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Discussion Starter · #1 ·
Was just wondering how exactly do you calculate gear ratio. I don't think I'm doing it rite, I was told you divide bottom to top, But what I'm looking for is how do you calculate for different size 8 tooth, or 9 tooth drivers. For example: I'm using a 43 bottom and 25 top with an 8 tooth driver on one sled and on another sled I'm working on has a 9 tooth with exact same bottom and top gear, 43/25 . How much difference would there be in gear ratio. Both sleds are 136s with 1.5 tracks.
 

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Another thing that confuses me is when someone tell me to gear up or down. When I go from a 25 top to a 26 top I'm I gearing up or down,
In this scenario you would be gearing up because your bringing the gearing closer to a 1-1 ratio. Now if this was in the drivin side and you went up a tooth you would be gearing down, or going farther away from a 1-1 ratio.
 

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Discussion Starter · #7 ·
In this scenario you would be gearing up because your bringing the gearing closer to a 1-1 ratio. Now if this was in the drivin side and you went up a tooth you would be gearing down, or going farther away from a 1-1 ratio.
Thanks for the feedback, starting to understanding it now. Gonna do some testing this weekend with different set up, always had a good hole shot, would leave the other sleds by a length or 2 but always got run down last 75 feet, on a 660ft track.
 

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Another thing that confuses me is when someone tell me to gear up or down. When I go from a 25 top to a 26 top I'm I gearing up or down,
To find your chaincase gear ratio divide the top gear into the bottom gear EX: 43 divided by 25 = 1.72:1. 43 divided by 26 = 1.65:1. The higher the number the lower the ratio.

And you thought you were confused before. LOL

Lynn
 

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I can't give you the ratio difference between the 8 and 9 tooth drivers but I will explain it as best I can.

Picture the drive sprockets as a wheel. Each sprocket will turn one revolution with the lower chain sprocket . The 9 tooth sprocket will cover more ground than the 8 tooth sprocket which in theory would result in higher ground speed. This is because the 9 tooth sprocket is larger in diameter. If you are gearing for top speed the 9 tooth will give you more top end if you have enough ponies to pull it.

If you are looking to increase acceleration you will have to either decrease the size of the top chain sprocket or increase the size of the lower chain sprocket.

The best way to tell your progress is to use a timing system and a radar gun. You will have to play with gearing until you get your gear selection to where you want it.

Lynn
 

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Discussion Starter · #11 ·
I can't give you the ratio difference between the 8 and 9 tooth drivers but I will explain it as best I can.
Picture the drive sprockets as a wheel. Each sprocket will turn one revolution with the lower chain sprocket . The 9 tooth sprocket will cover more ground than the 8 tooth sprocket which in theory would result in higher ground speed. This is because the 9 tooth sprocket is larger in diameter. If you are gearing for top speed the 9 tooth will give you more top end if you have enough ponies to pull it.
If you are looking to increase acceleration you will have to either decrease the size of the top chain sprocket or increase the size of the lower chain sprocket.
The best way to tell your progress is to use a timing system and a radar gun. You will have to play with gearing until you get your gear selection to where you want it.
Lynn
Yea that was my plan this weekend. Gonna use a buddies radar gun. And the way you explained it here makes it a lot easier to understand. After testing my sleds with different gears I'm even goon test with a big wheel kit in them too. All suspension are lowered and adjusted for a 160 pound soak and wet driver lol. I'm using stripped down ZX skids in my ck3 chassis, hope fully someday proline skids will be under them. We only snow drag here not to much ice drags. That's why we need alittle bit of a suspension on are sleds, tracks can get pretty rough.
 

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Keep a close eye on clearance issues for the studs around the bulkhead and rear heat exchangers. Some of these spaces are tight. Be sure the upper track wheels and axle are set in the lowest setting in the chassis to add clearance with the big wheel kit.

Best of luck,

Lynn
 

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Discussion Starter · #13 ·
Keep a close eye on clearance issues for the studs around the bulkhead and rear heat exchangers. Some of these spaces are tight. Be sure the upper track wheels and axle are set in the lowest setting in the chassis to add clearance with the big wheel kit.
Best of luck,
Lynn
Thanks, letmgrow
 
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