Albuquerque Jim

I hate to post this because Schaefer will probably make fun of me or something.

But I was thinking...I like the way my 4Runner is geared for the highway (4.10's). But, offroad it sucks to have such high gears (and the fact that I have open diffs currently doesn't help). But that will change.

I see everyone going to lower diff gears which makes sense. But! what about having the best of both worlds? Keep my stock 4.10s and adding a dual case? Is it just a $ issue? I know it's cheaper to just do the diffs.

Can't I still get an unbelievably low crawler gear with a dual case without lowering my diff gears?

Flygtenstein

People who have problems trashing gears just keep the stock 4.10's, stronger gears, in the diffs and add crawlers to get the trail reduction. This is not so much a product of needing the gears for the road though.

In a perfect world, a person would do exactly as you mention, only add a second case and 4.7's so that the highway performance is unaffected. Obviously transfer case gears only impact 4wd use, dual cases give 2-low, but that is beyond the point for now.

Absolutely you can use a crawler and leave the street performance where it is it, your crawl ratio will just not be as low because you will not have lower diff gears.

I know Marlin has adaptors to get you to dual cases, not sure if you could get the output on the correct side though.

I regeared my diff's because I needed more gearing for the highway. Diff gears affect both road and trail. Dual cases, essentially more transfer case gearing, affects only trail.

Spank, can we get a spank in aisle 2???

Albuquerque Jim

Wouldn't mine be the same as Schaefer's?

Joe

The way to figure out your crawl ratio is to multiply your transmission ratio X your transfer case ratio X your axle ratio. If you add a second transfer case (crawler) just multiply the crawl ratio by your second transfer case gear ratio to obtain your crawl ratio using the crawler box.

As an example, 2.6X2.8X4.10 has a crawl ratio of 30. Not bad but not real good either as the number your looking for is 50 or greater. Up your axle ratio to 4.88 your crawl ratio will go to 36. Add a second transfer case with a 2.8 ratio and your rig with a 4:10 axle will have a crawl ratio of 84. Now you're able to pis* in the tall grass with the rest of the big dogs. If you want a little more hummmm in the cab go to the 4.7 gear ratio 2nd transfer case and your crawl ratio jumps to 140, which may be overkill to most daily drivers. I think like Steve, "its just money and you'll make more, so just go for it."

Sorry, I was typing while you and Flygtenstein were posting so you can disregard my babbling.

Flygtenstein

Jim, your diff is on the same side as Steve's, but your tranny is an auto, correct? I don't think that an adaptor exists to put your tranny with a gear driven case which are only passenger side. Maybe one exists to use your stock case as the front case, not sure though.

With an auto, you can get by with less numeric gearing because you have the torque convertor factor and you can modulate the gas.

I have 5.29's x 2.28 x 2.something first gear x 2 for the torque convertor. Basically I am at 80 or so to 1.

Steve will likely post specifics on 252 in a while.

sschaefer3

Sure you can get a crawler with stock gears, just be sure to get the 4.7 gear, it would not be worth it for 2 stock cases. What you saw was the "ultimate".

Albuquerque Jim

Adrian,

I have a 5 speed, so I think the same set up as Steve's will work except I think I have 23 splines instead of 21? Is that right Steve?

44Runner

Little off, you will have the same setup as me, 23 spline. If I recall correctly Steve's tranny is 26 spline, correct Steve?

Anyhoo, if you are happy with the road manners of your truck, there is no reason to waste money on regearing your diffs. Regearing your diffs is ONLY for people who need more power on the road. You get more bang for the buck gearing wise to add t-case gears/crawlers....

Albuquerque Jim

Cool, Thanks 44

44Runner

No problem man.

Just for info purposes your current crawl ratio is 40:1. If you threw in a crawler with the stock 2.28 gears and kept your 4.10 diff gears you would have an overall crawl ratio of 92:1. Now granted that mod will run you over 1200 bucks not including labor (it can be done yourself no problem). Regearing your diffs will run almost 500 bucks in parts and it is not likely you can do that work yourself and labor for that is pricey. Now say you went all the way up to 5.29s. Your highway RPMs are gonna be way higher than they are now and forget about gas mileage and your crawl ratio only goes up to 52:1.

That is just to further prove to you and others that your train of thought is dead on right. If you don't need diff gears, by all means, don't waste your money on them. They are no way to get a good crawl ratio. The ONLY reason to regear the diffs is if you have gone to a bigger tire and you are unhappy with the truck's power on the street.

Albuquerque Jim

44, can you post how you came up with the ratios, I keep getting something different.

Flygtenstein

Sorry Jim, I thought you had a post 2000 and therefore an auto, I am glad Dave set me straight.

I needed diff gears to be tolerable on the road and do not have the option of crawling without a lot of time and money.

You seem comfortable with your diff gears and can much more simply than I, add a crawler. Only problem is you still have open diffs. I would have a hard time opening my diffs for lockers and not add somewhat lower gears.

As Steve said, get 4.7's in the second case. It costs more, but you have all the choices, it seems that 125:1 does have a place, but 252 really works on the trail.

Albuquerque Jim

Adrian,

There is no question I will be locked, at least the rear soon!

I will go with an e-locker in the rear (just a 3rd member swap) so no need to mess with gears.

And if I do decide to go lower (all $ related) I will probably use the diffs out of a 4cyl and get to 4.56's (just swap both front and rear).

A front ARB locker will be down the road. As well as the crawler, I was just thinking out loud and wanted to get some validation on my thought process.

Joe

Figuring the "proper" crawl ratio is FM to me when you have to consider tire size, RPMs (auto only) and then the usual formula. I think you can only multiply the low transmission gear, the axle ratio and then either the transfer case ratio or your torque converter ratio (not both) to get your crawl ratio. I've got an automatic with 4:56s and I'm at 33:1 crawl ratio meaning my engine turns over 33 times for each revolution of my 33” tires. When I get around to installing the box, I'm only going the 2.8 route, as for me the 4.7 is definitely overkill.

sschaefer3

Mine is 26 spine to 23 spline back to 26 spline.


The 3.4 would be 23 all the way through.


I had to regear the diffs with the little engine, I doubt I would regear a 3.4 with a crawler either.

Here is how Marlin/Travis calculated mine:

Final Drive Ratio:

2.7L 5 speed first gear transmission ratio: 3.954
Chain driven transfer case: 2.566
Marlin Crawler box: 4.70
Ring and Pinion: 5.29

3.954 x 2.566 x 4.70 x 5.29 = 252:1


The best part of the 4.7 gear is that you have a stock lowrange, 125 to 1 low and a 252 to 1 low.

For example:

Holy Cross City: 252 on all the rocks, but the trail up to the creek 125 to 1.

Chinamans: 125 to 1 with the tanny in 3rd most of the time and 252 on anything that gathered a crowd. The new obsticle was 125 to 1 tranny in 2nd. That was a perfect combo not to destroy the frame. Mike Caskey also said he likes 125 to 1, 2nd gear.

Wheeler Lake: 252 going up the crack with no spotter, Stock low the rest of the time.

sschaefer3

You say that now. Just wait, you'll want to go lower and slower.

44Runner

Sure thing.

Stock ratio:
3.83 x 2.56 x 4.10 = 40.19968

Ratio with crawler with stock 2.28 gearing and stock diff gears:
3.83 x 2.28 x 2.56 x 4.10 = 91.6552704

Ratio with just 5.29s in the diffs:
3.83 x 2.56 x 5.29 = 51.867392

Personally, when I rebuild my crawler about a year or so down the road I will probably add 4.0 gears and make my over all this:
3.83 x 4.0 x 2.56 x 4.56 = 178.839552

I am currently at 102:1 and can idle up just about anything...

Joe

Ya, you're probably right Steve. When the time comes this winter to install the box, I'll probably hesitate and stumble around and go the 4.7 route. I stopped at Marlin’s last Monday and found him to be up to his eyeballs in work. He still recalls you very fondly with your camera and questions. He told me the 2.8 with my setup and the V8 would be very sufficient but I could go the 4.7 if I wanted. If I do opt for the big dog setup I think I’ll put bolts through my motor mounts or sure as hell I’ll twist them off.

Albuquerque Jim

V8?, what are you runnin' Joe?

Please tell!!!!

44Runner

What is your exact setup? With an auto you definately don't need to go as low as us manual guys, just make sure to get a BIG tranny cooler.

I would definately not shell out the bucks for 4.7s unless you actually do need them. With a manual, crawl ratios become a pretty exact science, not so with an auto.

EDIT: Dave's PSA: If you wheel at ALL with an auto, your first mod should always be a huge tranny cooler. Heat is the main enemy of an automatic transmission and wheeling is above even towing on the heat creation scale.