Sunday 11 June 2023

The SR500 Sidecar - shortening a sidecar strut

I admit it, I have a (basic) engineering degree. Most of the time in my life this does not adversely affect me too much. But every now and then the little engineer in me wants to come out and play. On those days, when he does come out, he can be the most overcomplicating and obsessive person you can imagine. Here's an example.

For quite a while the front sidecar strut was too long, which in this case meant that there was next to no room for adjustments to alter the lean of the bike. It was pretty spot on, but as the little engineer in me demanded adjustments, I decided to give in. (Also the strut had to be repainted as the paint flaked off in one spot over the Winter months.)

So the strut was put in the lathe (unfortunately it is exactly as thick as the spindle throat so no chance of a quick job) and clocked in on the steady rest.

Parted the clevis off, which is only held on by a bit of weld and a press fit section that goes into the tube.

Touched up the slightly recessed weld in the middle of the tube where I shortened it the first time, not very elegant, I know, but I was young and pressed for time. 

Finally TIG-welded the clevis back on, which looked quite a bit neater than the original MIG weld that used to be on there. Probably quite a bit stronger as well.

And that's it - applied a fair amount of paint and hung it up to dry. Real world effect of all of this? 20mm more thread for adjustment of the lean angle, which quite frankly I'll probably never use and a well painted strut, which makes the rest of the bike look a bit more shabby. I'd call it a win.

Friday 9 June 2023

Everyday TR1 - Fork oil change

 ... together with a bit of theory. To kick said theory off: My TR1 doesn't run a pair of stock forks, but an old XS1100 set, because I wanted to use the bigger 298mm disks. They are almost a straight swap, you'd only need a different XS1100S front wheel or special wheel bearings for the thicker axle.

That aside, the XS1100 forks have a few other things going for them: first they are intended for a substantially heavier bike. Which means, the fork springs are perfectly adequate for a TR1 and if one were so inclined he or she could run some much lighter weight oil than is common on bikes of this era and thus improve the overall riding comfort A LOT.

Also, unlike the stock forks, these specific ones aren't bent, which resulted in a bit of a surprise after I loosened the pinch bolts and both fork-legs still attached to the front mudguard just started to slide out.

With the caps off, I tend to rinse them with diesel until no more damping can be felt and the diesel, that comes out is (mostly) clear again.

Bit of patience and turning them up-side down gets rid of whatever it was that was in there before.

And in the case of XS1100 forks, which should be filled with 212ml of 10W30 oil, I went with 230ml of 10W fully synthetic fork oil.

And no the mix of old oil with diesel didn't smell very pleasant. I think "pretty rotten" would be a rather appropriate term to be honest.

The surprising bit: This isn't the original 1978-vintage oil, but only two or three years old, yet still it smelled terribly. Regardless of which, the whole episode was totally worth it as the suspension quality is in a league of its own compared to before. Might try a slightly lighter weight oil next year, just to see if it improves the overall finesse of the forks (I doubt it), but they are very responsive even on light bumps and don't bottom out on hard braking anymore. I guess I have to call this a massive success.