rear chain adjustment

[mikeb]

sorry if this has been well answered, but i cant find any threads about it (tho half recall reading some once).
So, adjusting the rear chain on a swing arm super rocket (not enclosed chain case): obviously you need 2 helpers 3 days and 4 arms as its much tighter off the stand than when on it, prompting repeated trial and error adjustments (on centre stand) and tests.

can anyone share their clever tricks for doing this boring job without an army of helpers and heaps of time

thanks
Mike

[beezermacc]

Undo the lower shock mounts, slacken the top shock mounts and swing the shocks out of the way. Put something under the rear wheel, better still under the ends of the swinging arm, so that the chain is at its tightest spot, check for tight spots, then set the wheel so that there is a little bit of slack in the chain. Beware that the swinging arm is set in torsion blocks so it won't (shouldn't!) lift as easily as you might expect but the weight of the bike is normally enough to stop the whole thing lifting off the floor when you're raising the back wheel. It's still easier with a bit of help!

[bikerbob]

On this site go to Service Literature Scans etc. Then Instruction owners manuals The last one in the shaded section Swinging arm manual from 1959 go to page 36 where it describes adjusting the rear chain which should have 11/4 inches of free movement for me the main problem when adjusting the chain is to get the  the wheel alignment correct assuming that it is correct before adjustment then just count the number of flats on each side when adjusting the adjuster bolts. I have a jig which is made up of 2 lengths of wood which clamps the front and rear wheels with compensation at the front for the difference between widths of the front and rear tyres and notches cut out for the center stand this fits both my A7 and A65 using this I can get accurate wheel alignment.

[jachenbach]

Adjust it per the book, put it on the centerstand and measure the slack. You then have a new spec and easier procedure.

[Billybream]

Adjust it to the book works for me, just ensure the rear wheel is off the ground.
You may find if two up or fully laden the chain may need to be readjusted.

[Butch (cb)]

I just do it on the side stand. Is that wrong?

[duTch]

 I'm no expert, but when adjusting a chain, I figure that having the chain in riding mode ie; Mainshaft centre /S/A spindle/ axle in line being the tightest possible, and back it off a bit from that. logic being that on large bumps (we have them here, it's what we pay rego for) it won't stretch to the max.

 To do that would be best as explained above, or at least on no stand, just balance it somehow stick props under the H'bar ends or some other magic shite.

   Having said that, I only run a Plunger, which is different so if I wanna get serious(reluctantly)) have to pull it down to max with ratchet straps to ensure max tight, and back the adjusters off a tad or two (that's around a beesdick or four), so there's about a half inch or so at max tight which gives about an inch or so at ride height- seems to work so far after 10K miles, but still working on it.

[Slippery Sam]

Not done many miles on mine - but a chain's a chain and the same applies to BSA and Honda alike.
Try a paddock stand - you'll never find anywhere to put bobbins - so use one that can take the cups that fit under the SA.
Alternative is - adjust on the centre stand but don't nip the spidle - drop to the ground, check slack - back on the centre stand and either re-adjust or nip up (one man job - if not the quickest).

cheers Raymond.

[Peter in Aus]

My book says adjust rear chain on the center stand with 1 1/4" slack in the middle, that is what I do
Peter

[mikeb]

thanks for the tips guys. yes a chain is a chain is a chain, and I may have been over-complicating this, but the difference between on and off stand is more than i expected. i need 2"-ish on stand to get 3/4"-1" off stand with weight on the bike. mine is way different when on the side stand compared to centre stand or on the wheel and weighed down. wheel alignment not too hard with a steel bar alongside the tyre surfaces inside the centre stand - I'll try the string trick next time (as per a different post on the forum).
i tired the tie-downs on the swingarm across the seat trick and it was especially useful when putting new shocks on last week with the new rubber bushes being much tighter.

so problem solved for now.

cheers
Mike

[BSA500]

For the alignment side of things I get the measurements from the centre of the swingarm spindle to the wheel spindle the same. Then I don't have to construct/find a straight edge that avoids the main stand etc.

[Peter in Aus]

For the alignment side of things I get the measurements from the centre of the swingarm spindle to the wheel spindle the same.

Sounds simple but just how do you do that?
Peter

[Greybeard]

I've been sighting along the back tyre edge to the centre stand. Seems to work.

[duTch]

Quote from: BSA500 on 22.02. 2017 11:39

    For the alignment side of things I get the measurements from the centre of the swingarm spindle to the wheel spindle the same.

Sounds simple but just how do you do that?
Peter

 maybe ...with a measuring stick ??

[BSA_54A10]

Because the chain is not concentric with the swing arm, it will be at the tightest on full swing, up or down & loosest with the swing arm parallel to the ground
Naturally the slack in the chain will vary as the chain swings through it's full arc
The figures given are the minimum slack at the tightest point which is either fully compressed or fully dropped, the latter being the easier to do
You can fully compress the shock by using a pair of ratchet tie downs to load up the swing arm.

Wheel alignament
Prop the bike or get someone to hold it upright.
Use a plumbob to drop a vertical line from the middle of the axels and mark that spot on the ground ( nails in your lawn, sticky dots on a floor, chalk on concrete.
Move the bike & measure the distance between the font & back dots