[How-To] Modified Colchester lathe headstock "clutch housing" - fixing headstock oil leak on Colchester Chipmaster/Harrison 10-AA

[paul s]

Neither of the two nylock nuts on the ends of my 1183 rod will unthread - they both spin, but I can't remove them. How is it possible that both nuts are stripped?

 

[FliesLikeABrick]

Neither of the two nylock nuts on the ends of my 1183 rod will unthread - they both spin, but I can't remove them. How is it possible that both nuts are stripped?

That indeed does seem unlikely. Sorry to ask the obvious question, are you sure the rod itself isn't spinning? I don't believe there is anything that keeps it from spinning unless you hold the far end. It does have a taper in the backside that should in theory lock in the "1275 Operating Collar", but once the nut backs off a little bit it is possible that taper would break loose and allow the rod to spin

 

[paul s]

I checked again - the rod is not spinning. It is one continuous rod, all the way through, yes? Both nylocks at the extreme ends are spinning; maybe I should buy a Powerball ticket?

 

[FliesLikeABrick]

I checked again - the rod is not spinning. It is one continuous rod, all the way through, yes? Both nylocks at the extreme ends are spinning; maybe I should buy a Powerball ticket?

yeah one ~5/16" rod all the way through, it is the part that links the clutch movement to the brake bobbin depending on which way the operator lever is moved. I don't have any good suggestions for you except to split the nut off. It's a normal 5/16" nylock nut, not something bespoke that you would have a hard time finding a replacement for. If you do decide to split one of the nuts, do the one on the back/clutch side -- you'll have way better access than trying to do it inside the brake housing, and I believe the rod can be pulled out from the brake bobbin side with it still attached to the bobbin -- so that you can figure out what to do about the rod and second nut somewhere other than hunched over your lathe cursing at your oily hands.

 

[paul s]

... so that you can figure out what to do about the rod and second nut somewhere other than hunched over your lathe cursing at your oily hands.

Make that, bleeding oil hands - I just sliced my knuckle open on #1232 while trying to remove the nut again. By the way - should the brake cone be soaked in oil, or dry?

 

[FliesLikeABrick]

Make that, bleeding oil hands - I just sliced my knuckle open on #1232 while trying to remove the nut again. By the way - should the brake cone be soaked in oil, or dry?

That part of the housing is filled with oil, prepare to RTV that cover back on when you put it back together

 

[paul s]

I also noticed that on the back end, an oring is visible just behind 1232, seems to be floating on the shaft and not engaged in any sort of housing.

 

[Beckerkumm]

Great write up. Your clutch is a later Matrix design- by later I mean 1960s era. The rollers with the needle bearings may be part of that revision as I've seen plain rollers on a shaft on an earlier design on my Smart Brown. Is your machine Whitworth or post that period ? Dave

 

[FliesLikeABrick]

I also noticed that on the back end, an oring is visible just behind 1232, seems to be floating on the shaft and not engaged in any sort of housing.

Yeah there is one on each end to prevent oil from leaking through the input shaft, along that rod. If the o-ring got hard and shrank, it isn't surprising that it would have come out of the groove. There is a groove on the inside of the input shaft (one on the clutch end, one on the brake end) which would otherwise retain it when you get back to putting it together later. It's a standard nominal 3/8 o-ring per @ARKnack, I think my original post in this thread has a picture of where those o-rings normally sit.

The manual says this is .364 ID - for a sealing fit on the .375 rod - and .070" thick.
Society of Automotive Engineers (S.A.E.) designation is a size zero o-ring. # -012

-
oh this probably means those nylock nuts are 3/8-16 intead of 5/16-18 but same idea, normal/easy to replace.

Great write up. Your clutch is a later Matrix design- by later I mean 1960s era. The rollers with the needle bearings may be part of that revision as I've seen plain rollers on a shaft on an earlier design on my Smart Brown. Is your machine Whitworth or post that period ? Dave

Fortunately this is not Whitworth, it's all normal modern Inch hardware

 

[paul s]

The threads on the end of the rod are 5/16", just measured them. After lunch, it's off to get a nut splitter. I did think about heating up the nut - it almost feels like there are no metal threads, just nylon. I'm hoping it's just the nut that's compromised, and not the rod.