Non-Cush Hub Conversion?

Tornado

Tornado

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Im planning to make up a new rear wheel for my 74 850. Picked up a never used rim in great condition. The hub that came with it is the pre-71 type which bolts to drum with studs, not the cush drive paddles as on later type. Can the hub be modified to take the cush drive by milling the slots for the cush rubbers or to complicated?

Any major issues with using non cush drum and hub on the 850, such as shock loading in the gearbox etc?
 
seattle##gs said:
The cush drive is a set of rock hard and thin blocks. I don't see how they could work as a cush drive.
Click to expand...
Not as hard as aluminium though is it? So some ‘give’ must be there. How useful or important it is though, I’ve no idea.

I’m guessing Norton did this as a ‘trickle down’ from the racers which were suffering gearbox failures? Started out as a good idea but ended up being hampered by cost?

I’ve often wondered why the Brits put such effort into shock absorbers in the 50s with big spring loaded ramps on the cranks etc, this put a lot of cost into the products and they were producing really quite low power.

I wonder if it was a hangover from pre war days when big singles were mated to inadequate / antiquated gearboxes, often hauling sidecars etc?

Or maybe it was the riding style of the day, even road testers were obsessed about achieving ridiculously low ‘minimum none snatch speed’ in top gear, maybe people lugged their engines too much back then?

Lots of race bikes etc get built sans cush, but they’re never ‘lugging’ they’re always spinning fast and in the right gear. I’ve built lots of Triumphs where a belt drive has meant the stock cush is removed, and race bikes without cush drives, and have never noticed any ill effect.

Having said all of that… if a bike has a cush drive already, that causes no issues apart from needing new rubbers once in a while, I’d be hesitant to remove it for no real benefit. If changing rubbers once in a while is the issue, Ludwig already has the solution for that !
 
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Tornado said:
Can the hub be modified to take the cush drive by milling the slots for the cush rubbers or to complicated?
Click to expand...
The metal isn't there to make the slots without welding unless that's what you meant.
Non-Cush Hub Conversion?
 
I had a friend who put a bolt-up hub/drum combo in a Commando and regretted how harsh it was, to the extent of backtracked and having a cush hub laced in.
Even the Dommies, which the bolt-up hubs were fitted to, had a rudimentary cush in the clutch.

I think you should go ahead - then report back on your findings.
 
Sounds like a lot of work without any R&D to back it up. I wouldn't do it. Doesn't mean squat that I wouldn't do it though. I can't do machine millwork with a hacksaw and file. ;)

Andy Molnar does not use cush anything on his race bikes. Race bikes are not ridden from home to the local cafe on signal regulated surface streets though and aren't expected to last forever without needing some attention. Mr Molnar said they have not had any failures running the race bikes that way, but his race bikes are fit with TTi gearboxes, which are as far as I can tell from using one smoother shifting than the AMC gearboxes.

I don't have any cush in the RGM belt clutch or the stock rear hub of my P11 and can't tell any difference from when I did have cush in the AMC clutch. I may not be putting enough energy into worrying about it though and missing something.
 
I put a bolt up rear wheel on my 850
I absolutely hated it
Mainly the crunch into first was the main thing I didn't like
As was going down the box to slow down
But that's just my take
Nowadays I have apprillia pegaso wheels with a very decent cush drive on my 750
 
I'm also interested in this topic, since I have a hub and rim from a Yamaha MX bike sitting in my workshop. Needs a suitable caliber and master cylinder added to the frame, but it would give a far lighter rear wheel, inspired by our own Ludwig's efforts.
It's totally lacking a cushdrive though.
 
The only comparison I have is with honda sohc 750s. when we removed the cush drive hub to acquire a disc rear brake, we suffered substainially higher primary chain failures.
I converted my first year commmando to cush drive and noticed quite a bit of perceived improvement (seat of the pants). I used the bolt up hub cover with rubber plugs so the difference is not apparent from the outside,
 
Fast Eddie said:
Not as hard as aluminium though is it? So some ‘give’ must be there. How useful or important it is though, I’ve no idea.

I’m guessing Norton did this as a ‘trickle down’ from the racers which were suffering gearbox failures? Started out as a good idea but ended up being hampered by cost?

I’ve often wondered why the Brits put such effort into shock absorbers in the 50s with big spring loaded ramps on the cranks etc, this put a lot of cost into the products and they were producing really quite low power.

I wonder if it was a hangover from pre war days when big singles were mated to inadequate / antiquated gearboxes, often hauling sidecars etc?

Or maybe it was the riding style of the day, even road testers were obsessed about achieving ridiculously low ‘minimum none snatch speed’ in top gear, maybe people lugged their engines too much back then?

Lots of race bikes etc get built sans cush, but they’re never ‘lugging’ they’re always spinning fast and in the right gear. I’ve built lots of Triumphs where a belt drive has meant the stock cush is removed, and race bikes without cush drives, and have never noticed any ill effect.

Having said all of that… if a bike has a cush drive already, that causes no issues apart from needing new rubbers once in a while, I’d be hesitant to remove it for no real benefit. If changing rubbers once in a while is the issue, Ludwig already has the solution for that !
Click to expand...
Also responding to comment that Norman White thought the cush drive did nothing....bear with me.

I think it is possible what Norman really meant was that Commando cush drive was ineffective. He did design and make a belt pulley with a cush drive. But when I wanted one he had stopped making them and didn't want to do a one off for me.

Lots of Seeley Commandos have Steve Maney's Cush drive rear wheel.

A cush drive somehwhere in the transmission is a 'good idea', will you notice the difference? No, possibly not, but your gearbox might.

I have a race used TTi. I recently replaced a lot of the gears that had some tooth, but more dog wear. My transmission does not have a cush drive. It has a Rickman rear hub.

It should be born in mind I bought this gearbox used in 2014 and it was used in a sidecar for a full season before I bought it. I have used it from 2015, with one very full season and a few less so.

I discussed the wear with Bruno Perlinski, he said he has never seen any particular teeth or dog wear in a TTi box, and he has seen far more than me.

However, Bruno builds and races Seeley style bikes, with a Maney style rear cush drive. Is the cush drive the difference in our experiences? Maybe!

If anyone out there is making cush drive Commando crank belt pulleys (35T, 40mm 8M belt) I would love to hear from them.
 
I replaced my AMC clutch on the 650 with a commando clutch conversion and belt.

AMC clutch has a cush, meaning there was no rubber (except the belt, which doesnt really count) between crank and the rear wheel.

I didn't notice any detriment/ harshness? Has been like that for about 15,000 miles. The gearbox probably wanted a rebuild before I fitted the commando clutch, and it got it prior to about 1000 miles tour last summer. I am not sure if the lack of cush precipitated the reqbuild, but I think not.

I do flog the 750 featherbed, which has the same set up. Thats not a very practical machine, but I still did 1000 mile tour on it a couple of years back and it was fine?

Just my thoughts, not advice, but an illustration that "suck it and see" might not throw up any problems for your application?

Andy
 
SteveA said:
Those are Suzuki cush rubbers, as used on GSXR750s etc. I've run those on the race track. They will last much better on a Commando than the crap Norton used.
Click to expand...
Yes, but on a Suzuki they don't have to deal with the heat generated by a drum brake.
 
Looks like ive now found an original drum brake rear wheel for an 850 fully assembled locally for a good price, so if it looks good will likely go that route...saves a wheel build and a venture into non-cush territory.
 
My bolt-up 'S' type rides very much the same as my later bikes, and TBH I've never noticed any difference. The gearbox has survived the last 55+ years, so I'm hoping it'll hold out OK in future ;)
The only gearbox damage I've seen was on 850s, maybe a combination of greater torque causing more shaft flex, or poor hardening of the gear teeth - the 2nd gear pair on my Mk2A were badly spalled, and the new replacements went the same way within a couple of thousand miles.
My 920 build will have a Maney cush drive & disc brake on a T140 hub, so I guess I'm not really advocating for the Norton way 🙂
 
B+Bogus said:
My bolt-up 'S' type rides very much the same as my later bikes, and TBH I've never noticed any difference. The gearbox has survived the last 55+ years, so I'm hoping it'll hold out OK in future ;)
The only gearbox damage I've seen was on 850s, maybe a combination of greater torque causing more shaft flex, or poor hardening of the gear teeth - the 2nd gear pair on my Mk2A were badly spalled, and the new replacements went the same way within a couple of thousand miles.
My 920 build will have a Maney cush drive & disc brake on a T140 hub, so I guess I'm not really advocating for the Norton way 🙂
Click to expand...
This.
 

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