2005-2006 4x2 rear axle swap

I have a 2006 tundra 4X2 double cab. The 3.92 rear end is going bad. I have found a 2005 with a 3.62 that I would like to swap out. Will these interchange. I understand the different ratios.

 

If it will be swapped out as a complete unit, it should work

But if you have bigger tires or armor or any other added weight, you would want to upgrade your gear ratio, not down grade them

 

Thanks for the info. Not going to be hauling any heavy loads just trying to get it on the road.

 

Is the donor axle from a double cab? I’ll have to look it up again. I’m not sure if they are the same width/length.

 

There is no difference in the housing between the cab sizes.
They are all the same, just with different differential gears and may have an LSD in there.

 

3.62 is odd. Is it coming from a manual v6 truck i wonder?

 

Thanks for clearing that up. I’m actually a little perplexed that Toyota even offered a 3.62 gear ratio. I know the 4.0 v6 came with 3.77 and the 05-06 v8s regardless of cab have 3.92.

 

I would bet its actually a 3.58. Never heard of or seen a 3.62. Only 3.58, 3.73, then 3.90's.
https://www.lcengineering.com/LCTechPages/DIFFERENTIALTOYOTATECH.html

 

I've never seen a 3.62 either.

 

First of all I own a RCLB...Along the same discussion topic, if I were to replace my terribly rusted axle housing and internals with a really nice donor that appears to have come from a 2004 DC (which is a little wider I found), is there any problem other than extending the emergency brake mount? Everything else appears to line up fine. I am planning to put spacers on the front wheels to fix the perceived difference in extension beyond the fender

 

Is your truck 4x2 or 4x4? Some '04 DCs came with 4.10s from the factory.

 

It is a 4x4

 

I remember hearing that the flange the driveshaft connects to is different between rwd and 4wd but haven't compared to see if thats true. @assassin10000 do you know by chance?

 

So I would confirm the gear ratio on that '04 DC axle before sticking it on the truck. I'm saying this because my '04 DC has stock 4.10s, while most other first gens have 3.91s. You want the differentials to have the same gear ratio.

You could always swap out the internals from your current axle into the '04 axle.

 

Well as they say ...here is the rest of the story, my previous axle was an open differential while the new one is a limited slip....which I prefer ...and would like to keep, as it is in good shape

Is there a code or something on the outside that I could check to confirm the gear ratio?

 

Yep, they're different. You can just swap the flange though.

That's what I did, I currently have a 04 DC 4x4 rear diff which has 4.10's & OEM LSD (also a solid pinion spacer and new pinion seal) in my 05 rwd.

The gear should have a small stamp from Toyota that says the ratio. Otherwise count the number of ring gear teeth and divide it by the number of pinion gear teeth.


I suspect that 05 gear set is also 3.92. I don't think we got an option for 3.6 gears on these trucks. Only 3.91/3.92, 4.10 and 4.30 that I can recall.

 

So getting back to this topic, can you swap the lsd from a 3.92 DC onto a 3.77 V6 ring and pinion? I want to swap the 3.77 gears into the DC housing and keep the lsd.

 

Yes.

Just need to set backlash/pattern correctly. Measure (and write down) both before disassembly.

 

Great, now I just need to figure out what size tire I'll need to keep the speedometer the same.

 

05 & 06 use the abs sensors to determine mph. I went from 3.9 to 4.1 and didn't have to change anything.

 

Well that's nice, how do changes in tire diameter effect this? I planned on going to a 275/50/17 which would be about 27.83" diameter.

I have a 2wd AC and would like a usable sport truck. Already ordered the SOS Performance lowering kit and have a set of 17" TRD pro wheels. Complete DC axle housing for the slight extra width.

 

Tire size will effect speedo by whatever % it is different. Most online tire size calculators will tell you a close average to this (as actual tire diameter varies by mfg, even if the #'s on the sidewall are the same).

https://www.tacomaworld.com/tirecalc?tires=265-65r17-275-50r17

About 9% based on my stock tires.

 

I appreciate all the effort you did calculating all that but this is going into an 06 AC with 3.91 oem rear and 265/65/17 oem tires.

The goal in using the 3.77 gears and 275/50 tire was to keep the speedometer the same as the oem 3.91 265/65 while losing that extra 1.75 inch of actual height at the axle and having a decently wide tire.

You mentioned a 215 which would just be useless on a tundra in any situation. Occasional light hauling and an emergency tow is all this truck will see. No point in a larger diameter tire or lifting a 2wd truck.

 

Yeah, unfortunately gearing will have zero effect on that (speedometer that is).

It will get your rpms back in the same range if that's a worry for you. I prefer the gain the 4.10's gave me over the 3.91's on stock tires.



Maybe there's a way in the software from Toyota (techstream) but I don't know if it's possible.

Maybe @empty_lord could chime in?

 

I have no personal experience with Yellow Box, but it may do the trick.
https://www.yellr.com/

 

We cannot change the speed curve sadly

 

I don't know why you keep bringing up a 215 16" tire. Yes, it is useless. I'm using 17" wheels, period.

Ok so as long as the rpm stays in line with the stock rear gear ratio and tire size and speedometer isn't effected then that's what I'm looking for. I'm already traction limited so there's no point increasing the rear ratio for acceleration.

 

I appreciate your input, I will start a new thread to document the build since we've answered the thread related question.

 

I think you missed what I was getting at. In any case:

Changing tire size (diameter) will change the speedometer.

Changing gear ratio will not effect the speedo.

Engine RPM will be determined by tire diameter and gear ratio. It doesn't matter what the speedo shows.