7.5" Rear E Locker

I got my first Taco recently—also my first 4x4 rig. I want to keep it relatively stock, however a rear E locker would be nice.

Axle code B03A: 4.10 2 pinion open 7.5 ring gear.

I'm looking at buying a whole 3rd member from ECGS

Will an 8" ring and pinion 3rd member fit into my axle casing? Will my current axles work with an 8" ring gear & locker? are the splines different?

 

6-lug 1st gen Tacoma have one of two axles from the factory. The non-e-locker axle uses what is commonly known as the 8.4" diff. The e-locker axle uses what is commonly known as the 8" diff.

I'm not sure why some of the door tag decoders say 7.5". I never see that number used anywhere else in reference to Tacoma rear axles (edit: I'm referring to 6-lug axles only; 5-lug axles are 7.5" but OP's truck is 4x4/6-lug).

Welcome aboard, and congrats on the decision to keep your truck mostly stock. Modified trucks are a messy rabbit hole to run into, and these trucks are great stock.

If you want to avoid the hassle of wiring an e-locker (it's not that hard, but it's still work), a Truetrac is also a good option. Much better than an open diff, more useful than an e-locker in most situation except rock crawling, and without the drawbacks of a clutch-type LSD or ratcheting ("Lunchbox") locker.

 

If yours a 4x4, non-elock, it will be an 8.4. 5 lug 2nd are 7.5

You will need the entire TRD rear axle that has the elocker. the 8 & 8.4 third is not interchangeable.

also, make your match the rear differential gear ratio to the front

 

This statement is only relevant to swapping in a factory e-locker. The OP said the plan is to buy an e-locker from ECGS. He can get a Harrop 8.4" e-locker that will fit his axle.

 

i have selective reading lol

 

I talked to a salesperson at ECGS on the phone and he also referred to the non-e-locker as an 8.4". This confused me because neither of my sources (being this "OEM Gear Ration Chart" from Tacoma World and this "Differential Info" page from LC Engineering) confirm that the non-e-locker is 8.4" in diameter. Is the "8.4" namesake unrelated to the actual dimension?

I'd like to order a whole 3rd member without physically removing mine from the axle housing beforehand. I'm open to a truetrac (and curious how they work if not like a typical clutch LSD) but I would still want a whole 3rd member. I've done enough diff rebuilding/setups to know that I don't want to do anymore.

 

Tacoma 6-lug (4wd & prerunner) had 2 options: trd 8” elock or 8.4 non-elock. 5-lug had 1 option: 7.5”

 

I see two points of confusion.

It's been a while since I've paid attention to the pinion designation, so I had to refresh myself. I think you read them incorrectly.

The chart says the first letter represents the ring gear size. A is 7.5", B is 8.0". You said your axle code is B03A, which would represent an 8.0" ring gear--not 7.5" like you said in your first post. I'm guessing you looked at the last letter instead of first?

So, if your diff has an 8.0" ring gear, that's still confusing because everyone is saying you have 8.4". The LCE page explains this...

So, yes you have an 8.4" diff, but yes the ring actually gear measures 8.0".

 

ECGS sells assembled Truetrac third members.

I'm not good enough to explain all the physics involved, but open, Truetrac, and clutch-type LSDs react differently when one wheel has less traction than the other.

An open diff "unloads" all rotation through the low-traction wheel--one wheel spins and the other doesn't.

A clutch-type LSD "locks up" and forces both wheels to spin at the same speed. This can cause the entire rear end to slide if it happens in the middle of a turn, where the two wheels need to spin at different speeds.

A Truetrac will never fully lock up and will only unload if one wheel has zero resistance--ie, zero traction, ie it's off the ground, and even then you can use the parking brake to add some resistance and prevent unloading.

Again, I can't fully explain the physics but the key feature that a Truetrac uses worm gears internally. The design isn't exactly the same as a Torsen diff but the end result is similar. If you have an intuitive understanding of worm gear drives--a worm gear can drive a ring gear but a ring gear can't drive a worm gear--you might be able to imagine how worm gears in a diff would be useful.

 

OP I have the Eaton E-locker installed in my '03. My '03 had the same B03A "8.4 inch 3rd member". I had a local off-road shop do the install. I had to buy the locker itself ($1500) and the master install kit ($450), and pay another $1200 or so in labor. All in all though I'm very pleased with the locker. I can use it in 2Hi, 4Hi, and 4Lo, and it engages/disengages instantly when I toggle the switch.

I went the Eaton route, because I had just installed new rear wheel bearings and axle seals, and all new brake drums/shoes/hardware. Buying a used TRD axle housing (8") would've likely meant doing all that work again in the near future. And supposedly the 8.4" open diff is stronger, so in theory I've got the best of both worlds (stronger diff and a better locker than OEM).

 

Technically the "8.4" differential uses an 8" gear, but it is not compatible with the 8" Elocker differential. People refer to it as 8.4" mostly to differentiate between the two. The 8.4" diff is stronger than the 8" because of they way it is designed.

 

Ok great, thank you all for the info. I got the "7.5" measurement from a breakdown at the bottom of the LCE page. I'm interested in the ECGS route because they sell a whole 3rd member which makes installation a lot easier & according to their website, a 3rd member (not including the core charge) is ~$750. That's right in my ballpark. I'm very comfortable wrenching on my own truck. I now have confidence that my rear diff is an "8.4".

Also, did some research into Tru-Trac and I'd rather go with a true E-locker.

Thanks for all the help!

 

I had the OEM locker in my 1st gen and did the gray wire mod to be able to activate it anytime (not just in 4-Lo). I think I only needed it once on the trail (in many thousands of miles across the west in CA, NV, Oregon, Utah, Idaho). I used it several times for fun to do donuts in 4-Hi in snow covered parking lots. The 1st gen with a moderate lift (I had the 2” OME) and good tires can get to a LOT of places.

The 2nd gen I have now (4.0L with supercharger) had the locker swapped out for a TruTrac by the original owner due to loss of traction in the rear on pavement with the extra power. I have not once desired the eLocker in this truck and the TruTrac is very good. Since it’s an OffRoad 2nd gen, if I ever need more traction, I can turn on A-TRAC for the system to pulse 1 to 4 brakes to simulate front and rear lockers.

I’d recommend holding off on getting a locker and see how capable the stock 1st gen is. $1000+ can get you a lot of other things.

 

I don't plan on getting into anything too hairy, but I do like the peace of mind a locker affords. I live in a snowy area, and snow is the only kryptonite I've found to older Toyota 4x4 systems. (no TCS to pulse breaks and divert power.) I've pushed my old 2WD ranger out of enough snow banks. It's not the end of the world, but I like the idea of minimal mods with maximum capability.