I have an 09 Nytro XTX that i am putting a 162" Timbersled rear skid in and am wandering if I go with a 2.5" lug track what size of drivers do i want to use 7 or 8 tooth. I will be purchasing anti racheting drivers.
7 or 8 tooth drivers
- Thread starter brianwcooper
- Start date
D
I could be wrong but I dont think you can fit 8 tooth drivers in the Nytro.
I believe AA is correct. 8 tooth drivers will not fit in a stock Nytro with the stock front cooler in place. You go fom 7 tooth to 8 tooth drivers you are adding about .9 inches in diameter to your driver or almost 1/2 and inch protrusion forward towards the cooler. You would need remove the front cooler and put in a block off plate from Van Amburg that opens up the space in there by about an 1 1/2 inches or so. If your a good welder you could cut it and move it forwars youself. I would suggest going 7 tooth and then change out your gears. On the Nytro with 7 tooth drivers and 20/40 gearing you are looking at roughly 78 mph. Go to 8 tooth drivers and you get about 90mph. The same goal can be achieved by going to a 21/38 gear ratio with 7tooth drivers and you don't have to modify you cooler. Going to 21/38 also allows to use the 68 link chain you alreay have so there is no cost there.
So if I go with the 7 tooth drivers and the 20/40 gearing i have to change my chain then? I am mostly going to be riding in the mountains so definetly have no need to do 90mph.
90 MPH track speed needed for climbing .
Here are some driver diameter specs that may help. As you can see track pitch can make pretty big difference in driver size.
2.52" pitch
10 tooth = 8.021"
9 tooth = 7.219"
8 tooth = 6.417"
7 tooth = 5.615"
2.86" pitch
8 tooth = 7.283"
7 tooth = 6.373"
3.00" pitch
8 tooth = 7.639"
7 tooth = 6.685"
2.52" pitch
10 tooth = 8.021"
9 tooth = 7.219"
8 tooth = 6.417"
7 tooth = 5.615"
2.86" pitch
8 tooth = 7.283"
7 tooth = 6.373"
3.00" pitch
8 tooth = 7.639"
7 tooth = 6.685"
No. You already have 20/40 gearing with a 68 link chain. Your sled is NA correct? If so I would go 7 tooth driver with 20/40 gearing. The stock Nytro in deep pow won't turn the track fast enough to benefit from going to 21/38 gearing. If you were a lake rider or trail rider I would do it but not for climbing unless your running a turbo. In fact if you are NA and want to climb some hills I would try the 19/40 combo for a little better bottom end to help turn over that bigger track.
Alright that's what someone else had told me too. I was just making sure. My sled is NA for now so i am probably going to gear it with the 19/40. My stock chain should work with that right?
I shouldn't have any problems with clearing the cooler in the front of the tunnel? Hartman told me that i would have to cut my track down a 1/4" because there is not enough room for the air and snow to go up front, but I see a ton of people running 2.5" tracks on Nytros.
F
You should have plenty of room. I'm running 8 tooth drivers with a 2.25" track and still have oodles of clearance for a 2.5". If in doubt, tip the thing on it's side and get the tape measure out.
Your XTX came with a 2.52" pitch track. If you are putting on a 2.5" Camo Extreme in a 3" pitch you will need to purchase 7 tooth 3" pitch drivers. 8 tooths are too large to fit as MTNVIPER shows. The ones to get are the Avids.
I already ordered some 7 tooth 3.00 pitch drivers. I thought i should have more than enough room but when he said that i was a little worried. I also was wandering if anybody has ran the 39-19 tooth gearing with a 162" track?
You ordered exactly what you need. As for gearing Yamaha has used 20-40 for about 7 years on the 4 strokes until they went with 18-40 in 2010 for the SE's. Interestingly enough the non SE Nytro 153 for 2010 stayed with 20-40 even though the 153 SE got the 18-40. A ratio of 2.2:1 or greater works best for mountain sleds.
T
good thread. i'm changing my Nytro to a 162" track adn getting 7 tooth avids drivers. what do you guys think about 19/40 or 19/42 gears for the 162" track? want it to pull hard on the low end not too worried about the top end speed but would be nice to still get 85mph or so. with my stock 20/40 and 153" track i got 96MPH.
T
:face-icon-small-hap
