Long term Triumph Chopper project

[El Skitzo]

Yes I'm back to my old tricks of putting another rigid Chopper together, but this time starting from scratch.

At this stage I'm just collecting the hard to get major parts, with the hope of having a roller together by the end of this year. From there things should progress more quickly.

The start was getting hold of this front frame loop which an acquaintance picked up at the Northam Swap meet many years ago, and has passed through the hands of three other people I know before I got my hands on it. It's a 1965 Triumph Thunderbird frame and the numbers are good for rego. I think this frame has been passed around long enough, and now deserves to become a bike again.




As you can see I've since acquired a 6" stretch and 2.5" hardtail for it, and a complete engine/gear box from a 1971 Triumph T120R.




And more recently I've got my hands on a 2" over P&P Girder front end, which will require some frame modification to fit within the 550mm rule for rego. This isn't the gas tank I'll be using as we plan to fab ALL the tins for this bike, but I was stoked to get this tank back off my previous Chopper and this is a good place to store it for now.

I do have a complete spool hub/drum brake rear wheel on it's way from the states, and once that arrives will worry about a front wheel and getting the roller all together and start with engineering.

[Prof]

Outasight man! Knowing you it will be a righteous rigid chop when you are finished.

Very choice girder. Did it come from Oz or the states?

A suggestion re 550 Ridikulus Rool... Angle the girder forks back (ie the axle) to achieve 550 by moving either the bottom link triple tree mount back or the top link triple tree mount forwards the appropriate amount. A secondary (though to me major) benefit is an increase in trail which with a short girder is minimal bordering on dangerous.

I can speak from experience as I ride my father's 1934 KSS Velocette with a girder and it is a tank slapper waiting to happen because the girder links push the axle forwards so much...


If you can get 5"-6" trail rather than a couple of inches you will have a safe good handling chopper.

Changing the length of the links is not a solution as it makes for crazy geometry as the girder moves up and down.

Picture is of dad in later years. This was his second bike and he had many crazy stories to go with it as he was a crazy son of a gun in his youth (and later actually!!).

[El Skitzo]

Thanks Prof.

Angling the girder back is an option, and there is a set of holes in the legs to allow me to do that, but the front of the bike will be angled up pretty sky high doing that, and I want this bike rego'ed 100% legal the way I ride it every day.

I want the bottom frame rail parallel to the ground or close too, so I need the height of the front axle from the ground to be pretty similar to the rear. I need to talk to an engineer first but the idea at this stage is to chop the frame, and stretch the stock cast neck upwards around 4 inches or so, to be completely different to any one else.

I found the girder for sale in QLD and had it sent to WA. Needs some rechroming and set up work, but I'm just so stoked to get my hands on one.

[Prof]

I usually lengthen the front down tube (s) and the set up the steering head to the correct angle. Best to keep away from the cast/forged steering head if you can. If you can get in a bit more rake and then pull the girder back as per previous post you should end up with a good looker and good handler. Look forwards to seeing what you come up with.

Anad to agree the chopper will be nicer parallel or almost parallel to the ground. You also then sit down nicely into it and don't need such high handlebars, though ADR's for that era allows ape hangers anyway.

[TriNortchopz]

You've got a great start for a good lookin' chop! Good that you are gettin' that frame back in use - too bad hacksaws cut that frame tube, instead of pullin' the rocker boxes to get the engine out...
Love that P&P girder, they ride so solid compared to a springer. I use the info I got from Paul Durfee of Durfee Enterprises for measurement of them; measure from the center of the axle hole to the center of the upper pivot point on the fork leg. Durfee used the Indian Scout girder length of 24" as standard length; the P&P on My Norton Commando measures 40", so it is +16", and the square Durfee girder on my '69 T120 is 36", so +12".
The P&P allowed for either stock rake or +10 degree by moving the lower pivot point to the rear set of holes - I'm wondering if you flip the legs around, you could have it -10 degree rake, pulling the front wheel closer to the frame...then with your plan of stretchin' the front frame post, you can set the neck rake to what is need with the girder in the 0 degree rake position.
That bolt-on rigid looks like a good length.

A long ways from a stock '65 T-bird:

http://www.classic-british-motorcycles. ... rbird.html

Good luck with your build!

[El Skitzo]

Thanks for the input guys, you've definitely given me a lot of food for thought with setting up this front end.

I'll need to keep the stock cast neck for rego here in WA, and I do plan on keeping the rake stock as well, so just literally moving the neck position upwards, but we'll see what happens.

But it sounds like we'll have plenty of scope to play with the positioning and setup of the girder legs to meet our 550mm rule and hopefully get the trail dialled in safely. Once we have it sitting on wheels we'll be able to accurately see what our opinion are, and I'll be pretty open minded.