Jump to content
Ultimate Subaru Message Board

EA81 & EA82 transmission Crawl Ratio's


TheSubaruJunkie
 Share

Recommended Posts

I was snooping around when I did the gears for my Toyota, and found a crawl ratio calculator.

 

So I punched some numbers using this as a guide to transmission gear ratio's:

Gear%20ratios.JPG

 

And what I came up with was;

EA81 Dual Range 4spd Crawl Ratio of 20:1

EA82 Dual Range 5spd Crawl Ratio of 22:1

 

this is with a 3.9 final diff.

 

In comparison, my toyota with the new gears has a crawl ratio of 90:1. And when I stack a second transfercase it will go up to 208:1.

Link to comment
Share on other sites

Saw one on pirate that had a 10.34 low:eek: Was like 2700$ Yipes.

 

i have 163.1 right now.

 

4.44 diffs,6.5 zookie t-case,3.545 ea82 d/r,1.59low soobie.

 

when i grow up i want to buy an atlas t-case for the buggie i WILL build.i will get a 3 or 4:1......cheers, brian

Link to comment
Share on other sites

Yeah I wasn't poking fun at Subarus crawl ratio's... just thought it would be nifty to know.

 

163:1 is impressive for the Sube Brian, I can't wait to see it in action.

 

 

you and me both.i been getting the tow rig(dodge diesel) up and rollin the last few days.got some work to do on a friends car here pretty quick,and then back at it.mainly i am just waiting to buy some things.so the fund reservoir is slowly being filled up right now.but there is plenty to do between now and then anyway.......cheers,brian

Link to comment
Share on other sites

you and me both.i been getting the tow rig(dodge diesel) up and rollin the last few days.got some work to do on a friends car here pretty quick,and then back at it.mainly i am just waiting to buy some things.so the fund reservoir is slowly being filled up right now.but there is plenty to do between now and then anyway.......cheers,brian

 

yeah, I've been working on my future tow rig ('72 K20) as well... :) Brat is just sitting in the garage, waiting to be put back together..... luckily most of my spending for the Brat is done... just brake lines and optima left for the most part.....

Link to comment
Share on other sites

So I have a 22:1

My brother has 93:1

 

I have 27" tyres

He has 35" tyres

 

So his first low is 1/3rd of my first low at idle speed... :(

 

But I still try crawling over every offroad track...

 

This is the real issue, a Crawl Ratio does not tell the full tale!

Tires are a factor that no one really figures in.

 

I think there should be a "Creep Ratio" ( a ratio that factors crawl and tires together).

This would give a more meaningful representation of the ability of a drive train setup.

 

A stock Subaru with stock tires has a reasonable Creep Ratio.

When you go over sized with the tires, your crawl ratio does not change.

Your Creep Ratio just went in the toilet!

 

Now...just how do you calculate a Creep Ratio to give a meaningful number...:confused:

Link to comment
Share on other sites

Now...just how do you calculate a Creep Ratio to give a meaningful number...:confused:

 

I just came up with this calculation on the spot, not sure if its good and works but it looks to...

 

My SUBARU

27 inches

x 3.14159 Pi

=84.82293 inches radius

 

63360 inches in a mile

/84.82293

=746.967 rotations to a mile

 

1000 engine RPM

/22 crawl ratio

=45.4545 wheel rotations a minute

 

45.4545 WRPM

x60

=2727.27 WRPH (hour)

 

2727.27 WRPH

/746.967 rotations per mile

=3.651 MPH

 

-------------------------------------

 

My brothers 4RUNNER

35

x Pi

=109.95565

 

63360

/109.95565

=576.23232

 

1000

/93

=10.75268

 

10.75268

x60

=645.1608

 

645.1608

/576.23232

=1.119 MPH

 

 

1000rpm in low first

Subaru = 3.651 MPH

4Runner = 1.119 MPH

Link to comment
Share on other sites

So this begs the question,

 

What is the Creep Ratio of a stock Subie?:confused:

 

Apparently a small change in the numbers makes a big difference in the ability to power the wheels.

 

I notice a BIG difference with 27" tires and the stock tires.

 

Are the stock tires 22" ?

I don't have any stock tires left to measure...

Link to comment
Share on other sites

there are gear calculators out there for when going to larger tires, it gives you the new gears you need to have to get back to the stock "feel" power wise. these calcs do not take into consideration additional weight of the tires.

 

http://www.ramblerman.com/blazer/gearcalc.htm

 

And he's a chart where you can see how you move across the bands when changing sizes...

 

http://www.tellico4x4.com/moreinfo/ratio.htm

Link to comment
Share on other sites

So this begs the question,

 

What is the Creep Ratio of a stock Subie?:confused:

 

Apparently a small change in the numbers makes a big difference in the ability to power the wheels.

 

I notice a BIG difference with 27" tires and the stock tires.

 

Are the stock tires 22" ?

I don't have any stock tires left to measure...

 

So, doing the math,

 

A stock Subie 22.65" = 3.06 MPH

A Subie with 27" = 3.651 MPH

4Runner = 1.119 MPH

 

Apparently a 0.6 change in a ratio makes a big difference!

This is the only real ratio that makes sense as it accounts

for tires not just gears.

Link to comment
Share on other sites

low gears are overrated!!!

 

IM 100% sure that the wrong gears are not much fun, I just switched the rear diff to 3.9, and the 3.9 5speed w/1.59-1 low range is ready for install sooooon, Roxy still has the P/t RX trans that was awsome for high speed dirt roads with 13's, but not too good for 28.5 swampers. It does jet on the hyway. cant wait to switch. COBCOB beer party wrench day ?????? picture.php?albumid=123&pictureid=985

 

album.php?albumid=123&pictureid=985

Edited by mykingcrab
Link to comment
Share on other sites

  • 12 years later...

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
 Share

×
×
  • Create New...