Rebuilding to ride
Things have moved on a little and there’s news of the next project too.
Rapid progress has been made on the bits of our Project 90, a lot of them are in and where they should be.
Aflurry of activity has resulted in the project Triumph frame having a coat of admittedly ‘rattle can’ black (but at least it looks tidier), some stainless steel from Andy Molnar and a few more pieces from Burton Bike Bits. The engine is now assembled, okay so the gearbox isn’t in yet but at least the cases are all together and the engine turns over. The cause of such activity? Finding a restoration of a Triumph TR5A/C on the internet, it looks so good I’m determined to have an assembled bike to work from.
Quietly one evening I played the blowtorch over the castings so the bearings and various hollow dowels could easily drop in. The old method of determining when a casting is hot enough for such things to happen – spitting on it and if the spit bounces off you’re good to go – is okay but I was shown another method some years ago which works for me. There’s this big hole in the casting, a bearing to go in it, I’ve a cheap pair of calipers – seriously cheap at 75p years ago – measure the bearing, heat the cases, the inside points are set at the bearing diameter, when they rattle about in the hole the bearing will drop in. While I was at it the hollow dowels went in too and I left it overnight to cool down. Overkill? Yes, but I’m not running a restoration business where time is money.
Next day the sludge tube was fitted into the crankshaft and the end plug screwed in, it only took two goes to line up the locating hole for the flywheel bolt to hold the tube in place. Pumping the crank full of oil and fitting the con rods is a very satisfying process, as is sliding the drive shaft through the bearing in the drive side case.
According to the manual the cams should go in the drive side case too and the timing side slipped over the top. This was the first hurdle to overcome as try as I might this couldn’t happen. Luckily, the cams run direct in the case and it’s possible to feed them through their bearing holes. It makes lining up the breather disc tricky but not impossible. A light smear of liquid gasket and the cases went together easily, the pre-sized bolts were on hand and everything nipped up, the crank even turned reasonably easily too.
The pistons I have are from a 1967 T90 and are 9.5:1 compression ratio… this may well be a little high these days but in the Sixties 5-star petrol was available at quite a lot of petrol stations. Will I end up using them? Not sure, there is an option of a
compression plate under the barrel at some point and there are formulae to work out how thick a plate should be to give a lower ratio. Even the earlier T90s had 9:1 but I’m thinking more 8:1 for the use I have in mind. So, the pistons, a light warming with a heat gun and in went one gudgeon pin as the piston was lined up with the con rod eye, the second one wasn’t playing ball at all, it liked being on the bench and was determined to stay there. It went in eventually, quite easily…
Most of us delving into engines will realise dropping something into the crankcase when it’s together is bad, most of us will use some method of covering the crankcase mouth in case a circlip is dropped. I use the cloth method and in however many years since I first lifted the barrel on an engine to change a little end bearing or rings or something the cloth has never been needed to save the day… until now. Pesky little circlips refused to go in their groove and two of them dropped onto the cloth. Still, they’re in place and the piston rings too after checking them in the bore as a precaution.
Now, I know you’re supposed to use piston ring compressors to close the rings up for the barrel to slide on but I don’t have any the right size so used a more organic method of carefully placing the barrel on the pistons and compressing each ring by hand… feel free to write in. in any case the barrels are now in place, the pistons go up and down and some nice new stainless steel nuts and washers hold them in place. The fun task of sorting through the bag of pushrod tube sealing washers still awaits.
A job I’ve been putting off is to assemble the rocker box I took apart for no other reason than I wanted to polish the alloy. All the bits are there but I recall last time I did the assembly on such a thing it was a nightmare to try and line up the shims, springs and rockers… this time though it went surprisingly easy.
At this stage there’s an engine on the bench in the cradle and there’s also space on the bench to lay other things out such as the gearbox. The gears are in good condition but the high gear bush has split but my spares box has a high gear without a split and that’s the one now with the other cogs. Once they’ve been washed thoroughly in the parts washer, rinsed, dried and oiled they will go back together.
It’s possible to make all sorts of clusters up thanks to the variety of cogs produced by Triumph and some aftermarket ones for the trials scene but standard is the way forward at the moment. There are wide and close ratio clusters out there as options and clever people can tailor a cluster to almost any need, however that seems a little excessive for my needs with this bike. Maybe once it’s together and I’ve ridden it – that’s actually a possibility now – I’ll find I can’t live without dropping the bottom gear much
lower and fitting the close ratio third and maybe I won’t.
I’ve had to steel myself a little and will be replacing the badly hooked drive sprocket on the shaft just for the time being, though thinking about it I don’t need to put it on to assemble the engine further, so maybe it will stay in the box where we put things we’re not going to use but can’t bear to chuck out. Once the cluster is in place I can fit the clutch and things will start to look up a little. Before that though, there’s a hollow dowel to replace in the gearbox inner cover, it got mashed on the end somehow and it is a through dowel. As such it needs setting in place correctly. So a bit of heat on the case, the old dowel pulled out, the new dowel with a smear of grease is inserted in the hole, a distance piece the correct thickness hung over the end and a bit of tube, or an old socket actually, put over the exit hole, a few turns of the vice handle and the dowel is set in place.
Before all is assembled I’ll lap the clutch hub onto the mainshaft taper so it seats properly then it can be washed off and when the time comes to assemble it we’re good to go. I will need to get a new primary chain, it’s a duplex and will need to be fitted in one go with the front sprocket and clutch drum, a task which I never look forward to as there are so many potentials for the roller bearings to drop out, or the Woodruff keys to drop...
In the frame
One afternoon in the summer, I set up a stool outside, fitted a wire brush to my angle grinder and removed as much of the paint and rust as I could from the main frame, sub frame and swinging arm. I was quite pleased with this method though eventually the frame will be blast cleaned and properly painted, but this will do for the moment as there will be the odd bit of bracketry to go on and until the dry build is complete I’m not sure if
there will be welding to happen too. So, while still in bits, the bits are big ones and will be assembled easily. I’ve forks to sort out though and have options there too, the easiest method would be to bung the original forks back in but I can only find one slider at the moment. I do have several sets of BSA forks which are for bigger stanchions than Triumph used. These would fit the ethos of the build but not the bottom yoke as it would need to be opened up by a few millimetres which would weaken it and defeat the object of putting stronger forks on.
The search for the missing slider goes on… it will be there.
Above: Just before assembling the crank and cams, there was a dry run to make sure all the studs and bolts were on hand.