Difference between 2WD & 4WD rear axles?

[Stone_Blue]

Does anyone know the difference between the two?....I'm calling around to possibly find a replacement rear axle, and it seems there is a difference between 2WD & 4WD...

And no, its not just because of gear ratios, or ABS vs non-ABS, or locking vs non-locking... There supposedly is some other difference....???

[bobbygail@aol.com]

The flange where the rear driveshaft bolts to the differential is different on 2wd vs 4wd. On the 2wd version there are four bolts that are fixed on the flange unless you take the flange off and remove the bolts (PIA). On the 4wd version there are four bolts you can completely remove to bolt the rear driveshaft onto the rear axle flange. The bolt hole patterns are the same on the 2wd and 4wd flanges. The 4wd rear driveshaft has a slip yoke at the rear that allows for in and out movement. That is the only difference I have noticed. If you have a 2005-2006 you could use either a 2wd or 4wd rear axle. Not sure about other models.

[Stone_Blue]

Thanx! Thats a good start.

Well, I just did a little more research, and it seems there IS a difference between the gearing on 2WD vs 4WD.

Even though both "officially" list a 3.91 or 4.10 ratio, the 2WD 3.91s have a 3.916 ratio, with a 47/12 tooth ring/pinion.
While the 4WD have a 3.909 ratio, with a 43/11 tooth ring/pinion.

Which means the 4WD is probably quite a bit stronger (less teeth means thicker, beefier teeth, and more meat on the gears themselves).

Same thing applies to the 4.10 gearing.

2WD= 4.083 ratio, 49/12 tooth ring/pinion.
4WD= 4.100 ratio, 41/10 tooth ring/pinion.

The minute differences in gear ratio MIGHT not make a difference, but for anyone sourcing new gears/diffs/complete axles, that tooth count is definately something to consider. Also, if getting just gears, I bet the shims, spacers and spider gears will be different, due to different thicknesses of the ring gear....Probably other internall diff parts differences as well, like possibly bearings and even carriers.

So as far as the differential goes, definately best to make sure you stick with either the same 2wd vs 4wd application that you are replacing.

I still wonder if there are any differences between the housings themselves? I know Toyota has different part numbers for 2WD & 4WD...

Sooo... I guess my original question is moot at this point, and I better stick to the same application I have (4WD).

But I was also wondering if an ABS rear could be used to replace a non-ABS.
I dont know much about ABS, but I'm under the impression that ABS just has sensors installed at the four corners, wired into a module under the hood that is plumbed into the brake lines, and THAT is what controls the pulsed pumping of the brake system?....So everything else at the four corners should be the same as non-ABS? (ie wheel cylinders, shoes, calipers, pads, lines, and the rear brake hardware?)

Also, if a locking (not true locking, just has an LSD) rear axle, could be installed in place of a non-locking. (This question, I would be inclined to say Yes, other than maybe the flange difference that bobbygail mentioned). But then again, the LSD WAS offered in both 2WD & 4WD flavors.... ??

Anyone have any ideas?

[tundra3400]

the axles will also have a ratio of 4:30 if it came out of a 3.4L v6 automatic tundra.

[Stone_Blue]

the axles will also have a ratio of 4:30 if it came out of a 3.4L v6 automatic tundra.

Yup ...I didnt mention the 4.30s, because all the 4.30s seem to be the same, whether from 2wd, 4wd. All are 43/10 teeth ring/pinion.

[Remmy700P]

Vehicles equipped with ABS will have some sort of toothed collar on the axle just inboard of the hub.

[Stone_Blue]

Yup...I guess I knew that too. But having the sensors and the rings wont have any other affect on anything, if they are left ungplugged, right?

[Remmy700P]

Not sure what you're asking. If your vehicle has an ABS system, the ECU will throw a fault code if you do not have all the sensors properly connected and functioning.

If you don't have ABS, I'm not sure if an ABS sensor ring-equipped axle will fit or not.

[Stone_Blue]

Not sure what you're asking.

If you don't have ABS, I'm not sure if an ABS sensor ring-equipped axle will fit or not.

Yup, this one ^^
I have an '00, so NO ABS installed....I've looked quite a bit, and not many 1 Gen rear axles around the NE....So wondering if it would be OK to use an 03-06 rear WITH ABS, to increase my chances of finding a rear axle...I guess I just need to know if there are any other differences in the rear axle assembly itself, besides just the sensors and rings... like if the sensors arent hooked up, do the rear brakes still work the same as a non-ABS?

[silet]

In most cases ABS axels, diffs and hubs can be used in non-ABS suspensions.

[UPbuilder]

Yup, this one ^^
I have an '00, so NO ABS installed....I've looked quite a bit, and not many 1 Gen rear axles around the NE....So wondering if it would be OK to use an 03-06 rear WITH ABS, to increase my chances of finding a rear axle...I guess I just need to know if there are any other differences in the rear axle assembly itself, besides just the sensors and rings... like if the sensors arent hooked up, do the rear brakes still work the same as a non-ABS?

The brakes will work just fine using an ABS rear with them not hooked up in a non ABS vehicle.

[Stone_Blue]

Kewl Thats what I needed to know...So I cant think of anything else that would be a problem using an ABS rear assembly in a non-ABS....That will help me source an axle assembly.

[silet]

Stone_Blue, are you looking for a complete rear axle and why? Also what year model do you have?