I haven't completely grasped exactly how the different ratios effect the gearing of a vehicle, and probably never will. But, if someone can tell me what the first and second numbers mean, I may be able to understand it a bit more. If possible, try to explain it like such and such gives you more take off speed/crawling ability, that kind of stuff. I would greatly appreciate it!

 

Which gears are you talking about? T-case, differential?

 

Anyone can type stuff into wikipedia, but it may give you a better understanding.

http://en.wikipedia.org/wiki/Gear_ratio

Truck looks great in your avatar Jay!

 

Thanks man

 

You can also plug in different gear ratios into this on-line calculator to find out the affect on vehicle speed at a given RPM:
- http://www.4crawler.com/4x4/4LoCalc.shtml#FindMPH

In short, you divide the engine RPM by the total gear ratio/reduction (of the transmission, transfer case and axle) to get the wheel RPM.

 

http://auto.howstuffworks.com/gears.htm

http://auto.howstuffworks.com/differential.htm

http://auto.howstuffworks.com/transmission.htm

 

wow, lots of info to go over! Thanks, I'll see what I can gather from it all.

(I was talking about the differential gears, but it's probably good to know the other gear ratios as well)

 

Okay, I know yall are trying to help, but I'm not totally oblivious to how gears work. I looked at the info and it touches on the different gear ratios, but none of it says anything about my application, which I guess none of you knew in the first place, so that's really my bad.

So differentials -

I know that people have said that I should re-gear my 4runner, but a few have said that it already has 4/88's in it stock. I know I have heard of these ratios: 4/88's 4/10's and that I should put them in the truck. WHY is what I want to know. I'm guessing better offroad, slowing the engine's energy down so that you have lower speeds going to the wheels for better crawling. I'm just hazy on that.

 

Ohhhh - you want to match your ground speed to your engine powerband by gear selection.

So, for instance, let's say you have 33's and regularly drive 70 MPH in 5th gear.

With 4.10's, you will be taching about 2200 RPM - well below the powerband of the 22RE or 3VZE - so every little roll or headwind, you will have to downshift to 4th. Offroad, the gear ratio multiplier is smaller, so you realize less torque at the wheels, making it harder to get moving at lower engine RPM's.

With 4.88's, you will be at 3000 RPM - right at the bottom of the powerband - so you will be able to hold 5th in the same situations. The gear mulitiplier (4.88x) is bigger, meaning you have more torque to the wheels for getting started.

The ratios for Toyotas are 4.10, 4.30, 4.56, 4.88, 5.29, 5.71. Higher numbers mean lower gears (higher RPM for the same speed).

 

Ahh, that pretty much hits the nail on the head! I'll have to study this a bit more but it does clear things up a lot. Thanks man, I appreciate it!

 

So If I put 5:29's in it for instance, I will have more torque to the rear wheels since it's a bigger ratio?

 

And the easy way to think about it is assume that the stock gearing and tire size was what you want to restore with a change in tire size. So just take the new tire size (diameter in inches) and divide by the stock tire size and multiply that by your stock gear ratio for what you need to use to get back to stock.

So assuming 4.10 stock gears and 28" tires, going to 33's gives you (33/28) = 1.18.

4.10 * 1.18 = 4.83, or close to 4.88.

 

Yep, and you'll have higher engine RPMs for a given highway speed. I ran that combo for a few years and liked the power (and better MPG), but if you have to drie at 70MPH+ for long distances, having that engine screaming along at 3300-3500 RPM all day long is tiring. Also realize your speedo/odo will be off so either live with it or get it re-calibrated.

 

huh, okay, I think I finally understand it. So I guess having an automatic transmission would be better with 4:88's anyway because of the overdrive feature? Or is it basically like 5th gear in a manual? By the way I was told that this runner has 4:88's stock, but I'll have to get up under there and see for myself.

 

For an automatic and 33's, you generally want 5.29 gears to get back to stock. The autos usually have one step higher gearing than the manuals.

 

but if I have 29's (tires) will an automatic be better? I am still pretty far from getting bigger tires, and my bfg a/t's still have a good bit of tread left.

 

Is and automatic better than what?

Basically you have stock size tires, and if you have stock gears, you are basically set. If it ain't broke, don't fix it.

Suppose you could go from the stock 4.3x to 4.56 gears but probably not worth the effort.

 

yeah, what he said.

 

better than a manual transmission on the highway if you put a higher gear ratio in the differential. I know that the automatic transmission has an overdrive setting, I'm not sure if it's equivalent or better than 5th gear in a manual. (basically I'm bummed that I have an auto instead of a manual trans. and I'm trying to see if having an auto is better anyway) I liked my old 4x4 with the manual transmission, and going from that to a 4runner is a huge step up for me, but I have to use the automatic transmission that's in the runner cause I don't have the money to get a manual....yet. I really appreciate all the replies, this is by far the most help I have gotten from just about any thread I have posted here on YT. Most threads I start go unanswered and I usually never get anything out of posting. But this has explained a lot to me and again, has been the friendly, helpful response that I should expect with any thread I post.

 

This site is amazing. Check it out.

http://www.grimmjeeper.com/gears.html