Swing arm & gearbox cradle wear

I would suggest as long as there is no free play between bush and swing arm then loctite should work. I think the spindle needs to be a sliding fit in the swing arm tube with no free play, which it is on my Mk3 plus the later design has the two cotter pins for extra support. I doubt if the two bolts on their own would lock the spindle and could lead to excessive movement and subsequently poor handling.

The centre stand holes can be welded and remachined as can the cradle holes. I made new bushes to suit.

Something else to check is the thrust faces of the cradle for wear where the swing arm bushes and oil seals bear. If it's not too deep then it can be remachined but you will have to then shim the swing arm bushes to reduce clearance between the bushes and cradle. The less the better, I've got mine to within 0.004". This should also result in an oil tight assembly so long as you don't damage the seals on assembly. A radius on the cradle edges helps to prevent this.

I've also fitted countersunk top hat bushes to the rear three cradle crankcase mounts and gearbox top and bottom mounts. Plus centre less dowels fitted to the crankcases and gearbox shell. I've used countersunk socket screws to secure crankcase and gearbox rigidly to the cradle and effectively turn it into a unit assembly. Also helps handling by reducing play between cradle and crankcases.

If you go for the later swing arm/cradle then you should benefit from a stronger design and therefore better handling. Hope this helps.

You could go for oversize bushes to restore the interference between bush and swing arm, then ream bushes to suit spindle assuming the one you have is not worn, otherwise replace with a new one.

The cradle would appear to be worn out in my opinion. Any free play here will be multiplied at the rear wheel. Not sure if it's possible to ream the cradle tube and fit oversize spindle? Reaming could leave the tube a bit thin though.

All comes down to money in the end. I think you're better off with the later, stronger design, but if you stick with what you've got then the free play needs to be eliminated.

Most of the info. in my previous message I obtained from 'World's straightest Command' find it on Google. I also have a web site (hope it's ok to advertise my own site here - ad will be going in RH though!) www.parallelengineering.co.uk - also on Google.

No problem, and thanks!

The later cotter pin type are a much better bet if funds allow, but replacement swingarm pins were available in 0.005", 0.010" & 0.015"oversize, I haven't looked for while, but would imagine they still are as it's a common enough problem on the models with just the 1/4 set screw in the center to locate them, I've rescued a few cradles like this over the years. You simply pick the smallest size that will restore the bore in the cradle to round again & then ream out the cradle & bushes to suit the chosen size. This may help with your concerns over the lack of outer compression effecting the bush fit on the pin as once loctited in place, a new bush should still be tight on an oversize pin.

Regards, Tim

Hi Robin, I have just obtained a Mk111 cradle, so I have a ' 74 850 Cradle and swinging arm assembly spare if you need one. email me on shoestring2005@btinternet.com. Its better to brace the swinging arm first, then re-engineer the bushes and spindle to suit. Hope you sort it OK, regards, Paul

I may be wrong, but is the MKIII cradle a slightly different width to the previous types or is the other way around? I believe it can be made to fit though.