SRM dynamo belt drive

[chaterlea25]

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"""

 
John

[RichardL]

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.

[duTch]

 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).

[TT John]

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.

[mikeb]

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.

[jjbsa]

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.

[RichardL]

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.

[mikeb]

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?

[RichardL]

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.

[TT John]

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

[duTch]

 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

[muskrat]

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

[duTch]

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