Author Topic: Adjusting the Rear Chain!  (Read 2736 times)

Offline LJ.

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Adjusting the Rear Chain!
« on: 22.07. 2007 08:47 »

Grrrrrrrr Grrrrrrrr!  *problem* Just what is the secret in adjusting this chain? Lemmee explain...

Had to adjust the primary chain yesterday, easy, just move the gearbox back a little until the chain is the correct tension. This then slackens the rear chain which then needs adjustment, is this also easy?? NOPE!

I had put on a fully enclosed chain case, new rear sprocket and a 22 or 23 tooth gearbox sprocket along with new chain, all this fitted not so long ago. What I don't understand is how the chain can appear very slack in one place and then quite tight after turning the wheel half way round?? ??? What's happening here? The first thing I checked, was to see if the wheel was running straight, in which it is.... Is it time for yet another chain? this one not having done many miles! Yet the chain is clean... well lubed. What more can I do?
 *help*
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Online bsa-bill

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Re: Adjusting the Rear Chain!
« Reply #1 on: 22.07. 2007 10:29 »
check that gearbox and rear wheel sprockets are turning true, most likely they are but could just be bent mainshaft/or dummy rear shaft or badly machined gearbox/rear sprocket.

new chains do sometimes have tight spots

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline a10gf

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Re: Adjusting the Rear Chain!
« Reply #2 on: 22.07. 2007 14:09 »
LJ, hope your are not under water !

Seem to remember the phrase, "adjust the chain for correct tension at the tightest spot", if it then does not seem extreme loose at some point do not worry (of course must not risk touching anything). IMO better with a little too loose chain than too tight.

For a test, mark the tightest spot on the chain as it is now, loosen it then change it's position relative to front \ rear sprocket and see if the tight spot moves, then make your deductions about what can cause it (off center sprockets, bent shafts, uneven chain), if you really want to go into it, and have plenty of time and inspiration, you may tweak the position of involved parts to compensate and distribute any unevenness between them, or buy new parts till the problem (by chance) goes away *smile*

Good luck
E.

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Offline Beezageezauk

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Re: Adjusting the Rear Chain!
« Reply #3 on: 22.07. 2007 20:19 »
Hi LJ,

I've had this problem myself and proved that the chain had stretched in one place more than the other.  Although I didn't have a fully enclosed chainguard.

I took the chain off and threaded an old one on temporarily at the same time.  I laid the suspect chain on a piece of clean cloth with the open links facing upwards.  Then I tried to bend the chain into an arc and one part arched round more than the other.  I took a one metre straightedge and measured the distance from the centre of the straightedge to the chain at its tightest spot, then did the same at the slackest spot for a comparison. 

If the difference is as much as you have described, and considering the mileage that you do, I would suggest that you replaced it.  If not, it will certainly get worse rather than better.

You can always complain to your supplier in the hope that he might replace it!!  If he won't (or can't) you can always cut the bad section out and keep the good bit for spares. 

BTW, do you know if it is from a well known manufacturer.  It might be an industrial chain that is not meant for the rigours of a motorcycle.

Let us know how you get on.

Beezageezauk.

Offline fido

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Re: Adjusting the Rear Chain!
« Reply #4 on: 23.07. 2007 08:07 »
Yes, a lot of the loose chain available at autojumbles is not proper bike chain so you are safer with a purpose made length in a box.

Offline dpaddock

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Re: Adjusting the Rear Chain!
« Reply #5 on: 05.08. 2007 13:52 »
As stated, use only Renold or other quality motorcycle chain.
Also as stated, tension the chain at its tightest position with someone in the saddle. Make sure the chain is ALWAYS slack - nothing destroys a chain like running it too tight.
David
'57 Spitfire


Offline fido

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Re: Adjusting the Rear Chain!
« Reply #6 on: 06.08. 2007 08:08 »
Lawrence, If you like you can swap your A10 for my rigid A7. The A7 rear chain lasts longer as it's not constantly going up and down with the suspension. The primary chain is a nice duplex type with it's own adjuster, no mucking about with gearbox position  ;)