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DJinCA
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#846199 04/15/21 6:12 pm
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I posted a picture of this clutch on the Triumph board but when fitting it I found that I actually made it for the A65. The Triumph version needs the damper retaining plate moved outboard to clear the sprocket door.
[Linked Image from live.staticflickr.com]
[Linked Image from live.staticflickr.com]

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Hi

Looks good David, does the outer cover have clearance when the clutch is disengaged!

John

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A basic requirement, I think. Yes, it clears the cover.

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Hi David

Ha ha, well scored. After another look at your photo it would be the actual body plate tang's which would be closest, looks the business. How does the centre x-over to the shaft!
By the way the Suzuki clutch I converted a few years back had minimal clearance with the outer cover, but any clearance is enough.

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Uses stock fat washer and shouldered nut.
[Linked Image from live.staticflickr.com]

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I posted on this on the triumph board.
Think i may have a snag with the outrigger.
Is there any form of cush drive?

Last edited by NickL; 04/19/21 2:00 am.
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This uses stock Yamaha type cushions between the chainwheel and basket. The B50 design uses stock KTM cushions between the drum and hub as done in the 450 and 525..
The outrigger problem could be solved by making the hub longer and have the outrigger bearing run on the hub rather than the mainshaft. If more space is needed between the back of the clutch and high gear, a little can be gained but not much.

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Is the sprocket basket alloy or steel? I've used an alloy sprocket and shards of anodizing speckled the oil, which was shared with the motor.

I have extra plates and narrow linings in the Firebird clutch now with heavy race springs, but it's still boarder line. You can fit a rear wheel with a cush if necessary. I have both on the 883 and Ben and my brother.


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This one is bare aluminum but the final ones will be hard anodized. Steel would be more expensive. The B50 clutch does not have the double ball bearing on the chainwheel, just a bushing, because there is no room. The KTM has a needle bearing but the hub is shorter and does not have the long taper in the mainshaft. If a new door were made with a bearing then a thrust washer could be used to keep the chainwheel in place instead of spiral rings which take up room on the hub..

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I'll have the engine on my bench in a week or so, i'll do some measuring.
Looks like a nice job David, i prefer chain over belt drives.

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I was able to squeeze a little more room between the hub and door. I measured 2.450" between the end of the mainshaft and the high gear (not the bushing). If the bushing were cut back to the end of the high gear a SCE138 (13/16" x 1-1/16" x 1/2") needle bearing can be built into the door.

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I use a 6204 bearing with the centre machined out to fit the mainshaft.

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Not within the capability of most users. I presume you have a special collet to hold the inner race to grind it?
No room for a 14mm wide bearing, perhaps it would be better to supply a new door with the needle bearing? Probably needs a felt ring to keep dirt away from the bearing.

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The shaft isn't hard enough to run a needle directly, plus the 6204 is the sealed type.
The bush is cut off on the top gear, the bearing can sit back a bit.

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The 5Spd high gear runs needle bearings on the mainshaft, I do not think the 4Spd shaft is any softer but have not checked. Torrington makes inner races with 13/16" I.D., 1.0" O.D. but only 0.765" and 1.015" long. They can be shortened, two can be made from the 1.015" for the 0.438" wide B-167.

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I presume the bearing is a slip fit on the shaft and sealer is put on the I.D.?

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Normally use a drop of 638 on the shaft/bearing inner.
Tried a needle race years ago and it wore the shaft, once again
this is on a sidecar outfit,,,,,,,bloody brutal. Plus the ball race
does allow a little deflection and is sealed. (Well,,, sort of anyway)
Engine breaths into primary.
Could try a 60042rs 12mm as opposed to 14.

https://imgur.com/cSUhbJq
https://imgur.com/a8DiS9r
https://imgur.com/WkKULq9

Last edited by NickL; 04/22/21 10:57 am.
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Are you selling the clutch kit Dave?

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Not this one. I am working on a slightly different design using the KTM Belleville spring and pressure plate.
NickL, they do make thin section ball bearings but in that size they are only 4mm wide. Probably too light even if ganged together. The needle with inner race would have more load capacity than the 6204. Is the breather outlet off the primary also or is the primary breathed into like the later engines? I do not think there would be much leakage past the needles and a felt cover would catch it.

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Originally Posted by DMadigan
Not this one. I am working on a slightly different design using the KTM Belleville spring and pressure plate.
NickL, they do make thin section ball bearings but in that size they are only 4mm wide. Probably too light even if ganged together. The needle with inner race would have more load capacity than the 6204. Is the breather outlet off the primary also or is the primary breathed into like the later engines? I do not think there would be much leakage past the needles and a felt cover would catch it.

6004? https://www.skf.com/au/products/rol...deep-groove-ball-bearings/productid-6004

Available as 2RS version too.

The engine breathes into primary and it does pi$$ out if you don't use a sealed bearing.
The engine is vented to atmosphere but via around a 10mm breather so you still get
a pressure wave in the primary, enough to blow past a bearing.

Last edited by NickL; 04/23/21 12:04 am.
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I am surprised that a 2RS keeps the oil from blowing by. The seals are made for grease, not oil. I made new inner primary cases for the triple with a ball bearing replacing the needle bearing to hold the chainwheel/clutch. The prototype just had a 2RS ball bearing but it would not completely keep the oil from weeping through so I had to add an oil seal running on the spacer between the chainwheel and clutch.
A seal can be put in the door to run against the face of the high gear nut. That might be better than going to a lower capacity bearing.
Another choice is to completely change the clutch design to the one I drew for the B50. The dampers are in the hub, same as the KTM 450, instead of the chainwheel. The clutch drive plates are mounted in the chainwheel and the drive plates mount on a drum. The Belleville spring pulls the drum and pressure plate together for drive. The dampers go between the drum and hub.
Not having the dampers between the chainwheel and basket narrows the clutch by almost 1/2". The double row ball bearing for the chainwheel can be retained.
Just thought of another change, make the high gear longer with a cylindrical end beyond the sprocket nut threads that extends through the door. Then with the ball bearing running on the high gear there is no leak path to the outside. A seal can be put in the high gear, like the five speed version, to seal between the gearbox and primary.

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I can live with a small weep of oil which you get with the 2RS.
It's far more important to have the bearing there.
I normally put an o-ring on the mainshaft between the top gear and the bearing
not ideal but it works, lasts a season anyway. It's just nipped between the two
faces.
The ball race lasted me for a season when i raced, that was with a 900 motor
so i think it'll be ok. They are cheap and easily available just have to set up
and machine a few at a time, ceramic tool and a jig plate.
Getting involved with changing gears etc makes the job of fitting the clutch
way more complicated, the case isn't under any large pressure so oil leak is
very small. If it's just a bolt on unit you'll sell more, if the gearbox has to come
out etc it'll put people off plus it'll cost more.

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I was thinking the extended high gear and door with bearing would be part of the 5 speed gearbox. The clutch would be the same bolt-on replacement in either case. The high gear has a seal in the end so the gear oil and primary oil stay separated.
Going over the original design with the cushions in the chainwheel and the KTM version with the cushions in the hub the latter makes the clutch thinner. The limitation is the distance to the mainshaft under the pressure plate. A little more room can be had if the one race of the ball thrust lifter bearing were part of the lifter rather than a separate part. The lifter would have to be hardened but that should not be a problem. Even without that the clutch is narrower.

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The oil transfer into the primary or g'box is tiny so i don't see that as a problem but
as you say a seal would be nice.
If you are doing the whole 5 speed setup then using an extended top gear is definitely
the way to go, you can make the sleeve compatible with a larger bearing id.
A splined mainshaft is even better as most blokes have trouble with the taper, certainly
on larger motors.
That clutch would be so much better anyway so even as a fitment for a standard bike
without the outrigger it would be a very saleable product. Just producing ones and two's
for racers is not going to earn you much, better to leave those adaptations to the users.
We have a couple of decent 4 spring units just now but i would be interested to know
the sort of money you are talking about for one, they don't last that long and that unit
does look like a very nice job. But then i wouldn't expect anything less from you.

Can you reduce the tooth count on the basket? I'd like to run the box as fast as i can.
say 48-50t?

Last edited by NickL; 04/25/21 1:49 am.
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A B-218 needle (1-5/16" x 1-5/8" x 1/2") will run on the high gear already hardened for the roller RJ009 bearing. The B218 inner race is just smaller than the sprocket spline.
What do they use for a stop for the clutch hub when using a splined mainshaft? Just the run-out of the cutter? Or do they have a step in the shaft?
Yes, the basket teeth can be reduced, a fair amount of room between the plates and chain. I have to figure out what length chain will work.
Of course the big question is what colour it should be.

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