8 tooth drive sprockets vs 7 tooth

[Mountain800]

How would changing from the 7 tooth drivers on my Axys to old 8 tooth Pro drivers affect my gearing ratio? Any one done this? Positive/Negative affect?

Also : does someone know for sure differense on running ethanol/premium fuel setting? Is it Just mapping richer? Timing?

Thanks.

 

[mountainhorse]

IMO... the decrease in-lug tip clearance will negatively affect your performance.

What AXYS sled do you have? (model, track length and lug)?

Moving to the 8 tooth will raise your ratio, which is counter-intuitive for mountain performance... but may be good for flatland use if top speed is your goal.

As a note... the belt drives don't "shine" for high speed use.

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[Mountain800]

SKS 155" with the 2.6. But iam changing to challenger extreme 2.5.
Mykkje theory for changing drivers is rolling resistance. I thinking the pro chassis "rolled" easyer. ... any thoughts? I do see the disadvantage inn clearance. But again the pro chassis hadde the 8 with no problems.

 

[byeatts]

IMO... the decrease in-lug tip clearance will negatively affect your performance.

What AXYS sled do you have? (model, track length and lug)?

Moving to the 8 tooth will lower your ratio, which is counter-intuitive for mountain performance... but may be good for flatland use if top speed is your goal.

As a note... the belt drives don't "shine" for high speed use.

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hmm raising to 8 tooth's will not lower ratio , it will raise ratio about 7%.. MH is very sharp and I'm sure its just a typo.

 

[ak]

SKS 155" with the 2.6. But iam changing to challenger extreme 2.5.
Mykkje theory for changing drivers is rolling resistance. I thinking the pro chassis "rolled" easyer. ... any thoughts? I do see the disadvantage inn clearance. But again the pro chassis hadde the 8 with no problems.

Seeing that your in Norway ( not real high altitude) And your going to a slightly less lug height I would use the 8 tooth.

 

[Mountain800]

Thats what I also think. Higher not lower. But sure this is what he meaint.
And I am thinking of going 8 because less "rolling" resistance. And better "grip" on track. Isnt there more folks experiencing a "braking" effect on axys vs pro chassis when of the throttle? Not sure this is on only the drivers....and I thinking I could gear lower in chaincase to solve gearing beeing Higher. ...any thoughts?

 

[byeatts]

Thats what I also think. Higher not lower. But sure this is what he meaint.
And I am thinking of going 8 because less "rolling" resistance. And better "grip" on track. Isnt there more folks experiencing a "braking" effect on axys vs pro chassis when of the throttle? Not sure this is on only the drivers....and I thinking I could gear lower in chaincase to solve gearing beeing Higher. ...any thoughts?

I have a small mod shop and have been building very strong Mountain sleds with 3 inch tracks since the 3 inch was developed, I am new to Polaris and have primarily been building Doo,s so I ask the veterans who have been running the poo,s questions, Your never too Smart to take advice. anyways the 3 inch track when going from a 2.5 is spot on by simply making the 8 to 7 driver change , The 7% keeps everything in check without any gearing change although the stock Poo,s are geared too high for mountain riding right from the start. the clutch will never be at a 1-1 shift ratio which gains about 10% efficiency during mountain riding. IMO 2.3 ratio is the best for the 8 tooth /2.5 track

 

[Mountain800]

I have a small mod shop and have been building very strong Mountain sleds with 3 inch tracks since the 3 inch was developed, I am new to Polaris and have primarily been building Doo,s so I ask the veterans who have been running the poo,s questions, Your never too Smart to take advice. anyways the 3 inch track when going from a 2.5 is spot on by simply making the 8 to 7 driver change , The 7% keeps everything in check without any gearing change although the stock Poo,s are geared too high for mountain riding right from the start. the clutch will never be at a 1-1 shift ratio which gains about 10% efficiency during mountain riding. IMO 2.3 ratio is the best for the 8 tooth /2.5 track

For tree riding (slow speed crawling lots of throttle on off) I found the old pros best gearing choice was 19/43 in chaincase. 8 tooth. IT saved belts and made my sled really respond the way I like.

The gearing on my Axys sks 155 feels really good with stock gearing and 7 tooth drivers. Preatty sure im running that magic 1/1 clutching. The clutching is not stock.

If I am going 8 tooth drivers I may need to gear down inn chaincase. My reason for doing the 8 is as said. .. feels like the 7 need very tight track tension and so I feel track rolling resistance too mutch.

And I have LOTS of miles on the "old iron" pro. Starting to get some on axys platform and I am still over impressed of its big improvements over pro chassis but I am always looking for improvements.

 

[mountainhorse]

My 2 cents.... with respect to others with different experiences or opinions.

I've not heard of any properly tensioned, to the Polaris spec, AXYS tracks that were ratcheting unless there was another issue.

Looser than Polaris spec will lower the performance of your track.... which is counter to the old school thought of "looser frees up hp".

Sticky, heavy, costal or "spring" snow... clearance plays a much bigger role than light pow.... which is probably why a gear change helps to power through the parasitic loss from less clearance.

Going to the 8 tooth driver cuts your lug-tip to tunnel clearance by more than half... measured at the "choke point"... the tightest spot which is the fwd. roof of the tunnel ... and not the outlet of the tunnel.

One thing I've always been curious about... and have never checked or been able to...
Does an 8 tooth driver actually have another tooth engaged on the track than a 7 tooth driver when installed in the same sled?
(With the top/rear-most tooth just barely touching the drive-nub... how many teeth are in contact with the track in both scenarios?)



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[mountainhorse]

hmm raising to 8 tooth's will not lower ratio , it will raise ratio about 7%.. MH is very sharp and I'm sure its just a typo.

Thank you... Fixed it.