Darn belt drives

lcrken said:

comnoz said:

That style belt has been the most durable I have ever used except for a Polychain. Jim

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I've had good luck on the race bikes with 40 mm wide HTD belts, using both Bob Newby and Norman White drives, not so good luck trying 30 mm wide belts. I'd like to have tried the Polychain GT belts, but all my belt drives have HTD toothform pulleys, and they aren't compatible. Back in the dark ages I tried one of the original Bob Oswald drives with the rectangular tooth form belts, and stripped the teeth off almost immediately. I think his later kits used a better belt design.

Jim, have you tried the new Polychain GT Carbon, the latest replacement for the GT2? It looks pretty trick.

Did you make your own clutch basket for the Polychain, or does someone sell a Polychain primary drive kit for Nortons?

Ken

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Ken, I didn't have problems with the HTD belts until I started getting into the high rpm stuff. I think the problem was more to do with heat than torque. I never used a 30mm HTD on a racebike but I did use the 30mm synchroflex and the 40mm HTD and both worked OK when I was reving over 8500 as long as I replaced them a couple times a season. The belts would start to lose teeth if I waited too long.

I made my own sprocket and drum for the polychain that I ran on the trans I built. The carbon belts were not available at that time but the aramid 36 mm polychain was indestructable even on the CRM 900 with 125 horse. The only time I ever replaced them was if they got a rock under them and punched a hole. I never had one fail even with a hole in it.

I did get a carbon belt for the rear drive on my streetbike [e-bay] but I haven't installed it. I figured I would see how the aramid belt held up first. The carbon belts are pretty pricey if you buy them from a supplier. Jim

I've got to have one of the oldest belt drives in existence. This is a QPD - the first one you could buy as far as I know. They were made for early square toothed belts and would not finish a race. Everyone told me it wouldn't work, so of course I had to do it. I hated the chain mess & weight so I converted it to round tooth by reshaping the teeth with the crude tools I had available at the time - drill press, chain saw files & porting tool. I ground down an engine sprocket and pressed it into the alum pully with horizontal pins to prevent slippage. Loctite/riveted the clutch drum together & had a custom belt made for me by Gates and went racing with the first belt drive on the track that would go the distance (early 80s). Soon after they began showing up on the market in similar fashion as offered by several suppliers. I used it throughout my racing career - now I'm running it on the street and its still doing fine although I've replaced belts on occasion.

I love it when you guys start talking shop...other than the fact that often I have no clue as to what was said...

So which belt should us mortal types look for in a kit?

Russ

Just posting a nod to Jim Schimidt's beastly ole relic : )

rvich said:

I love it when you guys start talking shop...other than the fact that often I have no clue as to what was said...

So which belt should us mortal types look for in a kit?

Russ

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For a streetbike I normally use a Norvil or an RGM. RGM takes a little more work to make it right most of the time. {A lathe comes in handy.}

I have a personal preference for the Synchroflex belt used on the RGM drive.

The Synchroflex belt has stainless steel wire for a tensile member. The Gates belt used on the Norvil drive [and most drives other than RGM] has an aramid member. That allows the Synchroflex belt to stretch a bit more when absorbing shock without damage.

The downside to the Synchroflex belt is the damage done by the wire if the belt comes apart from running too tight.

Either type of belt is adequate for long service on a streetbike. Over-tightening is responsible for 99% of the early failures I have seen with either belt. Jim

Is the RGM kit from Tony Hayward? I got one from Tony around 15 years ago and got 50,000mi out of the Syncroflex belt. The belt went toes up in the ditch a couple years ago and I replaced it with the spare I got with the kit. They are the beige ones and I ran the original in ATF. I've got the second belt running dry in a sealed primary. Maybe the new Gen III belt would be a good idea if you want to run it dry and sealed. Is there a good source for them out there?

rpatton said:

Is the RGM kit from Tony Hayward? I got one from Tony around 15 years ago and got 50,000mi out of the Syncroflex belt. The belt went toes up in the ditch a couple years ago and I replaced it with the spare I got with the kit. They are the beige ones and I ran the original in ATF. I've got the second belt running dry in a sealed primary. Maybe the new Gen III belt would be a good idea if you want to run it dry and sealed. Is there a good source for them out there?

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I get mine from Clubman Racing Accessories. He stocks several different lengths.
I am not sure if the Tony Hayward kit was made by RGM or if he just used the same belt manufacturer. It's been a while since I have seen one.
I ran my original beige belt in a closed primary for about half of the 72000 miles I got out of it. No lube. Jim

Jim did ya forget the spare in the fairing or not the right belt?

Hi,
One of the lads in my club had his belt drive shred last weekend.
He said it looked like an explosion in a Candy Floss factory. He did have a spare with him but recons the large washer holding it on the pully broke causing the belt to shred.
No long term damage caused anyway.
My belts done about 15000 miles so far so must have another 20 years left before it needs replacing.
I remember leaving my Atlas in gear on a hill leaning against a fence years ago overnight. Next morning the single chain had stretched to hell. I must have had 2 or 3 primary chains on that bike in 5 years.
Cheers

Hi Comnos & rpatton.

Spoken to Tony Hayward many times over the years!!!! If you phone him, you will be on the phone a long time. As I like to chat as well ,a very long time.
I have Tonys belts on my Triumphs cos they came with the bikes. (Daytona Bonnie Rickman Trident) I dislike Triumph clutches,pip nuts rollers & thrust washer. On my race bikes I went to Bob Newbys system. Quality,simple & light. Expensive to buy but spare parts are cheaper than Triumph spares? Anyway I was buying my spares from Tony for the race bikes & he did an exchange system with RGM ie he made belt parts, they exchanged Triumph spares. Good deal all round. Tonys parts were made by Pit engineers after the coal mines went tits up with dear Arthur & they all ended up on the dole. If you are looking for spares Commando Triumph triple or twin ask Tony for a price list as he can be miles cheaper than others. He was also the first person to sell the "red " ie higher temperature belt. Dont expect the conversation to be brief!
Got to say I have Norvil & Neb htd units 30mm on road bikes & 40mm on the race bikes & they work fine. Dont like the Commando circlip but!!!

all the best Chris

Don Tovey wrote;

the large washer holding it on the pully broke

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This pulley that Don refers to was on a MK3 Commando. It is a Norvil conversion, and the near side carrier plate is screwed on to the pulley and has countersunk holes for the taper headed allen screws. This carrier plate was found in two pieces in the p/chaincase cover and pretty mangled up, and we think that this had had a stress failure across the screw holes, and allowed the belt to run off the front pulley and destroy itself. This belt drrive has been checked many times and always appeared to run true. Only a few weeks before this incident all looked well.

I also used to run a Norvil belt drive on my MK3, and on doing a maintainance check at about a year old, also found a piece of plate (fractured between two of the countersunk holes) laying in the bottom of my chaincase. The other piece of carrier was still located on the pulley luckily and had saved me from a failure similar to my friend. Now I am aware that my belt wasn't running true, and had worn a lip on the plate which will have weakened it, and contributed to the failure.

Has anybody else had a carrier plate failure on a Norvil belt drive?

Incidently the chap with the carrier failure has now had a steel plate manufactured for his belt drive, locally by an engineer, as the Norvil plate appears to be anodised alloy? So hopefully will avoid this happening again.

Checked mine recently and seems ok but I did have an issue with the machined face (next to the oilseal) touching the oilseal. Only a few thou had to come off on a surface plate.

I've used the Norvil belt drive for many years. The inside plate on the front sprocket got worn away by the belt over the years, despite me being careful to get alignment correct. The belt didn't fail though, just wore the edge a bit. I made a new plate with a larger outside diameter from a piece of brass sheet rather than take out a mortgage for a replacement Norvil one. The originals are anodised aluminium. I also fitted the RGM additional gearbox top bolt adjuster to try & get alignment spot on. I changed the belt as a precaution. I bought it from an industrial supplies company for about half what Norvil wanted.

Ian

I guess that is another advantage to the RGM drive. It has steel plates for the shoulders.

An engineer at Gates Corp told me one time that belt alignment was not as critical as chain alignment. He said that a belt that was too tight was usually the reason the belt wanted to run to one side or the other.

I guess I got lucky because I have never even checked the belt alignment on my MK3. I only have the stock single adjuster on my MK2. Jim

hobot said:

Jim did ya forget the spare in the fairing or not the right belt?

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Steve, I installed the spare belt that had been riding around in my fairing for many years. I have yet to find the one you sent me. It is hiding somewhere in my shelves. I will need to find it to replace my spare. Jim

OK, sorry/glad the grope monster has a clan installed at your place too. Its the brighter red kind so that fooled me on the one you displayed. Hope it lasts till ya forget about it again anyway.