Topic: Transfer Case Basics

[GA Runner]

I know a transfer case puts your truck into 4 wheel drive but how exactly does it work or do that? And what does changin the gears to 4.7:1 gears do for your transfer case? I'm 17 and tryin to learn all this.

[jimbo74]

READ:


http://auto.howstuffworks.com/four-wheel-drive.htm

http://www.marlincrawler.com/htm/transfercase/tcaseinfo.htm

http://www.marlincrawler.com/htm/transfercase/dual_07_intro.htm

http://www.marlincrawler.com/htm/transfercase/getratio.htm

[blackdiamond]

I'll assume that you have been on a 10-speed bike at least one in your life.  Do you remember how the front chain had two rows of teeth (gears) and the rear wheel had 5 rows of teeth (gears)?  The overall gear you were in depended on the combination of front and rear you chose.  Think of the gears on the wheel as the transmission (5 gears equals a 5 spd transmission) and the front gears as the transfer case.  On a bike, the larger the gear on the front the harder it was to pedal and on the smaller the gear on the rear the harder it was to pedal.  The basic idea is that the more times the pedals go around compared to the rear tire the easier it is to pedal.

The transmission and transfer case do essentially the same function as the two sets of gears on the bike for your truck.  Each time you upshift the transmission you give the engine less leverage (1st is 3.93 to 1 and 4th is 1 to 1) on the rear tires which is why you need lower gears to climb hills.  The difference in gearing in the transfer case provides the ability to drive the front tires (4wd) and also another lower range of gears.  The stock transfer case low range gearing is 2.28 so going to 4.7 provides almost double the leverage for the engine on the tires.

Make any sense or am I just typing to myself? 

[MiniSimp]

Make any sense or am I just typing to myself? 

 

[GA Runner [OP]]

that actually makes a lot more sense now. thanks 

[GA Runner [OP]]

so this will make it a lot easier when you go off roadin right? this wont add any traction will it?

[jimbo74]

so this will make it a lot easier when you go off roadin right? this wont add any traction will it?

it can, in a roundabout way.... it will not directly correlate to traction of the tires being it is not a locker or a tire itself, but by allowing the slower speeds, there is less likelyhood of stalling out and breaking the traction you do have.... more often than not, its that little momentum you have that will get you over that obstacle

[GA Runner [OP]]

ok gotcha. what does the different spline count mean or do?

[jimbo74]

ok gotcha. what does the different spline count mean or do?

more splines is an increase in strength.....

turbos had a 23 spline

you can upgrade a regular 21 spline to a 23 speed for more strength if needed

[GA Runner [OP]]

ok so a 21 spline would be fine for my truck?

[blackdiamond]

21 spline is adequate for the majority of people.

I'm not sure if the splines themselves are stronger of if it is due to the larger diameter of the shaft required to "fit" two additional teeth on.  I believe I have seen the shafts sheared off which makes me think it's the larger overall diameter.  If this is the case,

Think of it as a carrot that you want to twist into two pieces.  A smaller carrot will break easier because it has less area resisting the twisting force you put on it.

Tell me if I'm patronizing you, that isn't my intent, just trying to compare it to something you can visualize or have experienced.

[GA Runner [OP]]

yeah that kinda makes sense. so if you are gonna change the gears go ahead and get the 23 spline cause it will be a little stronger?

[Rocksurfer]

Just make sure what you are getting will work with your truck.

[GA Runner [OP]]

if you have a chain driven t-case can you still put 4.7:1 gears in it? or do you have to buy a new t-case? i think mine is a chain drive...

[jimbo74]

if you have a chain driven t-case can you still put 4.7:1 gears in it? or do you have to buy a new t-case? i think mine is a chain drive...

no, you dotn have gears that can be replaced.....


now you can buy an adapter to adapt your trasmission to a gear drive case that can have 4.7 gears in it....

[GA Runner [OP]]

could you buy another t-case of another toyota and swap it out for mine? how much do adapters cost?

[jimbo74]

yes, you need a gear drive case and an adapter

www.marlincrawler.com

[jimbo74]

more specifically:

http://www.marlincrawler.com/htm/transfercase/pickup_dual.htm

[BigMike]

more splines is an increase in strength.....

In the realm of the Toyota gear drive transfer case, it is the increase in minimum cross-sectional diameter of the 23-spline input which yields it's increase in strength

it will not directly correlate to traction of the tires being it is not a locker or a tire itself, but by allowing the slower speeds, there is less likelyhood of stalling out and breaking the traction you do have.... more often than not, its that little momentum you have that will get you over that obstacle

Think of it as trying to move across a frozen lake. If you get set in a sprinters position, and try to blast off with all your might, your increase in feet velocity will get you no where fast. But it is the man who moves slowly and carefully about the icy surface who may reach his final destination.

It is all about static friction. Higher acceleration between two points will increase the likely hood of breaking static friction, at which point kinetic friction results. And since kinetic friction has a lower coefficient of friction than compared to it's static counterpart, forward progress is lost in the process.

By decreasing your vehicles wheel speed, you increase the odds of maintaining that static frictional connection between your tire and the ground, thereby providing a means for your vehicle to obtain forward progress.

Go Slow or Go Home


GA Runner,

Is that transfer case picture above taken from your 4Runner in your avatar? If so, your 4Runner must be powered by a 3.0-liter 6-cylinder. Is your truck equipped with an Automatic or a Manual transmission?

[GA Runner [OP]]

yea thats my 4runner and it is a v6. its a manual. why?

[TIMS89CRAWLER]

if it is a v6 and manual then you have a chain driven t-case..... therefore you will need the v6 trans to 4cyl t-case adapter from marlin.....

http://www.marlincrawler.com/htm/transfercase/pickup_dual.htm
MC-14210, 30-4GT V6 Adapter Plate, $349

   

[BigMike]

That is very good news. By using our conversion adapter plate, you are able to replace your 1989 chain drive transfer case with a 1979-95 gear drive transfer case.

The chain drive transfer case you have now uses a planetary gear set to achieve it's gear reduction, whereas the gear drive transfer case uses a counter shaft to achieve it's gear reduction.

The problem with planetary gear reduction system, is that in order to increase it's gear reduction, progressively smaller components are required which diminishes the system's strength exponentially.

This is true to a counter shaft gear reduction type, however at a lesser rate. With the space and size restrictions of the Toyota transfer cases, a redesigned lower gear ratio chain drive unit will be considerably weaker than the gear drive unit of the same gear reduction.

For this exact reason, the after market of the chain drive Toyota transfer case is non existent.

Therefore the best way to reduce the final gear drive ratio of a Toyota truck equipped with a chain drive transfer case, is to replace it's chain drive transfer case with a 1979-95 gear drive transfer case.

The conversion adapter mentioned in the first sentence above, is a thin 1" thick billet aluminum plate that converts the bolt pattern of your transmission's tail housing to allow a gear drive transfer case to be mounted behind it.

Once the gear drive transfer case is mounted behind your V6 transmission, the sky is the limit: Your truck will be opened up to the wonderful Marlin Crawler world of after market parts including 4.70:1 low range gear replacements to multiple gear reduction transfer case systems.

What sort of plans do you have for your 4Runner? What types of terrain are you looking to tackle?

[BigMike]

ok so a 21 spline would be fine for my truck?

Beings that your truck is a 6-cylinder, we do not recommend running the 4-cylinder 21-spline variant due to the increase in torque and weight of your engine and drivetrain, respectively. Furthermore, our gear drive transfer case conversion kit mentioned above only supports a 23-spline transfer case to maintain the integrity of your 6-cylinder drivetrain.

[GA Runner [OP]]

Thanks that really helped  right now i go muddin and trail ridin and things like that a lot but once i get out of high school and can afford it im plannin on makin my truck into a rock crawler

Your truck will be opened up to the wonderful Marlin Crawler world of after market parts including 4.70:1 low range gear replacements to multiple gear reduction transfer case systems.

When you say multiple gear reduction t-case systems do you mean that there are other gear sets for a transfer case?

[BigMike]

When you say multiple gear reduction t-case systems do you mean that there are other gear sets for a transfer case?

No, I am referring to multiple gear reductions as in dual or even triple gear reduction transfer case systems, ie. "The Marlin Crawler Dual Case"

The beauty of the Toyota gear drive transfer case is that it's gear reduction portion may be stacked upon one another thus doubling or even tripling the number of gear reductions in the drive train.

[GA Runner [OP]]

so let me see if i get this straight... you can have gears reducing gears? how does a dual or triple t-case work?

[blackdiamond]

The stock gear driven transfer cases are made up of two sections, one provides the gear reduction, or "low range," and the other provides the four wheel drive, or the front driveshaft output.  Marlin Crawler, as well as others, sell an adapter that allows us to "stack" multiple gear reduction sections.  If you look at the transfer case section of the website you can see pictures of both and you'll notice two essentially identical section at the front with an adapter in between.

[TRACKER]

The stock gear driven transfer cases are made up of two sections, one provides the gear reduction, or "low range," and the other provides the four wheel drive, or the front driveshaft output.  Marlin Crawler, as well as others, sell an adapter that allows us to "stack" multiple gear reduction sections.  If you look at the transfer case section of the website you can see pictures of both and you'll notice two essentially identical section at the front with an adapter in between.

i like it better if you explain it with 15 speed mountain bike - the 10 speed one was perfect

[blackdiamond]

i like it better if you explain it with 15 speed mountain bike - the 10 speed one was perfect

I don't know of any bikes with three different sets of gear rings, it would require two chains.   

Maybe Marlin could design a crawler for a tandem mountain bike.