Triumphrat

koan58

Hi all,
Took down my 1960 T120 for unusual clatter.
For the 1st time found that the intermediate (idler) timing gear spindle had become freed from the crankcase.
What should be a press fit is now a sliding fit, tiny bit of wobble, with the spindle still fairly tight fully in, so I don't think Ive let it wear much.
Found worn cam bushes, the drive side very worn (~8-10 thou slop), timing side less worn (~5 thou slop).
I have various thoughts about dealing with the spindle, from loctite to machining of crankcase.
Must have happened to other triumph twins, what have you done, and how did it work out?
Many thanks
Dave

Mr.Pete

Rather than make a new pin to fit better,you could just get one end of the pin plated.
Copper plating,nickel plating or hard-chrome will work.If it has 0.0005" interference in the case,it won't move.
Face the oil hole downward.

koan58

Thanks Mr Pete, that is what I call lateral thinking!
Will investigate what local platers can do, and give some thought to the metal.
Initial thoughts are zinc/copper too soft, don't know hardness of cadmium, maybe nickel would be ok, got an idea chrome needs primer layers. Just guessing.
Much food for thought.
I had been thinking of loctite, with worried doubts, thinking of the alternating loadings of the cam pinions working on the slight wobble that the spindle has in the case and fretting away at the loctite.
The spindle is "supported" rather loosely (maybe a oouple of thou clearance at a guess) by the hole in the timing cover boss, how good a fit is this meant to be?
I have wanted to think that the spindle loosened because of the worn cam bushes, but the timing bushes are only moderately worn, so I'm having some difficulty convincing myself of this. The bush in the centre of the pinion allows a little rocking on the spindle, so perhaps is worn beyond 1.5 thou, but I wouldn't have thought it horrendous (but will be replaced as matter of course, with cam bushes). Cam journals (timing side 0.8723-0.8725" ok I think, drive side 0.8080-0.8085" just ok I think).
I'd like to understand why it's happened, for peace of mind!
Any thoughts much appreciated
Dave

Mr.Pete

Copper seems to work OK for things like this.The aluminium isn't all that hard,either.
I've seen them come loose before.I wouldn't blame the cam bushes.The outer case doesn't do a lot to support the pin,and shouldn't be tight.

Cam journal size shouldn't be any problem.You will have to ream the new bushes to fit the cam.The drive side is the difficult one to get right.

koan58

Thanks again Mr Pete
I'll accept it as an act of god! or ed turner!
Got the new cam bushes, a sloppy fit on the 2 thou down drive journals, so hoping they'll be close to good when pressed in, will rub with wire wool if necessary, as with the timing side. Don't wanna ream with triumph tool, as cam journals aren't as new.
Have you come across those "reaming not necessary" bushes, as advertised by Oliver at Tri-Supply? I can only imagine that they've got big enuf clearance to accomodate new journals, and hence be sloppy for anything less. Only guessing, all I ould get out of him was "they work".
Cheers Dave