T120 rebuild - repairs

I thought I would post some of the repairs I made while rebuilding my '67 T120 (which is not finished yet). I would not have been able to do the repairs without a workshop, lathe, pillar drill and various other tools and facilities that a workshop offers. I decided I would repair what I could, and replace only when absolutely necessary.

I got the bike with the following parts completely or partially f***ed: forks, broken off sidestand lug, front drum, rear drum, wrong and loose steering head bearings in the frame, and that's before I got to the internals.

Before I took the thing totally apart, I wanted to make sure that the wheels were in line and the frame straight. I live on a farm so I had some handy, straight steel poly tunnel tubes that I swiped from a pile. Since the swinging arm spindle is hidden, I felt it was OK to centre drill each end, so that I could use a large pair of dividers to check that the rear wheel was centred in the swinging fork and then see if the front end was twisted. The rear wheel spindle already has centres drilled. The non-stock alloy rims are WM2 front and WM3 rear, which is good (spreads the rear tyre better). I used spacers either side of the front tyre when checking the wheel alignment.

Turns out that the alignment was spot on. Front rim was centred in the fork, the steering head is not cocked and the spine is straight. That's a good foundation to begin with. I have been around bikes, and crashed ones, enough over the years to see by eye if things are out of line, so in this case I didn't use measuring equipment.







More in the next post...

The next thing was to repair the stock sidestand lug. I inherited this bike with a very nasty after-market stand and an even nastier welding job. I knew this would be awkward and would take time, so I took my time.

An angle grinder removed the old lug and welding snot, while being very careful not to dig into the frame tube itself, so the last bit was done with a file.

The hideous sidestand I inherited with the bike, with the broken-off factory lug to the left of the photo:


After-market side stand lug removed and frame cleaned up. The broken-off factory side stand lug, to the right of the cleaned up part of the frame tube, has not yet been dealt with.


I made up the protruding part of the lug from a lump of steel in my short ends box and fashioned it so that the stand fitted and then offered it up to the frame. I planned to use the old, broken-off factory lug as a platform on which to weld the new lug.



One of a series of tricky bits - a 'jig' to simulate the line of the header pipe. I stuck the engine back in the frame and fitted the stock LH header pipe and LH silencer. Once the silencer was clamped in position so it couldn't move, I removed the engine again but left the silencer and used a stiff cardboard cylinder the same diameter as the header.

continued from previous post, above...




There was a lot of jiggling to get the tilt of the stand in the right position when extended, while at the same time getting the footplate 'scoop' centred around the header pipe when retracted.

Finally, the lug tack-welded in place and fitting well in relation to the header pipe, with engine fitted. And there is clearance between the 'foot' and the header pipe so no clanging when retracted! The aim is to make it look like a strengthened version of the factory lug. Note to owners: never kickstart the thing on the sidestand - which is why the lugs break off on so many Triumph twins and triples AND you have to take the engine out to repair it AND ruin your new paint job. I will post better pics of the finished lug in due course.

Nice work Dave.

You’d best be careful... carry on like this and you’re gonna have a very nice motorcycle...!

Very cool, and interesting write up with pics too. Thanks for posting.

That primary belt is a bit loose.

Some more fixes. This is a fix for a problem that occasionally happens when an owner / mechanic uses a non-stock bolt to secure the bracket for the upper mudguard stays. The bolt engages with a square nut that fits into the slot in the fork slider. If the bolt is too long, it will create a dimple in the bore of the tube that will ruin the stanchion lower bushes and make the stanchion very difficult to remove or replace (see the first pic). As far as I'm aware, you can't get new fork sliders for the twins. You might be lucky to get some second-hand, but then how do you know the condition?

I decided I would have a go at fixing them. I measured the bores further down and decided they would be serviceable. Here are the tools I used (see second pic)-

1. an expanding mandrel with lengths of studding, which is drawn up and down the fork slider with nuts over strong washers/spacers, gradually reducing the dimple in the bore. The mandrel has to be within a thou of the bore diameter, so that it can't distort the bore when drawn over the dimple. It is tapered either side to provide ramps which make it easier to draw the mandrel over the dimples, using plenty of oil. It took a few hours to get it to where I could then use the other tools, below. An expanding mandrel, alone, probably won't remove the dimple completely.

2. an abrasive flap wheel which will take out the remaining - now much smaller - dimple, used sparingly.

3. a slave cylinder hone, which will smooth off any remaining burrs and will tend to generate a parallel and circular bore - IF it is used judiciously. The extension was used to remove a bit of corrosion from the bottom of one slider.

I now have two useable fork sliders, which will be married to new bushes and fork stanchions, which are a perfect fit in the triple clamps and both measure exactly the same on OD (hooray!). You can't be certain of this with some suppliers. These were from TMS. Les Williams supplied some I fitted to a friend's triple; they were also spot-on dimensionally and finish was good too.