I'll try to make a long story short. Both rear axle seals have been leaking. Decided to tackle the job my self. Drained the fluid, it was time anyway, and out came teeth from the gears and fluid that looked like graphite. Looking in with a flashlight I can see the missing teeth on the gears.... Now I need to rebuild the third member too. Problem is that nobody from Toyota or aftermarket can tell me which axle I have. According to the code on my chassis, A03A, I have a 7.5 " w/ 4.10 gears and 2 pinions. According to Toyota, my truck should not have that axle and they can't sell me new gears for my Tundra, because there "computer" doesn't show a 4:10 gear set for the Tundra. All the stuff I've read on the net says my truck should have an 8.4" rear end with 3:91's and 4 pinions. ARB also only lists a locker for the 8". A local shop did a trutrac locker in a Tundra last month. THey said it was a nightmare. Detroit said they had an 8", Toyota said it was an 8", but it was actually a 7.5" with 4:10, same as me, which should be standard in the 5 speed v6 model. According to everything I've found, my V8 should have the 8.4" commonly known as the 8" with 3:91's. I've checked Yota Yards and all the mfg codes call out A03A. I've yet to find a B03A, which according to Toyota, is the 8" rear axle....

Has anyone else ran into this? or know about a Toyota axle mix-up? I feel like I got a V6 rear end in my V8...

I'm completely baffled. I found another 3rd member with code A03A for $600.00. It has 100,000 miles on it. I only have 75K. Though I've been told that the kind of damage that I have incurred comes from abuse and wheel slippage catching suddenly. So, 100K on this used axle is OK? anyone want to comment. I won't be shy, I tow alot and do occasional wheel'n, and there is usually two throttle positions... FULL or Idle. I do drive my truck hard.

In the end, I don't know if I care that much about which axle I end up with. I'm just frustrated that knowbody really seems to have a handle on the Tundra axles. I'm running on borrowed time... I put the thing back together and the clunking is getting louder and more frequent.

My thought was to take the 3rd member from the used axle and throw it in my truck and go about my business. What do you guys think?

Thanks,
Z

 

Well, to know your ratio for sure all you have to do is carefully jack it up, mark the shaft at the flange, and have someone spin a tire 2 exact revolutions while you are counting the mark as it goes around relative to the flange. Yes, you can easily see a .2 difference. I could. Can't help you on the inches question...

 

Go here for your axle code: https://www.yotatech.com/forums/f2/97-up-toyota-truck-axle-codes-67962/

James

 

So the ratio is 3:91. I can't get the size of the ring gear, but I'm willing to bet that it's the 8.4" like it's supposed to be. So the A03A code is completely incorrect in the late model vehicles and Toyota's book is messed up. I'm visiting a dealer today, I'll keep you posted. I also decided to pick up the 3rd member for 600 bucks I found from a 4x4 shop. Then I'll just swap them out this weekend.

In the future I'll re-gear my old 3rd member, and front diff and add ARBs and make the swap again.

Z

 

i think that the code refers to the front diff, which is a 7.5" the rear 3rd is the "8.4" the same one used in non TRD Tacoma's

 

So, the A03A code on the sticker of the chassis is incorrect. The Toyota dealer is talking with corporate about this. The front diff code calls out a 7.5" with 3.90's, which is correct. However the A03A is calling 7.5" 4.10's, which dead wrong since we all know what should have happened the first time I put it in 4 wheel drive 5 years ago if the codes were actually correct...

So, the 3rd member I took out of a 2000 Tundra that had code A03A as well was an 8.4" with 3.90's even though Toyota says it's a 7.5 with 4:10's. I swapped it this weekend and now I'm back to normal... no more klunk... klunk... klunk....

I've had extened conversations with Toyota dealers and techs... Here's the scoop in a nutshell. This Nutshell is only for Tundra's and Sequoa's 00-02 w/ V8 4x4... they only came out of the factory one way! 7.5" front diff and a 8.4" rear diff(known as toy's 8") with 3.90 gears (3.909 to be exact). So there you have it. I hope that anyone else running into a similar issue finds this thread useful

Project Costs:
New bearings and seals for rear axle $295
Used 3rd Member in great shape with proper backlash $645
New 3 ton pro floor jack(always wanted one of these) $125
7 hours of time spent(includes new brakes front and rear while I was at it)

Damage Summary:
The klunking was comming from one of gears in the spool. Almost all the teeth were missing from the gear(they weren't technically missing as I found most of them in the bottom of the axle housing) There was a ton of play in the gears and the backlash was wicked loose. I attribute this damage to hard offroading and the tendancy for me to smoke the rear wheels... For the way I drive, I'm not surprised by the damage and it does NOT leave me unhappy with my Toyota at all. I love my Tundra and when this one dies, I'll buy another...

Thanks to all of you who replied, your suggestions and guidance helped steer me in the right direction.

Z