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BigJimny Meet 2019 (17 May 2019)

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Gear ratio's & tyre sizes

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08 May 2019 10:51 #207522 by sniper
Hi Guys, can someone tell me the tyre size I would need to run with the following set up:-

M13A VVT engine to R7ME gearbox to G13b transfer box to 4.3 diffs

I bunked off school too much.....

sniper

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08 May 2019 11:46 - 08 May 2019 11:48 #207529 by Lambert
Replied by Lambert on topic Gear ratio's & tyre sizes
From memory and I could be wrong but about a 31 or so. Standard vvt box to 1.3 transfer to vvt diff. All the ratios are in the wiki section and grimjeeper pages can calculate.

Dreadnaught (black 2011)
Last edit: 08 May 2019 11:48 by Lambert.

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08 May 2019 15:04 #207536 by sniper
Replied by sniper on topic Gear ratio's & tyre sizes
Thanks mate, I'm hoping for one of the wizened sages to lead me through by the hand..... bit thick and I want to understand what I've read....

sniper

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08 May 2019 17:45 - 08 May 2019 17:48 #207546 by Riccy
Replied by Riccy on topic Gear ratio's & tyre sizes
Grimmjeeper isnt that hard to use: www.grimmjeeper.com/gears.html

the numbers are in the wiki: www.bigjimny.com/mediawiki/index.php?tit...ssion_gearing_ratios

But I have done it for you ;-)

essentially to keep the gearing as stock as possible with that combination, but a larger size (because of the diff ratio increase relative to the original setup together and original tyre size*) you need 235/75R15 tyres, which are 29" roughly.

*based upon the original R7me gearbox, stick operated transfer box, 3.9 diffs and 205/70r15 tyres, and compared with the diff and tyre sizes swapped.

Grimmjeeper lets you play about comparing two setups side by side, meaning its very easy to see the difference changing the setup will have. With the above mentioned setup you will have near identical revs in most gears at any given speed to what you have now, except bigger tyres. The low-box may not be low enough for very slow rock-crawling, but fine for jimny style bouncing around.

You could push it to 31" and still get around, but it would be a bit slower. example info from grimmjeeper suggests at 70mph in 5th gear stock is doing 3987rpm. with 235's and the 4.3 diffs its doing 3994. With 31's its doing 3721rpm. Lower revs sound good, but I have found that there isnt the power to make much use of that, hence more expense!

J999 MNY, M16 VVT
R7me gbox & 5.16 Rocklobster, 285 75 r16 Toyo MT, 2x ARB Lockd' diffs, 7" lift, Recaro's, Custom bar, arches & guards, Snorkel, K&N, Winch, CB, etc, etc

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Last edit: 08 May 2019 17:48 by Riccy. Reason: didnt make sense!
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08 May 2019 18:44 #207552 by Lambert
Replied by Lambert on topic Gear ratio's & tyre sizes
Thanks Riccy!

Dreadnaught (black 2011)
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08 May 2019 18:48 #207553 by Lambert
Replied by Lambert on topic Gear ratio's & tyre sizes

Lambert wrote: From memory and I could be wrong but about a 31 or so. Standard vvt box to 1.3 transfer to vvt diff. All the ratios are in the wiki section and grimjeeper pages can calculate.


So near. Must try harder to memorize everything!

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08 May 2019 19:06 - 08 May 2019 19:36 #207558 by jackonlyjack
Well i now know low box @2000rpm 1st gear is returning 2.98mph
How do i change to different gears on grim reaper can't get my head round it :dry:

HaHa found it drop down menu number of forward gears :laugh:
Saying 70mph @ 4219rpm may need bigger boots :ohmy:

Jack
Last edit: 08 May 2019 19:36 by jackonlyjack. Reason: Added a line

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09 May 2019 16:56 #207625 by Riccy
Replied by Riccy on topic Gear ratio's & tyre sizes
70 at 4219 isnt horrendous, especially as you will probably be doing 60-65 in reality most of the time. Makes for a quick jimny ;-)

J999 MNY, M16 VVT
R7me gbox & 5.16 Rocklobster, 285 75 r16 Toyo MT, 2x ARB Lockd' diffs, 7" lift, Recaro's, Custom bar, arches & guards, Snorkel, K&N, Winch, CB, etc, etc

SL06 ULS ULYSSES
06' pickup tipper project

greenlaning.blog/
www.youtube.com/user/riclemus

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