Primary chain & tensioner - 3CL

Thanks guys for your help.  :)
I've just has another play in the garage by putting the cover on part way with the tensioner in place. I can just see through the gap to see the tensioner moving up against the chain. I can feel the chain is being tensioned to some degree by dropping a steel rule down onto the top run of the chain and seeing it move as I screw in the adjuster. It moves no more than 1mm. 

Piet, I understand the lock nut. It is backed right off so playing no part. With the cover off I'm turning the screw itself until it stops, or 'bottoms out' as I've called it, in other words at the end of its possible adjustment. I first wanted to confirm that the screw was supposed to stop or 'bottom out'.. I think it must.

To turn to the chain(s) - I measured about 5mm of sag which equates to about 10mm total movement up & down in the top run of the un-tensioned chain. Thats not much (Dellortoman was talking about much more than that?) and I would have thought a new chain wouldnt be much, if any, tighter than that anyway.Would you call that knackered? Judging by the amount the adjuster is taking up (1mm) when tensioned in-situ I'd have 4mm sag.

Apologies if Im making this seem complicated.

Cheers

Lee   
 
Put the cover back on and go ring its tits off  ;)

If it becomes noisey or has excessive backlash on n off throttle ! Change them out along with Cush drive rubbers  8)
 
Lee

The adjuster bolt is a long grub screw that's fully threaded along its length. See the photo below.

With the primary cover off, you should be able to screw it right through the hole and out the other side. It doesn't "bottom out". It sounds as though yours is stopping part-way through its travel. If so, then the thread must be damaged or the bolt bent. If it's bent, get a new one. If it's a buggered thread, you may be able to recover it by running a die along it to clean up the thread.

30490216.JPG
 
Dellortoman said:
Lee

The adjuster bolt is a long grub screw that's fully threaded along its length. See the photo below.

With the primary cover off, you should be able to screw it right through the hole and out the other side. It doesn't "bottom out". It sounds as though yours is stopping part-way through its travel. If so, then the thread must be damaged or the bolt bent. If it's bent, get a new one. If it's a buggered thread, you may be able to recover it by running a die along it to clean up the thread.

30490216.JPG
Click to expand...

Thanks D'man. The grub screw definitely stops so I agree it must be buggered. The photo in my earlier posting shows it in as far as it will go. I'll have a closer look tomorrow. If it screws in all the way obviously that increases the amount of adjustment and that makes a lot more sense to me.

Cheers for your help.
 
Aha! I think we've got to the root of the problemo! I also have a tensioner bolt that has damaged thread and the locknut won't screw thread all the way along the screw. I'd say it's where the locknut has been clamping. I have thread repair thingies that are designed to clean up and reshape the threads rather than recut them, like a full-on die. I'll probably use on on the tensioner bolt.
 
Need to be carefull with those adjuster screws if OE.  They are quite hard all their length, can bugger up a low-quality die quite quickly!

With a new chain, I'd expect the adjuster bolt to protrude around 12-15mm from the lock nut after "tensioning".  Leaves space for 2 copper washers so the dome nut doesn't bottom on the adjuster and damages that thread.  With later adjustment, one copper washer can be omitted.

piet
 
OK success! :D
Took the opportunity to treat myself to a decent tap & die set today (as good excuse as any). The grub screw was straight and the threads just needed a clean. The issue was with the thread in the cover. I tried a different M10 bolt and had the same problem of bottoming out. On close inspection the inner edge of the threaded hole was slightly damaged, just enough to stop the screw going all the way through.  I ran a tap through it with very little effort and, bingo, the screw can be screwed right the way through with the fingers. Now there is plenty of adjustment!  See pics below (hopefully)

Tomorrow I'll put the cover back on part way, like before, and try the adjusting the tension again to see how much adjuster screw protrudes. I think the chains will probably be ok.

Thanks for your advice everyone. You've gotta love these forums!

Cheers Lee
 

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Ventodue said:
(clap) to Cam for correctly interpreting "bottoming out" ...  :-*
Click to expand...

I suspect nobody figured it could be such an idiot-simple problem. It takes an idiot to see it!

Although the simplicity makes it all the more puzzling that John couldn't figure it out for himself. He had the damn thing in his hands an could see how it was supposed to work.

Sorry John, I don't mean to give you a hard time. I guess it's a case of not being able to see the wood for the trees. We've probably all fallen victim of that on occasions.
 
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