
It's a bit less noisy, makes the dynamo spin faster, which on a 12V/electronic ignition conversion is necessary I found, and if a belt breaks it makes less damage than a chain.
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Online muskrat

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Re: SRM dynamo belt drive
« Reply #11 on: 31.07. 2016 21:47 »
G'day Richard.
I've had a few go like that. Too tight a tension or heat. The correct tension is like a cocI< in a sock (very loose, easy 1/2" deflection).
Cheers
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Online morris

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Re: SRM dynamo belt drive
« Reply #12 on: 31.07. 2016 21:51 »
G'day Richard.
I've had a few go like that. Too tight a tension or heat. The correct tension is like a cocI< in a sock (very loose, easy 1/2" deflection).
Cheers
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Offline coater87

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Re: SRM dynamo belt drive
« Reply #13 on: 31.07. 2016 22:03 »
 I agree with Musky, on the too tight.

 The other thing that will cause a blow out like that is the wrong grease. I dont know about your case, but some grease will eat some belt material.

 Lee
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Online RichardL

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Re: SRM dynamo belt drive
« Reply #14 on: 31.07. 2016 22:50 »
That "easy 1/2 deflection" is, I think, hard to gauge from person to person, given different finger strengths. I wouldn't mind if they spec'd it in inch-pounds. I think I could come up with a rig to measure that.

OK, I know, I'm over-thinking it. Hey, I obviously can't be out on the bike right now.

Richard L.
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