Author Topic: Tight Primary Chain  (Read 805 times)

Offline tommo903

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Tight Primary Chain
« on: 13.10. 2016 13:46 »
Hi all,

While I was in the process of changing the oil in the primary chaincase a few days ago, I noticed that the chain was very tight, no give whatsoever. I haven't adjusted it yet but slightly more worrying is that I've no idea how long it has been like that, as I only bought this A7SS a couple of months ago and only done a couple of short rides.
Can anybody tell me please what possible impact this may have had to any of the other components and would it be wise to bin this chain for another?

Thanks, Steve
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Offline TT John

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Re: Tight Primary Chain
« Reply #1 on: 13.10. 2016 14:15 »
Could be that the gear box was not tightened up correctly, causing the wheel to drag it back re-adjust the gear box and make sure that it is secure after adjustment , then check the drive chain at the wheel and adjust, no need to throw out a good chain, it should be okay, I doubt if it would have caused any damage.

TTJohn
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Offline Billybream

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Re: Tight Primary Chain
« Reply #2 on: 13.10. 2016 17:11 »
When adjusting the gear box mechanism don,t forget the bolt under the gear box, best not to loosen to much when making the adjustment. This bolt then needs to be quite tight after adjustment has been made. Also the rear chain will need checking after any adjustment to the gearbox.
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1960 Super Rocket, owned since 1966, back on the road 2012 after being laid up for 29yrs.

Offline Rocket Racer

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Re: Tight Primary Chain
« Reply #3 on: 14.10. 2016 00:26 »
Certainly worth checking primary chain tension routinely, its easy to get wrong and so easy to check. If the gearbox can, it gets pulled backwards by the loads on the drive chain so will always tighten up rather than loosen.
And while you should be fine; too tight will put additional loads on the drive side main bearing and the gearbox sleeve gear bushes  - there's quite a lot of overhang from the gearbox bearings to the primary chain, as well as wear the primary chain and sprockets faster and typically generate a lot of heat.
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A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline Greybeard

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Re: Tight Primary Chain
« Reply #4 on: 14.10. 2016 09:27 »
Plunger frame + semi-unit engine/gear box = smug face  *roll*
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Offline The Artful Bodger

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Re: Tight Primary Chain
« Reply #5 on: 14.10. 2016 10:09 »
My Huntmaster will tighten the primary chain every time it's adjusted if I use the adjusting bolt to tighten the chain until it's about right. Due to play / backlash in the adjusting bolt area, the back wheel can pull the gearbox backwards tightening the chain by taking up this backlash.
  By slightly over tightening the primary chain then turning the adjustment bolt the other way to loosen it off slightly, the back lash is taken up and the gearbox is hard against the adjusting bolt stopping it from being able to be pulled towards the rear by the back wheel. Never had a problem since I realised this.
Colin
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Offline Greybeard

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Re: Tight Primary Chain
« Reply #6 on: 14.10. 2016 10:22 »
...back lash is taken up and the gearbox is hard against the adjusting bolt stopping it from being able to be pulled towards the rear by the back wheel...
Makes a lot of sense to me.
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Offline raindodger

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Re: Tight Primary Chain
« Reply #7 on: 14.10. 2016 13:41 »
Totally agree with T.A.B.  been doing the same for years.

Tim.
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