And yet another T120...

Hi Eddie,

Late to the party as usual ;)

Great looking bike, and I agree the '68 is the best!

I note that you rate the smoothness. Mine was also the smoothest running Triumph twin I'd ever owned until I put a '68 flywheel on my T140.
I then sold my '68 due to relocating. I know where the '68 resides, and still wonder if I should 'make that call'...

My own view, for what it's worth... leave the f***ing thing alone!
You're in grave danger of changing it into something that is no longer as nice as a '68 Bonnie ;)
Belt drive sounds good though, and an SRM (or similar) clutch pressure plate would be a good upgrade.

When I built my Combat (sold the day I visited you!), I liked the fact that it was a 'showroom' bike, and it was great to know that (apart from sensible mods) a stock bike could be so good.

But like they've already said... it's your bike :)
 
Yes, looks like it is a Tony Haywood kit. That's the only pic I have at the moment. I can take more detailed pics of the clutch if you need. I inherited this set up so I don't know if it is a straight bolt-on job. I would guess it is.

And yet another T120...
 
Dave, that looks nice, and as TT says, I'd be fairly sure that's a Hayward job.

I used Hayward on all sorts of race jobs, right up to a 906cc NRE built in unit cases, I always liked them. I like how it keeps a decent Cush drive.

I don't like how the bearings and thrust washer run dry (if the cases is run dry), whilst it hardly matters on a race bike (racers don't tend to cruise around with the clutch in, or at least they shouldn't) it is a bigger issue for a road bike, especially if used in heavier traffic.

The Newby kit looks proper sexy, and (I think) has a sealed clutch bearing. The down side is it does away with the Cush drive!

Decisions, decisions!

@ Andy... calm down dear... I'm not hot rodding this one... honest...!
 
Fast Eddie said:
Dave, that looks nice, and as TT says, I'd be fairly sure that's a Hayward job.

I used Hayward on all sorts of race jobs, right up to a 906cc NRE built in unit cases, I always liked them. I like how it keeps a decent Cush drive.

I don't like how the bearings and thrust washer run dry (if the cases is run dry), whilst it hardly matters on a race bike (racers don't tend to cruise around with the clutch in, or at least they shouldn't) it is a bigger issue for a road bike, especially if used in heavier traffic.

The Newby kit looks proper sexy, and (I think) has a sealed clutch bearing. The down side is it does away with the Cush drive!

Decisions, decisions!
Click to expand...

Just my opinion: this is not a Norton and it should not be too difficult to keep oil in the primary case! So run it wet; you get to keep that quite decent stock cush drive, which is a big help for the poor old gearbox, and you keep those uncaged rollers lubricated.

Although, being somewhat of a newbie to classic Triumphs, I will bow to the experienced!
 
daveh said:
Fast Eddie said:
Dave, that looks nice, and as TT says, I'd be fairly sure that's a Hayward job.

I used Hayward on all sorts of race jobs, right up to a 906cc NRE built in unit cases, I always liked them. I like how it keeps a decent Cush drive.

I don't like how the bearings and thrust washer run dry (if the cases is run dry), whilst it hardly matters on a race bike (racers don't tend to cruise around with the clutch in, or at least they shouldn't) it is a bigger issue for a road bike, especially if used in heavier traffic.

The Newby kit looks proper sexy, and (I think) has a sealed clutch bearing. The down side is it does away with the Cush drive!

Decisions, decisions!
Click to expand...

Just my opinion: this is not a Norton and it should not be too difficult to keep oil in the primary case! So run it wet; you get to keep that quite decent stock cush drive, which is a big help for the poor old gearbox, and you keep those uncaged rollers lubricated.

Although, being somewhat of a newbie to classic Triumphs, I will bow to the experienced!
Click to expand...

Hi Dave, I partially agree sir. The (other) downsides to oil in the primary are that the clutch works better dry, and with a belt, there is a theoretical issue in that it can effect tension, as the oil on the pulleys (between pulley and belt) effectively increases their size, so oil may cause your belt to be running tighter than you think when you check it. However, I have no idea how true this second issue really is.
 
Fast Eddie said:
@ Andy... calm down dear... I'm not hot rodding this one... honest...!
Click to expand...

I'm calm, I'm calm!

;)

I run the Burton Bike bits one on my T140 with their clutch plates, and an SRM pressure plate. Great clutch with no slip or drag.
I still run oil in the primary and no issues.
 
Well, I think I'd just about declared the Bonnie "finished" and this morning, I took it out for a bit of a blast.

Then it went a bit wrong, with a strange gearbox failure.

I stripped it out and saw a failure mode I've never seen before, the 'edge' had broken clean off the cam plate around the 4th gear notch area.

In all my years of thrashing, crashing and trashing Triumphs, I have never seen this before.

Ah well, I guess it's not finished just yet after all...
 
I am very sorry to hear about that gearbox failure, after all that work. But why did the camplate fail?

It could have been fatigue or a defect during the manufacturing process, but I strongly suggest you examine everything very carefully to eliminate any other cause, e.g if the slot in the camplate where the selector fork rollers run is indented and if the rollers are a sloppy fit on the pins on the selector forks. Worn dogs can result in the forks themselves holding the dogs engaged, placing undue stress on the forks and camplate.

It could also be caused by insufficient engagement of the dogs in the first place. Among other things, you could check that the quadrant has sufficient room in the inner cover to fully engage the dogs. The camplate failure was in the area of 4th gear. So, when in 4th gear, with the new camplate, check that there is at least some daylight between the quadrant and the slot in the inner cover.

That's all I can think of until you report back.

Dave
 
Well, the gears look good to me, some wear, but nothing too bad. One of the selector forks has clearly been rubbing up against the gear though and shows signs of rubbing and heat.

The gearbox was assembled by the PO with neither an inner or outer gasket, I'm wondering is this led to a lack of end float and to this rubbing? And that this rubbing could have transferred loads to the cam plate? It's the only thing I can think of as the rest of the box looks fine.

Overall, I have to confess that now the bike is down this far, I am probably going to fit a new 5 speed cluster, it was on my mind anyway but I had resisted the urge, so now it just seems like a shame not to!

Have also emailed Bob Newby...
 
The plot thickens ...

I hate rebuilding a bike to 'as before' condition, life's too short for that, a rebuild is an excuse for upgrades in my book!

So, I wanted to use this gearbox disaster to try a Bob Newby belt drive on this bike, but the main bearing seal retaining area on my cases is damaged and won't therefore support a dry chaincase, which is a bit of a bummer, and required a re-think...

So, onto plan B, I've bought a synchoflex based kit (as per Tony Hayward) from Burton Bike Bits and will run it wet.

The brand new 5 speed cluster and associated bits n bobs are on there way from TMS (made by LF Harris to original drawing etc, so should hopefully be good kit).

So much for my plans to keep this bike stock! But then again, why break the habits of a lifetime !?!
 
Fast Eddie said:
The plot thickens ...

I hate rebuilding a bike to 'as before' condition, life's too short for that, a rebuild is an excuse for upgrades in my book!

So, I wanted to use this gearbox disaster to try a Bob Newby belt drive on this bike, but the main bearing seal retaining area on my cases is damaged and won't therefore support a dry chaincase, which is a bit of a bummer, and required a re-think...

So, onto plan B, I've bought a synchoflex based kit (as per Tony Hayward) from Burton Bike Bits and will run it wet.

The brand new 5 speed cluster and associated bits n bobs are on there way from TMS (made by LF Harris to original drawing etc, so should hopefully be good kit).

So much for my plans to keep this bike stock! But then again, why break the habits of a lifetime !?!
Click to expand...

Good approach! I wish I could say how the Hayward belt drive and clutch that I inherited worked for me, but the rolling chassis was so dreadful when I bought it, I took the entire bike to pieces.

Please keep us updated on the new cluster and belt conversion, with pics!
 
Belt drive kit has arrived from Burton Bike Bits and it looks very nice indeed.

Brand new Morgo barrel, sans pistons, has also arrived from them, they're great folks with fast service etc. I've only ever had (very) second hand Morgo blocks before, new ones are very nicely finished, even down to the paint. Made in England too !

The barrels will go on the shelf for a bit whilst I'm waiting for the MAP pistons to arrive. I intend to get the bores treated by Laystall, probably a tad overkill, but what the hell !!

That should hopefully give me time to get the gearbox and primary fitted and tested 'as is' before swapping the top end.

Will post pics soon I hope... when some actual progress is being made... at the moment it's just thoughts, talk, and ££ !!
 
Dave, whereabouts in Dublin are you? I get over there occasionally with work, fancy meeting up for a Guinness sometime?
 
Fast Eddie said:
Dave, whereabouts in Dublin are you? I get over there occasionally with work, fancy meeting up for a Guinness sometime?
Click to expand...

PM sent
 
For the record, for those interested in such things, the belt drive kit with alloy clutch drum and steel front pulley is just under 2lbs lighter than the duplex chain. A triplex would be heavier still of course, but I don't know by how much exactly.

Although 2lbs isn't a huge amount, it is all rotating mass, so in theory, should make a difference. In practice however, I doubt it!

There is still plenty of scope to bash some more holes in the pulley and clutch drum though...
 
Fast Eddie said:
For the record, for those interested in such things, the belt drive kit with alloy clutch drum and steel front pulley is just under 2lbs lighter than the duplex chain. A triplex would be heavier still of course, but I don't know by how much exactly.

Although 2lbs isn't a huge amount, it is all rotating mass, so in theory, should make a difference. In practice however, I doubt it!

There is still plenty of scope to bash some more holes in the pulley and clutch drum though...
Click to expand...

It's the rotating mass at the periphery that has the most 'flywheel effect', like with a wheel, hence alloy rims. Since the clutch drum is alloy, you have already gained a substantial reduction in inertia, which should make it easier for the gearbox. The drive pulley is relatively insignificant, whatever its weight. I wouldn't touch either.
 
Well it's true that weight at the extremity has the biggest difference Dave, hence I suppose, a big plus in favour of a belt that weighs nowt compared to a duplex / triplex chain!

New 5 speed cluster and other bits n bobs arrived from TMS today, those boys are the business, so helpful and knowledgable, with such an amazing stock, and always of perfect quality.

Looks like I need to look at the inner gearbox cover next, the main shaft had pushed the bearing hard up against the circlip, such that the circlip is 'dished' and the bearing is shot. Also, although it's hard to be sure, I think it has deformed the circlip housing a little. This seems to back up my earlier theory about being assembled sans gaskets, and this causing end float issues.

The kick start has been allowed to smack hard against the kick start stop too often as well, which has ovaled the locating hole somewhat.

It's all reparable with some welding and machining, but I don't think it's worth it, probably best just to replace the inner cover I guess.

I think I've found one, so re-assembly should hopefully commence this coming weekend.

Onwards and upwards...
 
Fast Eddie said:
Well it's true that weight at the extremity has the biggest difference Dave, hence I suppose, a big plus in favour of a belt that weighs nowt compared to a duplex / triplex chain!

New 5 speed cluster and other bits n bobs arrived from TMS today, those boys are the business, so helpful and knowledgable, with such an amazing stock, and always of perfect quality.

Looks like I need to look at the inner gearbox cover next, the main shaft had pushed the bearing hard up against the circlip, such that the circlip is 'dished' and the bearing is shot. Also, although it's hard to be sure, I think it has deformed the circlip housing a little. This seems to back up my earlier theory about being assembled sans gaskets, and this causing end float issues.

The kick start has been allowed to smack hard against the kick start stop too often as well, which has ovaled the locating hole somewhat.

It's all reparable with some welding and machining, but I don't think it's worth it, probably best just to replace the inner cover I guess.

I think I've found one, so re-assembly should hopefully commence this coming weekend.

Onwards and upwards...
Click to expand...


Yes, you can replace the inner cover, which involves the least amount of work.

The mainshaft is held against the inner cover bearing (and retaining circlip) when the mainshaft nut is tight. There should then be enough clearance for the sleeve gear on the drive side to spin freely. The layshaft is floating and all you need is some clearance (e.g. 5 thou). If things are tight when the inner cover is buttoned up, then use a gasket and measure the slack on the layshaft. If you find that there is too much slop, you will need a shim behind one of the thrust washers. Or a thinner gasket, which you can make.

I would assemble each shaft with its full complement of gears separately, and at first without an inner cover gasket, to see how things are. It might not be that the gearbox was assembled without gaskets that caused the circlip to bell outwards and damage the bearing. It could be that someone bashed the clutch end of the mainshaft to free the clutch hub and didn't use the hub puller, or did use the puller and the hub still wouldn't shift and then they bashed it!

Then you will have a lot of fun timing the quadrant and checking that each gear selects! (It's all ahead of me with my rebuild!).
 
You must log in or register to reply here.
Back
Top