chain or belt?

Had a run up to my local race track last Sunday, in the the pits was a commando race bike with a broken primary belt,
The clutch toothed wheel had quite a bit of "wobble" ,
I remember belt drives need to be in alignment and any miss alignment puts extream edge loading on the belt. so are Nortons subjected to poor belt design? are chains better ?

many many happy Commandos are running around with belt primaries

mine included, some 20,000 miles on the first belt since replaced on general principle and not of failure

most everyone agrees that adding a left side threaded gear box adjuster allows precise alignment

It's not something you do just because it's "better".

If you have no immediate, significant reason for it, it's not worth the life cycle cost.

Triplex chains can withstand a little mis-alignment and running in ideal oil bath conditions should last for massive mileages. In the Rotary Norton world fully enclosed rear chains are known to last 180,000 miles. The Norton triplex setup is heavy but there is room to remove metal from the inner diameter of the steel plates and drill some lightening holes in the bronze plates steel backing. A good duplex chain is probably adequate and will reduce the weight of the chain by a third.

I've never weighed both the chain and belt assemblies, but the belt assembly is considerably lighter than the chain assembly. Not to mention being able to run a dry primary with a belt drive. The rollers on the triplex chain have a habit of splitting and eventually the chain needs to be replaced. A correctly aligned and tensioned belt will probably last longer than most will ride their Nortons. And that's without a dripping primary!

Had similar on Peel with unknown insidious clutch wobble developing from lots of WOT red zone lower gear lack of lube sleeve bush dissolving time till belt walked off to end up all combined with charger front sprocket mess. After some quality fettering AMC box she was good to go again and lasted after bushes grooved and Dextron II inside.

Hi John

I run Bob Newby clutch kits. RGM kits, Norvil kits, Steve Maney kits. I even have Hayward kits on my Triumph roadbikes (keeps the standard clutch which I don't like) I would not go back to chain. As Paul says if you have a good standard set up save your money. However in my opinion besides new carbs its the best thing you can do to your bike. The belt on the 750 race bike has done 5 seasons the big one has done 3.
The 8mm htd belts have done over 20,00 miles on the roadbikes & the RGM stripped its wire cords, I cut the belt down to about 20mm wide & ran it like that for over 6,000 miles.

No Darley this year, will you be at Donnington?

Chris

Hi Chris,
Donnington, yes..last year was brill! They are taking on Goodwood ,but no cars...V8 Moto Guss , honda 250 6 the whole shooting match.
Then a Lancaster/spitefire fly over....what more could we want...are you there?

Chris said:

Hi John

I run Bob Newby clutch kits. RGM kits, Norvil kits, Steve Maney kits. I even have Hayward kits on my Triumph roadbikes (keeps the standard clutch which I don't like) I would not go back to chain. As Paul says if you have a good standard set up save your money. However in my opinion besides new carbs its the best thing you can do to your bike. The belt on the 750 race bike has done 5 seasons the big one has done 3.
The 8mm htd belts have done over 20,00 miles on the roadbikes & the RGM stripped its wire cords, I cut the belt down to about 20mm wide & ran it like that for over 6,000 miles.

No Darley this year, will you be at Donnington?

Chris

Click to expand...

AndyChain recommends fitting an IWIS duplex chain to primary drives, he reckons that it's one of the few chains still made to old school standards, he would not suggest fitting current Reynolds branded triplex chains. Worth searching his posts on this forum. Other people seem to have problems getting belts properly alighned, so I would think three times before going down the belt route, unless you had to replace clutch and engine sprockets any way.

Unless playing racer games there's not much reason to fit a belt [less oil mess] but belt does refine the shifting and flying carpet lightness sense, just takes going through the tranny to stabilize the mainshaft/clutch wobble plus dual adjuster top mount to fine tune-hold alignment then lots of turning and turning till the nicely loose enough belt stays on track all by itself. If blazing around in lower gears playing racer games then better tug on clutch now and then and at first hint of wobble, back into the tranny bushes or may not ride home that day.

The duplex chains from a Merc diesel are not a standard duplex.

I have sold many for Commandos but not as many as I have for laverdas.

Commando owners seem to be shy at putting on a product that should outlast the bike
need no conversion and cost the same as a dubious triplex.

There are many stories about belts both good and bad, I smile when I see figures like
20,000 miles when a cheap chain should do 3 times that. Despite the number of chains
I have sold in the iwis brand the there are very few comments on here. In some ways
that is a good thing. Especially good are the cam chains in the big pin version.

Come on guys some feedback would be nice.

Andy

Without a doubt the advantage of the belt is two-fold:

1. Greatly reduced weight in the primary system. The weight savings for the big clutch lump hanging off that spindly mainshaft alone is worth it.
2. I believe the ratio with the belt allows the gearbox to turn slower, thus further reducing the load on a gearbox that was designed for a 30 hp lump.

Add to that no primary oil leaks and for a regularly ridden bike you can't beat it.

Dave, if you turn the gearbox slower it increases the torque loading on it. Turning it faster decreases the torque loading and is often done to lighten the load on a transmission that is near the limits. The idea is, speed up the gearbox, then reduce the gearbox sprocket size accordingly to end up with the same final ratio as before.

Does the belt drive perhaps run at a higher ratio to speed up the gearbox?

Glen

Unless special pulley ordered most if not all off the shelf belt drives are about 2:1 [like Dreer sold Haywood and Maney's] so slow gearbox down from chain drive ratio. If making enough power and using it to risk tranny better add out rigger too.

Andychain said:

I smile when I see figures like
20,000 miles when a cheap chain should do 3 times that

Click to expand...

Andy, I assume you are serious when you say a cheap chain should last 60,000 miles.

Really? please elaborate..

Myself and everyone I know buys off the shelf (cheap) chains, and they definitely need replacing in far, far
less than 60,000 miles, and that is with attentive adjusting and oiling.

are you talking about our Commando triplex primary chains running in oil lube or rear drive chains?
You are the expert on chains so please tell us how cheap chains should last 60K?

I have owned my Norton for 37 years with over 140,000 miles and in that time I have been through 2 triplex chains then 4 years ago I put a RGM belt drive kit (steel kit) in with 2 gearbox adjusters and no clutch wobble, after 5,000 miles without any problems then all of a sudden I lost 3mm off the side of the belt, it was trying to run off the front pully plate, a new replacement belt, readjusted it and after a 2,000 miles the same thing happend and still no clutch wobble, still trying to run off the front plate, it was so bad that the belt retainer plate shatted in 3 peices, not happy, didn't break the belt just wore out 3 to 5 mm off the side of the belt.

Before this happened again I sent away for another belt kit for my other project bike (alloy kit) but ended on my bike to replace the steel kit, but after some time I just couldn't get it to run without the belt trying to run off the front pully, I spent 3 days reajusting and still the same resualts, so decided to go back to the chain drive, as I never had any problems with chains and I am still running my orginals clutch plates with early Ford tranny oil.

I found running a belt drive made no diffrents to running a chain, the bike ran just as smooth with both, but will be running a open belt on my project bike (1960 650 Manxman).

Ashley

I think a mistake people make is aligning the hub to be perfectly square to each other. Whether the clutch hub is preceived to move or not, you can be sure under load it gives to some extent.

When I use the 2 squares method with one square on the front hub and one one the clutch hub, the perpendiculars will have a gap of 1/16 to 1/8" of an inch out at the ends indicating that any stresses will bring the hub to square but not so much to cause the belt to feed to the inner.

The other beneifit from this is that under normal running the belt will "favor" the the inner where there will be less stress than riding on the outer of the hubs.

My belt rides right to the inner edge of the clutch hub yet will not go beyond and has never touched the inner case. I also shim the clutch hub as close to the inner as applicable.

The original Renold was a very good product and it was nice to see person had
140,000 from 2 chains (very near my suggestion of 60,000.

If you look at previous posts from me I stated, and stand by, that 99% of all
triplex available to is budget and will not last on Commandos. Laverda owners
found this out over 10 years ago. They are also not cheap with chains ranging from
£25 up £85. I would still not put any of them on a primary drive.

I will not go into the advantages of the Merc duplex AGAIN as I am quite frankly
getting bored with the issue. Anbody can ring me or see me at shows and I will
gladly point out the differences and the advantages of the Merc chain.

Again I state that Laverdas had the same problem and this chain solved it so
it is not an unknown product. Tongue in cheek comment.......of course I know
that Commandos produce far more power than Laverdas !!!!!!!!!!

I shall wait for the Norton Mafia to call.

I look forward to hearing from you and remind you all that the iwis product
is available not only for the Merc duplex primary, the Alton starter (much discussed),
the cam (available in big pin and std automotive quality) and lastly the rear chain
where crank are available. Unashamed ad.

Andy