5sp triumph box, atlas head + lots more

74ok said:

british bikes by brian

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think a modded norton frame here, commando? (mentions rear isolastics)

swingarm info? (aah yz 70s yam sumpin),

apparently use of the atlas head allows top engine mount delete

Click to expand...

74ok said:

british bikes by brian

Share your videos with friends, family, and the world

www.youtube.com

think a modded norton frame here, commando? (mentions rear isolastics)

swingarm info? (aah yz 70s yam sumpin),

apparently use of the atlas head allows top engine mount delete

Click to expand...

Brian Holzigal said:

This is of course a bitsa built over a few years from parts collected. The frame was pretty ordinary but staright with no loop and a few holes for chooper tanks I guess. Cheap. Very cheap, always a good starting point for a special. The gearbox is Triumph 5 speed cluster stuffed into a swingarm pre-unit Tri box, 54-62. Not that hard to do. The clutch is therefore triumph. T140 stator bolts thread into a thick flat plate bolted in place of an inner primary. Motor came from everywhere. Stock cam, single Mikuni, 750 cylinder and Atlas head, cheap compared to Commando heads, just drill to 3/8" bolts. There was no need for a top steady as I fitted a 3rd iso mount under the swingarm, cradle to frame a copy of the top one under the oil tank which gives good stability and allows vertical movement. This setup triangulates the swingarm pivot. I have this on other Norton Commando specials. The Triumph box is not particularly hard to do, I hang from top cradle mount and remake lower mounts but going with a standard primary is a bit more trouble. I have another one with a beatup ES primary and a bearing support on the high gear. Playing with going to ES with that. The pictured S'Fighter is on blocks with some work started, to try and fit a Sporty starter. The triple trees were made at the same time as a Triumph S'fighter and use kawa forks. Mid 90's. Tank is from Legendary I think in Florida. Swingarm is Yamaha mono, you know they said they invented it in ads back in the 70's although I believe mono rears was about in the 30's. Vinnies for one. Wheels are someone elses guess, from Mid Ohio swap. I like this type of 3 spoke wheel. So it is a pile of parts bolted up to make a bike. Runs good and rippin thru 5 gears is a trick on a Norton.

Click to expand...

Brian Holzigal said:

This is of course a bitsa built over a few years from parts collected. The frame was pretty ordinary but staright with no loop and a few holes for chooper tanks I guess. Cheap. Very cheap, always a good starting point for a special. The gearbox is Triumph 5 speed cluster stuffed into a swingarm pre-unit Tri box, 54-62. Not that hard to do. The clutch is therefore triumph. T140 stator bolts thread into a thick flat plate bolted in place of an inner primary. Motor came from everywhere. Stock cam, single Mikuni, 750 cylinder and Atlas head, cheap compared to Commando heads, just drill to 3/8" bolts. There was no need for a top steady as I fitted a 3rd iso mount under the swingarm, cradle to frame a copy of the top one under the oil tank which gives good stability and allows vertical movement. This setup triangulates the swingarm pivot. I have this on other Norton Commando specials. The Triumph box is not particularly hard to do, I hang from top cradle mount and remake lower mounts but going with a standard primary is a bit more trouble. I have another one with a beatup ES primary and a bearing support on the high gear. Playing with going to ES with that. The pictured S'Fighter is on blocks with some work started, to try and fit a Sporty starter. The triple trees were made at the same time as a Triumph S'fighter and use kawa forks. Mid 90's. Tank is from Legendary I think in Florida. Swingarm is Yamaha mono, you know they said they invented it in ads back in the 70's although I believe mono rears was about in the 30's. Vinnies for one. Wheels are someone elses guess, from Mid Ohio swap. I like this type of 3 spoke wheel. So it is a pile of parts bolted up to make a bike. Runs good and rippin thru 5 gears is a trick on a Norton.

Click to expand...

Brian Holzigal said:

The Triumph box is not particularly hard to do, I hang from top cradle mount and remake lower mounts but going with a standard primary is a bit more trouble. I have another one with a beatup ES primary and a bearing support on the high gear. Playing with going to ES with that. The pictured S'Fighter is on blocks with some work started, to try and fit a Sporty starter.

Click to expand...

baz said:

Excellent work
I too have an extra ISO under my gearbox and I have run it without a head steady and I can't tell any difference in handling,but I refitted it just incase
I have a 5 speed pre unit triumph gearbox that's fitted with a Dave Nourish output shaft so I can use a commando clutch that'll be fitted when time allows and I'm looking forward to it

Click to expand...

Brian Holzigal said:

No doubt you'll enjoy the 5 speed. Steep hill work in particular. I first did this 3rd iso thing in 1988 and had just built up a Fastback, out of bits. I still had my 1st Commando from 1977. I was not all that confident in the handling as when things are a bit loose in the iso and s'arm pivot the rear seemed to step out a bit when it got around to playing teamwork so I figured a mount under would help control the cradle movement and wear. I suppose a Norvil top mount or similar would help too. I started pinning the s'arm pin about then. I find the extra mount reduces the need to shim / adjust regularly. I remember Herb Beckers race bike had one but he made his 3rd iso as a slide support with nylon/ plastic slide blocks twixt the cradle lower and clamped (I think) braces on the frame. Vertical movement but no side play. I saw that in 2003?
As for the Triumph box I didn't bother with a spline on this bike as a belt with wide enough pulleys will take care of alignment. I had a bloke back in 87 make me a spline 5 speed shaft and it is in a red/white /blue special Interback seen on my youtube thingie. This uses a chain. They can be expensive so doing a chain on some of the Norton stroker unit Triumphs with taper-taper I gut a Tri sprock and remove teeth off Nort sprock, set align and weld. Takes a while. This gets me the correct Tri primary ratio.

Click to expand...

Brian Holzigal said:

No doubt you'll enjoy the 5 speed. Steep hill work in particular. I first did this 3rd iso thing in 1988 and had just built up a Fastback, out of bits. I still had my 1st Commando from 1977. I was not all that confident in the handling as when things are a bit loose in the iso and s'arm pivot the rear seemed to step out a bit when it got around to playing teamwork so I figured a mount under would help control the cradle movement and wear. I suppose a Norvil top mount or similar would help too. I started pinning the s'arm pin about then. I find the extra mount reduces the need to shim / adjust regularly. I remember Herb Beckers race bike had one but he made his 3rd iso as a slide support with nylon/ plastic slide blocks twixt the cradle lower and clamped (I think) braces on the frame. Vertical movement but no side play. I saw that in 2003?
As for the Triumph box I didn't bother with a spline on this bike as a belt with wide enough pulleys will take care of alignment. I had a bloke back in 87 make me a spline 5 speed shaft and it is in a red/white /blue special Interback seen on my youtube thingie. This uses a chain. They can be expensive so doing a chain on some of the Norton stroker unit Triumphs with taper-taper I gut a Tri sprock and remove teeth off Nort sprock, set align and weld. Takes a while. This gets me the correct Tri primary ratio.

Click to expand...