1977 Bonneville back on the road

B+Bogus

B+Bogus

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Jun 28, 2009
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It's barely turned a wheel since I got my Commando sorted, but it's still a great bike on our local back roads...

[video]https://youtu.be/uDHRcUNDMJU[/video]
 
Nice vid.

I agree, a good Bonnie is great in the twisties. I'll have to dig mine out soon. (much the same as you I guess in that it doesn't get used as much as it should.
sam
 
Thanks Sam,

One thing it did do was make me appreciate how good the Triumph gearbox is in comparison to the Commando. The relative merits of their respective clutches slightly redresses the balance though... :roll:
 
Having a T150v for so long I knew there was going to be little joy in the Commando box so I went off
and bought at TTI for the Commando. Since I was already under water with that decision I went ahead
and put in a BNR belt/clutch.
If you miss the nice box on the Triumph you won't be disappointed to go my route.
...you will, however, be broke.
A T140 is a fine bike except for the vibrations. Maybe balancing the crank can help but Ive never done that.
 
Onder said:
Having a T150v for so long I knew there was going to be little joy in the Commando box so I went off
and bought at TTI for the Commando. Since I was already under water with that decision I went ahead
and put in a BNR belt/clutch.
If you miss the nice box on the Triumph you won't be disappointed to go my route.
...you will, however, be broke.
A T140 is a fine bike except for the vibrations. Maybe balancing the crank can help but Ive never done that.
Click to expand...

A very well made point, and I totally agree. I got a Quaife for my Proddy Racer but it still hasn't seen the light of day. Must get my finger out :roll:

I fitted the early lighter 'Thruxton' 650 flywheel to the Bonnie and re-balanced the crank, and it's transformed the bike. I was happy to bin off those anti vibe handlebar mounts in favour of solid mounts and very little vibration gets through to the bars now.
 
I remember the first time I rode a Triumph with the rubber bar mounts. It was odd at best. But Ive come to be a big fan as they
really do work. They dont last long though the rubber is beaten to death by the vibrations. But I just change them out and just
yesterday was wondering how I could put them on a Commando!
Not a fan of T160 but I do like the rubber mounted foot rests!
 
B+Bogus, glad the light flywheel worked, the one you swapped with me is waiting balancing but not sure who to use, who balanced your re-flywheeled crank.
 
kommando said:
B+Bogus, glad the light flywheel worked, the one you swapped with me is waiting balancing but not sure who to use, who balanced your re-flywheeled crank.
Click to expand...

I've used Bassett Down for years and never been unhappy.
 
I've always found the AMC box on the Commando & 650 ss to shift flawlessly up and down. I don't recall ever missing a shift on either bike and clutchless up shifts are easy.
The box is getting near the limit of it's capacity with an 850, but as far as operation goes, I can't imagine nor have ever found anything that shifts slicker than the AMC. Recently I've ridden several modern bikes that do not shift as nicely as the old Commando or SS. My new Thruxton R that gets rave reviews for shifting is about on par with the AMC.

My 05 Daytona is not, nor is the 2011 BMWR1200RT .

I don't doubt that the T140 box is good, just can't see an operational fault in the AMC box, it seems to be the gold standard.

What am I missing?
 
worntorn said:
I've always found the AMC box on the Commando & 650 ss to shift flawlessly up and down. I don't recall ever missing a shift on either bike and clutchless up shifts are easy.
The box is getting near the limit of it's capacity with an 850, but as far as operation goes, I can't imagine nor have ever found anything that shifts slicker than the AMC. Recently I've ridden several modern bikes that do not shift as nicely as the old Commando or SS. My new Thruxton R that gets rave reviews for shifting is about on par with the AMC.

My 05 Daytona is not, nor is the 2011 BMWR1200RT .

I don't doubt that the T140 box is good, just can't see an operational fault in the AMC box, it seems to be the gold standard.

What am I missing?
Click to expand...

I need to have a good look inside my Norton box as its no where near as sweet as the many Triumph boxes I've had and clearly no where near as sweet as your two. And that's despite it being low mileage and rebuilt by Norman White!

But, to your question comparing the two types, I'd say this: Triumph boxes don't crack between the two bearings, layshaft bearings don't disintegrate and throw riders off, they will comfortably and reliably take 85 RWHP, and they are a nicely spaced 5 speed cluster, all 'off the shelf' with no exotic parts required.

I believe it is actually a Quaife design (but stand to be corrected on this). Many Triumph / Weslake twins and Triumph / BSA triples are still racing T140 type boxes today. Compare this to the growing use of TTI boxes on Nortons...
 
Thanks Eddie, saved me a few words :)

I've found the pre-MkIIA Norton box has too big a jump between 2nd and 3rd, whereas the later box is much better in this respect. Unfortunately it's at the cost of a big jump between 1st and 2nd.
The AMC box feels positively agricultural in comparison to the Triumph box - even with the crossover linkage the T140 has a light and positive shift with much less lever throw required.
All the Triumph boxes I've seen have shown little or no wear on the gear teeth, even after considerable mileages, but not the case with AMC boxes - 2nd gear looks like scrap, with brinelling evident from less than 1000 miles from new.
 
I was aware of the durability advantage of the Triumph 5 speed but the comments seemed aimed more at operational advantages the Triumph has over the AMC.
I guess my toe is not terribly sensitive as the amount of motion required to shift the AMC doesn't seem a burden at all. My modern bikes do require less motion but I've never thought them superior because of this. As long as the box shifts quickly, smoothly and always hits the gear both up and down, I'm happy.

What amazes me is that many big bore chopped case Vincents have AMC boxes fitted. Talk about an overload on a trans originally designed for maybe 25 HP and 25 ft lbs! Surprisingly they do seem to work for awhile.
Even the Triumph 5 speed doesn't do well behind a big bore Vincent. Roy Robertson's 1330 Egli racer uses the Triumph 5 speed. He told me he has blown up 3 of these to date. He suggested the Surtees/Quaife 5 speed cluster might have a better chance of survival in this role.

Glen
 
worntorn said:
I was aware of the durability advantage of the Triumph 5 speed but the comments seemed aimed more at operational advantages the Triumph has over the AMC.
I guess my toe is not terribly sensitive as the amount of motion required to shift the AMC doesn't seem a burden at all. My modern bikes do require less motion but I've never thought them superior because of this. As long as the box shifts quickly, smoothly and always hits the gear both up and down, I'm happy.

What amazes me is that many big bore chopped case Vincents have AMC boxes fitted. Talk about an overload on a trans originally designed for maybe 25 HP and 25 ft lbs! Surprisingly they do seem to work for awhile.
Even the Triumph 5 speed doesn't do well behind a big bore Vincent. Roy Robertson's 1330 Egli racer uses the Triumph 5 speed. He told me he has blown up 3 of these to date. He suggested the Surtees/Quaife 5 speed cluster might have a better chance of survival in this role.

Glen
Click to expand...

Well, to be fair, the Triumph case is the weak point on the pre-unit box. Hence Nourish made a stronger case he sold. Was that Roy's issue?

Gearbox durability on racers has a lot to do with riding style I think.

But, irrespective of the Tri vs Nort debate... just wish my Norton box was half as sweet as yours!
 
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