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JImny - correct gear ratios

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10 Jan 2018 12:08 #188241 by mlines
Replied by mlines on topic JImny - correct gear ratios

yakuza wrote: The analogue speedometer is a friction based device so there will be variations from car to car in addition to the obvious tire difference.


Which jimnys have the analoge speedo?

Certainly the SJ series which was known as a Jimny in some markets has analogue but I do not know of any SN series that do?

Martin

2003 M13 early KAP build.
3" Trailmaster lift with 1.5 Spacers on front
Customised winch bumper and roll cage
235/85R16 Maxxis Bighorns on 16" Rims, 4:1 Rocklobster, Rear ARB locker and on-board air
Corrected arms all-round, rear disks, Recaro seats and harnesses

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10 Jan 2018 12:26 #188243 by florinelu07
I've looked at the chart and it seems that the speed at 3000rpm/4th gear of 88-90kmh is correct, but by placing an older gearbox (non VVT) on an VVT engine, wll affect the actual gear ration and road/off-road performance?

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10 Jan 2018 13:11 #188247 by yakuza
Replied by yakuza on topic JImny - correct gear ratios

mlines wrote:

yakuza wrote: The analogue speedometer is a friction based device so there will be variations from car to car in addition to the obvious tire difference.


Which jimnys have the analoge speedo?

Certainly the SJ series which was known as a Jimny in some markets has analogue but I do not know of any SN series that do?


Oh? oops my bad, sure i have seen a mechanical wire in there in the dashboard..?

2005 Jimny M16A VVT, 2" Trailmaster, 235/75-15 MT
1987 SJ413 lwb, G16BB, 4" trailmaster, 2xARB, 4.16:1 transfer, 325/60-15 MT -project in pieces..

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10 Jan 2018 13:22 #188248 by Riccy
Replied by Riccy on topic JImny - correct gear ratios

florinelu07 wrote: I've looked at the chart and it seems that the speed at 3000rpm/4th gear of 88-90kmh is correct, but by placing an older gearbox (non VVT) on an VVT engine, wll affect the actual gear ration and road/off-road performance?


Having spent some time swapping all the various combinations of boxes about I have a bit of understanding on the combinations.

You can put a earlier (r7me) gearbox into a vvt jimny with some messing about, but if that was the only thing changed you wouldn’t be able to achieve that sort of speed as it would be so over geared. Setting off in 1st would be like trying to go in 2nd or 3rd currently. Likewise if the diffs were changed.

A better option would be to fit an earlier stick type transfer box, which would lower the final drive ratio (desirable for off-roading). Some larger tyres would be needed if you wanted to keep the revs the same on highway speeds.

The vvt r72 gearbox has a lower final drive speed than the earlier box if that helps explain it.

J999 MNY, M16 VVT, R7me gbox & Rocklobster,
31x10.5r15 Cooper STT, 2x ARB Lockd' 3.9 diffs & twin compressor,
6.5" total lift, Zookbob HD steering shock, Ignis recaro's
Custom bar & arches, rocksliders & guards,
Snorkel, K&N, 13500lb Winchmax, Buzzweld, etc, etc

Plus ULYSSES (06' trayback project)

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10 Jan 2018 14:19 #188250 by Lambert
Replied by Lambert on topic JImny - correct gear ratios
Notwithstanding having got the wrong end of the stick earlier I have a question; does it actually matter if it is slightly different to other similar vehicles if it is working and not making any odd noises?

It's not a Jimny. It's my Jimny

Mooo said Ermintrude (black)
Boing said Zebedee (blue)

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11 Jan 2018 09:33 #188275 by florinelu07
What does the final drive number represent?

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11 Jan 2018 12:35 #188280 by mlines
Replied by mlines on topic JImny - correct gear ratios
Its the differential ratio

Martin

2003 M13 early KAP build.
3" Trailmaster lift with 1.5 Spacers on front
Customised winch bumper and roll cage
235/85R16 Maxxis Bighorns on 16" Rims, 4:1 Rocklobster, Rear ARB locker and on-board air
Corrected arms all-round, rear disks, Recaro seats and harnesses

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11 Jan 2018 13:11 #188281 by florinelu07
ooooooo

I have to say that till now I haven't thought about it....
So first ratio comes from the selected gear, second ratio form the transfer case and third from the diffs (fur sure these last two ratios are identical).

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11 Jan 2018 13:38 #188282 by mlines
Replied by mlines on topic JImny - correct gear ratios
Yes,

So for example

2005 VVT manual gearbox Jimny, engine at 4000 RPM and in 5th gear High Ratio

Gearbox input = 4000 RPM
Gearbox ratio = 1
Gearbox output = 4000 RPM

Transfer box input =4000 RPM
Transfer box ratio = 1
Transfer box output = 4000 RPM

Diff input = 4000 RPM
Diff ration = 4.3
Diff output = 465 RPM

Wheel input = 465 RPM
Wheel diameter = 28 inches
Road speed = 77.7 miles per hour


2005 VVT manual gearbox Jimny, engine at 3000 RPM and in 1st gear Low Ratio

Gearbox input = 3000 RPM
Gearbox ratio = 4.425
Gearbox output = 678 RPM

Transfer box input =678 RPM
Transfer box ratio = 2.002
Transfer box output = 338.6 RPM

Diff input = 338.6 RPM
Diff ratio = 4.300
Diff output = 78.5 RPM

Wheel input = 78.5 RPM
Wheel diameter = 28 inches
Road speed = 1.5 miles per hour

For the road speed calc you can use your maths from school or a web calculator - www.4qd.co.uk/road-speed-calculator/

Martin

2003 M13 early KAP build.
3" Trailmaster lift with 1.5 Spacers on front
Customised winch bumper and roll cage
235/85R16 Maxxis Bighorns on 16" Rims, 4:1 Rocklobster, Rear ARB locker and on-board air
Corrected arms all-round, rear disks, Recaro seats and harnesses

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11 Jan 2018 17:48 #188288 by Riccy
Replied by Riccy on topic JImny - correct gear ratios
Thats a cracking explanation Martin! Add that below the table in the wiki and it should solve a lot of questions ;-)

J999 MNY, M16 VVT, R7me gbox & Rocklobster,
31x10.5r15 Cooper STT, 2x ARB Lockd' 3.9 diffs & twin compressor,
6.5" total lift, Zookbob HD steering shock, Ignis recaro's
Custom bar & arches, rocksliders & guards,
Snorkel, K&N, 13500lb Winchmax, Buzzweld, etc, etc

Plus ULYSSES (06' trayback project)

Please Log in or Create an account to join the conversation.

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