And yet another T120...

It's a (nearly) 50 year old bike at the end of it all Dave, with who knows how many POs down the line!? So yes, all of that, and more, is highly possible.

I shall keep a close eye on things when I get to re-assembly...
 
I managed to obtain a NOS 5 speed inner gearbox cover, which makes me feel much better than welding and machining the old one back to good health. In fact, on closer inspection, I saw the old inner cover had already had a weld repair at some point in its dim and distant. So all in all, I'm much happier fitting a NOS item.

Today I got that assembled with new bearings, camplate quadrant, gear lever bush, kick start stop, etc and all looks good.

I also opened out the high gear bearing inner in the crank case / gearbox housing to accept the bigger 5 speed high gear.

So, with a little luck, I hope to get some assembly work done this weekend.

Fingers crossed...
 
Fast Eddie said:
I also opened out the high gear bearing inner in the crank case / gearbox housing to accept the bigger 5 speed high gear.
Click to expand...

How did you do this? Just curious.
 
daveh said:
Fast Eddie said:
I also opened out the high gear bearing inner in the crank case / gearbox housing to accept the bigger 5 speed high gear.
Click to expand...

How did you do this? Just curious.
Click to expand...

It's easy Dave. You're not touching the bearing surface, or anything dimensionally critical. Is just the inner part that the high gear passes through, without touching it.

So, all you need is a half round file. Simple as that. You don't even remove a lot of materiel. It was literally a 2 minute job.
 
You've been getting on with your bike Nigel and by the sound of things you're happy with the progress!

Jg
 
auldblue said:
You've been getting on with your bike Nigel and by the sound of things you're happy with the progress!

Jg
Click to expand...

Dead chuffed with it Jimmy, very light and great fun for blatting around on, especially in town and on back lanes etc. both Don't think it'd be my first choice for long distance work, although the PO proved it more than capable of this.

Progress was great until the gearbox set back, but I'm trying to turn this set back into progress by upgrading it, thus ensuring we will have made progress when it's back together, so at least I'll feel like the work was worthwhile if yer get me.

There's probably a book title here somewhere... "Phsycology and the Art of Motorcycle Maintenance"...
 
Fast Eddie said:
auldblue said:
You've been getting on with your bike Nigel and by the sound of things you're happy with the progress!

Jg
Click to expand...

Dead chuffed with it Jimmy, very light and great fun for blatting around on, especially in town and on back lanes etc. both Don't think it'd be my first choice for long distance work, although the PO proved it more than capable of this.

Progress was great until the gearbox set back, but I'm trying to turn this set back into progress by upgrading it, thus ensuring we will have made progress when it's back together, so at least I'll feel like the work was worthwhile if yer get me.

There's probably a book title here somewhere... "Phsycology and the Art of Motorcycle Maintenance"...
Click to expand...


Auld bikes are auld bikes, that's why there's no point in getting frustrated. A setback is an opportunity for improvement, no point in counting rivets.

As for the book , maybe "Psycosis and the dark art of motorcycle maintenance " by Ladybird.
 
New high gear bearing fitted yesterday, along with the seal. New high gear and sprocket fitted along with proper thin O ring, tab washer and nut.

I went forwards and backwards with my thinking on gearing as I was going to use this oportunity to fit a one-tooth bigger gearbox sprocket, but in the end I kinda concluded that this isn't an out right top speed bike, nor is it a long distance tourer requiring a high cruising gear. It's an around town and back lane blaster, so, I fitted the stock 19 tooth. If I do still feel it's under geared, TMS sell a neat one piece sprocket / drum casting with 43 teeth rather than the stock bolt on 46 tooth sprocket.

Surprising how time consuming and fiddly all this stuff is when doing it with the engine in the bike and kneeling on the floor as opposed to being comfortable and organised with the engine on the bench. And yes, I did consider pulling it out altogether, but I know what would happen if I did that...!
 
The 19 tooth will be handy to blow off the odd car at the traffic lights!
 
I came to a 'my Kingdom for a horseshoe' kinda momentent where lack of a tiny o ring for the gear-lever shaft and an oil seal for the mainshaft stopped play with the gearbox! Note to self: more care required when creating parts ordering lists in future!

So, bored, I thought I'd stick a degree disc on it and look at the cam timing...

OMG... I had forgotten what a minefield this is... especially when trying to us ethe opening / closing times given by Triumph. So, I looked at lobe centre timing, again, there are differences of opinion here, Triumphs figures work out at 100.5 degrees.

Long story short, and I've only had a quick look so will verify later, the exhaust looks absolutely cock on. I currently think the inlet cam is out by (almost) a tooth. I haven't had the timing cover off yet to look at th marks, but it may have been a deliberate choice by a PO to soften the bike up by using 6T timing mark instead of T120?

That's not my thinking though, I want it to be pure Bonneville! So I'll look at this all a bit closer in the next shed session...
 
And yet another T120...
And yet another T120...
And yet another T120...
So, thought I'd practice the photo uploading...

Here's the new inner gearbox cover, all assembled with new internals and ready to rock.

And a pic of the lovely new 5 speed cluster, patiently waiting its turn for assembly.

And one of the new sprocket and high gear assembly in situ.

And one of the bike with degree disc fitted as I currently open the can of worms that is Triumph cam timing...
 

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And yet another T120...
So, here are the new Morgo barrels and billet MAP pistons. Interestingly, although they are both from different suppliers, they are both supposed to be for stock 76mm bore, however the pistons have zero clearance! This doesn't actually bother me, on the contrary really as I can now have them bored by my trusted boring man to my chosen tolerance.
But it just goes to show that in this game, we should always check, and always double check.
They'll just be shelf ornaments for the time being, but I will get around to fitting them when I get a round tuit... trouble is, I'm out of round tuits currently.
Anyone got any spare...?
 
Double-check with MAP on the proper tolerance, then ensure that your machinist uses a torque plate.

"Measure twice, cut once"

Even better - measure THREE TIMES and cut once...
 
As far as I'm aware, it's not normal (over here at least) to use torque plates on iron barrels.
 
Nice new 5 speed cluster in its new home. It was quite straightforward getting this far, then things slowed down a lot...
I couldn't get a nice change and after a LOT of faffing around I finally identified the cause as being the new gear selector quadrant! Nice!
So, gearbox assembly is stopped again whilst I sort the quadrant out.
Definitely 2 steps forward and 1 step backwards at the moment...

And yet another T120...
 
Interesting. Long story short, the new LF Harris casting (or forging?) of the gear change quadrant, in the area where the two curved springs are, was roughly cast and poorly shaped, such that the springs got bound up and hooked over the end of the quadrants tang. The issue was exacerbated by the new quadrant springs, which where significantly longer and stiffer than the old ones.

I filed and re shaped the quadrant and fitted the old springs and it now seems to function correctly.

I'm never confident until it's road tested, but it look correct so far, and I managed to get the transmission buttoned up.

Next job is cam timing. Another barrel of fun...
 
Triton Thrasher said:
Doesn't mean it's a bad idea.
Click to expand...

That's very true.

I know it's popular on Harley's etc, with their huge holes bored into long, thin alloy muffs. But, I'm not entirely sure what 'problem' they solve on iron block engines like Triumph.

Whatever the benefit, it can't be huge otherwise it would surely be a more common practice? I've never done it (and I've had a few dozen bored over the years I guess), Dave Degens doesn't do it (how many thousands of Triumphs has he bored over the decades?!?).

I've also worked at quite a few automotive engine plants over the years and have never seen it done there either.

So on balance, it's fair to say that I'm not convinced it's a huge deal.

And, more to the point, I do not possess any torque plates!!

Thus, whilst I'm certainly not 'anti torque plate' per se, my lack of understanding of the 'need' and my lack of actual torque plates, conspire to dictate that I'll probably do without. Once again.
 
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