I,M in the process of adapting a set of paso cases to suit my tt1 swingarm. A circular piece of alloy has been welded to the drive,left,case to add the 10mm required. But,rather than boring and fitting bushes for the 28mm spindle,i intend to bore to 28mm,slide in the 28mm pin to the width of the cases,then push a 17mm pin through to locate in needle rollers in the swingarm. Before I go ahead,can anyone see any problem with this method. I do have a set of brand new late 750 f1 cases,but would really like to make use of the paso ones. It would seem to me that this mod may well be stronger than original,only adding a little weight,

Hi Ian...
What I'm envisioning is something similar to a steel rolling pin? The first thing that comes to mind is the 28mm pin is going to pass through an oil filled cavity. This means a tight pressed fit after the cases are together or seals. If your swing arm is going to ride on bearings then the 17 and 28mm pins will need to be kept from rotating. The internal bore of an original swing arm pin may not be that good tolerance wise and may not provide a good fit for the 17mm pin.(sloppy) A 28mm pin machined in aluminium may be a thought. If you can use F1 cases then why do you need the 17mm pin?

thanks for the reply. Yes,the 28mm pin will push through the case and I will fit oil seals just to be safe. On measuring,the needle bearings for the s/arm are 28x 22.The internal diam of the original pin is close to 22,this can easily be reamed to create a good fit with the through pin to be used for the spindle. Grub screws to be fitted in rear of cases to hold the pin in position. Allready ,I am thinking of making the 28x22 pin from aluminium as your suggestion. It looks a straight forward fix. I am going this route as it seems a shame to not use the paso cases,as the tt1 we use has modified paso cases altered as the originals and works well. This will allow me to sell on the new f1 cases which are rare nowadays to help with a few mods I might want to do. The engine build will end up as 818cc with the pistons v2 which I am using.

I had made a mistake in my original post when I stated 17mm for the pin when it should have been 22. This caused your thought of a sloppy fit. Better make my mistake on here rather than on the lathe!!

There is another way, ok so its not as pretty but it works.