Clutch crownwheel clearance.

[Bombay Mix Pilot]

Hi all, Got a bit of a snag, building my new engine transmission and when all lined, shimmed & torqued up the chain rubs on the raised lip for the end of the layshaft/bearing on the endplate. Fitted progressively thicker shims and at the moment have a 1.37mm fitted, this seems to have created clearance but due to a small bit of rock on the bronze bush you can with a bit of pressure still get it to rub occaisionally. Odviously removing the rock will help so will have to try another bush to try and remove this but also the shim thickness will have altered my chain alignment but only by 0.36mm, the chain etc seems to run real nice by hand when assembled. Other than the mentioned bits to try does anyone have suggestions ? What kind of clearance should you have at that point between the end plate and chain ? Also want to avoid clutch - kickstart clearance problems what with shimming the crownwheel up further.

Thanks in advance

Andy

[Bombay Mix Pilot]

Just as an update the spec is - Mec Eur 47 tooth lightened crownwheel, Std spider, Vijay 150 super gearbox shimmed up nicely, 18 tooth front sprocket with 82 link chain, Race type chain tensioners top & bottom. Any thoughts guy's ?

Cheers

Andy

[rog60]

NOT being an expert as some on here, but the clutch bush/bearing on my setups has always protruded a little at the back of the crownwheel giving sufficient clearance for the chain to endplate with a .5 shim behind the crown wheel. I don't know whether manufacturers of the bronze bushes vary in the dimensions of this item.
I confess I have never bothered to check chain alignment as I believe the chain can run quite evenly with quite a degree of mis-alignment.

Anyone else?

[Bombay Mix Pilot]

Thanks for the reply, yeah I set my crownwheel/spider/bronze bush up to the dimensions in Sticky's book, with the spider sticking through .1mm when all assembled. You are also correct in thinking that the bushes are made to differing tolerances as I just tried another and it wont even go into the crownwheel centre. I have another bush coming and some more crownwheel shims to see if I can get the desired setup, am still concerned about the kickstart/clutch clearance, might be ok as we're only talking about .5mm ish raise on the crownwheel compared to what they reckon is a standard shim thickness. On the subject of the chain, the way a roller chain is designed means it will tolerate a degree of deflection but to what degree for a Lammy duplex chain I dont know. Oh well, can but try all possibilities, this engine is taking ages to get done. Any more suggestions/info/advice will be gladly accepted.

Cheers all

Andy

[J1MS]

You can always fit Two sidecase gaskets to pull the Kickshaft further away from the clutch if its a tight fit with the thicker clutch shim...

[Andy Pickering]

I had a hell of a job getting mine something like as it was built by an blind indian with 2 fingers, Mine was causing probs because the kickstart shaft was rubbing the top clutch plate causing it to slip so had to file the inside of the kickstart shaft enough so it cleared and sorted the clutch which is now fine, So if you wanted to shim a bit more and are worried about the clearance you could file a bit out, hope this helps..also scooterloopyjohn has machined up some what looks like quality bronze bushs so you might want to try one of them....viewtopic.php?f=12&t=3960

[rog60]

also scooterloopyjohn has machined up some what looks like quality bronze bushs so you might want to try one of them....viewtopic.php?f=12&t=3960

Also I meant that the bronze bush protrudes further than the spider at the back of the crown wheel, probably by as much as .3/.4mm