steering head angle.

[john caffrey]

Having built an 880cc (XS650) Yamaha motor with 90 degree crank I want to either : modify one of 3 monoshock chassis to "twinshock" or build my own "Twinshock" chassis based on these chassis. ( As a pro road race chassis builder (Vendetta) it won`t be a problem other than knowing the STEERING HEAD angle ? Two of my outfits are EML (monoshock) - a Honda CR500 about 1990 and a KTM about 1991 and the other looks like a VMC ? (Believed to be "Batman & Robin" outfit !! ) The problem is that they all seem to have different steering head angles !!! Can anyone help with suggestions ?
Another question - I`m used to building ultra light road race & trials chassis out of Renolds 531 or T45 tube with 17 swg wall thickness and was horrified to find seriously thick and heavy tube on these chassis as well as my RT22 Wasp, obviously built for strength not weight - are these tubes high quality tube as above or is cheaper CDS (cold drawn seamless) acceptable ? Thanks.

[ian.uk]

Try putting this request on the twinshock chairs forum. I for one will be interested to see the answers as there is currently some dispute about the eligibility of homebuilt or modified chassis. It would be a shame to waste time and money.
Best of luck.

[john caffrey]

Thanks for your reply Ian. I am aware of the "eligibility" debate but am not too concerned as I`ll be 70 yrs old before 2013 season starts and I ride for fun ! We run the Welsh Classic Sidecar Championship on a really simple set of rules - (1) Twinshock (2) Fourstroke (3) Aircooled . THAT`S IT - SIMPLES ! I suspect that self interest is fuelling much of the eligibility debate and I doubt if there would be sufficient entries to run if the proposed "rules" were implemented - it`s hard enough to get Track Officials as it is - who would enforce the "rules" ? In the Classic period there were dozens of "homebuilt" / "modified" chassis racing with a (lovely) variety of engines - not everyone had or wanted a Wasp. I modified a few frames for friends IN THE PERIOD, usually BSA or Norton and I`ve recently removed / replaced frame tubes to enable the owner to fit a different engine to the one originally fitted - why would these NOT be eligible ? No one protests or complains about eligibility in the Welsh Championships - its about having FUN racing and insulting each other - roll on 2013 ! **** I still need those steering head angles !!!

[Doogle]

Oh God, we are off again...
As long as you are slow, and the bike isn't sparkly shiny you will be fine John. That seems to be the rule.
At least you are running a proper motor, not a poxy Rotax!

[Rob O]

check out the post at the bottom of this page "building a sidecar"