Re-Gear

Yes sir you will.

 

I'll admit manuals are much more fun to drive. I enjoy rowing gears, but the auto is much nicer for crawling, plus you just drag the shifter down into 1st and the tranny stays in first, so in that aspect it's not much different than a manual.

 

Well what do you think, you've driven cross country? At 80 I turn almost exactly 3k. Theres a lot of wide open out this way and I wouldn't want 4.88s.

With the auto's .72 5th vs 6th @ .85 I think theres a good 450 or so rpm difference around those speeds.

Hard to say for sure what the 4.88s would do to economy but my mileage isn't too great at 80 and I imagine higher rpms would make it all the worse.

I really have no trouble with power either. 4.88s in town could be nice but I'm happy with what I have.

 

I always figure these guys with the 4.56s or 4.88s and 33s just must not have the same kind of highway systems we have out here. Going to Elko or wherever, I'll go 80 for 4 hours one way. Seems like it'd be rough with 33s.

 

Hey Maximus. What gears do you have? I am thinking o going with 4:56 with my 35s. But I want them a little lower than factory. Will 4:56 offer that do you know?

 

Play with this guys:
http://www.grimmjeeper.com/gears.html

The 5spd auto is the Toyota A750F tranny, the 6spd manual is the RA60F, the 5spd manual is the W56 and the 4 spd auto is the A340F.

The transfer case high range is 1 and the low range is 2.567. This isn't perfect because gears aren't completely perfect and tire sizes tend to be far from perfect.

 

I came up with all these numbers once upon a time.

http://www.tacomaworld.com/forum/technical-chat/179500-re-gear-writeup.html#post4194656


I have 4.56s Jamie. They're a little lower than stock.

 

I don't usually drive more than a couple hours 1 way, and again my rpms are much lower yours because of the tranny. If I had a manual I wouldn't have gone with 4.88's. Plus as always bigger tires are in my future I went and looked at some 36's, but sadly they were R15's and that rim just doesn't fit on 2nd gens...

 

Thank you sir i figured as much. Idk i dont daily drive my taco anymore. Its a half and half shared time with my car so i might just skip gearing and put in the arb front locker. Any thoughts on that?

 

Install is most of the cost. If you want gears it won't add much.

 

I am very curious about this as I have a 6" lift and 35's, I thought about re-gearing but did not know where to go...was thinking the 4.56 but I am very new at all of this. I also have the 6sp manual and I read that with 35's I shouldn't have to re-gear because I can manage the rpm's myself with the manual?? I am going to be doing quite a bit of highway driving. Could someone please shed some light on where I should go from here!!

Thanks in advance,

 

Easiest would be to drive a truck like yours with gears.

But...

basically you've got gears...

You've got gears in the transmission, you've got gears in the transfer case, and you've got gears in the differentials. We use gears to change direction, or to change speed or torque.

You can think of more torque as more of a reduction and more speed as less of a reduction

At any rate you want to be able to operate your vehicle and different speeds, if you had just a clutch and a 1:1 output from your engine you'd never get anywhere.


When you change to a larger tire it's almost like changing gearing, you essentially gear up and reduce torque and add speed. You'll notice this as a loss of "power".

To get back to a stock ratio you can change your differential gearing to compesate for the larger tires. You'll still lack stock "power" because of the rolling weight and mass and resistance but you'll be back to stock rpm ranges for each gear.

With 3.73s and 35s theres likely few chances to use your 6th gear effectively, the rpms are just too low and your engine can't produce enough torque to keep the truck going. Now with 4.56s and 35s your RPMs jump up, you're back into the "powerband" or area where the truck can make enough torque to keep up the speed or accelerate.

You can read more here, really explains gears well.

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

Also once you start understanding here's a bunch of numbers
http://www.tacomaworld.com/forum/technical-chat/179500-re-gear-writeup.html#post4194656

 

If we assume that an engine produces a fixed amount of power, we can use gears to give us a speed or a torque advantage. Gears can never give us a power advantage. When we increase torque we decrease speed and the opposite is true. If a smaller gear is the drive gear torque will be increase and speed decreased. This is the case of a differential.

The change in mechanical advantage is easily measure; the ratio is proposional to the radius of the gears. Or the number of teeth on the gears.



Also, as far as differentials...

why not just make all the gearing in the transmission right?

Well... diffs do several things...

They transmit motion 90* for one, they provide a gear reduction which is better to have closer to the wheels, as you're putting more force (torque/leverage) on things it's better to have it closer to the wheels so you're putting less strain on the majority of the drive train components. The only thing that has to handle that extra torque (twisting force) is the axle shafts. If you had the extra gear reduction sooner you'd have to transmit that extra torque all the way back, adding extra strain to everything.

Diffs also allow differential action, which is to say they will allow you to transmit power to both tires equally while going straight but still allowing you to take a turn without binding, since one wheel will speed up and one will slow down through a curve.


So back to larger tires, essentially you're increasing the speed and reducing the torque of the system. By adding lower (numerically higher) gears, we can compensate for that. It doesn't add power, it just reduces speed and adds torque. Which you'll feel as a truck that feels like it has more "power".

That should get you started anyway.

 

I guess this is pretty helpful also, better explains some of the things I touched on.

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

This is why we change the gearing in the differential, it will put you back into that stock band/gearing. It's also much easier to change the gearing there than anywhere else and also limits what is exposed to all that extra torque.

 

I guess I should say it's possible to go the other way and increase torque/lower speed too much to the point that you're running very high RPMs (beyond useful) going down the highway and you consume more fuel, or it limits your overall top speed. Currently with 35s and 4.56 gears in 6th gear I can travel 80 at 3k rpm and get 15mpg with all the shit bolted on my truck and it'll pull hills just fine in 6th on cruise control.

Even with 4.88s you could comfortably do 80 even 90 but you may lose fuel economy over 4.56s at that speed.

With 35s and 4.56s I can still hit 110, on a track of course.

 

Hey thanks for all the info max. Learn something new everyday!

 

Not a problem, hope it all made sense.

 

That is a good amount of information, a lot of it I was unaware of!! I am pretty mechanically inclined and understand gearing from my stang days, but I know it is a bit different when we are talking about trucks.

The same principals yes, but I just want to make sure that I will not pre maturely burn out something because I did not change them out. Also I want to be able to utilize my overdrive for better mileage. I do a lot of freeway driving and do not want to be all wound up screaming rpm's up to redline just trying to get down the road!!

 

Nice explanation Max!! Everything looked right to me in it.

You are correct. Hmm... Learn something new everyday. haha

The R155 isn't available in the drop down, but here are the gear ratios according to wikipedia:

R155F
First Gear: 3.95:1
Second Gear: 2.06:1
Third Gear: 1.44:1
Fourth Gear: 1.00:1
Fifth Gear: 0.81:1
Reverse Gear: 4.22:1

 

Thanks Max! +1