The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: a10gf on 07.04. 2010 17:47

Title: Primary chain tensioner
Post by: a10gf on 07.04. 2010 17:47
As seen on the picture, chain runs very towards inner edge, should I worry and do something about it (maybe shims behind cush drive & clutch) ?

Thanks
e
Title: Re: Primary chain tensioner
Post by: beezalex on 07.04. 2010 18:18
I would check sprocket alignment.  One of the most overlooked things on vintage bikes.  It could just be that the tensioner has some tilt in it, though.  You could check that with a machinist's square.
Title: Re: Primary chain tensioner
Post by: a10gf on 07.04. 2010 19:43
Spot on regarding the tilt! Never before had this part out for inspection. Reason for the missing 3rd outer wear groove (and the extreme inner groove wear) explained. As for alignment, will have a close look upon reassembly whenever that may be.

Thanks
Title: Re: Primary chain tensioner
Post by: muskrat on 07.04. 2010 20:05
G'day e,
           good to see one prob found, but even with the out of square rectified it looks like it will still be too far inboard. Mine runs a good 4-5mm further out. Check alignment as beezalex said, you may need to shim out the cush drive bearing with 67-2056,7,8 to line up with clutch.
Next time I have mine apart I am going to line the tensioner with nylon the same as they use for chain guides on MX bikes.
Cheers
Title: Re: Primary chain tensioner
Post by: a10gf on 07.04. 2010 20:18
2nd good tip of the day, I've never thought of, or heard of, these shims, now I see them in the parts book. None of 'em on my setup. Amazing, the amount of details that are to be found (and learned) on just one type of bike...

Thanks again.
Title: Re: Primary chain tensioner
Post by: beezalex on 08.04. 2010 18:02
Aah excellent.  Glad you found it.  BTW, the tensioner in my Golden Flash is lined with teflon.  I mainly did this because, at the time, I had trouble finding a decent replacement.  But now, i can see that it's doing a great job with minimal wear.

Cheers!
Title: Re: Primary chain tensioner
Post by: muskrat on 08.04. 2010 20:39
G'day Alex,
               did you rivet or bond (glue) it on. What type of teflon & how thick ??? I always thought it was a bit of an errr in the design.
Cheers
Title: Re: Primary chain tensioner
Post by: BSA_54A10 on 09.04. 2010 12:39
I use old bearing outer races for spacers behind sprockets.
Just knock out the balls and then you can grind the outer down to the exact width you need
Title: Re: Primary chain tensioner
Post by: beezalex on 09.04. 2010 13:38
G'day Alex,
               did you rivet or bond (glue) it on. What type of teflon & how thick ??? I always thought it was a bit of an errr in the design.
Cheers

Well...teflon is kind of hard to glue (Nothin' sticks to it...really) so I attached it with countersunk screws at the ends.  One thing to be aware of is that the original tensioner has a hardened surface which makes it a B*TCH to drill through.  But once you do that (four holes, two at each end of the skid), a 1/4" thick piece of teflon attached with #8 CSK screws 1/8" below the surface has worked out well so far.  I really should have taken a picture before I put the cover on...maybe next time I have the cover off.
Title: Re: Primary chain tensioner
Post by: muskrat on 09.04. 2010 21:55
Thanks Alex, will put it down on the list of things to do.
This forum is really "full of it", ideas that is.
Cheers