Norman White Belt Primary

lcrken · Apr 8, 2013

I don't recall seeing pictures of this belt primary on the forum, and I think it's interesting enough to post.

This is a drive I bought from Norman White sometime in the late '80s (I think). Norman used plates (steel and sintered bronze) from the smaller (than the Commando) clutch from the AJS Stormer. It's smaller and lighter than the usual Commando belt drives ( Maney, BNR, Norvil, etc.), but has worked very well on my 750 featherbed/Commando race bike for many years. I did try it on a 920 once, and stripped the belt, so I still use a BNR with the larger engines. On the other hand, a similar kit worked well on a well-built 872 Norton racer, so maybe I was just unlucky.

I recently removed the system from my featherbed/Commando when I installed a 920 engine in place of the 750 to run some landspeed events, and it seemed like a good opportunity to take some pictures.

The clutch pulley is 64T and the engine pulley is 36T for a 1.78 primary ratio. I've always preferred a ratio around 1.75 because it definitely helps my gearbox live longer. The belt is a 40 mm wide has 880 teeth.

Ken

cjandme · Apr 8, 2013

lcrken said:
This is a drive I bought from Norman White sometime in the late '80s (I think). Norman used plates (steel and sintered bronze) from the smaller (than the Commando) clutch from the AJS Stormer."--------thanks for the post Icrken, I was just on the Norman White web site a couople of days ago but didn't look at their belt drives, If it's the same one that they're selling today , I'd love to get one for my (stock engined) project bike, but at 1980's prices , but since that ain't happenin' it'll just have to wait. Cj

lcrken · Apr 8, 2013

I haven't looked at Norman's site, but I'm sure the price is no longer the 540 pounds I paid in 1989. I just found the receipt, and that was the date I bought it.

I should have mentioned above, the engine pulley has a vane style cush drive (shock absorber) in it. That was one of the options at the time, and it added 100 pounds to the price.

At the time, Norman offered the kit in 3, 4, or 5 plate configuration, with a variety of pulley sizes available for different drive ratios.

Ken

SeeleyWeslake · Apr 8, 2013

Ken,

I guess we were thinking similar thoughts on clutches back in 89.
Here ia a pic of the Norman White beltdrive clutch I bought for my Weslake Commando racer. The NW clutch is the middle one, for comparison the one the left is the Newby which followed it and on the right is a stock (chain) commando clutch. I eventually gave up on the NW clutch as I had constant trouble warping the plates - I don't think it could handle the clutch starts with a high 1st gear. I did slot the steel plates which helped them survive a bit longer.
I never really got on very well with the Newby either. to get it not to slip I had to wind the springs quite tight which gave a very stiff pull. Evetually I went to a Hemmings Commando clutch and it has been virtually troublefree for several years now.
I still use the front pulley cush drive which has definitely been worth its purchase price in giving the gearbox an easier time.

lcrken · Apr 9, 2013

SeeleyWeslake said:
Ken,

I guess we were thinking similar thoughts on clutches back in 89.
Here ia a pic of the Norman White beltdrive clutch I bought for my Weslake Commando racer. The NW clutch is the middle one, for comparison the one the left is the Newby which followed it and on the right is a stock (chain) commando clutch. I eventually gave up on the NW clutch as I had constant trouble warping the plates - I don't think it could handle the clutch starts with a high 1st gear. I did slot the steel plates which helped them survive a bit longer.
I never really got on very well with the Newby either. to get it not to slip I had to wind the springs quite tight which gave a very stiff pull. Evetually I went to a Hemmings Commando clutch and it has been virtually troublefree for several years now.
I still use the front pulley cush drive which has definitely been worth its purchase price in giving the gearbox an easier time.

Great minds think alike, etc.?

I never tried the Newby coil spring clutch like yours. I used his Commando style clutch with diaphragm spring. I used the standard Commando bronze plates, and was very happy with it. The only time I ever experienced slip with it was after a start at Daytona, where the bike was geared very tall and required some serious slipping to get off the line. It slipped a bit for the first few turns, but then recovered and was fine for the rest of the race.

Ken

SteveA · Apr 9, 2013

Norman's clutch is currentlky quoted at £540 on his website?

But that would be without the cush drive front pulley, which Norman quoted me £400 for as a one off last year.

FYI the other small clutch out there today is TTi who make their own 62 tooth drum, used as standard with a 31t pulley for 2:1.

Bruce insisted that with his boxes there is no need for 1.75:1 primary, but quoted me for a 35t pulley anyway.

I am thinking to ask Norman if I get a better deal on a cush drive pulley as part of a primary drive kit.

cjandme · Apr 12, 2013

I'd never heard of a cush drive front pulley....seems like a good idea.

lcrken · Apr 12, 2013

cjandme said:
I'd never heard of a cush drive front pulley....seems like a good idea.

Norton experimented with a cush drive engine sprocket on race bikes (chain primary) back in the '70s. I have one of them tucked away somewhere, and it is the same basic idea as the one Norman White offers. I'm not sure if Norman came up with the design when he worked as an engineer and test rider for Norton, or if he decided to offer it after Norton closed the race shop at Thruxton. In any case, the quality of his products is excellent. I've run his belt drive on my race bike for at least 50 races, probably more, and all I've ever done is replace the belt.

Ken

bwolfie · Apr 12, 2013

Any pictures of the cush drive? One of us crafty types might have a go at it.

lcrken · Apr 12, 2013

bwolfie said:
Any pictures of the cush drive? One of us crafty types might have a go at it.

I'll see if I can find the chain drive sprocket. I think I already disassembled it, and I'll take some pictures. I know it's around somewhere. Every couple years I run across it and then forget where I put it again. I loaned it to a friend of mine a few years ago, and he made some drawings with plans to make some, but nothing has come of it yet. If I can't find it, I'll take the Norman White pulley apart and take some pics, but not till after April 15 (tax day).

Ken

Norman White Belt Primary

Similar threads