Chain Tension Issue

[Miztaziggy]

Well I'm no engineer, but I do have a degree in physics, so don't blame me if it doesn't work in practice even though it's fine in theory!!! Lol

[tony.mon]

Have you by any chance had the wheel powder coated?
Because if that isn't even it would produce ovality effects in the sprocket, and could explain why the sprocket is stiff on the hub.

[tinysmall]

Have you by any chance had the wheel powder coated?
Because if that isn't even it would produce ovality effects in the sprocket, and could explain why the sprocket is stiff on the hub.

But then wouldn't that be with all sprockets? His old one was fine when he refitted it.

[vtryorks]

Yes the wheel is powdercoated and I have considered that the coating may result in the carrier not sitting parallel to the hub. However, as tiny says, surely this would be a trait for all sprockets. Plus isnt a buffer provided by the cush drive rubbers? Or am I misunderstanding?

[vtryorks]

Well I have now fitted Renthal sprockets, front and rear. The issue persists and it is still once per wheel rotation, 10mm.

I have decided to bite the bullet on this one and take it to a reputable race mechanic for investigation. Hopefully it is something simple, but I've gone back over everything that was suggested and tried them, with no luck. Well at least, if it is one of these issues, I'm unable to spot it.

I'll report back once I find out what it was.

[tony.mon]

Yes the wheel is powdercoated and I have considered that the coating may result in the carrier not sitting parallel to the hub. However, as tiny says, surely this would be a trait for all sprockets. Plus isnt a buffer provided by the cush drive rubbers? Or am I misunderstanding?

What I was thinking of was that there could be a blob of PC on the edge of the hub housing, causing the hub /sprocket carrier to sit out of true.

Let's see what the workshop tech says.

[vtryorks]

I've looked Tony because you're absolutely right, that would set the carrier out of true and therefore cause a cam effect. I've checked it though and I couldnt see anything, even with the carrier and rubbers out.

Maybe I've overlooked something but I guess I will find out soon enough. Mostly I'm tired with messing with the chain tensioners. The way they operate drives me nuts and its hard to make the tiny adjustments I need to test a new setup each time.

I feel like I've gone as far as I can with it, taken everyones advice seriously but I'm just going around in circles.

[Miztaziggy]

Yes the wheel is powdercoated and I have considered that the coating may result in the carrier not sitting parallel to the hub. However, as tiny says, surely this would be a trait for all sprockets. Plus isnt a buffer provided by the cush drive rubbers? Or am I misunderstanding?

What I was thinking of was that there could be a blob of PC on the edge of the hub housing, causing the hub /sprocket carrier to sit out of true.

Let's see what the workshop tech says.

I had thought the sprocket would have been out of alignment on the wheel also - but - he said that when he installed his old sprocket, it was fine, which narrowed it down to the sprocket itself. Now he has tried a 3rd sprocket and that one is out also, it is very odd and confusing!!

[vtryorks]

Ziggy you're right mate. It is confusing, but I am absolutely positive that nothing has changed during/since the swaps. I deliberately left the carrier and rubbers in place so as to standardise the fitment between sprockets as much as possible. Nothing I do is making any difference.

I am not under illusions about my ability, its limited, but I'm not so stupid as to get spacers the wrong way around or refit the wheel incorrectly etc. Just feel like I've tried everything humanly possible with this, at least as far as my knowledge goes (utilising much help from here I must add).

[AMCQ46]

this is strange, short of fitting the sprocket on in all 6 positions and trying again, I dont know what to suggest.

There has to be someting in the hub making teh sprocket run eccentic, but why did you old sprocket seem to be imune?

has the old sprocket been "fettled" in any way, is there signs that someone has been at any of the mounting holes with a dremell or a file?

was the new renthal sprocket as tough to fit over the hub as the other steel one?

[vtryorks]

The old sprocket did not appear modified at all.

The Powerite sprocket (DID kit) was a tight fit, but the Renthal was NOT a tight fit at all. That just adds to the confusion. I did my best to centre the Renthal correctly, applying half torque on opposite bolts, then applying full torque in the same way.



Will have to wait and see, I really hope its not something totally stupid that I have missed. A fresh pair of eyes will remove "snow blindness" at least.

[Wicky]

Most peculiar - have you looked at the swing arm bearings, is there any play in that department? Also what's the output shaft & sprocket like under the clutch cover?

[tinysmall]

Very peculiar, and whilst it's not good that you are having to spend money to get this fixed, I am looking forward to finding out the cause.

[vtryorks]

Most peculiar - have you looked at the swing arm bearings, is there any play in that department? Also what's the output shaft & sprocket like under the clutch cover?

Swing arm bearings I cant check as I only have an Abba stand unless someone has a way to test whilt its on that.

Considered the other suggestion, but any deformation on the output drive shaft would result in 2 or more tight spots during each wheel rotation due to the ratio/gauge of the shaft vs the rear wheel and sprocket. Front sprocket has also been replaced, I've tested it with two new sprockets, same result each time.

I'm looking forward to finding out the cause too. Trouble is, I suspect its going to be something blindingly obvious and a bit of an anti-climax.

Then again, I always say that any climax is better than none at all

[Miztaziggy]

If this sprocket has some movement when you put it on the bolts, then it is most likely off centre and causing a cam effect.