Tf 999

XtrmTJ · May 12, 2010

When calculating ones FCR (final crawl ratio) dose one take into account the torque multiplied by the torque converter under 1000 RMP ? "If so" is that a multiplier of X2 ? or X1.75 ? TIA ! :beer:

JOOP · May 12, 2010

somewhere online there's a crawl ration calculator. Just find that. It asks for tranny, t-case, tire size, gears..

I'll see if I can find it.

Here's one

http://www.riversideruffriders.com/index.cfm?fuseaction=home.crawlCalc

clifty · May 12, 2010

www.grimjeeper.com/gears.html this should help ya a bit

XtrmTJ · May 12, 2010

I have found my final crawl ratio, (TY) I was asking after doing so, dose one calculate in the torque converter multiplier, (X2 or X1.75) when under 1000 rpm's ? My tranny being an automatic. It seems like I can crawl very well under 1000 rpms, then when the after 1000 rpms its capabilities seem to diminish ?

JOOP · May 13, 2010

Oh I don't know on that. That's why they have online sites to do the thinking part:redneck:

So what crawl ratio did you end up with? Mine is 51:1.. I need a lot more... Thinking about getting crawl box added to the scene. That'll push me up to 138:1

XtrmTJ · May 13, 2010

Right now I am at 61.1, but with an auto (TF999) I think it is a bit more then that. I am also thinking of a doubler. I run a 4to1 in the Tcase and 5.43 gears. I want 150 or 160 .

JOOP · May 13, 2010

XtrmTJ said:
Right now I am at 61.1, but with an auto (TF999) I think it is a bit more then that. I am also thinking of a doubler. I run a 4to1 in the Tcase and 5.43 gears. I want 150 or 160 .

What size tires?

I'm runing 39"s, ax-15- t-case 272, and axle 4.88. I would think with your 4:1 and 5.43 gears you would be pushing 100.

XtrmTJ · May 13, 2010

I run 15X39.5X15 S/S. I am - Trans(TF999), first gear, 2.74 X Tcase, 4.1 X Gears, 5.43 = 61 to 1

JOOP · May 13, 2010

ahh see my first gear is 3.83.. I need to decide 4:1 or crawl box. I think the 4:1 kit would be cheaper. If I go Crawl box I have to pay for new drive shafts too.

XtrmTJ · May 13, 2010

4to1 is easy, I did it on a weekend by myself on my bench, no big deal. I am looking at crawl boxs, so many ways to do it, just have to decide wich way to go, .. :masturbanana[1]:

Damnyankee · May 13, 2010

I use 1.7. this also takes into consideration eficency losses through a fluid type coupling.

JOOP · May 13, 2010

Yeh.. they look pretty simple but I'd have to save up the coin.

TreeClimber · May 13, 2010

XtrmTJ said:
I want 150 or 160 .

Why?

In real world wheeling with your jeep, do you ever stall the engine due to not enough torque? Have you ever smoked the tranny due to not enough power and/or gearing to get the tires to turn?

I've got two rigs. Both w TH400s, and 4.56 axles, running 37 in tires. The only difference is T-cases. One has 4.3, the other has a 3.8 with a 2.72 doubler. I have NOT found a reason to put the doubler into 10.2 range.

Skysthelimit · May 13, 2010

As a rule of thumb, a lot of guys go with 1.8 for the torque converter multiplier, so if you take your 61:1 and multiply it by the 1.8 for the torque converter, you are at 110:1. There are are a few guys I crawl with at 108:1 and 112:1 and they are rock crawler guys with autos and they both say they are almost too low. I think you are right in the sweet spot and maybe don't even know it. 150-160:1 is desirable for manual tranny guys, but 100:1 is sweet for autos. I'm 82:1 with my 5-speed and would like a bit lower (about another 30 for 112:1 or so), but that's with a manual, not an auto.

XtrmTJ · May 13, 2010

TY ! This is exactly the info I was looking for, No, I do not run out of power, No, I do not smoke the tranny, and now that I have a larger then stock pan, about 2-3 qrts, I have no fliud starvation and any angle. 110to1 is perfect, I will stay with what I have. A guy is always looking for that little bit of advantage, alittle more power, alittle more umph, alittle more get up an go. You are 110% corect, I am at the sweet spot. Thanks ! :beer:

ain'tstuckjustresting · May 13, 2010

Wow, I'm 124:1 I guess we'll see how it works out. I was hoping to drop back to 4.10's someday anywho.

Binder · May 14, 2010

You guys don't need gears that low with a auto. I have (before converter) 100:1, 50:1 and 25:1. Only use 100:1 to load on the trailer as it's too low for much else. 50:1 works well for technical stuf but 25:1 is best for most trail wheeling.........Save that money you were going to spens on gears and buy something fun like hookers and blow.:awesomework: