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Discussion Starter #1
Hey all. I was wondering if it was possible to swap the 4.10 ring and pinion with a 4.30 ring and pinion without replacing the whole rear end.

And if thats not possible.. is it possible to swap out the whole 4.10 rear axle for a 4.30 rear axle? would it bolt right up? Please forgive my newbness on this. Any info from more edumacated 4x4 guys would be greatly appreciated.
 

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Wish you were from CA. I'd swap the 4.30 parts or rear end with you. I don't tow with mine, don't need to hammer the gas, and don't like the dent in MPG from it.
 

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Tundrasocal, you might be getting better gas mileage with that 4.30 gear ratio.

Don't forget that your engine needs a sweet spot on the highway, and unless California is completely hill free, you will be downshifting into 5th to get into that power more.

And, if you decide to buy a different set of gears, don't forget you need to do front and rear (4x4 models) and that alone will cost you a few grand. Is it worth it to spend more money to save a few pennies at the pump? Nope.

Signcutter, as far as you're concerned, I believe the differential is bigger on the 5.7 so no swap of internals. The others will know better if it'll bolt up.

Secondly, don't forget to do 4.30s up front if you decide to swap gears if you're a 4x4. That'll cost ya some dough to get it built.

-rockstate
 

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Also, keep in mind that we are not able to change any software in the PCM so your speedo will be wacked and your shift points could be jacked up.

I also agree with Rockstate, or morning glory, or whatever the heck your name is, about the economy of the 4:30 gears. It will accelerate easier, requiring less throttle to reach speed. This could translate into better mpg than a 4:10 ratio would deliver. On a '69 elCamino I once had, I swapped out the 2.76:1 axle for a 4.11:1 positracion and my mpg increased significantly. I was running a 400 small block. It took far less throttle to get the car moving with 4.11s than with 2.76s. The engine didn't have to work as hard.
 

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Discussion Starter #5
Man.. I was hoping that all the stuff required would be an easy swap out of toyota parts. I thought increasing the diff ratio to 4.30 would negate the tire diameter increase... but now I see that this wont be a cost effective or practical solution. Thx for the info guys. I wish I had found this forum before I bought the truck. I didnt realize all the changes in performance a simple tire size change could cause. There is still hope with the hypertech speedo fix though.
 

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Man.. I was hoping that all the stuff required would be an easy swap out of toyota parts. I thought increasing the diff ratio to 4.30 would negate the tire diameter increase... but now I see that this wont be a cost effective or practical solution. Thx for the info guys. I wish I had found this forum before I bought the truck. I didnt realize all the changes in performance a simple tire size change could cause. There is still hope with the hypertech speedo fix though.
If the PCM would allow you to change the axle ratio input you would definitely want to do that swap. AFAIK, the carrier is the same for both ratios, so it would be an easy swap, mechanically. Since you have inceased tire diameter, you might be able to swap from 4.10 to 4.30 without causing a software conflict. I'm not sure how much the ABS talks to the PCM as far as comparing wheel speed/vehicle speed. If I were to sit down with it (think it over) for a while, I could probably determine if it would cause you issues.
How far off is your speedometer, right now?
 

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I chewed on this for a few minutes in between a movie and karate and taking my daughter to and from church.

The PCM has no idea that you changed tire size. It basically functions the same, but you lose power by reducing effective leverage and your speedo is not reading correctly.

If you change ratios (4.10 to 4.30) in the rear axle, the speedo will be more accurate because you regain the ratio lost by increasing tire diameter. Again, the computer has no idea you did this, but it sees the vehicle speed increase at the transmission. (everything in front of the ring gear is spinning faster)

BUT, your wheel speed sensors still read the speed offset by the tire size change. If the PCM compares these numbers to the numbers generated by the turbine speed sensor (or equivalent that generates vehicle speed input) in the transmission you may get a code from the conflicting information which could give you lots of flashy lights and limp in mode.

We really need a Toyota technician to chime in and give us some info on how much these 2 systems comunicate. I suspect they talk to each other a lot as part of torque management during tire spin/slippage.

Do we have someone with experience in this arena that could chime in?
 

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It's a good time to start this research, as we are getting close to a decision on our 4.88 gears. I'll talk to the Tech at my dealer and see what he thinks. I'll also spend some time on TIS.

I suspect a gear swap will work. The least expensive way will be to buy the 3rd members or complete axles from a salvage yard, and then sell your 4.10 axles.
 

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Hey, that would be an interesting experiment??? What would the difference be and how would it effect the tranny shifting???
 

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It's a good time to start this research, as we are getting close to a decision on our 4.88 gears. I'll talk to the Tech at my dealer and see what he thinks. I'll also spend some time on TIS.

I suspect a gear swap will work. The least expensive way will be to buy the 3rd members or complete axles from a salvage yard, and then sell your 4.10 axles.
I was hoping you or Mustang67408 would see this and coment. If Toyota would just allow us to change tire size and axle ratio in the ECU, this would be so easy.
 

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Discussion Starter #11
Great feedback as I expected here. I'm going to look into it further. If its possible I'm going to do it. WHY does toyota have to make such a simple thing such a pain in the rear!
 
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