# Primary Reduction Ratio

8 replies to this topic
• # DPWR400

Posted August 19, 2007 - 08:01 PM

First of all what gears are they using as primary reduction ratio? Second do all DRZ's have the same ratio of 2.960 (74/25). I have an 05 SM but only have a S shop manual. Lastly do all DRZ's use a 15 tooth counter sprocket stock? Thanks All!

• # g935cab

Posted August 19, 2007 - 08:41 PM

sm-15-41

s- 15-44

e- 14-47

• # William1

Posted August 20, 2007 - 03:02 AM

Primary for all bikes is 2.960 (74/25)
g935cab gave final ratios

• # DPWR400

Posted August 20, 2007 - 05:32 AM

Cool thanks for the info everyone, but I'm still curious how the primary reduction ratio is computed? Anyone??

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• # jlbenne

Posted August 20, 2007 - 06:18 AM

By teeth on the gears and simple division

74 divided by 25 is 2.96

• # MutualBill

Posted August 20, 2007 - 06:39 AM

to calculate final drive ratio of a given gear combination...divide the drive gear by the driven gear (tooth count).

This will give you your gear ratio. For example 15/44 ratio equals .340909090...or simplified...gives you a what is normally known a 3.40 drive ratio.

You multiply that number number by the gear ratio of the gear you have selected in the Transmission to achieve your total final drive ratio. By the way...the DRZ does not have a 1:1 ratio on any of its gears. 4th is slightly under driven and 5th gear is slightly over driven.

If you search...sombody did post the ratio of all 5 gears for the drz in the past.

• # DPWR400

Posted August 20, 2007 - 05:51 PM

okay so the primary drive gear has 25 teeth so that is where the 25 comes from but where does the number 74 come from?

• # DPWR400

Posted August 20, 2007 - 06:08 PM

I think I figured it out, the primary driven gear has to be the clutch basket, is that right??

• # Noble

Posted August 20, 2007 - 10:06 PM

Right. 74 teeth on the clutch basket

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