The following question was submitted to the T.T.O.R.A. message board (message number 17078.1) by Janster (JLIEBL1):
Ok guys and gals,
I'm a little slow and I wanted to clear things up. I haven't had a real reason to learn about gears and such.
Ok, you guys that are changing your gears... you change them in the rear and front diffs? I'm thinking you can't change one without changing the other? If you didn't change them together, your front and rear wheels would move at different speeds (which is not good)?
Is there something in the transfer (gears) that can be changed to do the same purpose but drive all 4 wheels? Or is that just too damn expensive and probably not available to do that?
When you change your gears to higher gears, does that make your engine rev higher? I mean...the drive shaft must turn more for the same amount of distance versus a lower gear ratio would?
Please pardon - its' about time I learn about this stuff.
Thanks for the help!
From: Supersized2001 (DAKOTA001)
Well first you must change the gears in both diffs or it will tear them apart. Your gears are matched to your tires, engine and tranny. If you upgrade to a larger tire then it's not matched any more and you will have to use more engine power to turn the wheels which is not good on it and you have less torque. When you go to a larger tire you can go to a lower gear which will take less engine power to turn them. Such as a 4:88 or 5:29 gear ratio. They have more teeth and will take less RPMs to turn the wheel one rotation.
As for changing gears in the transfer case. Some you can but ours you cannot. There are other options such as a gear reduction box and the route that Frankentaco is going with the klune-v but they are more expensive and most are custom setups that are not available for the Tacomas.
Gears are the cheapest route right now and will run any where from about $600 for parts and self install which is not recommended and up to $1200 or a little more for the parts and installation cost to have someone qualified to do it.
I'm sure someone can explain it better but I thought I would try to confuse you a little more first. (LOL)
Shawn explained it pretty well, but if you want more details and some cool graphics and animation, check out http://www.howstuffworks.com/gear.htm
Look at the links on how transmissions, transfer cases, and differentials work. Those are the 3 places where gear reduction takes place.
I've learned a lot about gears working on the Jeep. Since Jeep parts are so cheap and interchangeable, most folks start getting a larger range of gearing (a lower low plus an overdrive if wanted) by changing out the transmission. Then they match the differential gearing (both front and back) to the desired tire size. Then if they want to get an even lower 4L for rock-crawling, they go for new gearing in the transfer case. I'm doing all 3 things to the Jeep.
How ya doin! Ok here, I'll try to clear things up a bit:
YES - you MUST use the same ratio gears in the front and rear diff. If you did not the front would turn at a different speed than the back! Extremely not good!... SNAP GOES THE DRIVE LINE!!!
As far as transfer case low gear setup - you can't on our Tacomas because we have a chain-driven transfer-case! (the older Toyotas have a gear driven transfer case and they can just install super low gears in the transfer case!!) For the Tacomas you will soon be able to get Klune-V crawler like "Frankentaco" is having done right now. I don't know a ton about it but it is a super low transfer case gear reduction that (I think) goes between the tranny and the transfer case, but with this I think you have to lengthen the front drive shaft and shorten the rear because it moves the transfer case back farther, so this is a major mod, but it is the ultimate setup!!! Also I'm pretty sure that Atlas makes a gear-driven transfer case for the Taco with super low gears but I'm not totally sure! I've been researching this stuff a lot lately, cause I am planning to get a transfer case rear reduction, I just have to decide which way to go, Klune-v, Atlas, Marlin-crawler!! There is not a ton available for the Tacoma yet, but I think were really going to see a BIG increase in hard-core off-road equipment throughout the next couple years!!
Back to diff gears ==
Lower gears mean high RPMs
Higher gears mean lower RPMs
So if you put 33"s on you Taco, you would replace the factory 3.91 gears (or whatever ratio you have) with 4.56 or 4.88 gears to put your RPMs and power back to normal.
I am going to have 5.29 gears (and a lock-right) installed in my Taco in the spring, this is way to low for highway driving, at cruising speed (60-70mph) it will be at 3500 RPMs! But it will be AWESOME off-road and for crawlin!!
Sorry this was so long! I'm not very good at writing small messages!! LOL! Hope this helps ya out, later Jandy!!
Steve Dalton "TANKOMA"
From: Janster (JLIEBL1)
Great!! You guys are awesome!! Shawn, Sherry & Steve!!
Ok...I totally forgot about the transfer case being chain driven.
Yeah - that would get really expensive to change the interior parts of the transfer case. But now I do understand much more than I had before.
Back to General Tacoma Information
Back to the Main Page