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JImny - correct gear ratios

  • florinelu07
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10 Jan 2018 04:21 #188209 by florinelu07
JImny - correct gear ratios was created by florinelu07
Hi all

I have a Dec-2005 Jimny (with electrical controlled transfer box) and recently after driving a same technical generation Jimny (2012), I discovered that at 3000rpm, tacho indicated ~90kmh while in the tested car it was only 80kmh (10kmh less).

Just to make sure, I've asked a friend to check the rpm at his 2010 Jimny (same tech spec) and he confirms that his is cruising with 80kmh at 3000rpm in 4th gear.

All three cars are VVT (M13A engine with that big bulge on the front of the engine), with standard rims and 205/70 r15 tyres with H/T 7 A/T threads.

My question is what are the specific gear ratios for the Jimnys and if I should be concerned for the configuration that I've got (no need for the moment to fit bigger tyres).

I do have reasons to belive that at least the gear box was removed from the car at a moment in time (maybe for a clutch service). Currently the car has a 134kkm.

Thanks

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  • Lambert
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  • The quickest Jimny in Harrogate...(that I own)
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10 Jan 2018 05:41 #188213 by Lambert
Replied by Lambert on topic JImny - correct gear ratios
Don't worry too much and also remember that just because a tyre has the same size on the sidewall doesn't mean that it is actually exactly the same size as another different one. My 205 bfgs were visibly taller than the old unused Bridgestone spare from the factory.

Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
ADOS Attention Deficit Ooooh Shiny!

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  • florinelu07
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10 Jan 2018 05:57 #188214 by florinelu07
Replied by florinelu07 on topic JImny - correct gear ratios
True, but 10-12kmh is quite a variance.

Looking at the gear ratios specs, it looks right what I'm having on the car:

205/70/r15 = 2.09 meters circumference
3000rpm
4th gear ratio - 1/1190
transfer case High ratio - 1/1
~88kmh at 3000rpm

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  • Lambert
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10 Jan 2018 06:37 #188217 by Lambert
Replied by Lambert on topic JImny - correct gear ratios
Which is about 10 percent which is easily accountable for in the manufacture of different brands of tyres, and that's before you factor in tread wear and the vagueness of remoulded tyre sizings.

Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
ADOS Attention Deficit Ooooh Shiny!

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  • Lambert
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10 Jan 2018 06:46 #188218 by Lambert
Replied by Lambert on topic JImny - correct gear ratios
Other contributions are also made by tyre pressures, ambient temperature, speedometer calibration and vehicle loading. Tyre sizings are not mathematically pure there have to be tolerances built in.

Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
ADOS Attention Deficit Ooooh Shiny!

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  • florinelu07
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10 Jan 2018 07:03 #188219 by florinelu07
Replied by florinelu07 on topic JImny - correct gear ratios
I'll have a validation of the tacho readings vs. GPS.

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