Slow Monster rebuild

350TSS · 12-10-2017, 01:39 AM

This afternoon whilst admiring my new (to me) S4 purchase, I realized that the front fork legs from an S4 are a larger diameter than ’93 M900 at the bottom yoke. I should really have known that, I definitely do now.
No problem I thought, just use the S4 bottom yoke. But the steering stem is a different diameter which means I will have to do a mark 3 regulator rectifier bracket or think of some other means of accommodating it. Also, the clip-ons bought early on in the project will not fit. I got a bit discouraged when I realized also that the steering head tube in the frame is a larger diameter so the tapered roller head bearings may have a larger diameter. Will I need compromise bearings to fit an S4 steering stem to an M900 frame? When I take the yokes out of my S4 I will have to measure up and work out what to do – I am sure it is not insurmountable just annoying buggeration.
I really do not want to use an S4 top yoke which is, in my opinion, perhaps one of the worst pieces of design to come out of a Ducati factory. The S4 handle bars are bolted to the top yoke in a casting that partially shrouds the fork leg top, which means that there is no possibility of dropping the legs through the yokes, the top of the fork legs are retained by a single bolt clamp, there is no depth to the clamping face onto the leg and on top of that they have that stupid aluminium central retaining nut that requires a 6 pronged tool to undo it. Certainly not their best day in the Bologna design department. It is a styled component to pander to Japanese competition, all the best design follows the maxim that “form follows function”
Rant over.

12-10-2017, 01:39 AM	#11
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	This afternoon whilst admiring my new (to me) S4 purchase, I realized that the front fork legs from an S4 are a larger diameter than ’93 M900 at the bottom yoke. I should really have known that, I definitely do now. No problem I thought, just use the S4 bottom yoke. But the steering stem is a different diameter which means I will have to do a mark 3 regulator rectifier bracket or think of some other means of accommodating it. Also, the clip-ons bought early on in the project will not fit. I got a bit discouraged when I realized also that the steering head tube in the frame is a larger diameter so the tapered roller head bearings may have a larger diameter. Will I need compromise bearings to fit an S4 steering stem to an M900 frame? When I take the yokes out of my S4 I will have to measure up and work out what to do – I am sure it is not insurmountable just annoying buggeration. I really do not want to use an S4 top yoke which is, in my opinion, perhaps one of the worst pieces of design to come out of a Ducati factory. The S4 handle bars are bolted to the top yoke in a casting that partially shrouds the fork leg top, which means that there is no possibility of dropping the legs through the yokes, the top of the fork legs are retained by a single bolt clamp, there is no depth to the clamping face onto the leg and on top of that they have that stupid aluminium central retaining nut that requires a 6 pronged tool to undo it. Certainly not their best day in the Bologna design department. It is a styled component to pander to Japanese competition, all the best design follows the maxim that “form follows function” Rant over.