Ahoy !
Sure this has popped up before but I suspect the dimension on the plan is in error. He gives 1365.5mm (53 3/4" but by measurements off a Robin Hood IRS and making allowance for the four 10mm(3/8" end plates I get 1295mm (51"
(52 1/2 between backplate carriers - 1 1/2" thickness of 4 end plates)
Anyone come across this before ? Also what length tube do you need for the Champion Locost

Has the 'hood' got a shorterned drive shaft on one side?

If you are making this for a champion chassis the sierra track is very wide.

Thanks for help. The Robin Hood drive shafts are short on one side but I understand this is standard Ford and that RH uses the Sierra IRS complete 'as is' My measured 52 5/8" is close to the 52 1/2" figure I have seen quoted elsewhere. If I am right then I think Mr Rorty has used the overall width to the brake mounting plates and then added on another 1 1/2" (4 x 3/8 plates ) instead of toking it off giving the tube length in the plan of 53 3/4" (1365.5mm ) which if corrected gives 52 1/4" as his assumed axle width to brake plate mounts ?
On the basis that the figures from 3 sources (52 1/4" 52 1/2" 52 5/8" differ by TFoFEoFA, it looks as if 51" is the tube length required (1295mm) (average less 4 x 3/8" mounting plates) ? Anyone got a tape handy, beware the lump on top of the brake plate carrier which I assume is an anti torque lug ?
Take your point ref. wide Sierra axle on narrow Locost, looks like a roller skate ! I am after Mr Rorty's 'How to shorten drive shaft' instructions too !
Assuming that the Escort is 4" less than a Sierra then a Champion Locost De Dion tube would be 47" ?

Thanks for help. The Robin Hood drive shafts are short on one side but I understand this is standard Ford and that RH uses the Sierra IRS complete 'as is' My measured 52 5/8" is close to the 52 1/2" figure I have seen quoted elsewhere. If I am right then I think Mr Rorty has used the overall width to the brake mounting plates and then added on another 1 1/2" (4 x 3/8 plates ) instead of toking it off giving the tube length in the plan of 53 3/4" (1365.5mm ) which if corrected gives 52 1/4" as his assumed axle width to brake plate mounts ?
On the basis that the figures from 3 sources (52 1/4" 52 1/2" 52 5/8") differ by TFoFEoFA, it looks as if 51" is the tube length required (1295mm) (average less 4 x 3/8" mounting plates) ? Anyone got a tape handy, beware the lump on top of the brake plate carrier which I assume is an anti torque lug ?
Take your point ref. wide Sierra axle on narrow Locost, looks like a roller skate ! I am after Mr Rorty's 'How to shorten drive shaft' instructions too !
Assuming that the Escort is 4" less than a Sierra then a Champion Locost De Dion tube would be 47" ?

Standard sierra has got 1 shaft that is shorter than the other, so you can claw back with wheel offset or just stick on wider arches.

I'm not sure how rorty measured, I run full IRS on mine, just made it up as I went, pictures in my archive so cannot help any further.

Shortern drive shafts, cut, weld and sleeve the join if it fails due to power then get hold of the people in Birmingham who make stuff for grass track racers who will supply gun drilled hardened shafts for a couple of hundred to your size.

[Edited on 28/5/14 by mark chandler]

I personally would always try to use standard driveshafts, so I would measure a standard beam axle from the sierra and work back from there.

Even if you decide it's too wide and decide to narrow the axle it's a good reference for working out the correct lengths for the new or modified driveshafts.

Rorty's de dion axle is only suitable for tripod style CV's and not the lobros.

David

Have worked backwards from the standard set up in RH. Lo and behold using 51" as a tube length, the bat wing centres are in the right place to connect to brackets on Haynes chassis rails ! Will go with that and trial fit an IRS. Thanks for help.