G19 gearbox mainshaft spacer

[stumpy lord]

Hello Highbury, Some thing is going wrong here, E76 goes between G6 and the bearing in G2, It is held tight when you do up the clutch nut C20, Spin often happens and E76 wears, and sometimes breaks up, I have found 31 thou one is most used, At the other end you could grind a few Vs on the inner end of G4 ,To let the oil get to the G16 and G17, But Trev will tell you it will leak oil !, Or you could put Trev's Special grease inside G4, It is good !! to have some Lube in there !! Good Luck. If I have got this wrong !! Shout out !, Because Highbury needs help, Cheers Bill.

I have a collection of worn .031" thick E76, they all worn

, some more than others. consequently I would not entertain using such a thin shim in that position, for any thing wearing to the point of failure, and dropping into the gear box is to be avoided, what you possibly need is a hardened shim, but where you could get one from I do not Know. Possibly Trevor could help.

Having said that , my twin is running O.K. with a standard .031" thick E76 as are many, many more Twins.
stumpy lolrd

 

[greg brillus]

First you need to find out if you actually need a shim. It is quite possible that you don't need one. The shims can only ware if the clutch main shaft nut comes loose, or was not tightened correctly to start with. If you attempt to stop oil getting to the bush's in the output shaft, the bush's will fail for sure. I push the bush closest to the output sprocket in a bit further and slide a nice fitting "O" ring in there, stays in place with the spring cup washer held against the kick start ratchet assembly.

 

[highbury731]

First you need to find out if you actually need a shim. It is quite possible that you don't need one. The shims can only ware if the clutch main shaft nut comes loose, or was not tightened correctly to start with. If you attempt to stop oil getting to the bush's in the output shaft, the bush's will fail for sure. I push the bush closest to the output sprocket in a bit further and slide a nice fitting "O" ring in there, stays in place with the spring cup washer held against the kick start ratchet assembly.

Yes, I like the idea of pushing the output shaft outer bush inwards a little for fitment of an O-ring. I suppose it means stripping out all the gearbox bits and using a suitable drift.

It occurs to me that perhaps the E76 is an un-necessary part. The clutch pulls the input shaft left, the sprocket and nut clench the output shaft up, and pull to the right. So is E76 un-necessary? Would it be better to add some spacing at the G19, push the G6 inwards and ensure greater dog engagement?

 

[Bill Thomas]

As Trev said, E76 is to mesh G6 into the double gear, The double gear is held in postion by the selector fork, If it is not far enough in mesh it will burn the fork, Messing with the other end will do no good, Cheers Bill.

 

[clevtrev]

I would argue, that the design leads us to believe that the concept was to keep oil out, otherwise there would be a seal on the end of the output shaft, and there would be no shield on the end of the output shaft where it butts against the G6 gear. This puts the gear sort of inside a cavity. The only time the shaft might get any oil is when the clutch is lifted, or when the engine is stopped. Of course oilite being used for the bushings.

 

[greg brillus]

I feel we have completely missed highbury 731's initial question..... Ok when you asked if 0.021 thou clearance is ok, where are you checking this end float..? The G19 Washer should be 0.120 thou thickness, and yes wider in the center, and thinner at the outer. This is normal..... then the inboard washer G 20 should be 0.056 thou thick. If the G 20 washer is thinner than this, then this will give you more end float on the G 12 third gear. Remember this needs to be checked with the sprocket in place, the seal cup, and the large G 23 retaining nut tightened. The actual output shaft G4 should have no discernible end play at all, although it may wriggle about given it is a single row ball bearing, without the G 3 shaft to help align it via the two bushes. The actual third gear G 12 should move back and fourth about 0.020 or so, which is what I think your original question was about. Oh well, you now know how to set up the G 3 input shaft end float as a consequence of all this. I hope this answers your initial question......Greg.

 

[Bill Thomas]

Hello Greg, I only went on about the other end, Because Highbury talked of E76, Cheers Bill.

 

[greg brillus]

No worries Bill, After I re read the initial question I quickly realized that he was actually asking about the shimming on the output shaft not the input, even though this should also be checked. But the end float I think he is referring to re the G 12 Gear is quite normal. The real tricky one is what is the end float on the G 5 and all the lay gears when the G2 is buttoned up.......

 

[highbury731]

No worries Bill, After I re read the initial question I quickly realized that he was actually asking about the shimming on the output shaft not the input, even though this should also be checked. But the end float I think he is referring to re the G 12 Gear is quite normal. The real tricky one is what is the end float on the G 5 and all the lay gears when the G2 is buttoned up.......

Well, actually what I am concerned about is the input shaft clearance, for min end float and max gear engagement.

I measured end float using a steel bar across the clutch housing (packed out with about 3/16" of spacers) and a feeler gauge. That gave .021" end float, ie .015" too much. On pulling the input shaft, I found that there was no E76 present. I understand that the min thickness for E76 is .031", which might explain its absence - the standard E76 is .010" thicker than the clearance available. There are E76 shims available from VOC Spares measuring .005" and .0010". Is that standard thickness plus 5 or 10 thou? If E76 is wanted for restricting oil entry to the output shaft G4, then a simple shim of 5 or 10 thou will do, and take up the clearance with a thicker shim at G19.

So I think that the best answer is a thicker G19 and an O ring at the sprocket end of G4. But over to the experts - I'm open to correction.

 

[Bill Thomas]

I think we are getting a few mistakes here, Highbury started by saying he had G19 at .012 " thick at the shaft, I think Gregs 0.120 thou sounds better !, Have you had that end of the box apart ?, Any History of the bike running ? I was thinking , If there was a fault at the final drive sprocket end, It might upset the reading at the clutch end, Just my thoughts, Cheers Bill.