Top Speed Calculation

Gear Calculator - Apply your details in the fields below to view the mph.

Belt Safe
1:1 ratio
Caution
1/2 o.d.
Danger
Full o.d.
MPH  xx xx xx
KMH  xx xx xx
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Clutch Ratio Number of Drive Sprocket Teeth Track Pitch Constant
1 to 1 8 2.86 46.1
1 to 1 9 2.52 46.6
1 to 1 10 2.52 41.8
1 to 1 11 2.52 38.1
1 to 1 12 2.52 34.9
.83 to 1 8 2.86 38.4
.83 to 1 9 2.52 38.6
.83 to 1 10 2.52 34.7
.83 to 1 11 2.52 31.7
.83 to 1 12 2.52 29.1

Gearing Chart "Drive Sprocket Size" spreadsheet

MXZ/REV Gear chart - with chain size

XP/XM Gear chart - with chain size


Buy gears in Canada

Recreation supply in Saskatchewan - page 529 in 2017 catalogue - Silent chain and gears for skidoo

Royal distributing in Ontario - page 137 in 2017 Catalogue

 

Buy gears in USA

Venom/Team gears

Venom/Team chains

1:1 Clutch Ratio vs. Overdrive.

The gear calculator gives you the mph for 1:1 clutch ratio. Remember that this is where the belt climbs to about 7/8 of an inch from the rim of the primary. The only way the belt will or should go to the top of the primary "rim" is when you are able to do the highest mph attainable with your current drive ratio.
Example 21:45 @ 8150 rpms with 46.1 constant will offer up 82.5 mph.
@ 82.5 mph the belt will go up the primary clutch as high as approximately 7/8 from the rim. To get the belt to go up to the rim of the primary then the sled will have to go about 93mph (full shift overdrive)

Calculate Full shift overdrive (O.D. or o.d.)
For XP chassis you take the 1:1 mph and divide by .89. So then (82.5mph / .88) = 92.69mph

For MXZ/REV chassis you take the 1:1 mph and divide by .83. So then (82.5mph / .83) = 99.39 mph

When using the calculator, always good to calculate the mph for both shift ratios. 1:1 mph and the overdrive mph.
1:1 = 82.5
O.D. = 93

Click on (Engine overrevving on road (summit))

Calculate a mile per hour - a "how to"

Bottom gear / Top gear = Gear Ratio
Example 43/27 = 1.59 ratio - Note that gears are generally discussed with mentioning the top gear first like "Twenty seven, fourty three"
Gears are displayed in text as 27:43 with a " : " to separate the values.
More examples, 44 / 24 = 1.83 ratio and then written and spoken as 24:44

Example Top Speed Calculation; 2008 mxzx 600RS
Engine rpms - 8400
Top gear 23
Bottom gear 49
Gear ratio (49 / 23) = 2.13
Clutch ratio - 1:1
Track pitch - 2.86"
Constant # - 46.1
Formula then is (8400 / 2.13) / 46.1 = 85.5mph

How to calculate a drive sprocket constant

Here is example of skidoo 2.86 pitch track with 7 tooth.  You can replace the numbers with your own details.

The formula is also in Aaen clutch tuning manual.

When you scroll down the page, you will eventually see a chart with all the constants.

(2.86 pitch x 7 tooth driver) / 12 = X

(60 / 5280) = Y

(x)*(y) = Z

1/z = Constant

Therefore - (X = 1.67)*(Y = 0.01137) = 0.0189

1/0.0189 = 52.6651 (52.66)

Constant = 52.66

The formula is in any BRP race manual (drive section) and you just have to use the last part of the formula to figure out “Z” and then just go 1/Z = constant.

MXZX Rev chassis chain vs. Gear ratio

Example - 27:43(gears) = 1.59(ratio) = 76(Pitch chain)

27:43 = 1.59 = 76P
26:43 = 1.65 = 76P
25:43 = 1.72 = 76P
24:43 = 1.79 = 74P


image

XP/XM Chassis chain vs. Gear ratio

Example - 20:45(gears) = 2.25(ratio) = 102(Pitch chain)

20:45 = 2.25 = 102P
21:45 = 2.14 = 102P
20:45 = 2.05 = 104P
19:45 = 2.36 = 102P
21:51 = 2.42 = 106P
20:49 = 2.45 = 104P
20:51 = 2.55 = 106P
19:49 = 2.57 = 104P

image

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Gearing Chart spread sheet

Constants for other ratios.
Need for me to get an excel spreadsheet person to help me fill in the blanks.

Ratio Teeth Pitch Constant

1 to 1 7 2.52 59.86
1 to 1 8 2.52 52.38
1 to 1 9 2.52 46.6
1 to 1 10 2.52 41.8
1 to 1 11 2.52 38.1
1 to 1 12 2.52 34.9
1 to 1 13 2.52 32.23
1 to 1 14 2.52 29.93
.83 to 1 7 2.52
.83 to 1 8 2.52
.83 to 1 9 2.52 38.6
.83 to 1 10 2.52 34.7
.83 to 1 11 2.52 31.7
.83 to 1 12 2.52 29.1
.83 to 1 13 2.52
.83 to 1 14 2.52
1 to 1 7 2.86 52.74
1 to 1 8 2.86 46.1
1 to 1 9 2.86 41.02
1 to 1 10 2.86 36.92
1 to 1 11 2.86 33.56
1 to 1 12 2.86 30.76
XP.9 to 1 7 2.86
XP.9 to 1 8 2.86
XP.9 to 1 9 2.86
XP.9 to 1 10 2.86
XP.9 to 1 11 2.86
XP.9 to 1 12 2.86
.83 to 1 7 2.86
.83 to 1 8 2.86 46.1
.83 to 1 9 2.86
.83 to 1 10 2.86
.83 to 1 11 2.86
.83 to 1 12 2.86
1 to 1 7 3 50.29
1 to 1 8 3 44
1 to 1 9 3 39.11
1 to 1 10 3 35.2
XP.9 to 1 7 3
XP.9 to 1 8 3
XP.9 to 1 9 3
XP.9 to 1 10 3
.83 to 1 7 3
.83 to 1 8 3
.83 to 1 9 3
.83 to 1 10 3
1 to 1 7 3.29 45.85
1 to 1 8 3.29 40.12
1 to 1 9 3.29 35.66
1 to 1 10 3.29 32.09
XP.9 to 1 7 3.29
XP.9 to 1 8 3.29
XP.9 to 1 9 3.29
XP.9 to 1 10 3.29
.83 to 1 7 3.29
.83 to 1 8 3.29
.83 to 1 9 3.29
.83 to 1 10 3.29


850 summit

3.5 pitch, 6 tooth @ 50.30 constant

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