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millemille · 31-05-12, 06:18 PM

One of the reason for choosing a CBR swingarm is there's no top shock mount on the frame. It's on the the top of the swingarm so there's no worries about lining up the top mount.

The suspension linkage needs a new bottom tie point on the frame cross member. I've been over a CBR1000rr with a clinometer and tape measure and have all the measurements I need to place the linkage mounting point "in space" to replicate the CBR rear suspension geometry and then machine a mount to suit and then to weld to the frame.

Perhaps I should explain that I'm a mechanical engineer by profession and have built and looked after bikes raced in BSB, WSB, WEC and the Manx GP and the TT. I have use of a machine shop owned by a friend and have a wide range of contacts in the racing world for help, advise, equipment etc.

I've got a 300mm length of 65mm dia 5083 round stock that I'm going to machine a new, 50mm narrower, bearing tube for the swingarm and a length of EN24T for the new, correspondingly narrower, bearing spacer. I'll cut the existing bearing tube out of the swingarm and cut away the side walls of the arms to clear the inside of the frame spars. The narrower bearing tube will be welded in and the cut away side walls will be plated and the shock tunnel will be gusseted between the inside faces of the swingarm and bearing tube to recover some strength. Given that a stock CBR swingarm is strong enough to be used in BSB with 200bhp and slicks I'm certain the modified one will happily cope with less than 100bhp and road tyres.

Chain line is simple - get the front wheel centred in the forks. Line the rear wheel up with the front wheel. Chain line is easily set with offset sprockets or spacers, if needed, particularly as the spoked wheel hubs are narrower that monocoque wheels.

31-05-12, 06:18 PM	#9
millemille Member Join Date: May 2012 Posts: 318	Re: S-pokey-V One of the reason for choosing a CBR swingarm is there's no top shock mount on the frame. It's on the the top of the swingarm so there's no worries about lining up the top mount. The suspension linkage needs a new bottom tie point on the frame cross member. I've been over a CBR1000rr with a clinometer and tape measure and have all the measurements I need to place the linkage mounting point "in space" to replicate the CBR rear suspension geometry and then machine a mount to suit and then to weld to the frame. Perhaps I should explain that I'm a mechanical engineer by profession and have built and looked after bikes raced in BSB, WSB, WEC and the Manx GP and the TT. I have use of a machine shop owned by a friend and have a wide range of contacts in the racing world for help, advise, equipment etc. I've got a 300mm length of 65mm dia 5083 round stock that I'm going to machine a new, 50mm narrower, bearing tube for the swingarm and a length of EN24T for the new, correspondingly narrower, bearing spacer. I'll cut the existing bearing tube out of the swingarm and cut away the side walls of the arms to clear the inside of the frame spars. The narrower bearing tube will be welded in and the cut away side walls will be plated and the shock tunnel will be gusseted between the inside faces of the swingarm and bearing tube to recover some strength. Given that a stock CBR swingarm is strong enough to be used in BSB with 200bhp and slicks I'm certain the modified one will happily cope with less than 100bhp and road tyres. Chain line is simple - get the front wheel centred in the forks. Line the rear wheel up with the front wheel. Chain line is easily set with offset sprockets or spacers, if needed, particularly as the spoked wheel hubs are narrower that monocoque wheels. Last edited by millemille; 31-05-12 at 06:23 PM.