Rear Isolastic Clearance - Is this Too Much?

I was checking through the bike last night and decided to check the clearance on the rear isolastic mounting on my '74 Mk2 Commando. The clearance was 0.112" as viewed below. Is it possible to take up this much clearance with shims? Should I be looking for some other problem?



Thanks

Don

thunderbolt said:

I was checking through the bike last night and decided to check the clearance on the rear isolastic mounting on my '74 Mk2 Commando. The clearance was 0.112" as viewed below. Is it possible to take up this much clearance with shims? Should I be looking for some other problem?

Click to expand...

Was it 0.112" with the stud and nuts tightened or only loosened off as shown in your photo?

Hi LAB,

It was as seen in the picture. I am guessing by your question that these nuts need to be done up tight to take up some of that play.

Thanks for your VERY prompt reply.

Don

thunderbolt said:

It was as seen in the picture. I am guessing by your question that these nuts need to be done up tight to take up some of that play.

Click to expand...

Yes, clearance needs to be checked with the rear Iso. stud or front Iso. mounting bolt tightened (to 25 ft.lb.).

Thanks LAB,

Appreciated,

I am restoring this bike and at the present time stripping it down to the frame to have it checked for straightness and then will have it painted in the correct colour, etc and then start reassembly. That will include an engine and gearbox rebuild. This is a new experience for me for the Commando. I have done a Model 7 previously and some other bikes, Guzzi, etc but am new to Commandos so will be relying a lot on the experience of you guys that are familiar with these models. I have to remove the wiring next so could have some questions on that soon!!

Thanks

Don

You might consider retrofiting adjustable isolastics like the later models had. No shimming, Threaded collars that can be adjusted without removing the bolts and all that rigamaroll. Only the snootiest concours purist would care it wasn't original.

And this is one application where the torque value is rather important. Torque it to 25 ft lb, measure the clearance, determine what shim change is needed, modify the stackup, re torque to 25 again and verify.

I refitted the "Z" plates, spacers, washers and nuts and torqued the iso nuts to 25 lb ft. Remeasured the clearance and this time it worked out at 0.025" which is nowhere as bad as 0.112".

Thanks for the comments and suggestions.

Don