Primary case rubbing on s/arm

Hi All, I posted about this prob a few weeks ago & someone suggested checking spacers etc. It is an 850 in a mk2a frame(I think, the frame I mean!) it has adj iso's. There are no spacers between engine plates & g/box or engine, I can't see that any spacers are missing from iso's, I also noticed that chain spring link is rubbing as well but I can turn that round.

Any ideas/advise much appreciated, Paul.

Have you not aligned the inner case correctly on the centre stud and pulled it over ?

Cash

hayabusaman0 said:

There are no spacers between engine plates & g/box or engine

Click to expand...

There should definitely be a spacer (030023) between the gearbox and cradle at the top lug on the drive side?

http://www.nortonmotors.de/ANIL/Norton% ... 07&Part=34 Item [34]

The only time I encountered this problem, it turned out that the PO had left out the spacers/washers on the center stud for the inner primary cover. It's possible to pull the inner primary over enough to rub against the swingarm. It eventually bent the inner cover so much that it cracked around the three bolts holding it to the crankcase.

Ken

Yep it's all pretty tight down there. I have the same problem with mine. If all your gearbox spacers etc are in order about the only other thing you should do is to check the inner primary is aligned with the crankcases. You can check it by backing off the nut on the inner primary cover center stud where it goes through the cradle. If it is not shimmed correctly the back of the stud will come away from the cradle. If there is a gap there it needs to be shimmed which means either pulling the primary apart or cutting slots out of suitably sized spacers and sliding over the stud. Don't be tempted to jam in more than you need to get a bit more clearance or you will crack your inner primary. Good luck.

+1 on checking the spacer on the upper mounting bolt of the trans and the shims on the center stud. You mentioned that there were cracks around the front mounting hole of the inside cover where it attaches to the crankcase in your first post. It's possible that the case is bent so it may not come out when you loosen up the center stud. There are a couple other things that might be going on too if that doesn't clear it up.

Dave mentioned that the rear mounting bolts might have worn the holes on the cradle and the bosses in the crankcase by shuffling. It usually happens on the left side and it can allow the engine to become skewed to the left, relative to the cradle. The mounting surface for the inside primary cover would then not be parallel to the cradle so it's angled inward in the rear, even if it's shimmed correctly. People have bored the holes for oversize bolts or sleeved the cases and welded up the cradle to get it back to straight again.

The other thing might be that if you over tighten the domed nut on the primary cover it'll warp the inner cover to the point where it's pushing the back section inward. When you clamp down on the central fastener with the only contact between the two halves around the periphery then the centers are going to cave in. The center is stationary relative to the cradle, the swingarm and the sprocket, so the inner cover is going to bend and move toward the centerline of the bike around the outer edge. The inner cover is thinner than the outer and there's that big hole in it so it bends easily. I came across this because I'm using a 530 0-ring chain. I have enough room but if I over tighten the dome nut it pushes the inner cover into the chain and I hear it.

Thank you all. The spacer for the g/box is there & the inner cover was shimmed properly, when I bought it the front eng mounting bolt was loose & had worn the bolt & made the hole oval, I replaced the bolt, it looks like I may have to do something with the hole. If the iso's have gone soft I guess this would also do the same?

Thanks, Paul.

I don't think the iso's have anything to do with that space. The primary is bolted to the engine, is bolted to the cradle, and the swing arm comes right off the cradle. I bet it's your front engine mount, you may have to go up one size if you can.

Dave
69S