Over tight chain-funny noises

[1034am]

Hello, sorry if this topic has been covered, but my searches haven't yielded any results.
I recently installed a Gsx rear shock and mistakenly adjusted chain w/bike on stand instead of rider weight. When I rode it my weight tighten up the chain so much that I started hearing grinding noises.
I think it's the bearing behind thr front sprocket (shift shaft?)
Can anyone confirm this? Is there a link to illustrate repair procedure?
Thanks!

[J_Walker]

New chain?

O-ring chain or just rollers?

Just sounds like it's dry/stretched chain. when you rotate the tire like say the bikes off and you're rolling forward. you here any pops or cracks? if so the chains just warn.

[Joolstacho]

You MIGHT be lucky, but typically an overtight chain can ruin the gearbox output shaft bearing, or worse, can 'chop out' the bearing housing (in the casing).

[Watcher]

I don't know a single bike that calls for chain slack to be set with rider weight on the bike.

They're set with static weight on the rear end, typically just sitting on the side stand (NOT on the center stand).  IIRC factory spec is 20-30mm (1" +/- ~1/8").  That should leave more than enough slack when you're sitting on it, considering the GSXR shock is probably stronger than the factory GS shock.


I'd double check that your chain is in proper adjustment, in alignment, and I'd spin the rear wheel while observing the chain for seized links.

[1034am]

Chain is 1yr old, always been aligned perfectly.
The new rear shock jacked the back up about 4-6" at the end, and seemed to have more travel. I adjusted chain tension w/bike on side stand. The grinding noise was immediately apparent first ride, but I thought it was the front brake shoes (because I heard it when coasting, and it sounded like when brake shoes give out.)
Brakes checked out ok, so I re-adjusted chain tension w/weight on seat. (When unweighted chain was much looser on side stand than before.)
With chain properly adjusted noise is much better, but still present. (Metal-on-metal, dirt in bearing case, etc.)
It looks like outer bearings aren't too hard to change. Anybody know a link on replacing?

[J_Walker]

It looks like outer bearings aren't too hard to change. Anybody know a link on replacing?

I got bad news for you.. the ONLY way to replace that bearing, is by literally taking the WHOLE engine apart all the way down to the transmission halves. ... I think the only thing you can replace without splitting the cases behind the front sprocket is the little rubbery black bit.

http://cdn1.bikebandit-images.com/schematics/schematics/suzuki/suz012/su0209026091.gif

Be 100% sure it's not that chain, of anything else for that matter.. rear tire rubbing on something, chain rubbing on the hard plastic guides, or chain guard.

[user11235813]

Bike on centre stand, push chain up, it should very almost nearly touch the plastic guard on swing arm. This gives the same result as factory method but easier.

[gregjet]

Ok , first don't panic!...yet.
If you have overtightened the cahin there are TWO bearings that are likely to fail. The sprocket carrier and the counter shaft one. The CS one is smaller but the sprocket carrier is less lubricated and has a bigger leverage on it.
It can be very hard to tell where the actual sound is coming from.
If it is the sprocket carrier it is dead easy to change , so long as you havent split the carrier ( seen that one).
If it is the CS one , you can now officially start crying caus it is a case splitting job. Not hard to change the bearing but a gigantic job getting there. I have seen grown men buy a new motor rather then try and fix it.

Chain tension. The geometry of a CS mounted forward of a swingarm pivot means the tightest point is with the centre of the CS, swingarm pivot and the rear axle in line. The furthur up or down , the more slack it will be. If you put a shock that sits the rear axle lower ( than the original line) is will be a slacker point. If you then tighten it to the described tension is will be MUCH tighter as it passes through the 3point line and can be a huge load. With a longer shock, on this bike the unloaded chain tension MUST be slacker than stock.

[Sandgroper57]

Check your chain isn't touching metal at the front of the swing arm. It may have worn through the rubber guard due to the different angle.

[1034am]

Thanks for the help. I wanted to check w/the experts. I'm hoping to change spocket carrier & see if that works. Otherwise, winter is coming...

Quite a geometry lesson. Took me a couple reads to get it. Seems to fit exactly. I wonder if it was chain tension alone supporting me! I took about a 1/2 turn out of the adjusters.

Thx.

[Joolstacho]

"I don't know a single bike that calls for chain slack to be set with rider weight on the bike".

-This technique has been standard practice for many many years on almost any bike. As Gregjet says the 'normal' Swing Arm geometry is such that the rear suspension needs to be depressed a bit by the rider's weight and the specified slack measured with that deflection, -that way there should be adequate tension at both 'ends' of suspension travel.

[pliskin]

All 3 of my resent bikes called for chain slack to be set on the stand. This is right from the factory manuals. Setting the slack with load on the suspension is not a good idea IMO. Doing so could cause the chain to jump when the suspensions drops because the chain will be to loose. The trick to setting the slack on the stand is so the chain tightens slightly when you sit on it. If you don't have the right amount of slack it could be to tight when you sit on it.

[1034am]

Can anyone provide me with info regarding changing the shaft bearing? I've read in multiple places that it's possible to change (outer) without cracking open the crankcase, but all I can find is info on the seal.

Regarding the debate on loaded chain tension please keep in mind this is a long travel gsx rear shock on a gs500, so conventional thinking may not apply.