Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board layshaft thrust washer guide pin 76 T140

I found evidence that the pin in the gearbox that locates the layshaft thrust washer has been knocked in or worn away to some extent and the washer may have spun as it's got score marks on the back. I've got a new washer but the pin is too small to grab so my inclination is to grind it off and replace it with a steel pin of similar size (about 3mm) about 180 degrees away by drilling a new hole and shrink fitting it or using the dreaded good old loctite.
Does this sound about right? and how deep do you reckon I should set it in?
John

Having not done it, but,
1) the depth of the hole depends on the pin length.
2) Press fitting a pin ( interference clearance) would probably work.
I can't think of a reason why not.

Cheers Steve. I don't think anyone's selling the pins anymore, not that I can see anyway. I should think a 3mm mild steel pin of about 7mm-8mm length would do it.
John

Two problems:
1) you need to know the depth that can be drilled.
2) IMHO mild steel will again bend and possibly shear.
A hardened steel pin should be available from somewhere. A machinist would know where to get one - or make one. Determine the diameter of the needed pin and tell a machinist what size hole you are drilling. He will make a pin .001" or .0015" oversize. The interference fit should hold it if you can get a few mm into the case. I have no idea how thick there case is there. Certainly 5mm depth would hold if you can get that deep.
Good luck.

I had exactly the same thing happen on my T100R. I think the factory overdrilled the holes. I actually managed to remove my pin by drilling a small hole in the centre of the pin. The drill was held in a pin vice and this in turn was fitted to a battery drill. I believe it was a 1mm drill or similar size to great care and patience is required. When I had bored a reasonable depth I screwed in the smallest self tapping screw that I had in the junk drawer which had come from some electronic assembly. It was a cross point and I carefully managed to drive it home quite firmly. Once in place, I used a sharp pair of pincers to hold and lever the pin out. The relief as the pin came out could not be described here.
The new pin I bought was the same length so I had to get a friend to turn one up for me a bit longer.

If you do not want to drill it, you can take it to a shop that does electro-discharge machining. They can erode the old pin out. There are hardened steel dowel pins for locating parts. Look in McMaster-Carr or similar. Or you can get a piece of drill rod and make your own.

I didn't think that I would be able to drill into the pin either but as long as you have a sharp drill it will drill ok and it did come out very cleanly although a little patience is required to get a start in the centre (ish) without slipping off. I got a replacement pin for my T100R ok but it was the same length so don't put the new one in without measuring or it will disappear.

I think I'll have a go at drilling it and getting a small screw in, that's a good tip :bigt, and nothing to lose. If it drills reasonably well it can't be hardened to any great degree, I suggested mild steel as I thought a hardened pin might be too brittle.

The pin should be available from a Triumph parts dealer under part number 57-0912.

What is the minimum amount this pin should penetrate the thrust washer? I found a similar condition in the case of my T-120R. Thrust washer is 0.092" thick. Pin length is worn to about 0.015" and will hold the thrust washer as long as I apply pressure to the face of the washer. There is evidence of scoring on the back of the washer. I am trying to decide if my reassembly should stop while I replaced the pin or proceed as is. What is the risk of proceeding?

Thank you,
Jeff

When I did the rebuild on the T100R, I had a friend make up a set of drifts for the various bearings to be installed. I neglected to get him to cut away the drift for the gearbox needle roller bearing installation, heated the case drove in the bearing, sending the thrust washer pin part way into the case.....well you know the rest.....Ordered a new pin from the local brit guy and had the local machine shop guy install it 180 degrees away from the original which he ground flush. Anyway, I don't know if he had NOS pins in stock or brought it in new but it was available about three years ago.

British Cycle Supply shows that part in stock in the last catalogue I have. 57-0912 which goes to 62-0072 in their catalogue. 57-0912 is also for the T100 so it must be a common to more than one model part. Cheers, Wilf

You should replace the pin.
0.015" is not enough,and end float is likely to be that much,especially if you fit a gasket on the inner cover (they weren't standard).
The pin is easily drilled.I've tapped a small thread in one (2mmm or 2.5mm) and pulled it out with a screw.I just used a piece of 8 guage welding electrode to replace it,and polished the diameter down about 0.001" with emery paper to get the exact fit.