drive chain/chain guard interference

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Jul 8, 2007
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I'm looking for advice on this topic. I did a search but didn't find a solution.

I'm using a stock drive chain size, but a Fair Spares (UK) stainless chain guard instead of the chromed steel stock part. At the front of the chain guard, at the bolt, the chain is perfectly in the center of the chain guard. However, where the chain exits the rear of the chain guard to curve down and follow the brake drum/rear sprocket, the chain is up against the left side of the chain guard.

The left lower shock mount bolt which captures the chain guard is the correct thin-head variety. I'm stuck for another way to move the chain guard left and away from the chain, or to move the chain right and away from the chain guard, or both.

The only way I can even theorize to fix this is to make the bracket captured by the shock bolt, smaller horizontally. This might move the chain guard 1/8" to 1/4" left and give some clearance. Is it possible that rear wheel mis-alignment could cause this?

Surely it can't be correct that the chain is *supposed* to rub on the left side of the chain guard, can it? My chain is rubbing so much on the inside of the chain guard that a line is appearing on the *outside* of the chain guard, as a rub line.

Best regards,
Ken
San Jose, California
 
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Kenward, Can you not simply bend the chain-guard away from the chain? I generally have to do this with any chain guard I fit to get it centrally located without any rubbing. Given that your guard is stainless this may require a fair bit of force. I would also check that there is not excess clearance between the head of the slim-headed mounting bolt and the body of the guard itself, if this is the case you may have to squeeze the rear bracket in a vice to bring the guard closer to the shock absorber.
Good luck
Dave
 

Ron L

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Sounds like your problem is the bracket for the rear mount. Even with the stock guards, there is very little space between the chain and guard here. A slightly wider rear bracket pushes the guard against the chain. As Dave says your options are to bend the guard or squish the bracket.

There is no way to change wheel spacers or sprocket without affecting the alignment of either the chain or the wheels.
 
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I dealt with the rub on my 750 by going to an o-ring chain and ditching the chainguard! :lol: I use chain wax so no mess.

On the 850 I'm going to run a standard chain for now to help keep the cost down. I'll be using the 750's guard on it, so it sounds like I'll be doing some bending and squeezing. :shock:

Nothing unusual about that however. Rarely does an item simply bolt on, at least in my experience.

Debby
 
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Well, I guess I need to remove the chain guard and squish the bracket, as there doesn't seem to be anything else I can do.

Is the head of the lower shock bolt, which also captures the chain guard, hard up against the chain guard itself? My bolt has a thin head, so closing that gap seems my only choice.

Best regards,
Ken
 
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The reason the head of the bolt is so slim is that it is meant to fit into a small gap between the bracket and the guard. If there is excess clearance then this is your problem and a quick squeeze in a vise will do the trick.
 
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debby said:
Rarely does an item simply bolt on, at least in my experience.

Debby

Words of wisom and very true.

BTW, what kind of chain wax are you using Debby? I've used Boesheild on bicycle chains and that is about it.
 
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Coco said:
BTW, what kind of chain wax are you using Debby? I've used Boesheild on bicycle chains and that is about it.

I'm using Maxima Chain Wax. I've heard of people using Boeshield on motorcycle chains but haven't tried it myself.

Debby
 
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A bit off the thread here but I just had my rear and front sprockets machined for 520 chain by Stenor Engineering (www.stenor.com). Not a lot of use for those outside the UK but for anyone who is interested they did a fantastic job. 7 day turnround including post each way and only £50 for both including post which was 25% of the total! Workmanship looks good and they are keen to more of these.
 
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kenward1000 said:
I'm looking for advice on this topic. I did a search but didn't find a solution.

Surely it can't be correct that the chain is *supposed* to rub on the left side of the chain guard, can it? My chain is rubbing so much on the inside of the chain guard that a line is appearing on the *outside* of the chain guard, as a rub line.

Best regards,
Ken
San Jose, California

Ken--

I'll take some measurements for you tomorrow. The whole back-wheel Norton concoction can get a bit confusing. Ask me how I know. I suspect a lot of Norton guys and gals have been fussing over this time and time again.

Cheers--

wrench
 
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drive chain/chain guard interference


I'm practicing posting photographs so I thought I'd show the chain guard and its interface with the shock bolt. Note the thin head, which is not a garden variety hardware store bolt.
 
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My 750 did not have the correct bolt fitted there. It had (and still has) an ordinary thick-headed bolt. I suppose that could have been part (or all) of the problem. I have the correct bolt now, but haven't gotten around to fitting it, since that requires breaking the chain and removing the brake drum.

I bought a CNW chainguard for the bike, but the mounting clip is quite a bit smaller than the stock chainguard's, so I have to grind a wrench way down before I can install it. That means hours of tedious work on the bench grinder, so I've been putting the task off.

It's all on my list of things to do... :roll:

Debby
 

L.A.B.

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debby said:
I bought a CNW chainguard for the bike, but the mounting clip is quite a bit smaller than the stock chainguard's, so I have to grind a wrench way down before I can install it. That means hours of tedious work on the bench grinder, so I've been putting the task off.

Or...insert a screwdriver blade (or Allen key/wrench etc.?) of a suitable size between the bolt head and the clip to stop the bolt turning while you do up the nut?
 

Ron L

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Or...insert a screwdriver blade (or Allen key/wrench etc.?) of a suitable size between the bolt head and the clip to stop the bolt turning while you do up the nut?

Les, you're giving away the secrets! :roll:

Debby, I don't know that I would bother with thinning a wrench. I did that years ago only to find that the jaws of the wrench are too large to fit inside the clip anyway. Look closely at Jason's photo. Les has the answer. I don't know why Norton didn't think to put a square hole in the swingarm bracket and chainguard clip and use a "stovebolt" here.
 
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Ron L said:
Les, you're giving away the secrets! :roll:

:lol: :lol: :lol:

That's a great idea. Problem solved! :D

Why couldn't I think of that? :?

Thanks guys!

Debby
 
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Chain Sizes

Chain clearance problems are often caused by the difference in width between modern 530 chains and the original Renold chain. Fitting a original size Renolds often fixes any clearance issues. Pity they're so expensive...
 
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Jason Curtiss said:
Same picture just quite a bit bigger.

Nice photo and work there Jason. Very helpful.

Ken.... I did e-mail you some measurements. Let me know if you did not get them.

Cheers--

wrench
 
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