Crawl Ratio

[Patrolman]

Just curious what final ratios people utilize. I will kick it off.

1987 4Runner has a final of 88:1

[dieseldoc]

Jeep stock stuff= 4.10x2.72x4.10= 45.8
Jeep with new Tcase= 4.1x4.0x4.10=67.41 rock Trac 4.0 Tcase
Dakota build with black box, dana300, and a good gear set=228.53
The 4.10 first gear, black box 2.72, d300 4.0 gear set 5.13.

[Brian]

3.06 x 2.72 x 4.56 = 38:1

[Brucker]

Little Blue Shop Truck:

1st gear- 3.954
crawl box: 2.28
T-case- 4.70
diff's: 5.29
Final ratio: 224.14

[Java]

06 LJ all stock gearing with 33s.

4.46 (1st gear) x 2.72 (t-case)= 12.1312 x 3.73 (axles) = 45.249376 final.

[xaza]

I am currently running 4.88 gears x 2.8 trans x 2.72 t-case = 37.16. I am looking forward to a doubler which will jump that to 74.33 optional.
Wylie is running 4.56 x 2.8 trans x 4.0 t-case = 51.07.

[FINOCJ]

OEM for my cj5 is: 3.1x2.46x4.88 = 37.2 That just didn't cut it for an old standard transmission with carb (and points until recently). Seemed to work okay for TD ratings up to 4, but for 5 and 6 it took some clutch work and a lot of restarts.

so when replacing clutch I rebuilt the TC with Tera Lows and hopefully by next week will have
3.1x3.15x4.88 = 47.7 Not great but should work well enough for the trails I want to run - up to TD 6.

[redneck23ms]

mine is plenty low enough
3.80 1st gear
2.72 in the np231 doubler
2.62 in the dana 300
5.13 in the axles
= 51:1 with d300 in low and doubler in high
53:1 with doubler in low and d300 in high
and 138.9:1 in double low.

[Spieg]

67:1
(or 79:1 in reverse)

[Brucker]

mine is plenty low enough
3.80 1st gear
2.72 in the np231 doubler
2.62 in the dana 300
5.13 in the axles
= 51:1 with d300 in low and doubler in high
53:1 with doubler in low and d300 in high
and 138.9:1 in double low.

Alex brings up a good point. The beauty of the doubler or a crawl box is the select ability you gain. To be perfectly honest, I run 85% of the time in 2wd (RWD really) low which has a first gear ratio of 47.69. To give a frame of reference, I ran Brunce/Ironclads/T33a and then all of Miller Rock in 2wd low, and never even locked in my front hubs. I do run a welded rear though so both rear tires can constantly churn and in a couple different places some momentum was needed, but that was about it. I can think of two different places where the obstacles swallowed my 37" tires. But with a little momentum to get the front up, the rear will usually just climb.

[EKXJ87]

Just curious what final ratios people utilize. I will kick it off.

1987 4Runner has a final of 88:1

Thanks for starting this thread, I've never checked into this as "I'm still learning" look like my XJ's is running the same as Cliff's XJ 4.88 gears x 2.8 trans x 2.72 t-case = 37.16

[Patrolman]

I was more or less just curious where my 4Runner fell compared to other vehicles. Seems that it is "average" for my build which is more of an overland vehicle than a crawler. Didn't mention how mine is geared.

1st gear 3.93
crawl box 2.28
t-case 2.28
diff 4.30

[ColoJeeper]

2011 JKU Rubicon is 73.1 and 86 CJ7 is 75.1

[flashboiler]

Samurai: 3.652 1st gear, 6.5:1 tcase, 4.55 axle=108:1

[Mr6dwg]

80.23 for my 2000 TJ, I think.

[Brucker]

Thanks for starting this thread, I've never checked into this as "I'm still learning" look like my XJ's is running the same as Cliff's XJ 4.88 gears x 2.8 trans x 2.72 t-case = 37.16

Remember that with an automatic you can increase this by using your brake and making the output of your torque converter increase.

[newracer]

Only 69.3, I should change something. :speechless:

[Jim]

Only 69.3, I should change something.

Is 69.3 broken? If yes, then change. If all is well by you - get wheel'n!

[newracer]

Not broken. Just always looking for an excuse to upgrade. ;)

[Brucker]

Not broken. Just always looking for an excuse to upgrade. ;)

Let me guess.... Atlas time.

Front digs, twin sticks(2wheel front or rear low), gearing, and strength. Am I right?

[newracer]

Let me guess.... Atlas time.

Front digs, twin sticks(2wheel front or rear low), gearing, and strength. Am I right?

I'd love to install an Atlas. If I am going to do that I might as well throw some 1-tons under it at the same time, and stretch it some more.


In reality, I need to get the hydro assist installed and outboard the rear shocks.

To keep the topic on track my other rig ('07 JKUR) is 46.6.

[Jim]

Not broken. Just always looking for an excuse to upgrade.

LOL - this forum might be a dangerous place to visit. Enablers... the lot of'm!

[dieseldoc]

LOL - this forum might be a dangerous place to visit. Enablers... the lot of'm!
Hey I resemble that remark;)

[Froilan]

Torque conv: 2.2, 1st gear 2.48, xcase: 2.72, axle 2.56, geared hub 1.92=72.94:1 for my hummer.

[FINOCJ]

For what its worth - here is a little info about crawl ratios from Novak: I would guess some of you might disagree with the 'diminishing returns' part...

Note here that automatic transmissions offer the benefit of gearing built into the fluid drive torque converter. One can multiply an automatic transmission's low gear by a factor of 1.5 to 2.

Crawl ratios in the 60's are quite capable; in the 80's, very respectable, in the 110's, impressive and anything beyond the 130's is usually considered the point of diminishing returns.

[redneck23ms]

Yeah its not very often that I am in double low. Even then I may be in 2nd or 3rd gear to get the tire speed that I want. But it sure is nice to have 138:1 on super steep and technical stuff. I don't see where anyblower than that would be needed. Especially with a v8 or auto.

[Spieg]

Statements like the one from Novak tend to oversimplify the subject. Gear ratios only account for 1 part of the story. Tire size is of course a big factor. 130:1 on 29" tires is way different than 44" tires.

[Patrolman]

Exactly. Running my 32's and 33's, the 88:1 is sufficient. I found that with the 22re it just didn't have the power to get up some obstacles, which required slipping the clutch more than I was comfortable with. Putting in the crawl box eliminates any of those concerns.

[newracer]

I have considered installing a Rubicrawler in my JK. That would take the ratio down to 126.8.

[dieseldoc]

with deep low gears in the high 100 and low 200, gives you far more control in the big rock.
once you are running a tire over 37" that becomes a big deal.
when you are into trails with 8,9,an 10 raitings control is even more important.
being able to creep over a huge boulder near a steep ledge is far better than having to power over it

[FINOCJ]

Statements like the one from Novak tend to oversimplify the subject. Gear ratios only account for 1 part of the story. Tire size is of course a big factor. 130:1 on 29" tires is way different than 44" tires.

Good point. The next section from Novak does address that and they also are not generally focused on rigs that run 44s.

[FINOCJ]

Exactly. Running my 32's and 33's, the 88:1 is sufficient. I found that with the 22re it just didn't have the power to get up some obstacles, which required slipping the clutch more than I was comfortable with. Putting in the crawl box eliminates any of those concerns.

I fight the clutch issue as well...but clutches are way cheaper than the expense of swapping in a granny 4 speed! If only I had the money time and know-how.

[Patrolman]

I figured that putting in the crawl box (2nd t-case) was cheaper at about $400 plus my labor than being towed out after blowing the clutch. It was more of an insurance policy for me than anything. It doesn't get used much, but when needed it is very nice to have.

[Jim]

at about $400 plus my labor than being towed out

So you're offering $400 to any FR member that tows you out of a jam - sweet!

[FINOCJ]

I figured that putting in the crawl box (2nd t-case) was cheaper at about $400 plus my labor than being towed out after blowing the clutch. It was more of an insurance policy for me than anything. It doesn't get used much, but when needed it is very nice to have.

Seems very reasonable to me. I am looking at $1500 to get my crawl ratio to 80 not to mention significant changes to OEM on my old 'classic' which is important to me. Hopefully 50 will do for now