7 or 8 tooth sprocket

[pbuehning]

Would someone please explain, to this newbie, the pluses or minuses of a 7 tooth compared to an 8 tooth sprocket on a Homey Super XL AO. I've tried to understand some of the past threads, but, sometimes you guys go off on tangents. ROF-LMAO Thanks.

 

[Lawn Masters]

a 7 tooth sprocket gives optimal torque, while the 8tooth sprocket essentially gives you 14% more chain speed, with 14% less torque. I generally like the 8t rims on my saws, but I mostly have short bars and big motors too.

 

[skwerl]

A higher number of teeth on the sprocket is like a higher gear in your truck. lower tooth count equals lower chain speed but more available torque. Higher tooth count equals higher chain speed but less available torque. You generally want the highest chain speed that your saw will pull without excessive bogging. The faster chain speed means faster and smoother cutting.

 

[pbuehning]

Thanks. Forgot to add, 20" bar used mainly for bucking.

 

[Mr.]

A higher number of teeth on the sprocket is like a higher gear in your truck. lower tooth count equals lower chain speed but more available torque. Higher tooth count equals higher chain speed but less available torque. You generally want the highest chain speed that your saw will pull without excessive bogging. The faster chain speed means faster and smoother cutting.

By higher gear in your truck, he means lower number. I know skwerl knows this I just hate it when people confuse this.

Fred

 

[Mr.]

What do you have against the 9 pin roller sprockets?

Fred

 

[bwalker]

Some saws need 8 pins to run up to there potential. The 372 comes to mind.
Many people do not like bigger sprockets because they run bad chain and have poor operator technique. The higher tooth count sprockets are less forgiving whe use din conditiosn like this.

 

[Mr.]

The 9 pn was a joke. Don't overgear your saw or it will fall flat on it's face.

Fred

 

[bwalker]

I have never pseen a 9 pin for sale, so I have never tried then. A 8 pin works great on a 7900 and a 372 though as I have run em on both.

 

[Mr.]

I use Danzco. I have 8-14 pin custom roller sprockets.

Fred

 

[Tree Sling'r]

When we are falling hard butted doug fir, I sometimes will use a 7 tooth (not very often) on my modded 66s. I run my rakers lower than most, so on a hard butted tree, an eight tooth does not have the torque to get the chain through the wood good enough. But, on the other hand I use an 8 tooth mostly. I back bar a lot when I fall and an 8 tooth sproket with a good chain is sweet for limbing the beast of a tree I just killed.

 

[timberwolf]

Square filed 16 inch chain on my 066 and it is a toss up between 9 and 10, smaller softer wood and the 10 would be best, hard wood 11-12 inch or more and the 9 would take over, Ben I would think the 372 or 7900 could do ok with a 9, as long as the chain was sharp and the rakers set around .025 (depending on how far back the tooth is).

 

[WRW]

By higher gear in your truck, he means lower number. I know skwerl knows this I just hate it when people confuse this.

Fred

Did you mean "lower ratio"?

 

[Mr.]

A saw is one rotation to the sprocket. So more teeth the faster it turns.

On a truck, assuming it is in fourth gear and that fourth gear is 1 to 1 (manual), For every one turn of the engine the rear end will turn a fraction of a turn. Gears such as 3.00 to 1 and 2.72 to one are high gears and 4.11 and 4.55 are low gears. The lower the gear the slower it turns.

4.11 gears in a truck, seven pin. 3.00 gears in a truck 8 pin. You have the potential to go faster, kind of with the truck there are many more issues here, but you sacrafice torque to do it.

I know skwerl was just making a comparison and understands the concept.

Fred

 

[Crofter]

Mr.: skwerls intent and words gave no confusion to the issue he addressed; yours have. Unless it adds to the understanding of the issue it is only quibbling, no?

"A saw is one rotation to the sprocket. So more teeth the faster it turns"

I think you should go back and clear up the obvious potential for misunderstanding in your above statement.

I agree that too tall of gearing either on a saw or a vehicle is counterproductive. I thought skwerls post a decent anology and thought your ripping it up, questionable

 

[Mr.]

Sorry for the confusion. Use skwerls analogy. Not my intentions at all.

A saw is one rotation to the sprocket. For every time the crank turns 360 degrees the sprocket turns 360 degrees. I f there are more pins then the chain will run faster at the same rpm of the saw.

I was simply responding to wrw. I thought someone would see... Oh nevermind.

Fred

 

[Simonizer]

a 7 tooth sprocket gives optimal torque, while the 8tooth sprocket essentially gives you 14% more chain speed, with 14% less torque. I generally like the 8t rims on my saws, but I mostly have short bars and big motors too.

Excellent and fairly accurate answer. (14.28%) Cheers.

 

[Kneejerk Bombas]

A word of caution, if you go with a much larger rim, you might need to add a drive link to your chain.

 

[Mr.]

I add one for every extra pin and cut the bar at 11 pins some start sooner.

Fred

 

[Crofter]

Makes a diff too whether or not you have outboard clutch. I have seen a few horrid butcher jobs on the ends of bars to accommodate a larger sprocket. I think that is also referred to as a boob job. Some even have the silicone too, to keep the blinker fluid where it belongs.