Reverse hooked gearbox sprocket

Keith1069 · Oct 11, 2013

Ok I should explain what I mean. With all this talk about chains and that long thread going I took a closer look at my sprocket and drum. I use a 520 'O' ring and do lubricate it but not as often as I should (yes I know the resident chain man says no need!).
The drum is in good nick but the gearbox sprocket is hooked the opposite way I'd expect. Rotating CCW I would expect and usually see hooking to the right as the gear pulls on the rear wheel. Mine are hooked in the opposite direction. Any ideas?? clearly there are forces going on I don't understand. It was a modified 530 sprocket so will try a Dommie 1/4" this time.

staticmoves · Oct 11, 2013

I would imagine it is because you are seeing wear, as opposed to hooking that would be from a bending force.
evetually you will see the tops of those teeth dissapear all together, as they snap, or wear off.

pete.v · Oct 11, 2013

I would say that the radii of the base are wearing in and leave the impression of hooking in the wrong direction.

concours · Oct 11, 2013

Remember, without pics, it didn't happen :wink:

Keith1069 · Oct 11, 2013

I would say that the radii of the base are wearing in and leave the impression of hooking in the wrong direction.

That was my thought when I took another look. I can see where metal from the root of the tooth has been hammered and displaced, producing a radius that looks like the tooth has hooked. That's 14k miles after narrowing and 22k before. Here are the pics and thanks for responses......

[/img]

Matt Spencer · Oct 11, 2013

you can see the little burrs at the edges where the rollers have been doing there stuff , it sunk there & gone out .

NOW we can have a debate about ' Hardening ' . :mrgreen:

Hobot · Oct 11, 2013

If ya persist with 520 .240" wide teeth you will become familiar with deformed teeth. Yours is not much worn yet, as will fully fold/fan over or just pop off. Teeth shows newish mild chain 'stretch' yet to stay seated in valleys. The wear direction implies more time/loads applied to slowing up with engine drag than accelerating with engine power. Altas sprockets are direct no mod bolt on replacement. If much rev up engine braking in lower gears expect to visit bushes inside tranny too soon too.

texasSlick · Oct 11, 2013

Anyone have pics of a new sprocket for comparison? The right side (power on side) looks worn to me near the tops of the cogs.

I would not give up 50% of my bearing surface to run an O ring chain.

Slick

pete.v · Oct 11, 2013

texasSlick said:
Anyone have pics of a new sprocket for comparison? The right side (power on side) looks worn to me near the tops of the cogs.

I would not give up 50% of my bearing surface to run an O ring chain.

Slick

This one is almost new. Certainly not warn at all.

texasSlick · Oct 11, 2013

From PeteV's pics, it is obvious that some strange deformation is occurring on the left side as well. There seems to be wear near the tops of the cogs on the right, and in the valleys on the left. Anyone concur?

could it be the links are twisting CCW? That would stress the top on the right and the valley on the left.

Keith....is it possible to view the chain on the drive sprocket? Then apply rear brake and apply load to the chain with the kick start crank. If so, you may see how the chain distorts. This may be a useless exercise, as it appears you definitely need new drive sprocket.

Slick

pete.v · Oct 11, 2013

If the picture was taken from a different perspective it would look better. Rather then taking a close up, taking it from further away and zooming in would be a more realistic view.

Keith1069 · Oct 12, 2013

I would not give up 50% of my bearing surface to run an O ring chain.

Slick is probably right. Chains now last forever and don't stretch but drive sprockets wear more.

Anyone have pics of a new sprocket for comparison? The right side (power on side) looks worn to me near the tops of the cogs.

Not so much wear there but there is some.
I think I was surprised that the 'Hooking' was showing opposite to where I expected it but as pointed out by Pete V; the area on the low side of the tooth flank has been hammered by the chain rollers. I guess I'm more used to excessively stretched chains where they ride high on the teeth and the expected 'Hooking' occurs.

Keith....is it possible to view the chain on the drive sprocket? Then apply rear brake and apply load to the chain with the kick start crank. If so, you may see how the chain distorts. This may be a useless exercise, as it appears you definitely need new drive sprocket.

All apart right now (back to std cam and a minor bottom end rebuild (shells, fit valve oilseals properly (all the way down not on the top guide grooves that I've run all year, hence oily intakes etc). Fuel tank mount seeping, main fairing bracket needs some welding, swingarm with some movement in cradle).
Thanks for the comments gents. If it goes another 14k with a new sprocket thats 4 years riding for me and I'll be 65 yrs then, probably as long as I can expect to go

texasSlick · Oct 12, 2013

(

Thanks for the comments gents. If it goes another 14k with a new sprocket thats 4 years riding for me and I'll be 65 yrs then, probably as long as I can expect to go

Balderdash! I am nearly 73 and can still kick over the Atlas. Keep riding as long as you don't have a medical problem that precludes it.

Slick

Keith1069 · Oct 13, 2013

Balderdash! I am nearly 73 and can still kick over the Atlas. Keep riding as long as you don't have a medical problem that precludes it.

Nice one Slick. Had a femoral bypass in the non kicking leg just 2 years ago. Strength generally has not been the same since then, probably a bit in my head but I have to make sure she starts within 2-3 kicks from standing astride (usually does in 1 or 2) or I have to put the centre stand down and kick from there. I know an 80 year old with more strength than me and he's 40lbs lighter

texasSlick · Oct 13, 2013

Keith1069 said:
Balderdash! I am nearly 73 and can still kick over the Atlas. Keep riding as long as you don't have a medical problem that precludes it.

Click to expand...

Nice one Slick. Had a femoral bypass in the non kicking leg just 2 years ago. Strength generally has not been the same since then, probably a bit in my head but I have to make sure she starts within 2-3 kicks from standing astride (usually does in 1 or 2) or I have to put the centre stand down and kick from there. I know an 80 year old with more strength than me and he's 40lbs lighter

Well if the truth be known, I only start on the center stand these days. But hey! .... at our ages, we dont have to impress anybody....the young guys wont sneer, laugh, or ridicule us....besides, most of them will never have seen a Norton and will be amazed it doesnt start with a button! Moreover they will just leave thinking...."I cant believe that old fart is still riding". Remember what 'ol Churchill said...."never, never give up!"

Cheers,

Slick

andychain · Oct 13, 2013

Hooking is not caused by power. The pitch of a sprocket is fixed but the chain elongates
hence there is the quart into a pint pot syndrome. Something has to give and it is the
sprocket.

Andy

Lubing the outside of an O ring chain will have no effect on the sprocket wear.

Hobot · Oct 13, 2013

Hooking of .240" with teeth on full Commando torque can indeed fan em over till no chain traction but also wear may be aggravated/accelerated by sprocket teeth and chain link count-ratio phasing. Its just costs more time money maintenance to lighten up some components for race level performance-endurance, like tires and oil but the pay back may well be worth it. 14K miles with such nil effects is cost effective > for economy-ticket conscious throttle use.

texasSlick · Oct 13, 2013

@hobot 10-13-13 / 12.35 pm

Very informative post!

Keith1069 · Oct 14, 2013

Hooking is not caused by power. The pitch of a sprocket is fixed but the chain elongates
hence there is the quart into a pint pot syndrome. Something has to give and it is the
sprocket. Andy
Lubing the outside of an O ring chain will have no effect on the sprocket wear.

Definitely informative especially the above point (which makes sense to me) and Hobot's small pic/diagram.
Will measure the chain (difficult with O ring) and see how much it has worn since I have already stated it hasn't :? That comment was based on rarely needing to adjust, (only every 2000 miles instead of every 500 with DID heavy duty 530 I used to use). This 520 DID chain has done 50% more mileage than the non O ring 530 which were always totally knackered at 10k miles.

andychain · Oct 14, 2013

Keith I will make the point as I have done many times before.

There are many crap chains on the market. The original chain was 10B-1 and Renold.
This chain was excellent and worked well on 1000s of Commandos for many years. The fact
that Jap and ASA 5/8 catch various parts of the bike.

Instead of looking for a quality product most folks jumped to 520 and even O ring at that.

O ring will take HP off the bike and make your gear changes notchy. The only product I recommend
for Commandos is the iwis 10B-1. This chain has the advantage of a chromised pin (google it) and
is made well above the DIN standard. Yes it needs lube but is half the price of O ring and gives a
nicer ride. It is also very easy to fit and remove as it has connecting links and above all there
are crank links available for those bikes needing odd number of links, there are many Commandos
with this. As far as I know crank links have never been made for O ring and the same applies for
Jap chains.

Best regards

Andy

Reverse hooked gearbox sprocket

Similar threads