Poor mans clutch fix....for diaphram pressure spring

[Ratman]

I've had the Honda 1100cc Sabre that I ride now since 1993. I've been thru a couple engines and always had a slipping clutch. Prolly doesn't start slipping till I got 80 hp coming out of the engine...so its rideable. the usual fixes for the slipping clutch are new fiber disks and steel plates and a new clutch spring...they use a diaphram type spring. That's a couple hundred bucks so I don't like that. :)

Bikes that use the multiple coil springs for clutch tension can crank the nuts down tighter or buy stronger springs, but getting a stronger Diaphram spring is another story.

So I've been thinking about my slipping clutch for a few years. It really only slips when I want to get around someone in a short time...like drop it down into 4th or even 3rd and cob it on. Well slipping can't be good for it so I should fix it.

So I wondered about installing an additional clutch spring in my Sabre. The theory is that when I measured clutch fibre plates on my bike with a slipping clutch, the clutch plates are never warn thinner than stock. So that means that the diaphram spring has weakened, and that the fibre has hardened and has a decreased coefficient of friction.

Seems to me that an increase in clutch pressure would solve the problem since the slippage is only under hard throttle. To that end I investigated the possibility of installing 2 clutch springs in my bike.

I'm preparing my nV65 Sabre so I can beef up the clutch sprig. This snap ring groove to be wider for an added diaphram clutch springs. This grove needs to be wider by the width of the extra spring thickness.

From Honda V4 trans

I was able to hold the pressure plate, by hand, into the 2X4 and the c-clamped piece and rotate the al piece into the cutter

That's a .015 thick Harbor Freight saw blade and mandrel. It takes about 4 cuts to widen that grove by about 60 thousandths. What you going to do if you don't have a lathe?

From Honda V4 trans

V65 Sabre's and Magnas have a weak clutch. They have Diaphram type springs so beefing up the spring isn't easy. So I figured I'd try doubling those springs..... I put those slits in the second spring to weaken it.

From Honda V4 trans

This abrasive saw made quick work of partially slotting the diaphram spring.

From Honda V4 trans

Using the drill press as a hand press, I was able to feel how much I had weakened the slotted spring VS an unaltered spring. It was considerable.

From Honda V4 trans

Someone pointed out that the clutch with 2 springs would most likely have too strong of a clutch lever pull. I agreed, and put some extra slots in the second spring per album picture, to make the spring weaker.

Also I glued the 2 springs together with Silicone sealer to keep the 2 springs lined up.....that seems to be working.

When I installed the spring yesterday I found that I needed an additional special washer that I had to make to allow for the additional spring, but the install was fairly straight forward. I lucked out when the clutch side cover came off without breaking up the gasket (Luck beats good principal at work).

So far the clutch no longer slips. The clutch pull is stronger, but livable.

I don't know if any of you guys have diaphram clutch springs or not. I did find out that Hondas 1500 Gold Wings also have diaphram springs so maybe some other bikes have them also.

Here's hoping this info helps someone.

Since doing this work the clutch has been working fine, no slippy, for 1500 miles and I've gotten used to the extra clutch pull.

[chammyman]

I have considered this method.

I have a CBX750 FE (uses a 90bhp nighthawk engine) that has the same clutch set up. I also have vf750s with the same style of clutch and they never slip.

The cbx slips when going for it, even if you change gear wait for it to stabilise then gun it the revs will bounce up once 8 or k rpm is reached.

Like you found the clutch plates and fibres are all within new specs. I even bought a new spring from Honda which according to the service manual was below the new spec. But the spring is stiffer. It slips a bit less with it.

I looked at making a lockup for it which I still want to do.

I kept the old washer as I want to try something like you have done but wasn't sure of the best way to do the groove wider so the other spring would fit. I wouldn't have thought about weakening the spring either so good call on that.

My spring is different as yours has ears (before you weakened it) where the collar touches the inner circle, on mine its solid, I wonder which one is stronger to start with

[Ratman]

Originally Posted by chammyman

I have considered this method.

The cbx slips when going for it, even if you change gear wait for it to stabilise then gun it the revs will bounce up once 8 or k rpm is reached.

Like you found the clutch plates and fibres are all within new specs. I even bought a new spring from Honda which according to the service manual was below the new spec. But the spring is stiffer. It slips a bit less with it.
I kept the old washer as I want to try something like you have done but wasn't sure of the best way to do the groove wider so the other spring would fit. I wouldn't have thought about weakening the spring either so good call on that.

My spring is different as yours has ears (before you weakened it) where the collar touches the inner circle, on mine its solid, I wonder which one is stronger to start with

I wish mine had been a solid spring washer. I wanted my ears to stay lined up so the heavier spring force would be actuated by both ears at the same time.

I'm pretty happy with my conversion, I have a couple thousand miles with it now. I didn't elaborate on the extra spacing washer that goes on the inch shaft before the collar that the clutch nut tightens. About a 1.2" ID X .060 thick X 1.625 OD washer. I used a fender washer from Ace Hdw.

[concours]

Hace a look at this.. I know, I know, it's for an old Limeybike, but the diaphragm spring logicdiscussed may help you solve your ongoing issue. The clutch plates you are using are OEM? I know the Barnetts I bought are .008" thinner than OEM, and that's .040" less in the stack. http://atlanticgreen.com/ndnsclutch.htm

[Ratman]

Originally Posted by concours

Hace a look at this.. I know, I know, it's for an old Limeybike, but the diaphragm spring logicdiscussed may help you solve your ongoing issue. The clutch plates you are using are OEM? I know the Barnetts I bought are .008" thinner than OEM, and that's .040" less in the stack. http://atlanticgreen.com/ndnsclutch.htm

That's interesting, Concours. Kevlar (hot rod) disks for my bike are .004 or .005 thinner than stock. So that chart is saying that if our stock disk were a little thinner the spring pressure would be more. Hummmm.....may take some time to get my head around that. Thanks.

[concours]

Originally Posted by Ratman

That's interesting, Concours. Kevlar (hot rod) disks for my bike are .004 or .005 thinner than stock. So that chart is saying that if our stock disk were a little thinner the spring pressure would be more. Hummmm.....may take some time to get my head around that. Thanks.

Yeah, DynoDave, the author and scientist behind that stuff is in way deep. He dynoed and charted ignition systems for the old bikes... on his vintage Sun distributor dyno. And the oil pumps... even more testing! http://atlanticgreen.com/norton.htm

Here is the clutch stack data for the Notrun, for comparison http://atlanticgreen.com/clutchpak.htm
I spent the time getting it right for my bike,(custom ground a pressure plate to height) and the clutch is great, light pull, won't slip in high gear under full torque. I hope you can sort that one out as well!
The Norton clutch diaphragm spring may be slightly different in pressures than yours, the point being: stack height matters, and if that clutch worked properly AT ONE TIME (when it was new) then, how do we get back there? As opposed to a coil spring clamped clutch which really doesn't care if the stack is short, or tall, will work pretty much the same.

[troidus]

Originally Posted by Ratman

Also I glued the 2 springs together with Silicone sealer to keep the 2 springs lined up.....that seems to be working.

Could you have dimpled the mating faces enough to accept small spherical bearings to index the two parts?

[Ratman]

Originally Posted by troidus

Could you have dimpled the mating faces enough to accept small spherical bearings to index the two parts?

2 heads are always better than one. That's a damned good idea, Troidus. I'll consider that for next time, or if the silicone should fail.

[Ratman]

I'm working on a second edition of my 2 diaphram spring clutches. I've been doing this one in my patio so I've changed the procedure a tad. I'll give a couple pictures to add to the possible methods to accomplish this.
There's 2 screws that locate the pressure plate on the upper portion of the vertical board.

From Honda V4 trans

Let me add that I weakened the spring a little more than my first spring. I ran the slots to withing a 1/4 inch of the OD of the Diaphram Spring. Previously the hand lever pressure was a little high.

From Honda V4 trans

[mokokawi]

Hi.....I'm getting ready to install some new barnett friction plates for my friends '86 v65 magna ,he already bought the barnett's, I like your sprung mod .....but all I have is a dremel ....no lathe or drill press.....but I'm confident in doing mods ....as I've done some before.what do you think is best I can do.....I read about the thickness difference....and suppose the stocks are better....but he already has the barnett's.

Also....I've read about modding a socket to get the clutch nut off .....what side socket should I buy....some say 1 1/4 inch....some say something else.

[anotherguy]

What's the diameters (in/out) and free height? From here it appears a Harley spring may work. I've seen stock Harley clutches stand up to well over 100 ft-lbs. I've got more than a few of those floating around. You happen to own a bike even Barnett doesn't make a spring for.