SV special build - S-pokey-V.

When you say "do another frame to get suspension right" what does that entail?

[millemille]

Originally Posted by Stinka

When you say "do another frame to get suspension right" what does that entail?

Chop lumps out of the lower frame cross member...



Machine something like this out 5083 ally...



If you've measured and machined and cut everything right....



Apply some electric glue....

Jeez ! That's sexual mate

[shiftin_gear98]

Can't wait to see this finished. A*

[Jayneflakes]

This continues to be exciting. Nice work.

[millemille]

Another frame has been purchased and, once I've cleaned it and removed the paint and cut off the extraneous redundant brackets, it's going to Maidstone Motoliner for them to check the alignment.

Now this....





..is an eccentric headstock insert originally used on the factory WSB SRAD750's in the late 90's when Harris ran the WSB team. This particular one is labelled as "-6 top +0.5" - meaning it's for the top bearing and moves the steering axis backwards by 6mm (making the distance from the swingarm pivot to the front wheel contact patch short and hence moving the CoG forward and putting more weight on the front wheel) and also makes the head angle 1/2 a degree steeper so initial turn in is quicker...when coupled with the matched pair for the bottom bearing. They are an interference fit into the bearing cup and are aligned with the scribed/engraved centre line. By using a smaller diameter steerer and bearings you have the ability to, pretty much, move the steerer axis as much as you want. Obviously they make the head tube a fair bit longer, but with the custom yokes I'll be designing it won't be an issue.

I borrowed this one from the man with the bike and parts collection with the intention of using it for inspiration, but the gods have conspired in my favour as the sizes are the correct size to fit in the SV headstock and the SV and SRAD headstock are identical in the critical dimensions - meaning that all of the clever maths and machining needed to get the relative angles of the bearing cups right has been done already.

The man with the bits has agreed to sell me all of the matched pairs of inserts he has and I can get Harris, hopefully, to make any I may need at some time in the future.

Taken a load of pictures and measurements from the yokes as well as borrowing a variety of steerer tubes with offset inserts and bearings and will be firing up SolidWorks imminently.



The swingarm pivot adjusters have been designed the old fashioned way, with paper and pen, and will also be put into Solidworks, with a view to machining soon.

[millemille]

The latest frame I bought had one of the engine mount adjusters siezed in, and in getting it out the threads in the frame got badly damaged.

Which forced me to go back and look at the original frame to see if it was less work to make it right than to repair the new frame and then modify that.

Good news is the top headstock bearing pocket in the original frame is exactly the right size for the headstock inserts, having already been opened up for the Ducati steerer bearings...



The person with the collection of ex WSB SRAD parts managed to come up with 4 matched pairs of inserts....





..which gives me -6mm (steerer moved 6mm further back) +1 degree (steerer angle 1 degree steeper), -6mm +0.5 degree, -6mm 0 degree and -3mm 0 degree. They'e from the early iterations of SRAD 750 raced by Harris in WSB, there would have been a multitude of combinations of offset and angles made but these are all that survive with the previous owner. I'm hoping that there'll be enough adjustability with what I've got there to overcome any handling defficiencies there may be.

Yoke design has been completed and machining started...



The lower yoke will look like the gold lower yoke in the picture below...



...and the top yoke will be a more contempary design like this...



...with the offset adjustable by +/- 5mm using eccentric inserts between the steerer and yokes...



Looking at the rear suspension tie point. It occurs to me that there's a perfectly flat and true face between the two mounting lugs. So if I were to cut the lugs off and flatten down the stubs, as shown by the sharpie lines....



..I've got flat face to weld or bolt a new set of, shorter and adjustable, brackets to.

I'm also going to take the opportunity to change the swingarm pivot pin from the current weedy little SV650 item to the much more robust, but lighter, CBR1000RR pivot pin to match the swingarm and then design the swingarm pivot adjusters to suit.

This means changing the swingarm bearings and whilst they're out I'm going to address a slight distortion in one of the bearing pockets, due to the welding, that has been niggling away at my OCD from day one.

Onwards and upwards....

[shiftin_gear98]

I hope you work for NASA, or something similar. If not you really missed the boat.
Loving this thread.

Can the srad inserts not be turned 180deg. so you get +6mm?
Am I missing something? (not unusual)

Would they be used to get geometry that works then a frame made up to that spec?

Like the adjustable suspension tie point, make them asymetric so you can turn it over to get the adjustment? Provided there's enough meat to drill, tap and secure the bracket.

[millemille]

Originally Posted by dean0n0

Can the srad inserts not be turned 180deg. so you get +6mm?
Am I missing something?

They could be, but the top insert would need to be machined a bit more to relieve it to clear the tank. If you look at the original picture of the +6mm top insert you can just see that the wall thickness is different front to back...

Originally Posted by dean0n0

(not unusual)

You are Tom Jones and I claim my £5....

Originally Posted by dean0n0

Would they be used to get geometry that works then a frame made up to that spec?

Unlikely, but never say never...

Originally Posted by dean0n0

Like the adjustable suspension tie point, make them asymetric so you can turn it over to get the adjustment? Provided there's enough meat to drill, tap and secure the bracket.

I've decided to weld the bracket onto the machined face, rather than bolt it. Simply because it's one less set of fasteners to check. There will be inserts that, as you sugest, can be flipped to provide a +/- offset about a datum and can be adjusted to give both a vertical and horizontal adjustment...