Clutch

[Emerica1975]

I’ve been dealing with a clutch that is slipping when I get in 3rd gear and really open up the throttle. My engine is a 165 with a Webco head and the ports have been reworked to Puckett specs by Mutt and I have an expansion chamber exhaust and a stuffed plate in the crank case.with all this done to my engine it seems fairly quick and it really winds up. My question is 2 fold. I. In My parts book the clutch blow up lists a plate 38015-49 but my repair manual which is for the years 1959 to 1966 doesn’t show this plate in the exploded view of the clutch basket. I’m wondering why the plate is shown in the parts book but not the repair manual? Also I’ve been told you can make a clutch with 7 springs by indexing and drilling holes into releasing disc 37888-47 and useing that in place of thrust plate 37972-47. With a 7 spring clutch pack I doubt I’d have any slip. I’m wondering if others have done this and how well it works? Thanks!

[250_Sprint]

I read somewhere where adding flat washers of same thickness in the spring cups can improve clutch pressure and reduce slippage.
This may shed some light on the direction you need to go.

[pumpguy]

Way back in the day I had the exact same slipping clutch problem with a 165 engine built similar to yours. To increase spring pressure I put spacer washers under the springs.

Took the bike out for a spin to see if I could make the clutch slip. Well, the clutch didn't slip, but something else happened, THE CASES SPLIT HORIZONTALLY!.

The moral here: ITS THE NEXT WEAKEST LINK THAT WILL FAIL. Something to keep in mind when hopping up an engine designed for a much lower output.

[Emerica1975]

Thanks for the advice. I actually tried the washer in the spring cup already but when I tried to compress the clutch pack down to fit the lock ring that holds everything together I couldn’t get the the thrust plate compressed enough to fit the lock ring in place unless I removed the steel backing plate 38015-49. And when I did get it together I still had slipping in 3rd gear. I finally have bought new lined clutch discs and installed them and put the backing plate in but not washers in the spring cups. If it still slips I think I’ll buy new spring cups and see if then I can run the washers. But I’m also going to try to build a 7 spring thrust plate. I think that would possibly work best if I can figure it out.

[250_Sprint]

Keep in mind, the more spring pressure added to keep the clutch plates engaged translates to more pressure at the hand lever to disengage the clutch plates. That additional force might cause the clutch cable to sink deeper into the aluminum engine side cover. It might tax the strength of the release lever spring. It might pull the clutch cable end off the end of the clutch cable. It might deform the cable receiving end of the clutch worm lever.
Not to be a buzz killer, but all of this needs to be thought about.

-Good Luck

[Brent]

For what it's worth:
Years ago I replaced the clutch in my 1946 Indian. Even new it slipped. I was running the recommended oil in the trans.
After trying a bunch of things I had a thought. My Sportster had a wet clutch that shared with the tranny and ran H-D Sportstrans fluid. I flushed the indian and put that in. The clutch problem was solved. I'd rebuilt the Indian trans at the same time. I looked in on it after 14K miles and everything looked like new so I don't see how it might adversely affect these lightweights gears or clutch.

[MrMarty51]

For what it's worth:
Years ago I replaced the clutch in my 1946 Indian. Even new it slipped. I was running the recommended oil in the trans.
After trying a bunch of things I had a thought. My Sportster had a wet clutch that shared with the tranny and ran H-D Sportstrans fluid. I flushed the indian and put that in. The clutch problem was solved. I'd rebuilt the Indian trans at the same time. I looked in on it after 14K miles and everything looked like new so I don't see how it might adversely affect these lightweights gears or clutch.

Comes to mind the thought that, the new modern lubricants have so far advanced on friction fighting minerals and chemicals that the above message can hold very true in the modern world.
If it is possible to find some of the proper lube in the old fashioned dino oil make up that, the slippage problem might be solved.
Just a thought.

[Emerica1975]

I finally made a spring plate with 7 springs. Now I just gotta try it out. But here’s a picture of it.