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Gear Ratio Calculator

69K views 36 replies 21 participants last post by  ShowStop 
#1 · (Edited)
This has been around a while, Ive used it before, but until today I had never scrolled past the crawl ratio table to the bottom of the page, at the bottom it tells you your rpms at a given speed. This seems to be very accurate and is all calculated for you. No brain power required :D


http://www.grimmjeeper.com/gears.html

This calculator will tell you the following:
All final drive ratios.
Crawl Speed at Given RPM in Feet Per Minute
Road Speed at Given RPM in Miles Per Hour
Road RPMs at Given Speed

There are options to factor in crawlers, axle gears, and tire size. He might add in a 3 tcase calc for anyone running triples.

And each table, except the final drive table, has scroll menus so you can change rpms and mph.

And the last thing is there are 2 columns so you can do side by side comparisons of different setups.

For anyone unfamiliar with this subject read on.

In step 1 you choose your tranny.

2.7 5spd = W59
3.4 5spd = R150F
2.7 and 3.4 autos got either the A340F or the A340E.
As Ive stated below all choices will produce a 2.57 t-case low so it shouldnt screw up the numbers too much if you pick the Toyota tranny.

One thing though, on step 2, there is only one Tacoma tranny listed A340F. This step determines your t-case ratio even though you are selecting your tranny again. So if you have a 95.5 and up Tacoma, 4runner or FJC choose the A340F tranny.

EDIT: A Toyota Tacoma and FJC option has been added. Choose that for your t-case ratio.

Xtra Info:
This guy is in the process of adding choices: W59 R150F and A340E to step 2. They will all produce the same 2.57 tcase low, but its nice just to get the details right.

As for you 6-speed guys I dont think he's gotten that far yet. im sure he'd be gald to add it in but he may need some help from ya'll to get it correct as I believe he's a Jeeper. But give him some slack he's created an outstanding calculator.

http://www.grimmjeeper.com/gears.html
_____________________________________________________________

This may be useful as well.
http://www.ttora.com/forum/showpost.php?p=708600&postcount=22

GOTCOPE? said:
So here's my little chart. It is not perfect, there are exceptions, but its very close.

I dont include 4.30's as an option as they are too rare too be considered IMO.

All tires assumed 12.50's exceept the "31".
The 3.58 is proven to suck. The 3.91 is right behind it. Though it sneaks into the chart once, only b/c I added "31's".

31's (10.50)
2.7 A - Minumum 4.10 or 4.56. A 4.30 if you could find 'em is near perfect.
2.7 M 3.4A - Minimum 4.10
3.4 M - 3.91 or 4.10

33's
2.7 A - 4.88
2.7 M 3.4A - 4.56 or 4.88
3.4 M - 4.10 or 4.56

35's
2.7 A - 5.29
2.7 M 3.4A - 4.88 or 5.29
3.4 M - 4.56 or 4.88

37's
2.7 A - Dont do it you'll hate yourself
2.7 M 3.4A - 5.29 (either could get away with 4.88)
3.4 M - 4.88 or 5.29

For the drivetrain combos that have a "choice" base your decision on how much you wheel, what type of terrain you live in (hills, mtns, plains), amount of hwy driving, etc.

If you have a vehicle that is wheeled hard and put up wet, does a lot of hwy travel, and you live on the plains, but near the mountains, obviously its gonna come down to a coin toss. :flipoff4:

PS Anyone feel free to argue. Do I even need to say that? :D
______________________________________________________________

Another.
http://www.tacomaterritory.com/foru...15&postcount=11


GOT COPE? said:
Hey zero cool, everything looks good except you need to add a 2.57:1 t-case ratio option for us Tacoma and FJC guys.
And I think I read somehwhere that pre-Tacoma V6 pickups had a 2.56:1. Not sure though.

Ok I recall now that entering Toyota w/ A340F transmission gives the correct ratio 2.57:1 for us Taco guys.

The 2.7 4cyl Tacos have the W59 5spd tranny, so add in a Toyota w/ W59 and have that calculate a 2.57:1 tcase low.

The 3.4 6cyl tacos Tacos have a R150F 5spd, same tcase low 2.57:1.

The 4cyl and V6 auto is the A340E or A340F same tcase ratio 2.57:1 low.

RZN19# March1998-August1999 = A340E 3RZFE (2.7)
VZN195 March1998-August1999 = A340E 5VZ-FE (3.4)
VZN195 August1999-Spetember2000 = A340E 5VZ-FE (3.4)
VZN195 September2002- = A340F 5VZ-FE (3.4)
RZN196 September2002- = A340F 3RZFE (2.7)

The above is kinda irrelevant(before the calculator was updated), basically if you have a Tacoma it came with an A340F or E auto or a W59 or R150F manual and all have a 2.57:1 tcase.

And zero cool the fact you have the A340F as an option on the calculator is how I got the correct ratio even though I have a W59, but if you'd add in the other Toyota Tacoma tranny options that would be helpful and if you even denoted them as Toyota Tacoma A340F for example rather than just Toyota A340F that would be even easier for people I believe.
 
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#3 ·
Yep that's the best one I've ever seen. :kewl:
 
#4 · (Edited)
Just so y'all know, I'm the one who wrote this calculator. While I'm a Jeep guy, I do want the tool to be usefull for everyone. I saw that some people were having a few issues with the Yota material. So I swapped a few things around and added some labels to make the Yota stuff a little clearer. I also added the FJ's 6 speed manual.

Let me know how you like the updates or if you want any changes. I may not get to it for a week but I'll do my best.

Oh, and please spread this link around to anyone who can use it. It's free for everyone. Post it in forums, put links on your web page, whatever you like to spread the word.
 
#5 ·
zero cool said:
Just so y'all know, I'm the one who wrote this calculator. While I'm a Jeep guy, I do want the tool to be usefull for everyone. I saw that some people were having a few issues with the Yota material. So I swapped a few things around and added some labels to make the Yota stuff a little clearer. I also added the FJ's 6 speed manual.

Let me know how you like the updates or if you want any changes. I may not get to it for a week but I'll do my best.

Oh, and please spread this link around to anyone who can use it. It's free for everyone. Post it in forums, put links on your web page, whatever you like to spread the word.
where did you get the info for 5th gear on the Taco W59 tranny? I think the ratio should be .81 and not .85 the FSM has it at the latter even though Marlin's site lists it at .85 :confused: I know the W56 has .85

here are the '05 Taco tranny specs that you can add.
6sp manual

5sp manual

5sp AT
 
#6 ·
Hey everyone. This is very useful. Thanks to the person who created it. Now I have a question about it though, I have a 96 tacoma V6 and I don't know what undersdrive I have. Can anyone help me out? The gears I don't even know what it has, I know though it is stock system. Read my sign. to see what I have on it so far. I want to know what MPG I'm getting. Thanks!
 
#7 ·
damex85 said:
Hey everyone. This is very useful. Thanks to the person who created it. Now I have a question about it though, I have a 96 tacoma V6 and I don't know what undersdrive I have. Can anyone help me out? The gears I don't even know what it has, I know though it is stock system. Read my sign. to see what I have on it so far. I want to know what MPG I'm getting. Thanks!
unless you have a crawler, Marlin or Inchworm, you don't have one ;)
 
#8 ·
damex85 said:
Hey everyone. This is very useful. Thanks to the person who created it. Now I have a question about it though, I have a 96 tacoma V6 and I don't know what undersdrive I have. Can anyone help me out? The gears I don't even know what it has, I know though it is stock system. Read my sign. to see what I have on it so far. I want to know what MPG I'm getting. Thanks!
Look for yer gear ratio here: http://www.ttora.com/wiki

and like hytenor said, you aint got no underdrive :D
 
#15 ·
ripped from sonoran steel.
1996 - 2002 4Runner
Model Code

Ratio
RZN180L-GKMSKA 3.727
RZN180L-GKMSKA 4.100 With P265/70R16
RZN180L-GKPGKA 3.727
RZN180L-GKPGKA 4.100 With P265/70R16
RZN180L-GKPSKA 3.909
RZN180L-GKPSKA 4.300 With P265/70R16
RZN180L-GKPZKA 4.100
RZN185L-GKMGKA 3.909
RZN185L-GKMGKA 4.100 With P265/70R16
RZN185L-GKMSKA 4.100
RZN185L-GKMSKA 4.556 With P265/70R16
RZN185L-GKPGKA 3.909
RZN185L-GKPGKA 4.100 With P265/70R16
RZN185L-GKPGKA 4.300 Option With P265/70R16
RZN185L-GKPSKA 4.100
RZN185L-GKPSKA 4.556 With P265/70R16
RZN185L-GKPZKA 4.100
RZN185L-GKPZKA 4.300 Option
VZN180L-GKPSKA 3.727
VZN180L-GKPSKA 4.100 With P265/70R 16
VZN180L-GKPGKA 3.727
VZN180L-GKPGKA 4.100 With P265/70R 16
VZN180L-GKPZKA 4.100
VZN185L-GKMGKA 3.909
VZN185L-GKMGKA 4.100 With P265/70R16
VZN185L-GKPGKA 3.909
VZN185L-GKPGKA 4.100 With P265/70R16
VZN185L-GKPGKA 4.300 Option
VZN185L-GKPSKA 4.100
VZN185L-GKPSKA 4.300 With P265/70R16
VZN185L-GKPZKA 4.100
VZN185L-GKPZKA 4.300 With P265/70R16
RZN180L-GKMSKA 3.727
RZN180L-GKMSKA 4.100 With P265/70R16
RZN180L-GKPGKA 3.727
RZN180L-GKPGKA 4.100 With P265/70R16
RZN180L-GKPSKA 3.909
RZN180L-GKPSKA 4.300 With P265/70R16
RZN180L-GKPZKA 4.100
RZN185L-GKMGKA 3.909
RZN185L-GKMGKA 4.100 With P265/70R16
RZN185L-GKMSKA 4.100
RZN185L-GKMSKA 4.556 With P265/70R16
RZN185L-GKPGKA 3.909
RZN185L-GKPGKA 4.100 With P265/70R16
RZN185L-GKPGKA 4.300 Option With P265/70R16
RZN185L-GKPSKA 4.100
RZN185L-GKPSKA 4.100 With P265/70R16
RZN185L-GKPZKA 4.100
RZN185L-GKPZKA 4.300 Option
 
#16 ·
What happened to the calculator link? It's just coming up with a page full of ads now:(
 
#21 ·
Thanks! This will help determine my speedo error now that I have 4.88's and 35's :)

I think your crawl speeds are off though??? I punched mine in with the xfer and 4.7 underdrive, and my speed is comming up at 201 at 5000 rpm. Maybe the decimal has to be moved over 2 places?
 
#24 ·
Ok, I'm busting my brains out.

I'm running tyhe R150F tranny, and stock was 30.46" tires, with 4.11's...
Now I am running 34.46" tires, with 4.88's.

Can anyone help me determine the error? I think it's at about 5.6%
 
#25 ·
The way I calcluate it, your driveshaft will be spinning 4.952% faster with your current setup than it did with your stock setup at any given speed. That means your speedo is running 5% higher than it used to at any given speed.

So when your speedo says 65, you're really going about 62.

Naturally, you can have up to a 10% variance between speedo reading and actual speed from the factory. This can vary over time. The difference in air pressure between cold and warm tires can have that much impact.


For all intents and purposes, you're in the "close enough" category.
 
#27 ·
Except for that annoying background image, that is a really nice calculator.

Back in 1999 or 2000 I built this one for Marlin's site:
http://marlincrawler.com/java/getspd_calc.html

That was made a loooooooooong time ago and I've always wanted to improve it. Now that I've got the new Marlin Crawler website running, I have been wanting to bring back this old jew with many, many more options.

Thanks for the link, it has given me a lot of great ideas!

Mike
 
#28 ·
Under the "Tire Size Change, find new differential ratio."

I plugged in my numbers... New tire diameter is 33 and old 31. Current gear ratio is 4.10 im guess becasue I still have stock gears... so, whenit calculates the new info, is this telling me what gears to get?
Hi=3.97
New=4.36
lo=4.76
actual= 3.85


If im understanding this right, tthen 4.36 is the gears it recomends to get for 33 inch tires. I seemsm, however, that 4.56 is what most people use....How will the 4.56 compare with the 4.36 for power and gas milege?

Thanks and sorry for the noobness....
 
#29 ·
gears only come in certain ratios, you don't get to pick any # you want ;)
for the taco: aftermarket gears are 4.56, 4.88 and 5.29. OE are 3.58, 3.91, 4.10, 4.30 and 4.56 (some Runners had OE 4.88s but not in the Taco)

all of those "charts" do NOT take other factors into account: more aero drag, more weight, wider tires have more rolling resistance, etc. So, you havt to go with a lower ratio (higher #) to begin to compensate. And, with so little hp and torque from these engines you can only compensate just so much ;)
 
#32 ·
The only thing I am confused on is I thought our 4Lo ratio in the T-case is 2.28:1 and not 2.57:1 in 3rd gen Runners and 1st Gen Tacos.
 
#33 ·
2.28s in the early tcases is correct; 2.57 after that. Where are you finding something other than this?
 
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