Belt drive for pre cush drive 1970 Commando

freefly103 · Nov 25, 2014

Am considering installing a belt drive for my '70 Commando to alleviate oil leak issues from the primary.

The 1970 model doesn't have cush drive (at least that is my understanding). Is it ok to install a belt drive on this bike, as from what I read on here, the belt wont last long without a cush drive to absorb shocks?

SteveA · Nov 25, 2014

What makes you think your 1970 doesn't have a cush drive rear hub?

freefly103 · Nov 25, 2014

From my research on here e.g.

early-rear-hub-not-cush-drive-t19597.html

Chris T · Nov 25, 2014

Correct- the 1970 and earlier doesn't have a cush; but this is the first that I have heard that for that reason you should not use a belt drive for it- why? Does the belt have less flexibility than a chain- will something break?

freefly103 · Nov 25, 2014

Yes - refer this article from NOC website.

http://www.nortonownersclub.org/support ... elt-drives

dave M · Nov 25, 2014

The point being made in the NOC discussion is not that the belt drive is worse than a chain drive, but simply that it is no substitude for a cush drive. Since your model has no cush drive, neither a chain nor a belt will provide this.

You can indeed fit a belt drive to your bike in order to solve your leak problem. Be aware that belt drives tend to tighten up when hot, so they require less tension than you would expect when cold.

texasSlick · Nov 25, 2014

dave M said:
The point being made in the NOC discussion is not that the belt drive is worse than a chain drive, but simply that it is no substitude for a cush drive. Since your model has no cush drive, neither a chain nor a belt will provide this.

You can indeed fit a belt drive to your bike in order to solve your leak problem. Be aware that belt drives tend to tighten up when hot, so they require less tension than you would expect when cold.

+ 1

Lack of a Cush drive is tough on gearboxes, regardless of chain or belt.

Slick

dennisgb · Nov 25, 2014

Maybe you should upgrade the rear wheel to newer cush drive first?

freefly103 · Nov 25, 2014

Yes, that's what I'm thinking:

http://www.ebay.co.uk/itm/Norton-Comman ... 1712887920?

auldblue · Nov 25, 2014

I have a 69 and 71 neither has Cush drive fitted and I have no plans to fit any ,what could possibly go wrong ..........................................Is it Kaboom again bill.
But I am fitting a belt to my 72bat, for no particular reason.
J

dave M · Nov 25, 2014

I fitted a belt drive to a 71 Commando - which does have a cush drive - I felt it improved the shifting in terms of smoothness, but I suspect this is due to the weight saving rather than any inherent flexibility in the belt. The whole primary drive system is several kilos lighter than standard. My primary chain and sprockets were worn so this was an easy decission for me. I would certainly use a belt drive again and will probably do so on my next Norton build.

texasSlick · Nov 25, 2014

auldblue said:
I have a 69 and 71 neither has Cush drive fitted and I have no plans to fit any ,what could possibly go wrong ..........................................Is it Kaboom again bill.
But I am fitting a belt to my 72bat, for no particular reason.
J

The first Cdos without cush drive were blowing gears, which problem Norton solved by going to the cushioned rear hub. If you drive sensibly, there should be no problem. I fitted a Cdo clutch to my Atlas (thereby eliminating the Atlas clutch cushion), and put about 15K miles on it with no problem....but no wheelies please!

There are some who say a cush somewhere in the driveline is mandatory to dampen the power pulses of the engine...I am sure a cush is better than no cush, but you will have to be the judge of that. FWIW... I have since gone back to the Atlas clutch with the cush hub.

Slick

SteveA · Nov 25, 2014

texasSlick said:
auldblue said:

I have a 69 and 71 neither has Cush drive fitted and I have no plans to fit any ,what could possibly go wrong ..........................................Is it Kaboom again bill.
But I am fitting a belt to my 72bat, for no particular reason.
J

Click to expand...

The first Cdos without cush drive were blowing gears, which problem Norton solved by going to the cushioned rear hub. If you drive sensibly, there should be no problem. I fitted a Cdo clutch to my Atlas (thereby eliminating the Atlas clutch cushion), and put about 15K miles on it with no problem....but no wheelies please!

There are some who say a cush somewhere in the driveline is mandatory to dampen the power pulses of the engine...I am sure a cush is better than no cush, but you will have to be the judge of that. FWIW... I have since gone back to the Atlas clutch with the cush hub.

Slick

A Rickman or Seeley never had a cush drive rear hub, some of them never had a cush drive clutch hub either. Today most have a belt drive, some have a cush drive rear hub, some (very few) have a cush drive in the crank pulley!

It was never discussed as an issue way back when, now we worry about it. Irony: lots of gearboxes were breaking then, today we can get much stronger and better changing gearboxes, and we worry about it.

I don't think you will have much on an issue on a 750 road bike, if you avoid the wheelies like the man said.

Funny thing is I had a '70 fastback, and I thought it had a cush drive hub, maybe not!

texasSlick · Nov 25, 2014

SteveA wrote:

"It was never discussed as an issue way back when, now we worry about it. Irony: lots of gearboxes were breaking then, today we can get much stronger and better changing gearboxes, and we worry about it."

This is true of so many things about our Nortons....wet sumping, oil temperature, wheel diameter/tire size, tire pressure, etc (etc means there's more, but I am too lazy to think or write them up). Way back when, we just rode them, or was it that we were too poor to do anything about the issues, so ignored them?

Slick

SteveA · Nov 25, 2014

texasSlick said:
SteveA wrote:

"It was never discussed as an issue way back when, now we worry about it. Irony: lots of gearboxes were breaking then, today we can get much stronger and better changing gearboxes, and we worry about it."

This is true of so many things about our Nortons....wet sumping, oil temperature, wheel diameter/tire size, tire pressure, etc (etc means there's more, but I am too lazy to think or write them up). Way back when, we just rode them, or was it that we were too poor to do anything about the issues, so ignored them?

Slick

I think the thing was, yes, we just rode them and fixed what broke...the fact it broke wasn't such a surprise...things mostly did...and we figured we were leaarning from it.....which all kept most of us too poor to do development..or even worry too much about it......

And today we all have a tendecy to over analyse and look for problems to find 'neat' solutions to.....and the guys doing that have 'more disposable income'..'better equiped workshops'...and we have a handy way of discussing the issues way beyond the horizons we had 40 years ago.....and there is a a bigger industry of 'developers' in place of the 'repairers' from way back...

Yep, we should all find more time to go ride......

comnoz · Nov 25, 2014

I have installed several primary belt drives on bikes with no cush. I have not seen any issues.

Now if you were installing a rear belt drive a cush hub would be advisable. Jim

acotrel · Nov 25, 2014

texasSlick said:
auldblue said:

I have a 69 and 71 neither has Cush drive fitted and I have no plans to fit any ,what could possibly go wrong ..........................................Is it Kaboom again bill.
But I am fitting a belt to my 72bat, for no particular reason.
J

Click to expand...

The first Cdos without cush drive were blowing gears, which problem Norton solved by going to the cushioned rear hub. If you drive sensibly, there should be no problem. I fitted a Cdo clutch to my Atlas (thereby eliminating the Atlas clutch cushion), and put about 15K miles on it with no problem....but no wheelies please!

There are some who say a cush somewhere in the driveline is mandatory to dampen the power pulses of the engine...I am sure a cush is better than no cush, but you will have to be the judge of that. FWIW... I have since gone back to the Atlas clutch with the cush hub.

Slick

I also use single row primary chain with the old manx style clutch with the cush hub. The primary chain is only manually lubricated and the engine sprocket floats - stands up to race conditions. Even if the rear sprocket is rubber mounted in the stud holes or use a Japanese drum with the cush - can help. If the impact situation occurs in the gearbox you can lose the hardening off the gears. This is not about making shifting easier - all you need do is match the revs for that.

gjr · Nov 25, 2014

I have close to 15,000 miles on a belt drive primary and have not had a problem. I like the belt drive a lot. I did fit a cush drive rear hub ages ago, but it did not help with cracking the rollers on the primary chain. I don't think a stock rear hub would present any problems. Worst case, stick a spare belt in your side cover and replace it if it breaks.

Greg
'70 Roadster

Hobot · Nov 25, 2014

Belts transmit shocks as much of more than chain so some slackness helps by allowing some rebound in drive train on power pulses. Belts generally don't wear out in same sense of chains, they never stretch but are vulnerable to rubbing edges on pulley especially as clutch wobble may creep up for a surprise belt unravling. Belts should of been standard issue to my mind but the ole steampunk chain is proven quite adequate.

dennisgb · Nov 25, 2014

texasSlick said:
SteveA wrote:

Way back when, we just rode them, or was it that we were too poor to do anything about the issues, so ignored them?

Slick

Yes, but we also learned a lot in the past 40 years.

Belt drive for pre cush drive 1970 Commando

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