Been a long time since the last time I posted ... I guess I had not done anything stupid to my Mk3

Until this weekend maybe.

I attempted my first gearbox oil change. It had not been done since 2012 so I figured it would be smart even though the bike has only gone about 1500 milers since then. The problem I had was with identifying the drain plug based on the description and drawing in the workshop manual. There must have been a change in the case somewhere along the line because I kept looking and feeling for the two plugs (bolts) referred to in the manual as the "drain" plug and the "level" plug. Sure it was a bit dark in my shed, but did not explain how there was a single plug in that area. Of course I expected something a lot bigger to be the drain plug so I wrongly assumed the one plug was the level plug which I did proceed to remove. The lack of fluid exiting that port reinforced my notion.

Naturally I went looking for another plug and discovered a much larger one toward the front and between the engine mounts. I later learned that this was indeed the cam plate index plunger bolt (had to look it up after so little fluid drained out). So the issue with all of this is the damn thing won't screw back in properly! I tried about 20 times with every possible orientation that the threads wanted to go in. The farthest it will go is with the head still 1/8th inch out from the case. Did it really strip? Or is there that much push back from the plunger? I am stuck.

The assembly is numbers 29-31

Did you rotate the camplate when the plunger was out? Inadvertently maybe, with the gear lever? Spring shouldn't have that much tension, you may have to get underneath

I made sure not to touch the shift lever once I learned what it was. I'm skeptical about the resistance coming from the plunger, too. I have a feeling either the threads are damaged ... hopefully on the bolt and not the case.

contours said:

The problem I had was with identifying the drain plug based on the description and drawing in the workshop manual. There must have been a change in the case somewhere along the line because I kept looking and feeling for the two plugs (bolts) referred to in the manual as the "drain" plug and the "level" plug.

Click to expand...

Always in the same place. I assume you did find the actual drain plug...

...and level plug in the outer gearbox cover?

contours said:

The farthest it will go is with the head still 1/8th inch out from the case. Did it really strip? Or is there that much push back from the plunger?

Click to expand...

Is that with the washer and O-ring that aren't drawn or listed in the parts book and are Mk3 only?

L.A.B. said:

Always in the same place. I assume you did find the actual drain plug...

...and level plug in the outer gearbox cover?

Click to expand...

I guess I found the level plug. Based on your photo I missed the drain plug. I'll look for again tomorrow.

L.A.B. said:

Is that with the washer and O-ring that aren't drawn or listed in the parts book and are Mk3 only?

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Yes, the O-ring and washer are present. About 1/8 of an inch of threads are exposed. I don't dare try to tighten it further. A replacement for the bolt is easy to find. I suppose I should get one just to see if it will screw in further than my original.

L.A.B. said:

Andover Norton - WASHER - 06.6622

WASHER

andover-norton.co.uk

Andover Norton - O RING (CAMPLATE SPINDLE) - 04.0129

O RING (CAMPLATE SPINDLE)

andover-norton.co.uk

Click to expand...

contours said:

I guess I found the level plug. Based on your photo I missed the drain plug. I'll look for again tomorrow.

Click to expand...

The hexagon should be smaller than the non-standard one in my picture.

contours said:

Until this weekend maybe.

I attempted my first gearbox oil change. It had not been done since 2012 so I figured it would be smart even though the bike has only gone about 1500 milers since then. The problem I had was with identifying the drain plug based on the description and drawing in the workshop manual. There must have been a change in the case somewhere along the line because I kept looking and feeling for the two plugs (bolts) referred to in the manual as the "drain" plug and the "level" plug. Sure it was a bit dark in my shed, but did not explain how there was a single plug in that area. Of course I expected something a lot bigger to be the drain plug so I wrongly assumed the one plug was the level plug which I did proceed to remove. The lack of fluid exiting that port reinforced my notion.

Naturally I went looking for another plug and discovered a much larger one toward the front and between the engine mounts. I later learned that this was indeed the cam plate index plunger bolt (had to look it up after so little fluid drained out). So the issue with all of this is the damn thing won't screw back in properly! I tried about 20 times with every possible orientation that the threads wanted to go in. The farthest it will go is with the head still 1/8th inch out from the case. Did it really strip? Or is there that much push back from the plunger? I am stuck.

The assembly is numbers 29-31

Click to expand...

Try screwing the plunger housing (#31) in without the spring and plunger. Also, I'm not familiar with the O-ring and washer Les talked about (no MKIII gearbox experience) but make sure they will slide on the plunger housing correctly (getting caught?).

acadian said:

Did you rotate the camplate when the plunger was out? Inadvertently maybe, with the gear lever? Spring shouldn't have that much tension, you may have to get underneath

Click to expand...

contours said:

I made sure not to touch the shift lever once I learned what it was.

Click to expand...

How about before you learned it was the camplate plunger bolt and it had been removed?
If this were my predicament, I would assume my camplate is out of alignment to fully engage the plunger.

Chuck_Wagon said:

How about before you learned it was the camplate plunger bolt and it had been removed?
If this were my predicament, I would assume my camplate is out of alignment to fully engage the plunger.

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Though I'm sure the shift lever did not move the whole time, how would I go about realigning it?

Moved or not, the plunger housing should screw in. Try the test I said earlier - it will tell you important info on the problem and will hurt nothing.

Are there wires being crossed here??
From the diagram and part no's the problem originally looked like the index plunger (post #1, with diagram numbers), but then reference is made to a bolt, o ring and washer as per the spindle bolt (post #5 'Yes, the O-ring and washer are present. About 1/8 of an inch of threads are exposed. I don't dare try to tighten it further. A replacement for the bolt is easy to find. I suppose I should get one just to see if it will screw in further than my original.')?
I know it's early, but which actually is the problem area, or is it both?

EstuaryBoy said:

From the diagram and part no's the problem originally looked like the index plunger (post #1, with diagram numbers), but then reference is made to a bolt, o ring and washer as per the spindle bolt (post #5 'Yes, the O-ring and washer are present.

Click to expand...

That's because the Mk3 detent does have a washer and O-ring as I mentioned and why I asked if they were fitted (the answer being "yes").

The camplate is held in position by the selector forks and rod (not fitted in the pic.) so can only rotate even with the retaining bolt removed, so there shouldn't be anything inside the case that could prevent the detent plunger "bolt" (housing) from being screwed fully home.

contours said:

Until this weekend maybe.

I attempted my first gearbox oil change. It had not been done since 2012 so I figured it would be smart even though the bike has only gone about 1500 milers since then. The problem I had was with identifying the drain plug based on the description and drawing in the workshop manual. There must have been a change in the case somewhere along the line because I kept looking and feeling for the two plugs (bolts) referred to in the manual as the "drain" plug and the "level" plug. Sure it was a bit dark in my shed, but did not explain how there was a single plug in that area. Of course I expected something a lot bigger to be the drain plug so I wrongly assumed the one plug was the level plug which I did proceed to remove. The lack of fluid exiting that port reinforced my notion.

Naturally I went looking for another plug and discovered a much larger one toward the front and between the engine mounts. I later learned that this was indeed the cam plate index plunger bolt (had to look it up after so little fluid drained out). So the issue with all of this is the damn thing won't screw back in properly! I tried about 20 times with every possible orientation that the threads wanted to go in. The farthest it will go is with the head still 1/8th inch out from the case. Did it really strip? Or is there that much push back from the plunger? I am stuck.

The assembly is numbers 29-31

Click to expand...

Are you sure it's the plunger bolt, and not the pivot/spindle bolt? #29?

concours said:

Are you sure it's the plunger bolt, and not the pivot/spindle bolt? #29?
View attachment 95737

Click to expand...

Yes, I'm sure. It looks exactly like the assembly in the drawing I posted. It also seams like the O-ring will be difficult to remove without damaging it. The spring, plunger and bore are clean.

L.A.B. said:

That's because the Mk3 detent does have a washer and O-ring as I mentioned and why I asked if they were fitted (the answer being "yes").

The camplate is held in position by the selector forks and rod (not fitted in the pic.) so can only rotate even with the retaining bolt removed, so there shouldn't be anything inside the case that could prevent the detent plunger "bolt" (housing) from being screwed fully home.

Click to expand...

Apologies.... I reassembled mine using the Mk3 workshop manual which makes specific reference to o-rings and washers on the quadrant and camplate (as does the Clymer manual), but both, like the parts book illustration (as perpetuated by AN), made no mention of either being needed or used on the detent acorn nut......
(Though I now notice the exploded gearbox diagram in the NT manual shows both..... One out of three/four ain't bad!)

EstuaryBoy said:

Apologies.... I reassembled mine using the Mk3 workshop manual which makes specific reference to o-rings and washers on the quadrant and camplate, but like the parts book illustration (as perpetuated by AN), made no mention of either being needed or used on the detent acorn nut......
(Though I now notice the exploded gearbox diagram in the manual shows both..... One out of three ain't bad!)

Click to expand...

It's understandable as the washer and O-ring aren't in the parts book! Not even in the amendments section of my paper copy and a pity AN hasn't (as yet) added them to their drawing as OldBritts had but unfortunately, that page has gone now (and the part numbers were from the OldBritts list, the O-ring apparently the same part number as the camplate/quadrant O-ring). Mick Hemmings does mention the Mk3 index plunger washer and O-ring in his gearbox rebuild video at 43: 26.

Mind you, now I know what I'm looking at, Mr Emery at N*rvil lists o-ring and washer as Mk3 specific parts in his printed catalogue

EstuaryBoy said:

Mind you, now I know what I'm looking at, Mr Emery at N*rvil lists o-ring and washer as Mk3 specific parts in his printed catalogue

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Yes, their O-ring also has a different part number (066624).

Alright, so I got a pre-owned plunger housing bolt in the mail yesterday. The threads were in somewhat better shape than my original. I was able to use the o-ring and washer from my original as well. As I screwed the "new" unit in there wasn't as much side to side leeway this time. Although it still required two attempts and only a little less force to get it past the point my original would go.

The original would only go this far ...



The new one finally went all the way ...



With better lighting I was able to locate the drain plug this time. So the gear box has fresh oil.

The only remaining issue is my neutral indicator light doesn't work. I may have loosening the wiring down there when I was struggling with the bolt.
I'm sure the gear is in neutral because I can roll the bike freely and start up the engine. Haven't engaged 1st gear yet, but I'll try that today.

contours said:

Alright, so I got a pre-owned plunger housing bolt in the mail yesterday. The threads were in somewhat better shape than my original. I was able to use the o-ring and washer from my original as well. As I screwed the "new" unit in there wasn't as much side to side leeway this time. Although it still required two attempts and only a little less force to get it past the point my original would go.

The original would only go this far ...

The new one finally went all the way ...

With better lighting I was able to locate the drain plug this time. So the gear box has fresh oil.

The only remaining issue is my neutral indicator light doesn't work. I may have loosening the wiring down there when I was struggling with the bolt.
I'm sure the gear is in neutral because I can roll the bike freely and start up the engine. Haven't engaged 1st gear yet, but I'll try that today.

Click to expand...

Bad news - you cracked the gearbox housing putting it in. See this picture verses the last one. I can't say how big a problem it is, but you'll certainly need to keep an eye on it.