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Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: lillygunny on 13.06. 2012 23:27

Title: SRM dynamo belt drive
Post by: lillygunny 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
Title: Re: SRM dynamo belt drive
Post by: bsa-bill 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
Title: Re: SRM dynamo belt drive
Post by: alanp 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.
Title: Re: SRM dynamo belt drive
Post by: duTch 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
Title: Re: SRM dynamo belt drive
Post by: jjbsa 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
Title: Re: SRM dynamo belt drive
Post by: a10 gf on 16.06. 2012 14:26
^^^ excellent work!
Title: Re: SRM dynamo belt drive
Post by: lillygunny 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
Title: Re: SRM dynamo belt drive
Post by: RichardL 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.
Title: Re: SRM dynamo belt drive
Post by: mugwump 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.
Title: Re: SRM dynamo belt drive
Post by: RichardL on 31.07. 2016 21:26
Lots less noise and dynamo spins faster for more output.

Richard L.
Title: Re: SRM dynamo belt drive
Post by: morris 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.
Title: Re: SRM dynamo belt drive
Post by: muskrat 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
Title: Re: SRM dynamo belt drive
Post by: morris 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
But then, if you have small feet and a big...
Title: Re: SRM dynamo belt drive
Post by: coater87 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
Title: Re: SRM dynamo belt drive
Post by: RichardL 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.
Title: Re: SRM dynamo belt drive
Post by: chaterlea25 on 31.07. 2016 22:52
Hi All,
Following this and another topic the other day
My belt drive has done 20K miles at least , no washers and no grease  (touch wood????)
I have fitted other kits with grease to customer bikes and no reported failures
The fitting kit includes a warning something like """ be careful with the belt tensioning as tightening the dynamo strap nut tends to tighten the belt"""

 *dunno2* *dunno2*
John
Title: Re: SRM dynamo belt drive
Post by: RichardL on 31.07. 2016 22:57
I might have started out with it being too tight, but was careful to test after tighening the strap.

I think I was going with "1/2 twist based on the limit of my thumb/forefinger pinch strength".

Richard L.
Title: Re: SRM dynamo belt drive
Post by: duTch on 31.07. 2016 23:05
 As above,
 My first belt lasted just over 6K miles- no grease, but started shredding long before that. It didn't destruct, just stretched, and warped/twisted out of shape. I replaced it with a belt procured from the local bearing supplies (they had to get it in), and it's done ~3K miles since then, with no sign of distress at recent checkup, at which time was a bit tight, so backed it off some (still no grease).
 Replacement belt is polyurethane reinforced, 'Optibelt ' brand (Made in Ireland), and I bought in a spare a couple of weeks ago.
There are several different manufacturers. AT5-420 x width (mine= 10mm )

 Picture shows new-new belt overlaid on old one, and second pic shows the deflection I originally had with the 1/2 twist (SRM/Synchroflex), but I think when I backed the new one off, I did so it it was just clear of the cover screw boss (underside).
Title: Re: SRM dynamo belt drive
Post by: TT John on 02.08. 2016 10:43
I think Dynamo regulators belt drive system is the best, I've fitted them to my A10 also my A7, both bikes on a 6v + system and I cannot fault them, much better doing slow speeds, keeps battery up even with lights on.
Mike at Dynamo regulators has done quite a lot of research on his products, average price for top quality product. *yeah*
Title: Re: SRM dynamo belt drive
Post by: mikeb on 02.08. 2016 11:40
TT John - also the dynamo regulator belt system has extracting threads in the pinion pulley whereas the srm one does not. i have no idea how i'll get my srm soft alloy pulley off without distorting it without such threaded holes. (i don't need to yet, tho sure I will have to one day).  and the dynamo regulator one is +20% rather than +10 speed. wish I'd bough one of those, which is probably not what lillygunny wants to read.
Title: Re: SRM dynamo belt drive
Post by: jjbsa on 02.08. 2016 22:48
I run the Dynamo Regs belt setup and so far (3,000m) it has been OK.  However I think the weakness of all these toothed belt systems is the stress caused by gear changing, where the belt has to make the dynamo change speed very quickly.  Dynamo Regs, if I remember correctly, do make some vague comments about the inadvisability of doing high speed fast gear shifts......

I recollect that the original Beesa Bill had a belt drive that used a V belt.  That would slip under rapid gear changes at high rpms, and by doing so probably save all the components from too much stress.  I feel that toothed timing belts are not really necessary to drive a dynamo.
Title: Re: SRM dynamo belt drive
Post by: RichardL on 03.08. 2016 06:12
Dutch,

Thanks for the data on the belt. Made it easier for me to order a new one (well, one plus a spare) for the SRM drive. The brand is Jason Industries, made in France. Price was about $13.50/ea. Ordered from Motion Industries, a large supplier of power transmission and bearing products with outlets all.over the U.S. Next day delivery with no shipping charge (I think).

Richard L.
Title: Re: SRM dynamo belt drive
Post by: mikeb on 03.08. 2016 06:18
Richard and Dutch - so just to be clear, is that any kind of AT5-420-10?
do you have a manufacturer's part number for the ones you got?
any other 'gotchas' like temp ratings etc?
Title: Re: SRM dynamo belt drive
Post by: RichardL on 03.08. 2016 07:03
Mike,

From Jason Industrial AT5 420, 10mm wide (also shows the number "4215", but I don't know what that means). Top end temperature is listed as 176 F., same as SRM's Optibelt, except, Jason allows for 230 F. for short periods. Haven't run it yet.

Richard L.
Title: Re: SRM dynamo belt drive
Post by: TT John on 03.08. 2016 08:34
I have fitted both my A10 and A7 with Dynamo regulators, dynamo belt drive and found it to be the best thing I ever did, both bikes on 6v + earth it really does increase the charge at low speeds, also reduces the noise you get from chain drive.
Mike Hutchings, who runs Dynamo Regulators is I found, very helpful, I do not have any connection with this company.

Regards TTJohn
Title: Re: SRM dynamo belt drive
Post by: duTch on 03.08. 2016 09:22
 Guys, AT5-420 means from memory;

 A= shape, section or something of the teethy-thingos maybe

 T= Timing belt?

 5 = 5mm pitch (betwixt centre-centre of lumps, kinda like a chain)

  420 is the length of belt = 84 pitches X 5mm =420mm

 x10/? is whatever width of belt you need

Title: Re: SRM dynamo belt drive
Post by: muskrat on 03.08. 2016 09:28
G'day duTch. Where do you get your belts? The only place I found down here is http://www.piesau.com.au/
$28 each with a two week wait.
Cheers
Title: Re: SRM dynamo belt drive
Post by: duTch on 03.08. 2016 11:16

I went to the local bearing supply shop, they also do transmission stuff,  maybe marginally more plentiful in Metropolis though