clutch plate comparison

there was a discussion earlier on the wide v narrow clutch plates and IF they would work. well with the type of work I have done for over 35 years I thought a visual would help to show what is out there and works.the first 2 pictures are of a clutch pack that holds well over 300 HP.





this is a 7 driven 8 drive pack with single sided friction materiel and made by raybestos.
the next pic is a comparison of the size of the ones shown and a 750 surflex.



so as shown it is not the amount of friction area alone that matters but the effective mean radius. in what I do the thinking is to have more torque capacity there several ways to do this. 1 is to add more plates, 2add more clamping force. there several ways to add more clamping force. 1 increase hydraulic pressure or the apply piston area, or with out getting in the science of friction materials which I don't have that knowledge that is another way but will also have an effect on engagement property's.

Keep a' talkin' 2 us. :wink:

the one thing to add is the norton clutch is a rarity where you have the option to move the radius farther out. last year I had a dodge diesel converter rebuilt and was with the rebuilder when it was reworked. it was an after market high dollar converter and had an issue making to much heat and to loose. the heat issue was to much pump to turbine clearance but to the issue of torque capacity he was at a seminar put on by raybestos. part of the talk was about effect radius v total area and again effect radius won out.

External grab wears out ? Go on.

Are you saying that the Norton clutch capacity could be increased by decreasing the clamped surface in the area nearest the center, thereby increasing the PSI in the clamped surface in the area farthest from the center?

No he's saying that the total friction load a clutch can take is mostly determined by the type of friction materials rather more than just the surface area and after that is helps plates hold by increasing the radius-lever arm length OD loads resisted. Another way of stating it = is extra spring pressure gained over factory is not significant compared to the above 2 factors, type of material and OD its acting through. The extra plates are mainly to displace enough heat they don't melt, weld together or wear out fast but one plate can hold as much as a dozen otherwise, of same material and OD size of course. Its all very plain to those trying to ride on THE Gravel, surface area, pressure, type of materials and OD-leverage acting though. I tease thee not.

The clutch pack in the upper pictures looks to be out of a automotive automatic transmission, since it uses a hydraulic servo to engage it it has little in common with the average motorcycle unit besides having driven and friction plates.

The Norton clutch is a little different having minimal plates.
Beveldrive Ducati's (750's and 900's) from the early 1970's to mid 1980's had well known clutch slip, the plates looked similar to the Nortons friction width wise (but it had more plates and was a multi spring pressure plate)
How did they overcome that, they increased the inner radius of the friction material (narrowed and reduced the friction area while retaining the original OD)
Why, because that reduced the speed differential of the previous inner and outer radius of the (wide) friction band.

No different to narrow band brake rotors.

that is what I am saying, by taking the steel plate's and and increasing the OD you can increase the holding capacity.on your second part it is not increasing the clamping pressure as that is controlled by the stack height or a different spring if you could find one.

xbacksideslider said:

Are you saying that the Norton clutch capacity could be increased by decreasing the clamped surface in the area nearest the center, thereby increasing the PSI in the clamped surface in the area farthest from the center?

Click to expand...

you are correct in it is from an automatic transmission. it has more in common in that it is a multi plate wet clutch that has to apply under a HIGH load and not slip. it is a giving that it has the advantage of a controlled hydraulic apply pressure that increases with torque.norton's don't have this as it is a fixed spring.

Time Warp said:

The clutch pack in the upper pictures looks to be out of a automotive automatic transmission, since it uses a hydraulic servo to engage it it has little in common with the average motorcycle unit besides having driven and friction plates.

Click to expand...

the point is they are a both multi plate working IE has to apply under a load and hold.

Time Warp said:

The Norton clutch is a little different having minimal plates.

Click to expand...

that is exactly what I am saying to do on the norton clutch. the cheapest way is to increase the ID of the steel plates while using the original friction plates .

Time Warp said:

Beveldrive Ducati's (750's and 900's) from the early 1970's to mid 1980's had well known clutch slip, the plates looked similar to the Nortons friction width wise (but it had more plates and was a multi spring pressure plate)
How did they overcome that, they increased the inner radius of the friction material (narrowed and reduced the friction area while retaining the original OD)

Click to expand...

it is not the speed differential that is the issue. you are moving the center line of the effective mean radius to a larger one. like when you put on a longer lever.

Time Warp said:

Why, because that reduced the speed differential of the previous inner and outer radius of the (wide) friction band.

No different to narrow band brake rotors.

Click to expand...