Cush Drive Crankshaft Pulley

swooshdave said:

Why can't you just use a rear hub with a cush?

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Thought I had answered that, Rickman Hub is not Cush Drive, I have a Rickman Hub and a set of 6 race sprockets. I want to retain the original appearance, a cush drive sprocket will not be seen. There is also a space restriction within the original swinging arm.

When comparing cost, from where I am with a recently built wheel and set of sprockets, to go for a cush drive I would need a new Triumph 4 bolt hub (at least £120), Wheel building (£120 plus rim £100), the cush drive (Maney £260) disc carrier (say £100) and full set of sprockets.....sprockets alone could be 6 times £45 in the UK...nearly £1000!...over $1500! Assuming I can get it into the swinging arm and line it all up, or I might need to add another swinging arm!

Since I was named in a previous post I figured I should reply instead of just lurking.
I’ve run a Norman White crank mounted cush drive pulley for the last 22 years on my Commando /Weslake and Seeley /Weslake race bikes. I followed the same logic as Steve A ,ie figured I need to help the gbox survive and copied the JPN ideas. I also didn’t want to run a cush in the rear hub since I was using first a Triumph conical hub and then a Seeley/Manx. Overall I would guess the cush drive and higher primary ratio have helped the gbox . I’ve broken 2 mainshafts (Quaife)in the 22 years and have had to only occasionally replace gears. I did swap out the entire cluster a few years ago. Its possible the gearbox would have suffered more problems if I hadn’t used the cush drive since it was having to cope with a 75+ rwhp engine and race abuse.
My friend , the late Les Cook ran a Atlas Commando race bike for a similar period of time ( with about 65 -70 rwhp) and he eventaully got fed up replaceing gears in his 4 sp close ratio gox and fitted a cush drive Grimeca rear wheel . The Grimeca is a bit of a big heavy lump though.We both thought about the MAney but I didn't want the bother converting to a rear disc.

I originally used a Norman White belt drive clutch which is like a mini Commando one using AJS Stormer plates and diaphram spring. It didn’t’ survive the clutch starts very well and was frequently warping the plates. Tried a Newby but eventually wound up with a Hemmings Commando clutch which has been bulletproof. The advantage of the White clutch was that it was 64 teeth which, along with the 36 on the crank gave a ratio of 1.78 (the magic JPN number) The smallest Hemmings is 68 teeth which gives 1.89 which is still a big improvement over stock (57/26, 2.19)
If you can convince Norman White to make you one then his cush drive is probably what you want and if he'll only do a 36 then it's still probably worth going for .

Let me be the 1st to say "Welcome to the forum" SeeleyWeslake! Any chance in posting some photos of your bikes. I'd love to see some shots of the head from the inside and other engine details if it's something you can share. It would be interesting to learn how they have matured over the years too. That is some rare machinery you have.

Let me be the 1st to say "Welcome to the forum" SeeleyWeslake! Any chance in posting some photos of your bikes. I'd love to see some shots of the head from the inside and other engine details if it's something you can share. It would be interesting to learn how they have matured over the years too. That is some rare machinery you have.

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I second that!

hobot said:

Let me be the 1st to say "Welcome to the forum" SeeleyWeslake! Any chance in posting some photos of your bikes. I'd love to see some shots of the head from the inside and other engine details if it's something you can share. It would be interesting to learn how they have matured over the years too. That is some rare machinery you have.

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I second that!

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I bet these are some of his bike. :mrgreen:





Did I get it right?

Thanks for posting the pics Dave.
You did get it right and saved me the aggro of having to learn how to post pictures. I suppose I'll have to learn eventually.
The pics were taken at Portland AHRMA in 2010. A clue is that the bike is wearing its silencers on the ends of megaphones. Portland has a noise limit of 102db and they help get the open megas down to about 100db (from about 105)
I'll see what I can do on getting some interior shots posted .They shoudl probably go in another section since the only Norton Commando parts are the front end and the oil pump.

SeeleyWeslake said:

Thanks for posting the pics Dave.
You did get it right and saved me the aggro of having to learn how to post pictures. I suppose I'll have to learn eventually.
The pics were taken at Portland AHRMA in 2010. A clue is that the bike is wearing its silencers on the ends of megaphones. Portland has a noise limit of 102db and they help get the open megas down to about 100db (from about 105)
I'll see what I can do on getting some interior shots posted .They shoudl probably go in another section since the only Norton Commando parts are the front end and the oil pump.

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Of course you're right about the location. I bet I have pictures of your bike from over the years when you've raced at Portland. These were just the easiest to post. And yes, you'll need to learn how to post pics. :mrgreen:

Yeah, you can post them in the Commando section. Your bike is highly related to a Commando.

SeeleyWeslake said:

Since I was named in a previous post I figured I should reply instead of just lurking.
I
I originally used a Norman White belt drive clutch which is like a mini Commando one using AJS Stormer plates and diaphram spring. It didn’t’ survive the clutch starts very well and was frequently warping the plates. Tried a Newby but eventually wound up with a Hemmings Commando clutch which has been bulletproof. The advantage of the White clutch was that it was 64 teeth which, along with the 36 on the crank gave a ratio of 1.78 (the magic JPN number) The smallest Hemmings is 68 teeth which gives 1.89 which is still a big improvement over stock (57/26, 2.19)
If you can convince Norman White to make you one then his cush drive is probably what you want and if he'll only do a 36 then it's still probably worth going for .

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Norman said he would make a 40 tooth. My initial reluctance is only due to the price he quoted as a one off. My own arithmentics says however that value may still be there even at that price compared to the rear hub cush drive option. It has been really helpful to know of the experience of others. I am now even more determined to use a cush drive pulley. I am hoping however that if we can get enough interest then a small batch price might be better than a one of price .

Steve

SteveA said:

Norman said he would make a 40 tooth. .... I am hoping however that if we can get enough interest then a small batch price might be better than a one of price .

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I'm interested provided the belt profile used suits my wishes: I've been running a RGM AT10 belt and consider this to be overloaded so I'd prefer a Poly Chain GT2 profile (which means it would also be possible to run a narrow Poly Chain Carbon).

Which profiles are available for clutch drums? Newby, Hemmings?

And I'd like to run a relatively wide inner guide disc on the pulley - because I'm currently setting up a Sachse ignition with crankshaft pickup and the trigger disc is included in the guide disc.


Tim

Tintin said:

SteveA said:

Norman said he would make a 40 tooth. .... I am hoping however that if we can get enough interest then a small batch price might be better than a one of price .

Click to expand...

I'm interested provided the belt profile used suits my wishes: I've been running a RGM AT10 belt and consider this to be overloaded so I'd prefer a Poly Chain GT2 profile (which means it would also be possible to run a narrow Poly Chain Carbon).

Which profiles are available for clutch drums? Newby, Hemmings?

And I'd like to run a relatively wide inner guide disc on the pulley - because I'm currently setting up a Sachse ignition with crankshaft pickup and the trigger disc is included in the guide disc.


Tim

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Tim,

Norman also said I would need to tell him required tooth profile. I don't have a drum as yet, I had considered Maney or Hemmings, though confess I don't know which profile either uses. Maney quotes his clutch drum complete with belt and pulley. I guess we can see why the likelyhood of a one off sale comes up. There are too many different options. To get a better batch price a number of guys would have to decide on a common path.

Your ignition trigger idea is a good one, even if it adds another variable. Sounds much less vulnerable than mounting a crank trigger on an external plate. I have always been interested in crank triggering. The crank that ran in my Rickman as originally built came from the Norton experimental shop and had been run in tests with crank triggering in '75! No marks on the crank at all, just looked standard till we cut the end off flush with the taper, tapped the end and polished it!

SteveA said:

Norman also said I would need to tell him required tooth profile. I don't have a drum as yet, I had considered Maney or Hemmings, though confess I don't know which profile either uses. Maney quotes his clutch drum complete with belt and pulley. I guess we can see why the likelyhood of a one off sale comes up. There are too many different options. To get a better batch price a number of guys would have to decide on a common path.

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From what I've seen in some basic calculations I've done the best option by far is the Gates Poly Chain Carbon GT. This is compatible with the GT2 profiles and these are very common. I'd expect one or the other supplier to actually use this anyway.

Your ignition trigger idea is a good one, even if it adds another variable.

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Actually it would only add a bit of width to the disc and I'd love to have the disc removable. The Sache uses either a window for an optical trigger (means it uses two windows at the cam and thus one at the crank) or a magnet each to signal the beginning and one to signal the end of the "window". My idea is to use a magnetizable steel disc with a cutout and a Reed pickup close to the engine plus a rare earth magnet inboard the disc (stationary - which means it would be situated behind the crank in the "unwrapped" area of the belt) - I just hope that the overall setup wouldn't be disturbed too much by the alternator as I don't intend t build a race bike.



Tim

Why not just use a simple toothed wheel and a hall trigger? I would think the RTD systems used by Steve Maney use something along these lines, and heard they work very well.

The very 1st non contact breaker ign. triggers were IR LED, just light source and a slotted wheel in flat disc or cupped cap form. Can do a search to see DIY to off the shelf variety and most if not all are smaller than the Hall Effect gizmos.

Ignition stuff is interesting guys......topic is cush drive :wink:

Another thread maybe...crank ignition triggers....

You are sticking-stuck with the hubs and sprockets on hand so my spoked Suzuki GT750 Water Bufflo adaptation with cushions, changeable sprocket and disc brake mount won't help. I still think a tensioner somewhere in drive train might do as much as too compact cushion system allowed in the items being discussed.

Here's the cush drive in Ms Peel alternator for idea in tight narrow application.
The cog wheel extends past the cush section so will be removed for a belt pulley.

I had a comment from an engineer that a design should be based on available cush drive rubbers. So it would be good to know where that alternator originates and some dimensions.....

Though I may know since I do have a Suzuki GSXR750F, which althogh i have never removed the alternator I can now see looking at the microfische, does have a cush drive, but I suspect it is not designed for 70 plus crank HP.....and that the shaft size might limit its usefulness.....

Its a kinda of special rare DENSO 600 watt dragster alternator meant to plug directly into engine block to engage the gears. Note O ring seal I will remove. To me its cute'r case than utilitarian under hood types. I've two of them but yes too small a shaft for engine power loads. But its the design I was showing with nested split cushions. Identical to many rear hub cush drives whose bigger rubbers could be cut down thinner in thichness and Y spread and still be over kill compared to factory hub cushioner.


http://www.dom-france.fr/version_anglai ... /index.php
guarantee appropriate performance of chain or belt drives, absorb
vibrations from kinematical motion

SteveA said:

I had a comment from an engineer that a design should be based on available cush drive rubbers.

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Not necessarily as it is easily possible to cast such things from 2K polyurethanes - e.g. this one. The nice aspect of this is that after the rubber has worn out the pulley could easily refurbished.


Tim

From BI list:

On 1/16/2012 7:21 AM, neoludd <neoludd@EARTHLI>NK.NET wrote:
> I ran a narrow-1.75in- belt primary in my colonial Hurley-Pugh Wildebeest/Manxman knockoff for years. The usual primary shock absorber is a heavy spring/cam setup on the engine pulley.....so, I ran this 70 odd horse, 550 odd lb beast with no cush but that provided by the belt.....zero problems, from THAT area....and I got 30 plus K per belt, obe letting go early because it ate a pebble and holed itself. ......actually, any HD running a belt primary has zero shock absorpstion other than the belt.....

An Australia product to ponder
http://www.kushsprockets.com/sprockets

Steve Maney makes a cush drive for the rear wheel, but changes the rear wheel hub to do it. You need a Triumph disc brake hub. The beauty is you can alter sprocket sizes.
It works! I used to run a belt without it, it was an early beld drive... but I am sure it wore out the gear box teeth.