What's in your rear end?

The question comes up so often among truck forums, “Do I have LSD?” If you have a first gen Tundra, read on and you’ll know. There are other variations and friends of this question too, such as “Does LSD come with the tow package?” or “I got the TRD Off-Road package so of course I have LSD”. Read on, I’ll share what I know and hopefully it is true. My memory from 1999-2012 is hazy at best and that is when I learned what I know on the topic.

For the first gen Tundra there were two basic versions of the limited slip differential. There is a mechanical differential and an electronic brake assist style of limited slip. Let’s talk about the first version first, if you don’t have that then you really have an open differential.

My Kazuma


It attracts kitty


The real LSD is mechanical, it is the carrier for your ring gear and very likely built by Eaton. This was not part of a particular upgrade package, it was a separate item. It could have been included within a package, but was not a definite inclusion of any package. You can have the tow package and not have the LSD, you can have the TRD-Off Road package and not have LSD, and you can have the Limited Edition (or any variant of) and not have the LSD. Conversely you can have a bare bones truck and have the LSD.

When your truck has a mechanical LSD, you often will have a red and white sticker on the back of the differential that says LSD. Since this is a sticker they can fall off, or even worse you may have some shady person slap one onto your diff without having an LSD. I would not recommend worrying about the sticker to prove that you do or do not have an LSD. I also don’t suggest doing the spin one tire and watch the other tire method, this isn’t always going to work. The easiest way to know if you have a mechanical LSD is to remove the fill plug on your diff housing and use a flashlight to look into the bung of your rear end. If you see gears in there you do not have the LSD, you have an open diff and I’m sorry to hear it, you’ve stuck your eyes in the bunghole for nothing. If you see a cylindrical shape of metal in there, you have the mechanical LSD, congratulations.

(Picture looking through my fill plug soon to be posted)

If your truck came with the LSD from the factory, it is an Eaton unit with a 200lbs of preload in the clutch packs and 2 spider gears. If your truck had LSD installed at a dealership, it likely has the Kazuma unit with 400lbs of preload on the clutch packs and 3 forged spider gears. Some people have reported that the 200lbs Eaton unit was built by Hino, some have reported that the Kazuma was built by Eaton, I don’t for sure know that either is true but mine says Kazuma TRD all over it and says Eaton nowhere. With either unit the preferred fluid to use is 90W dino gear oil, sometimes called hypoid gear oil. Depending on the fluid of choice you may or may not need a friction modifier additive, the one used by Toyota was Sta-Lube and it comes in a giant toothpaste style tube. 80-90W oil is also acceptable to use with these LSD units. Some have reported using synthetic lube without a problem, but it is not recommended by Toyota and if they could make a little extra money selling you synthetic lube they would do it.

(Picture of Sta-Lube soon to be posted)

At this point we are going away from what I “know” and into what I “think” since I never had much interest in the electronic version. Your truck may have an electronic type of limited slip, I’m going to call it that, but it’s really more of a traction control safety feature than an off road assist, and isn’t what most would consider a true LSD. This is not to be confused with an E-Locker which our little bastard brother Tacoma’s got. The E-Locker is much cooler, it uses a solenoid within the gear carrier to lock up both sides of the axle for excellent traction. What our first gen Tundra’s got was a combination of sensors and brake controllers which apply brakes to the wheel which is found to have less traction. This may or may not come with a button that says VSC or TRAC or has a picture of a truck doing a burnout. There is a version of VSC which cannot be shut off manually, except when you go into 4wd. It is otherwise on all the time and tends to get temperamental when you have a lift or larger tires installed. If your truck has this and you keep it stock, it’s probably not a problem. If you plan to lift it and/or install bigger tires you better do some research on it first.

If you plan to do much off road driving, you may want to consider adding a locker instead of LSD. The LSD is great for a daily driven vehicle to have some comfort in the rain or have a little more leverage out in the dirt, but it isn’t as good as a locker in real off road conditions. It is however much nicer to live with than a real full time locker. I’m personally not a fan of air lockers, something about putting 150psi of air into my axle housing and hoping the o-ring seal is sealed just doesn’t sit well with me. I know lots of people have run them without a problem, but the thoughts of what could go wrong don’t sit well with me. I’m not going into detail on the different locker variations here, there are far too many and the real subject of this is what was available from Toyota.

I should have noted that the cool Taco E-Locker is an 8" rear and can't reasonably be swapped into the Tundra, we run an 8.4"
Sizing of diffs:

 

Great write up, informative for sure

 

Did you finally stop staring at squirrels long enough? Nice write up! I do know I dont have an LSD, and with my rear end up in the air and the truck in drive, if I stop one tire, the other goes backwards.

 

Good to know! anyone know how easy it is to swap an LSD into a non-LSD truck?

 

Nice write up!



But by the title I just have to do it. This is in my rear end!

 

Good info here. Early 1st Gens Rule with their real LSD.

 

Darkness "what's in your rear end?"

me:

 

Is there no search by VIN option anywhere? Or specific VIN digit?

 

Try yours at Toyota.com and let us know.

 

https://www.toyota.com/owners/my-vehicle/vehicle-specification

 

My 05 Real LSD
I looked inside when I changed oil, and its got the sticker.

 

That is pretty cool. I'm assuming it doesn't as I see no mention in specs?

Mechanical & Performance
4.7L V8 DOHC EFI ENGINE 4-SPEED AUTOMATIC ECT TRANS TOUCH SELECT 4WD SYSTEM COIL SPRING DOUBLE WISHBONE INDEPENDENT FRONT SUSPENSION FRONT STABILIZER BAR RACK AND PINION POWER STEERING 4 WHEEL ANTI-LOCK BRAKES PWR VNTD FR DISC/RR DRUM BRKS P265/65R17 RADIAL TIRES 17" ALLOY WHEELS

 

It would say Limited Slip Differential.

 

Now this thread has me wondering if this issue I'm diagnosing as a U joint is actually because I put the wrong fluid in my rear diff. I used Royal Purple 75W-90 as recommended by several other first gen owners. Apparently the manual calls for 80W or 80W-90..

 

Can you add what size our front and rear diffs are in case one decides to go shopping for LSDs?

 

Front: 00-04 Tundras have a high-pinion 7.5". 05 and 06 have a mid-pinion 8.0”.

Rear: 8.4”

 

Based on what it says here, does that mean that I have the factory installed LSD?

 

Yes. Most likely, the electronic brake assited version @Darkness eloquently expressed above.

 

Boooooo. You're right. My truck is 2wd, I could really use, at bare minimum, an lsd.

 

Yup, that site is how I found out mine was mechanical. I've been to it before looking up my trucks history, I had just never noticed it before.

 

Not sure, this is really geared towards first gen. I don't know much about the 2nd or 3rd gens.

For those checking the link, that's cool info to see. If the site says you have it that's awesome but if it doesn't mention it I would check anyway. At almost 20 years old these trucks can very well have had equipment added later.

@Casper421 I'll add that measurement note in, good call.

 

I looked up my VIN I'm toyota.com 4 my Tundra and it does claim to have limited slip differential. About halfway through your post you talked about having larger Wheels than stock but did not mention what possible symptoms may occur. I've been reading other threads about older Tundras with high mileage having surging type symptoms. Mine is doing this at 260,000 miles and wondered if larger wheels(20") on a limited slip differential might be where this is coming from. What do you think?

 

In 2003 I had a Kazuma / TRD LSD installed in my 2002 ... I have driven about 145,000 problem free miles since then.

 

What type of engine maintenance have you done over the years?

 

I doubt it would be related to the differential. If you had a differential problem your truck would lock up, rattle and/or pop. It wouldn't cause surging.

My diff went out and it pretty much made lots of strange noises and occasionally locked up as if I hit the parking break hard, the back end would jump, then it would be normal again.

 

So it looks like the 00’ 01’ didn’t come with the lsd...
so time to put one in!
Was it just the rear diff or did they put it in both?
Anyone have any links to share where I can get one by chance? and what else do I need when doing the swap? Thanks in advance gentlemen

 

@Ludogg808 only rear. If you are taking that stuff apart, consider if you want to regear. Also, you may consider a streetable locker rather than an LSD, really depends what you need it for.

Here's a link to an install by Zuk, he is installing the same combo have.

http://www.gearinstalls.com/Kazumatyson.htm

Call up the guys at Just Diffs, they're really good people and they know Toyotas. I went through them to buy my Nitro gears, Nitro install kit and solid collar.

 

Over 1500 views from people trying to find out whats in their rear end!

@Darkness

 

Or strange, soon to be disappointed perverts