Drive belts

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If using the Norvil belt drives, check the andodising hasnt worn off and the front drive pulley is starting to distort, happened to a mate on his Roadster and was chewing up belts.
 
Matchless said:
I had this happen on my 920. I think what caused it was the Norvil clutch & engine pulleys had become worn & rough which started to eat the belt. The problem lay with poor quality anodising. Often the so called hard anodising is no such thing because if it were you would not be able to scratch it with a scriber, which in the case of the Norvil parts I could.

Martyn.
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Yep, it looks like that has happened to mine. See pics in later post.
 
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Fast Eddie said:
Ralph, Steve Maney still had kits in stock when I spoke to him recently. Not expensive either.
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He has one less now. :)

Drive belts
 
lcrken said:
My experiences with the same Gates Powergrip HTD belts on race bikes is that the 920 works with the 40 mm belt, but not with the 30 mm belt. I have used the BNR drives on 920s for a long time now, and have had great luck with them. Back in the late '80s I tried switching to a different brand drive with a 30 mm belt (and a smaller front pulley), and almost immediately stripped the teeth off the belt.

That brings up the question of what primary drive ratio you are using. I've always used the 1.75 ratio drives, which use larger front pulleys. It looks like you are using a smaller front pulley to accommodate the stock alternator. If so, that is almost certainly contributing to the problem.

So far I've only used the original HTD belts, as well as the Optibelt Omega, and a few other brands. I haven't tried the GT3 that Ludwig mentioned, but they sound like a better choice. Gates also now lists the Powergrip GT4 s their latest and greatest GT tooth form belt, so maybe that should now be the go-to choice. Besides, I wasn't having any problems with the HTD belts. But next time I need belts, I'll look into the GT4.

The really hot new belt seems to be the Gates Poly Chain GT Carbon, but Gates says it is not compatible with the HTD pulleys, and I haven't seen anyone except CNW come out with a belt drive kit for Nortons that uses it.

Something to think about, anyway.

Ken
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I have a BNR on the racer and that came with a Continental belt, that got a hole in it when my ignition self destructed and was replaced with a Gates HTD, and so far so good, I do carry a spare to the races though.

The Norvil pullies are 34/72 so 2.11:1, the Maney replacement is 36/70 so 1.94:1, I don't think a bigger front sprocket would fit in the standard chain case alternator studs.

The Maney kit has an Optibelt Omega belt so everything is heading in the right direction with the new kit.

I have been reading about the Gates range of belts and they seen to be saying that the GT belt can be used as a replacement for HTD belts but then go on to say that they should be used with GT sprockets. I know this is the GT2 but I see no reason to make the GT3 and GT4 fully compatible with the older HTD profile.
 
Brooking 850 said:
If using the Norvil belt drives, check the andodising hasnt worn off and the front drive pulley is starting to distort, happened to a mate on his Roadster and was chewing up belts.
Click to expand...

Anything like this? this came to light when I cleaned the dust off the sprockets, and the reason for going to see Steve yesterday.

Drive belts
Drive belts


I now have Optibelt with the Maney kit.
 
I had a N$%$*l front pulley that was even worse than that. New belts lasted 2 1/2 laps of Snetterton. Anodising was nn existent when I scratched the sides. It had done less than 200 miles from new, but was on a bike when I bought it. Binned it and bought one from Steve
 
Hard anodised my arse! When I still worked in engineering one of the components I used to work on was long tubular shafts which were bought in stock 6082 thick walled tube. These came diamond hard anodized & I had to mill keyways along their length. Even with carbide slot drills it was hard getting through the outer skin & required frequent cutter changes per batch. Running a freshly sharpened scriber along the tubes made no impression whatsoever. Why the hell belt drive makers can't use the diamond hard anodising process is beyond me.
 
storm42 said:
I have been reading about the Gates range of belts and they seen to be saying that the GT belt can be used as a replacement for HTD belts but then go on to say that they should be used with GT sprockets. I know this is the GT2 but I see no reason to make the GT3 and GT4 fully compatible with the older HTD profile.
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It's a shame that the interchange guide doesn't cover the Powergrip GT3 and GT4 belts. But it does say that the GT2 is compatible with HTD sprockets, and can be used as a replacement, but that for new designs, it should be used with GT2 sprockets. As near as I can tell from the Gates web site, the Powergrip GT2, GT3, and GT4 belts all have the same GT tooth profile, just differences in materials that offer higher tensile strength, higher temperature specs, etc. So it looks to me like the GT3 and GT4 belts can also be used as replacements on the HTD sprockets. And from what Ludwig posted, the use of GT3 belts as replacements for HTD belts on Nortons has already been successfully demonstrated. The only problem seems to be availability in the right lengths for some drives. I'm sure they would be better on GT profile sprockets, but that doesn't seem to be an option at the moment.

Ken
 
storm42 said:
Are Gates drive belts sensitive to heat ? I have stripped the teeth off mine today and it is the second belt I have done on this bike.

The belt runs true with no run out on the pulleys and it was neither overly tight or loose, the case is as dry as a Commando case can be but it is sealed, I have seen some nice case plugs that seem to have a gauze in them, presumably to allow air in the case, is that necessary?

I was as comprehensive tooth strip as I have seen and left me stranded in Derbyshire and waiting for my mate to bring my van out to me.

View attachment 18531
View attachment 18532

There are worse places to be stranded whilst waiting for a van though.

View attachment 18533
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Bad luck with the belt drive Ralph, but you seem to have that sorted now. Is that my old tank on the bike then? Paint job looks lovely - and no dents either!
As usual, you are far ahead of me I'm afraid :cool:
 
storm42 said:
No problem buying from bearing places, in fact the place I get mine from will cut them to width, I think the point I was trying to make was that none of the belts are made with our purpose in mind.
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Exactly!
I have one bike with a belt drive secondary drive, and according to the manufacturer it is kevlar reinforced.... and very expensive, buying a new one is not an option at £200. Going to a bearing place for a non kevlar reinforced one is out of the question, so it's cheaper to buy chain and sprockets.
 
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SteveBorland said:
Bad luck with the belt drive Ralph, but you seem to have that sorted now. Is that my old tank on the bike then? Paint job looks lovely - and no dents either!
As usual, you are far ahead of me I'm afraid :cool:
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Hi Steve, hope you are well. Yes it is your tank and that is the yellow Norton, or was, I haven't painted the tank just given it a good clean, the paint has worn through where the knees touch and the dents are still there, but for now the rest of the bike needs a bit of a tablet so the tank won't get painted until I refresh the rest of the bike.
 
Bernhard said:
Exactly!
I have one bike with a belt drive secondary drive, and according to the manufacturer it is kevlar reinforced.... and very expensive, buying a new one is not an option at £200. Going to a bearing place for a non kevlar reinforced one is out of the question, so it's cheaper to buy chain and sprockets.
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I believe the service on a BMW scooter that calls for a belt change is approaching £2000, these things become very expensive when the belt manufacturer sanctions their use for our purposes. I think Harley has proved they can last a very long time though.
 
A mate has done 60,000 miles and counting on his belt, standard fitment on his 1550 Softail.
 
A while ago I had a Continental dealer calculate what size of HTD belt was required for my Commando,
based on HP, rpm , pulley sizes .. It came out 31 mm wide.
BUT : with a considerable preload.
Can't remember how much, but certainly not slack, like we tend to run them.
 
Fast Eddie said:
A mate has done 60,000 miles and counting on his belt, standard fitment on his 1550 Softail.
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My brother has replaced the rear drive belt on his '05 VRSC VROD twice, both times it had been punctured (by a captured pebble perhaps?) and broke at the puncture. And yeah, they're expensive.

(HD = hundreds of dollars)
 
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