Diff ratios

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TijmenvdS
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Re: Diff ratios

Post by TijmenvdS » 06 Sep 2017 12:11

RPM vs KM/H gaan altyd die selfde bly ongeag watter diffs gechange is of tires omdat RPM op die enjin gemeet word en Spoed op die ratkas so daai verhouding sal nie verander met tire of diff change nie. Verskillende modelle is sekerlik anders gekalibreer afhangende van standaard diff ratios. :mytwocents:
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SJC
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Re: Diff ratios

Post by SJC » 06 Sep 2017 13:00

kyk hier: https://tiresize.com/gear-ratio-calculator/

PS> n groot wiel en n klein wiel gaan mos nie dieselfde spoed draai om selfde afstand af te le nie, so dit sal mos n effek he op die spoed wat die enjin draai om sekere spoed te handhaaf? :think:

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Re: Diff ratios

Post by davidvdm » 06 Sep 2017 13:12

SJC yes jy is reg as dit kom by GPS spoed, maar op die dash se speedo gaan dit altyd die selle "lyk" want hy is uitgewerk op die rat verhouding van alles in die drivetrain. Hy kan nie sien as jy groter wiele op sit nie. So hy wys maar altyd die selle spoed teenoor revs. GPS is die manier om die verskil te check. Toe ek gaan van 29" na 33" bande op die Sani, toe gaan my speedo van amper 10km/h meer as GPS, na 12km/h onder GPS spoed.

Sal graag wil sien wat hy nou weer doen as ek 35" bande gaan.

Maar kyk my spreadsheet en kyk hoe verander die crawl spoed soos bande size verander. As dit by crawl kom, sou ek daarvan hou om 29" bande te hê, maar self met die 35" bande is ek op 26 meter/minuut. Ek het glad nog nie gekyk wat is my highway spoed teenoor revs nie, dit pla my net nie op die stadium nie.
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Peter Connan
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Re: Diff ratios

Post by Peter Connan » 06 Sep 2017 17:33

When somebody clearly states "True speed" I am going to assume GPS speed...

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davidvdm
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Re: Diff ratios

Post by davidvdm » 06 Sep 2017 22:08

Yip agree.... Hope I'm not the one being confusing :doh:

So this discussion got me back onto my spread sheet as I was now curious to see what my RPM on the Sani will be, once I am done and with my drivetrain and tyres.

Here is the update for those who may just be interested. I bashed this together while cooking supper, so please let me know if there are any errors in my calculations. Also remember that if you use this, you will need to input the second TC with a ratio of 1 (unless you have a second TC of course). I added some colour, to try and show where the cells in the second and third calculation box, gets it's information from.

I'm leaving it up to you to input your gearbox and TC ratios :wink: , and I also have no idea what your engine torque is, so I'm just leaving my old TD27 Sani/Hardbody figures in there.

Have fun :blonde:
Gear ratio calcs Rev1.xlsx
(15.54 KiB) Downloaded 17 times
David - Bfreesani
1997 Nissan Sani MK3 2.7TD - Hillbilly (SAFANI)
MQ C200 SFA
MQ H260 LSD Rear
MQ Transfer as second low range
5" Lift
33"x12.5x15" tires on 8.5J rims - Want 35's
DIY rock sliders
DIY Snorkel
Madman EMS

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