Locking The Diff: Differentials on A60, KE70 and AE86

First off, i'd like to say thanks to Stanley for writing about The Dog again on his blog. It sure gave me the confidence boost i need to dig deeper into my pocket and buy more useless stuff for The Dog. So thanks again to you Stanley. Your blog too is my regular stop in this otherwise crap slash pornstar infested internet jungle. Stanley and his Charmant is like me and The Dog fast-forwarded a year. Expect me to write about interesting stuff (including engine problems.. lol) similar to Stanley's current posts after a year or so. You can read more about Stanley and the white Charmer on http://stanleycarter.wordpress.com..

Okay back to business. What's that? Locking The Diff? So you're being cheap and decided to just weld your diff, eh Edgar?

"10-way" Limited Slip Differential.. lol

Noooo.. i don't want to stuff axle splines regularly by doing so especially knowing how difficult it is getting Charmant rear axles (though i might consider going that way if i got a spare with me).

Stuffed Axle Splines (courtesy of Jack aka Mouwt)

I am talking about settling once and for all the question haunting my sleep these last few weeks: Which differential type is my A60 Charmant using? Can i use the diff from (insert any Toyota RWD car here)?

Some of you may know that Charmant, KE70 and AE86 share many similar parts especially when it comes to suspension and power-train. It may come to mind that perhaps their rear diffs are also interchangeable. Knowing this could be useful if you're getting an LSD for your Charmant. Aftermarket LSD manufacturers like KAAZ support popular cars only like AE86 for obvious business reason. Good luck finding an LSD designed for your Charmant. Knowing so, the next logical step would of course ask: can i fit AE86's LSD on my Charmant? This post is written to help you answer that question.

Here are some pieces of the puzzle i get by Googling..

1. JDM AE86 uses T-series differential unless you have Australian AE86 that use S-series. Info taken from here. There you'll find also that T-series have 6.7" crown diameter and won't fit to a 6.4" S-series diff housing. An S-series can be identified by 1 long stud at the bottom.

2. KE70 uses 6.0" U-series unless yours is Australian which should come with Borg-Warner diff (what's with these Australian Toyotas?!). Info taken from here. You'll read there also that a T-series has 10 stud bolts holding the diff gears in while S-series has 8 bolts. That's one way to differentiate one from another.

3. 4A-C powered Charmant uses S-series diff. I got this info from a dude replying to a thread i started in ae86irl.com. You may need to register first before you can read it here.

Of course, if you're like me, you won't just swallow everything the internet shove into your mouth. They came out with Wikipedia, for f*ck's sake! Here's another solid piece of the puzzle, a picture of a 4A-C equipped Charmant rear diff housing (i must stress the 4A-C here since some Charmants are powered by 4K engine).
That's The Dog's diff housing in case you're wondering where i got that pic. You can't see all the stud bolts but, trust me, there are 8-stud bolts in total with one longer stud bolt at the bottom. See point 1 and 2 above and you'll see that it has all the signs of an S-series diff. With 8 stud bolts, that's certainly not a T-series diff used in AE86. So the answer to whether or not you can use AE86's LSD in a Charmant is now clear: NO you can't. What's that? More proof? Okay.. continue reading. Oh boy, you guys owe me a beer for what i am about to share with you. LOL.

Now that we've somewhat established that Charmants don't use T-series diff (will dig deeper about this later), how can we be sure that it's S-series instead of U-series as used by its cousin, the KE70? Besides, the link on point 2 above mentioned that U-series also have 8 stud bolts. The answer to that lies on a page of Charmant parts catalog i have below.
Above you can see that MTM (manual transmission) A60 Charmants use 6.38" diff. If you won't argue that some people prefer to round the number up to 6.4", then you'll see from point 1 that it's the same crown diameter as an S-series. Yet another supporting evidence that Charmants use that particular diff type. So Edgar, you're saying that since it's 6.4" then it must be S-series? Well that certainly is an arguable logic, i admit. But here's what i got to support my claim. Other than this of what i believe a complete list of Toyota axle code (which tells you that YES since it's 6.38" then it must be an S-series), below is a page of Corolla catalog i have also.
Inside the red square, you'll read that all CE70 Corolla (diesel engine powered Corolla) axle codes always start with S, meaning they all use S-series diff (AXC stands for Axle Code while FGR is Final Gear Ratio). Bonus info, blue square indicates that KE70s in general countries use U-series diff, a supporting fact to point 2 above.

Now that we know CE70 Corollas use S-series diff, here's another page to show you how an S-series look.
The picture above shows you the S-series diff as used by CE70. Notice the shape of the differential housing marked in blue circle and compare it with this other shot of my rear axle.
Looking pretty similar don't they? You can also now see the other stud bolts which is 8 in total and indicates it's not a T-series diff. So am i saying that a U-series don't look like that? As a matter of fact, i am because this is how a U-series looks like..
Notice the difference? I'll leave it up to you to find it..

Now i think we already have enough evidence to support the following claim:

1. A60 Charmant use S-series diff.
2. KE70 in general use U-series diff. Look at catalog page above and you'll also know that some KE70 use S-series diff.
3. AE86 use T-series diff.

Since a T-series diff won't fit to an S-series, a claim i am not eager to find out myself, then those aftermarket LSDs for AE86 are useless for Charmants. Then how do i get an LSD for my Charmant? Here's some solution for you..

1. Get a T-series complete rear axle which comes with LSD from the factory and fit it to your Charmant. A T-series should be an easy conversion from the stock S-series. Does such thing exist? Yes it does, for example see below.

2. Get a standard non-LSD T-series rear axle from, let's say, a Corona T130 and get an aftermarket LSD for AE86 from KAAZ. Gather the two pieces and stuff it under your Charmant. Careful though.. KAAZ makes two types of LSD for the AE86 and they are not interchangeable. See below product info taken from KAAZ website.
Model DAT1630 is for early or "zenki" AE86 while DAT1610 is for the later or "kouki". The thing that separates them is the axle thickness. 85-87 models (kouki) have 1–1.5mm thicker axles than earlier (zenki) T series axles. A Corona T130's T-series diff is similar to the early AE86 so you should get DAT1630 for it. Aftermarket LSDs are expensive so be careful guys..

3. Get a rare TRD LSD for an S or U-series diff housing. TRD once released LSDs for S-series and U-series diff. I personally got an offer once for a TRD LSD for KE70, so i am convinced that these babies do exist. I am not sure if a U-series LSD will fit to an S-series housing but i am inclined to think so since U-series' 6.0" crown diameter is smaller than 6.38" on S-series. If it in fact doesn't fit, then you need to get a complete U-series rear axle to house that TRD LSD. I believe U-series axle is also an easy swap to an S-series. (edit 15-Feb-19: just found out that you can't fit an S-series LSD to a U-series rear axle. it's not a problem of whether the casing fits but it's about the ring gear diameter itself being different. an LSD must be fitted with its designated ring gear diameter)

Which solution is best? That depends on two things: availability and your cash. In my case, all three solutions are applicable as they are all available so my best solution would be the one that burns the smallest hole in my pocket. I am still weighing these options for now.

Hope this helps guys..

*update 14-Jan-10*
Managed to take a shot of a KE70 differential. I'll leave it up to you to judge whether this is U-series or not. I am sure that it's not S-series (no longer stud bolt) nor T-series (only 8 stud bolts) but whether it's U-series, i can't tell. It looks a bit different from the U-series pic on the catalog. Borg Warner perhaps? Anybody?