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Antique Motorcycles

1968 Enfield Clutch Problems


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  #1  
Old 06-06-2017, 05:21:31 PM
TomBall TomBall is offline
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Default 1968 Enfield Clutch Problems

I have been working on a friends 1968 750 Interceptor. Had to remove the transmission to repair damage from a spun bushing. Replaced the bearings and seals and reinstalled. The clutch hasn't worked right since my friend has owned it. I replaced the discs and ordered new spacers as there were questions as to the originality of them. When together, the springs are almost coil bound and the clutch works hard with some drag. It is impossible to get it to release fully. Many so called mechanics have tinkered with this machine over it's life. Does anyone have one of these that has had clutch work done that is familiar with the clutch springs? I am pulling the clutch apart again to see if I can get different springs so it might release properly.
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Old 06-06-2017, 05:35:37 PM
Pat Barrett Pat Barrett is offline
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Default Re: 1968 Enfield clutch problems

Tom, I have no experience with those but, I'd suggest a hard look at the assembly, possibly two of something that look identical may be slightly different and assembled wrong. Also it's possible someone used parts from another machine that appeared the same but are not. I'd look and see why it's almost coil bound. Something sounds amiss with the parts thicknesses.
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Old 06-07-2017, 07:28:20 AM
TomBall TomBall is offline
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Default Re: 1968 Enfield clutch problems

Pat, The discs and spacers were bought from a longtime specialty supplier of parts for these machines. My next step is to order a set of springs and see if they are different. It gets aggravating putting things together and pulling them back apart. These bikes are kind of a pain to work on, although they are a cool bike to look at.
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Old 06-07-2017, 07:36:32 AM
TomBall TomBall is offline
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Default Re: 1968 Enfield clutch problems

This is the bike.
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  #5  
Old 06-07-2017, 09:54:27 AM
beezerbill beezerbill is offline
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Default Re: 1968 Enfield clutch problems

A couple of suggestions. But its been decades since I was in an interceptor clutch.

First off - get a parts book for the machine. Usually there will be a blow-up picture of the assembly - be sure that everything is assembled as in the blow-up picture and there aren't any missing parts, extra parts, or parts in the wrong place. Also, the parts book will say how many friction and steel plates there should be - make sure some extra ones weren't slipped in. Sometimes the innermost and outermost clutch plates are slightly different than the middle ones in that they have their teeth bent in or out a little bit or are dished somewhat. I think the Enfield clutch is this way. Check if that is the case with your clutch, and that the plates are in the right order. There may also be some spacer shims that go along with your spring spacers. I forget whether adding or removing spacers makes the clutch tighter - if you don't have any of the shims and the clutch is too tight, try adding some shims (sometimes washers work - make sure they are all the same thickness and the outer diameter doesn't interfere with the inside of the spring) and see if the clutch is less tight and the springs aren't near coil-bound. Also, check for any warped plates. They should be flat to within a few thousandths of an inch - no noticeable rocking when placed on something flat like a table saw surface.

Aftermarket parts for these things are all over the map as far as how well they resemble the original parts. This includes the clutch springs. Yes, trying different springs from a different supplier would be a good idea. If you are lucky, an original service manual will give a spring rate and overall dimensions for the clutch springs.

Be sure the outer drum and inner hub don't have any grooves worn in their teeth from the clutch plates. These grooves can cause the clutch to drag. They can be filed away, at the cost of making the teeth narrower and the clutch more rattley. With the clutch assembled dry, you should be able to easily pull in the lever. Pull in the lever and kick the bike over - the tranny main shaft with the hub and its plates should spin over completely freely inside the stationary drum and its plates. You should hear the plates rattle around a bit as you do this. And the plates should all spin true without any wobble. If this isn't the case there is still something wrong. Be sure the bearing inside the clutch drum is in good shape and not causing drag. And make sure the primary chain isn't adjusted too tight - this can also cause drag.

Check that the clutch cable is in good shape and isn't binding. Lube it up good. A binding clutch cable can cause the clutch to not release all the way, and can cause a feel of too much hand pressure required on the lever.

Finally, run light oil or, even better, ATF in the chaincase. Heavier oil can cause the clutch to drag, and some engine oils with friction modifiers can cause the clutch to slip badly. Google "wet clutch oil" for more information on this.

Clutches on Brit motorcycles are usually temperamental and require a lot of finessing to get them right - good luck and let us know how you make out with it. I will stretch my mind more on the Endfield clutch and see if I come up with anything else.

Last edited by beezerbill; 06-07-2017 at 10:42:09 AM. Reason: clear up some wording
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Old 06-07-2017, 12:15:42 PM
Andrew Mackey Andrew Mackey is offline
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Default Re: 1968 Enfield clutch problems

As Beezerbill noted - if the springs are nearly compressed to the point of contact, then there is a clearance problem. Too many discs, installation problem (directional plates?), warped plates, wrong parts, and possibly bearing interferance. From thee sound of it, you definately need to get back inside to see what is going on. With a lot of people in the machine already, you cannot tell what has been done in the past. Unfortunately, the best bet is to get a good parts and service manual and start from scratch!

Clutch plates should never be stored on edge - they can warp. They should also be completely dry - stored in a dry environment. Moisture will cause swelling of the friction material. When you dis-assemble, look for even contact on the faces. uneven contact may be due to wear of the basket assembly, bent or warped plates, worn or warped friction surfaces or even a bad bearing - even if it is new. The prescense of bluing can be caused over heat or lack of oil if a wet clutch. If the friction plates are blued, then they are probably warped. Only way to tell is to lay them on a sheet of glass, and see if they are completely flat.

Let us know what you find.
Andrew
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Old 06-07-2017, 05:35:35 PM
TomBall TomBall is offline
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Default Re: 1968 Enfield clutch problems

I have a parts and shop manual on the bike. The plates are right in number and assembly . I put in a new clutch cable. There are no spacer shims listed in the parts book, just fixed distance spacers. I took it apart today and pulled out the spacers that the book called for. I installed the spacers that were custom machined and also about 200 thousands longer that were in it when sent to me. I also noticed that the three weak springs ( this clutch has three weak and three stronger ones) were in the wrong location on the outer plate. Once corrected, and with the longer spacers, the clutch works much better with hardly any drag. I will drain the heavy oil out of the case and try atf and see what affect that has on the minor drag. I don't know why the factory spacers are causing problems, and may never know for sure. If the clutch responds to the oil switch then I will leave it as is. Like I said, there is very minimal drag, so I must be getting close.
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Old 06-07-2017, 06:31:18 PM
Pat Barrett Pat Barrett is offline
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Default Re: 1968 Enfield clutch problems

Thanks, Most of us, here, who repond to a query are always glad to hear of a problem solved and how. Thanks for following back up with us. Let us know how the oil change does.
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Old 06-07-2017, 08:49:25 PM
beezerbill beezerbill is offline
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Default Re: 1968 Enfield clutch problems

Nicholson's "Modern Motorcycle Mechanics" has scant information on Royal Enfields but they do mention something about shims under the clutch spring spacers. Next trick will to see if the clutch slips with the lower spring tension.

As far as the chaincase oil change - if the plates have a layer of thicker oil on them now it might take a bit for the oil to work itself off and the ATF work in. I run Mercon ATF (same thing as in my 89 Ford F150 tranny) in my BSA chaincase aid it works fine.

Good luck!
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Old 06-09-2017, 07:33:27 AM
TomBall TomBall is offline
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Default Re: 1968 Enfield clutch problems

Changed oil in the case yesterday. It helped a little with the drag, but there is still a very light drag that you can barely feel. It rode it around and it shifts well with no slippage. I don't find any mention of shims in the parts or shop manual. This clutch setup has three adjusting screws to change the tension on the three weaker springs individually in the case of the clutch not releasing evenly around the disc circumference. I tried to pay close attention to this upon assembly, but it is very tough to verify. Maybe that is the very slight drag I'm feeling. I tightened the clutch cable beyond normal to experiment with the clutch movement releasing the plates more and it didn't seem to help. Don't worry, I put it back to normal. It is very close and I'm waiting to hear from the owner to see if he wants me to go further. It's just another one of those projects that leaves you wondering. I have another friend that has one of the new version Enfields and I'm going to check out his clutch feel. I suspect they may have changed the setup by now.
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Old 06-18-2017, 10:54:39 AM
TomBall TomBall is offline
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Default Re: 1968 Enfield clutch problems

The owner was happy with the way it felt and took it home. The interesting thing I found out during my troubles is that the clutch basket floats on a boss and is not made to lock in position. The drive chain from the crankshaft goes around the sprocket on the basket so any sideways forces exerted by the drive chain could cause the basket to float when the clutch is disengaged causing inconsistent gap between the plates. This is just a theory of mine so don't take it as gospel truth.
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Old 06-18-2017, 02:19:45 PM
beezerbill beezerbill is offline
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Default Re: 1968 Enfield clutch problems

Glad the owner is happy with it. Hope he keeps up on the maintenance.

As for the clutch float - sounds about right.
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Old 06-18-2017, 09:57:09 PM
Thaumaturge Thaumaturge is offline
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Default Re: 1968 Enfield clutch problems

Glad you worked out the problems. I was going to suggest that you reffer to the originally specified oil.

Back about 79 a friend had a Kawasaki 1000LTD that I subsequently bought from him. It ran a wet clutch. Thinking to treat his bike right my friend tried using Valvoline racing oil in the crankcase. After the oil change the bike would not move! The clutch just sat and slipped.

To fix the problem we had to totally dissasemble the clutch and rinse each plate with gasoline. Put regular (Castrol 20W50) oil in bike and everything was fine again. Just something for others to keep in mind.
Doc
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Old 05-31-2018, 01:29:13 AM
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Default Re: 1968 Enfield clutch problems

I had a 1970 Triumph Bonneville and the clutch was slipping when I bought it as well as having the drag that you described. I found that the steel spacer plates were not flat from new. They are made from stamped steel. I took a few hours and with a machined steel flat plate and a small ball peen hammer. I was able to make them dead flat with no hammer damage to the plates. I checked the friction plates and they were all flat.
When all the plates were installed in the basket and the springs and cover on, I balance the spring tension by holding the clutch lever in and use the kick starter to turn the clutch pack. I watch the cover as it is turning and adjust the three springs until the cover spins straight. The clutch works smooth, easy gear engagement from neutral and NO slipping with a light clutch lever.
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Old 05-31-2018, 04:42:03 AM
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Default Re: 1968 Enfield clutch problems

Ooops... see I already posted it.
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