[rsmwrangler]

Roger, thanks guys! So regearing would be both a performance and a convinience factor when offroading. 4lo would be limited to some specially tricky spots or sections, right?

Look at it from the implict benefit from regaring your diffs not just because you have to regear because you're expecting to bump the performance or convienence onroad or offroad independently. It's tacit, when you need gears you regear to restore the missing torque leverage lost because you went with bigger tires, or because you want to bump that leverage a bit more and doing so affects all transfer case mode as it's all connected: engine torque, trans gear ratio, transfer case ratio, diff ratio etc.

I remember when i did 35's on my 1st JK with the factory 3.21's, I didn't feel that much of a difference driving on flat roads, sure she was a little more sluggish but it wasn't bothering me one single bit, that all changed when i added hills to my conmmute as she was really struggling to go up and i had to use 3rd gear manual (auto trans) to keep the speed at 65mph. Offroading in 4lo was also bad as i couldn't feel the torque multiplication at all so things like going downhill was not controlled at all and i had to ride on the brakes like crazy to hold her back going downhill. Regearing restored everything i had lost in the performance department after adding 35's for both onraod/offroad.

You'll know when to use 4lo cause even in 1st gear you'll feel the motor struggling if your transfer case wasn't multiplying your output torque to the wheels. typically you'll need it in heavy sand, heavy snow, heavy mud, going uphill with ruts/rocks etc, going downhill when you need to torque reduction to keep the vehicle under control etc etc. you use 4hi when the conditions warrant 4 wheel drive but don't need the extra torque, so for example going to the grocery store on a snowy/icy day when trying to drive in 2hi gives you lots of rear wheel spin so you pop the TC in 4hi and now you can drive in a more controlled manner.

Hope it makes sense.

 

[emcvay]

In the soft sand in the dunes here locally you won't get far in 4 hi (ask me how I know) but with 4lo you're good to go! Even with my 4.10's I was fine and running around mostly in 4th.

 

[White Elemant]

I thank you all for your input and insight, as quite often, this was not a simple matter of either this or that 😃

So one would benefit from regearing also in offroad (or otherwise severe) conditions, as to how "deep" into regearing one want's to sink in, is more of a question of personal preference.

 

[TerryC6]

There is a lot that goes into this when looking at off road performance, manual/auto, transfer case ratios. You can put to much gear in the vehicle though especially when it comes to auto's and I am going to pick on @Bob Sanders here. If I am not mistaken Bob has 5.13's, running 35 inch tires and has the 4:1 transfer case. He has a problem stopping the vehicle when in 4lo and first gear. The reason for that is below stall speed of the converter you are almost double the amount of engine torque being inputted to the transmission. The normal recommendation would be 4.56's. He can climb the side of a building be he can't stop it. If it was manual this would not be an issue or if he goes to 37's it should not be an issue.

In the end I think most of us regear because of larger tires killed our on road performance, that is where we spend most of the time.

 

[Bob Sanders]

and I am going to pick on @Bob Sanders here.

Well, I'm just thoroughly incensed and insulted!

Actually what I need is the bigger brake rotors. When the stock rotors die I will upgrade, but until then... neutral works fine too.

True... you can feather it out with a manual and a clutch.... but too much of that and you end up replacing clutches prematurely.

 

[TerryC6]

Well, I'm just thoroughly incensed and insulted!

Actually what I need is the bigger brake rotors. When the stock rotors die I will upgrade, but until then... neutral works fine too.

True... you can feather it out with a manual and a clutch.... but too much of that and you end up replacing clutches prematurely.

Of course I was not bad mouthing ya, just that to much gear and the torque multiplication you get with an auto can cause an issue. I am having to look at this because I will be moving to an auto whenever I pull the trigger on the V8, provided the state does not get in the way.

 

[Bob Sanders]

Of course I was not bad mouthing ya, just that to much gear and the torque multiplication you get with an auto can cause an issue. I am having to look at this because I will be moving to an auto whenever I pull the trigger on the V8, provided the state does not get in the way.

The big brake kit is a good idea if you're going to regear... particularly with a v8 and/or 4:1 tcase. At some point though the size of the brakes won't matter. You get enough torque going and even the best brakes just won't hold you back, and that's when shifting in/out of neutral comes into play. It's not a huge issue... you just have to remember to have your foot on the brake when you do hit neutral.

I was watching a video of a guy with a 4 speed atlas. Of course he had a manual so he could feather the clutch out at any time, but just as a point of demonstration even with big brakes, he stuck it in low 4wd, and couldn't hold it back with 2 feet jammed hard on the pedal.

 

[White Elemant]

I'm thinkin when you have so much torque your stock brakes won't stop you, you've overdone it.

What is the benefit of that? Being able to navigate any obstacle without touching the gas pedal? I mean a lesser amount of torque will do if you drive an automatic. It will not stall on you.

 

[TerryC6]

The big brake kit is a good idea if you're going to regear... particularly with a v8 and/or 4:1 tcase. At some point though the size of the brakes won't matter. You get enough torque going and even the best brakes just won't hold you back, and that's when shifting in/out of neutral comes into play. It's not a huge issue... you just have to remember to have your foot on the brake when you do hit neutral.

I was watching a video of a guy with a 4 speed atlas. Of course he had a manual so he could feather the clutch out at any time, but just as a point of demonstration even with big brakes, he stuck it in low 4wd, and couldn't hold it back with 2 feet jammed hard on the pedal.

Surprisingly the 4:1 transfer case is not recommended for V8 swaps has it is not as strong as the standard transfer case. The standard case or the Atlas 3:1 2 speed case is recommended. This is for the LS/LT motors. The 5.3 is close to 300 ft lbs of torque just off idle and the 6.2 at 350 ft lbs. When you are crawling and have the most in torque multiplication you don't need a lot of gear. Also the auto in these cases have a 4.03 to 4.7 depending on the transmission you go with.

 

[Bob Sanders]

I'm thinkin when you have so much torque your stock brakes won't stop you, you've overdone it.

What is the benefit of that? Being able to navigate any obstacle without touching the gas pedal? I mean a lesser amount of torque will do if you drive an automatic. It will not stall on you.

Well, I didn't say it won't stop. Those are your words, not mine. I said I need two feet on the pedal to hold it at a stop.
That's not at all the same as "....stock brakes won't stop you"

But yes, as already stated I should be using the big brakes. I simply refuse to throw good rotors into the garbage can. There is no sense in that. I will go with big brakes when the stock rotors and pads bite the dust.

 

[Bob Sanders]

you've overdone it.

Interesting... I was reading up on that... I haven't done it enough

My crawl ratio is around 92:1

According to this article below, 100:1 is what most in the real rock crawling world strive for.

The 100:1 range is about what most strive for in a rockcrawling rig. You can certainly get away with a much higher (numerically lower) crawl ratio, but the lower you go, the greater the odds of not having to back out of any obstacles on the trail.

Rock Crawling - Crawl Ratio Formula - 4 Wheel Drive & Sport Utility Magazine

Read about the Crawl Ratio Formula, try some test problems solve the equation. - 4 Wheel Drive & Sport Utility Magazine

www.motortrend.com

 

[Tweak]

Yall are over here trying to reinvent things we have known to be true for many many years.

Speaking trail only, lower is better. Go drive something with 4.10s and then drive the same jeep with 5.38's and tell me what works better.

We arent just spending all this money putting super low gears and 2 speed transfercases in our rigs for the hell of it.

My front axle can technically run a 7.17 gear, but nobody makes anything lower than 5.38 for the GM 14 bolt.

 

[White Elemant]

Well, I didn't say it won't stop. Those are your words, not mine. I said I need two feet on the pedal to hold it at a stop.
That's not at all the same as "....stock brakes won't stop you"

But yes, as already stated I should be using the big brakes. I simply refuse to throw good rotors into the garbage can. There is no sense in that. I will go with big brakes when the stock rotors and pads bite the dust.

Well I was being sorta humoresque, but omitted the smiley. Just to make sure: to each their own, I personally like using the gas pedal, even though the weird header arrangement in the 3.6 does take away some of the clarity of the song of the v6 😃

You, of course, arrange your rig as you please, from my point of view that does however seem strange. Two feet on the pedal does translate to one heck of a press, for me that would be more than 200 lbs of pressure and I'm no strongman. Better be careful, the back of the seat migh give in 😃

 

[Bob Sanders]

You, of course, arrange your rig as you please, from my point of view that does however seem strange. Two feet on the pedal does translate to one heck of a press, for me that would be more than 200 lbs of pressure and I'm no strongman. Better be careful, the back of the seat migh give in 😃

Well, you're kind of thinking in one world while talking about another.

The crawl ratio of your average 3.21 sport in 4lo is pretty bad. It's like 40:1 I think.
At that ratio you will need to rely pretty heavily on the gas and brakes while crawling over a large rock. You will have to gun it to get it up, and provided you don't overshoot the other side of the rock and launch your front end into space for a second or so, and you will have to brake pretty hard while coming down the other side to remain in control (probably two feet on the brake)

The question you SHOULD be asking is how often do you actually need to use the brakes at a crawl ratio of 90 or 100 to 1 (in my case roughly 0.5mph). I can crawl over that same rock without touching the gas.... OR.... the brakes. Unlike the 3.21 sport above, it CLIMBS down. It doesn't drop down.

 

[TerryC6]

Crawl ratio seems simple, the higher the slower you go and the more control you have. And this is true when talking about about just a straight gear calculations. But nothing is as simple as it looks. Things that have to be taking into consideration are tire size and engine torque output. And with a manual it is much simpler than an automatic. With a manual it really is just a simple calculation.

When talking about an auto thanks to the torque converter you get about twice the amount of engine torque below stall speed, the stall speed for the JK is about 1700 rpms or so I have read. Many times people talk about crawling at 1000 rpms for the best control. Taking the 3.6 that is about 200 to 215 ft lbs of torque. Now add the torque converter to the equation and we are putting into the first gear of the tranny 400 plus ft lbs of torque. Start to multiply gears and we end up with a whopping 31,683 ft lbs of torque out to the wheels, split by 4 and you have 7921 per axle. As Bob found out he can't stop that much torque with stock brakes. This is also why we see snapped axles shafts even with d60's.

 

[Bob Sanders]

This is also why we see snapped axles shafts even with d60's.

Yeah... but what also snaps axles (at probably a higher rate) is gunning the crap out of the gas pedal and all of a sudden having a spinning wheel grab hold.

 

[Bob Sanders]

I don't know what this guy's crawl speed is but it's an atlas 4 speed and it goes up and over effortlessly with no gas... and it looks like no brakes either. The question I have is how much gas gunning and braking would you have to do if you had the crawl ratio of a stock sport.

 

[White Elemant]

I for one have enough fine motor skills to modulate gas and brake with more range than "gun or step on it". I get what you are pointing at here, but the the option for high crawl ratio is not wreckless use of pedals.

I have the (slight) benefit of having the optional 3.73 gear ratio, dunno how "bad" the stock 3.21 is.

 

[Bob Sanders]

I for one have enough fine motor skills to modulate gas and brake with more range than "gun or step on it". I get what you are pointing at here, but the the option for high crawl ratio is not wreckless use of pedals.

Well... we're talking ONE rock as a point of example. Put a dozen or 2 in front of you......

I have the (slight) benefit of having the optional 3.73 gear ratio, dunno how "bad" the stock 3.21 is.

3.73 on a sport isn't much better. 3.21 comes out to 40 crawl ratio while 3.73 comes out to 44. Meanwhile the above article is calling 50:1 "reasonable" and 100:1 is what "most strive for".

Not saying that you can't crawl in a stock sport. You sure can.... at least on some of the more moderate trails anyway... but the point is the bigger the crawl ratio (within reason), the more torque and control you will have.

Now that being said, I don't really do rock crawling, but that doesn't mean I don't need it and use it. Just getting my boat into a very narrow road and driveway... well... put it this way... a truck or stock sport would be a disaster.
With the 4:1 Tcase and 5.31 gears, I climbed up and over that rock in front effortlessly in an area where I needed some serious control.

How do you get a 35 foot boat trailer to make pretty much a 90 degree turn on a dirt road no wider than a jeep?
You go OFF road of course

 

[Jab1719]

Well... we're talking ONE rock as a point of example. Put a dozen or 2 in front of you......

3.73 on a sport isn't much better. 3.21 comes out to 40 crawl ratio while 3.73 comes out to 44. Meanwhile the above article is calling 50:1 "reasonable" and 100:1 is what "most strive for".

Not saying that you can't crawl in a stock sport. You sure can.... at least on some of the more moderate trails anyway... but the point is the bigger the crawl ratio (within reason), the more torque and control you will have.

Now that being said, I don't really do rock crawling, but that doesn't mean I don't need it and use it. Just getting my boat into a very narrow road and driveway... well... put it this way... a truck or stock sport would be a disaster.
With the 4:1 Tcase and 5.31 gears, I climbed up and over that rock in front effortlessly in an area where I needed some serious control.

How do you get a 35 foot boat trailer to make pretty much a 90 degree turn on a dirt road no wider than a jeep?
You go OFF road of course

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I agree here. To me this is simple. When I did heavy 35s with my stock brakes and 3.73s my Jeep wouldn’t crawl in 4lo without me hitting the gas and the stock brakes sucked stopping me. Fast forward to 4.88s and a big brake kit and I can crawl with no gas pedal and I can stop the Jeep no problem now. Sure some trails I don’t really need the lower gearing and actually hit the gas to speed up a little bit but throw several obstacles in front of me and I can just focus on steering and watching my spotter and not worry about hitting the gas then the brake constantly.

Of course there are plenty of people who just gas through everything and end up fine but if I am spending the money on a lift and tires then I want the performance too and will regear.


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