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Clutch actuating ramps
#817078 07/22/20 8:08 pm
Joined: Dec 2014
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I have been fighting a dragging clutch on one of my Tridents. I have optimized the lifting of the clutch disc by choosing and rotating a spring and testing with paper to get even lifting. The drag is still there. So I am on to looking at the ramp mechanism. I have read all of the posts that I could find on the subject. I have a fair size pile of trash, so I dug out the ramps that I had and took some measurements.

I took a measurement of the thickness of the five inner thrust plates (57-2465). This is the one which mounts on the outer primary cover. All were within a couple of thousandths at .217”-.220”. I then took a measurement of the plate and a ball with the ball in the deepest part of the ramp.
Two of the ramps measured .366” and .367” and the other three .376”, .376”, and .377”. So about a .010” difference in ramp depth.

The 2 plates with the deeper ramps have a longer ramp length. I don’t have an accurate way to measure this, but using my calipers it appears the length of the ramp is about .050” longer.

I attempted to measure the same depth dimension on the lever (57-2547), but this proved more difficult due to the bearing or lack thereof. But of the 4 units I have, 3 have the shorter ramp and only 1 has the longer ramp. The one with the longer ramp is the third one from the left. It has no casting mark. The other one with no casting mark, on the far right, has the shorter ramp. My guesstimate with the calipers shows about a .050” difference here as well.

So I am wondering, do the shorter ramps have a difference in rate of change of depth, or are they just shallower? And if they are just shallower, it seems to me that the plates will just be farther apart when assembled. Am I missing something here? I puzzled over it for a while, but my head started to hurt so I quit.

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Re: Clutch actuating ramps
Dick Page #817093 07/22/20 10:31 pm
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I posted something a while ago about the different lift plates. Like yours, there is the blank on the back of the spring tab, the P the P. and the .P.
Best way to check lift is putting a dial gauge on the adjusting nut and try each lift plate.
On the bench, what you can do is take one base plate and scribe two lines on the edge about the cable throw apart. Take each lift plate and assemble on the base plate with the balls and put a scribe line on each at the rest position. Rotate each lift plate to the second scribe line and measure the total thickness of the base plate/lift plate and balls. Repeat with one lift plate and the various base plates.
The groove diameter in the plates is larger than 1/4". Any sideways motion of the lift plate (the cable only pulls on one side) will loose lift. A 5/16" ball is slightly larger than the groove diameter. The ball will roll along the edge of the groove which might deform the edge or groove the ball but the lift plate will stay center better. A 7mm is probably the closest you can get.
The stack height of the plates and balls only affects the adjustment nut location on the pullrod.

Re: Clutch actuating ramps
Dick Page #817097 07/22/20 10:54 pm
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I am surprised no one has worked out what lift is needed to disengage a non blue printed clutch, and made a lift plate to suit. Perhaps I am missing some obstacle to this. If there is an obstacle I'm all ears(eyes).

Re: Clutch actuating ramps
Dick Page #817112 07/23/20 3:12 am
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Whichever one you use make sure that there's no slop between the barrel where the cable goes and the arm. I replaced mine because of this. That arm had no mark on it, unfortunately I did this before Dave's post and didn't notice if the new one had a P on it.
I checked runout and did the paper slips test when I replaced the plate. I still had a little clutch drag, so I threw down for the Triples Unlimited bearing kit for the arm. Nothing dramatic, but just enough increased lift to stop dragging. I can actually find neutral at stop lights. laugh


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Re: Clutch actuating ramps
Dick Page #817142 07/23/20 11:42 am
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I read your recent posts Dave. I have used a dial gauge before to check lift and I believe the max I was able to produce was .029". But it has been awhile and I am not positive of that figure. I changed the primary cover and I think that is when the problem began. At the time, I didn't know there were differences in the lift plates, so I may have put anything in there. So off it comes and time to do some experimenting and measuring of lift.

Re: Clutch actuating ramps
Dick Page #817203 07/23/20 7:41 pm
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Both the lift and base plates would be needed to change the ramps. Both parts would have to be heat treated.The lift plate needs the arms riveted on and the barrel for the cable.
Much easier to make a hydraulic clutch lifter. No sideways pull on the lift plate, the adjuster nut sits on an angular ball thrust bearing and the hydraulics automatically adjusts for clutch wear.
[Linked Image from live.staticflickr.com]
You can also make the master with a variable throw like some modern masters to adjust the lift.

Re: Clutch actuating ramps
Dick Page #818984 Yesterday at 08:29 PM
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If the ball pockets were deeper and larger like for a 5/16" ball wouldn't that increase the throw?
Another option is to fabricate a double lead thread setup as used on the XS650 Yamaha...set up for pull rather than push.
Acme threaded rod and nut with double lead and are readily available in both LH and RH (RH needed for pull)
I have figured a way to use a modified Yamaha mechanism but it is not what I call a "clean" installation at this point. It allows for an EASY 3/8" throw.
Hydraulics are a great option, but are more $ and require the extra handlebar mounted cylinder. Let me know if I am re-inventing the mechanism here. Surely this has already been done.

Last edited by ApparatusMC; Yesterday at 08:37 PM.
Re: Clutch actuating ramps
Dick Page #819085 9 hours ago
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The pocket depth or size of the balls does not change the throw, only the angle of the ramps. Using slightly larger balls that fit the existing ramps and prevent the lift plate from moving sideways with the cable pull will increase the lift.
A thread with a nut will cause more lever force from the sliding friction between the nut and screw. An XS does not have nearly the spring force of the triple.
3/8" is far more throw than needed. Most of the lift is used to bend the clutch cover. Only 0.005" of lift are needed to clear the plate.
The rate of the Belleville spring is about 15lb/0.001". The lever force can be reduced by less preload on the spring but the clutch will start slipping earlier.


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