LSD on Charmants.. My Way

There are a number of ways to get Charmants running on Limited Slips. The methods that i know, have been mentioned on previous post. Here they are.
1. Get an AE86 rear axle that comes stock with LSD
2. Get a rare S-series TRD LSD that would fit Charmants diff housing perfectly
3. Get any T-series live axle and install aftermarket LSD from Kaaz or Cusco

Number three is my preferred method and to conserve energy, i won't discuss number one and two. What you basically do with this method is get a T-series open diff axle, swap it with the stock S-series and get an aftermarket LSD from Kaaz or Cusco. This is like method number one only you don't have to find T-series axle that comes with LSD because you're going to swap the open diff with aftermarket one. Since you can get drum brake T-series rear axle, you don't have to worry about working out the hydraulic e-brake system.

Why a T-series diff? There are three reasons that i can think of. First, because it has vast aftermarket LSD support since the AE86 comes stock with one. Kaaz and Cusco makes very good LSD for it. Second reason is that it bolts in easily to an S-series axle. You don't have to modify the lateral bar mounts on your Charmant because they line up perfectly. Third reason is the power handling. It can handle more power compared to our S-series. A seemingly never-ending debate on the actual max horsepower handling is on going but i believe it'll handle a 160 hp blacktop 4A-GE quite nicely.

Before i get into the swapping method, here's some terms we need to know.

The rear axle is connected to the gearbox via propeller shaft or driveshaft. There're many types of Toyota propshaft. Quoted from here:
There are at least 6 different variations in the driveshaft... either single piece, two piece, rubber shock dampener or straight tube, 20 spline(k40/K50/T50), 21spline(W51, W56) or 22spline (T50) front yoke, small universals with press in caps, small uni with circlip on outside, big uni with circlip on inside, small pinion flange locating ring, big p/f location ring.... yada yada. The shaft lengths do vary depending on what diff and gearbox was originally fitted with it. A smaller diff will have a longer driveshaft...

T-series diff has larger diameter compared to S-series diff on Charmant. Hence, the propshaft connected to T-series diff is shorter than our Charmant. This is why you can't just use your stock propshaft on a T-series diff. You need to shorten the propshaft by about 20 mm. How do you get around this problem? First you need to know if your propshaft is one-piece or two piece. Mine is one-piece as you can see here.

Yours can be the two-piece type. Here's how a two-piece propshaft looks like.

Basically if your propshaft is one piece, try to get also the whole one-piece propshaft from the T-series diff. Then, if your new propshaft front yoke matches with your gearbox output shaft, it should be an easy bolt in work. In my case, since my T50 gearbox has 22 output splines, i'll do my best to find a replacement T-series propshaft with the same number of spline. That would be difficult since in Indonesia, the local Toyota never made a car equipped with 22 spline T50 gearbox that comes with T-series diff (except imported ones, of course).

If your propshaft is two-piece, then you have to find a T-series diff that comes with two-piece propshaft and get the rear part of it. You only need the rear part as this is the part that Toyota chose to shorten. With the rear end of the propshaft, you'll just have to replace your stock one with the shorter one and you're good.

I have no idea if you're crossing from one-piece to two-piece or the other way around. I'd say two-piece to one-piece is easier compared to one-to-two. With one-to-two you'll have to find a way to mount the mid bearing on the middle joint to the chassis or your propshaft will be dangling.

If getting the propshaft is difficult, you can always take your old one to a machine shop to get it shortened. I prefer to avoid this since it may mess with the balance of the shaft if done improperly.

Okay so now you're at the junkyard looking for T-series rear axle assy. How do you identify one? If the axle is still attached to the car, check the ID plate on the firewall. You should be able to find the axle ID written there. What you want is something like T292 or T312. Basically it has to start with T, hence T-series diff. That's easy. What if the axle is already taken out from the car? First ask the junkyard owner the car model the axle came from. Google it. LOL. Seriously though, swapping T-series diff has been discussed millions of time on the net and there's a good chance that your donor car has been mentioned also. However, with the slight chance that the axle itself has been replaced earlier, you need to know how a T-series diff looks like. The most distinctive part between different rear axles is the diff housing. Here's how a T-series diff housing looks like.


In my case, my target is to get a complete rear axle and propshaft from Corona RT132. Just today, there's one parked on road-side car paint workshop and with permission from the owner, here's some pictures that i took.


Let's see what we have here. First pic shows you that this T-series comes with no sway bar. That can be either good or bad news. The good news is that Charmants also don't have sway bars so i don't have to figure out a way to mount a sway bar to the chassis. The bad news is of course on ride feel because sway bars help to increase stability. I wouldn't worry too much about that though. Toyota must have their own reason not fitting sway bars on this particular model.

The second pic confirms that it's indeed a T-series diff from how the diff housing looks. There are 10 stud bolts in total and it looks similar to the sample i showed earlier.

The third pic is even good news. It has one-piece propshaft! Same type as my Charmant. Now since RT132 comes with W50 gearbox which i believe has 21 splines on the output shaft, i can't directly use this propshaft. I need to replace the front yoke with my old one having 22 splines, allowing it to match with my T50 gearbox.

Silly me, i forgot to take the car's front look. No worries, here's a pic of RT132 i found on wikipedia.

Now that you have a live axle T-series open diff on your Charmant, all you need to do is get that aftermarket AE86 LSD of your preference. Careful though, AE86 LSD comes in two version, based on production year. Zenki or "early" AE86 has smaller half shafts compared to the Kouki or "late" ones. Here's some explanation pictures.


Let's say 2-way Kaaz is your LSD of choice. Here's a capture taken from Kaaz website.

In my case, RT132 has the same half-shaft diameter as Zenki AE86. What i need to get then is DAT1630 which is meant for also Zenki AE86.

Final note: installing LSD is not something a garage mechanic should do. Yes you can take out that diff, yes you can install that LSD on the diff housing but the main problem is adjusting so that the pinion gear drive matches perfectly with the ring gear. Here's what i am talking about. So do yourself a favor and let a pro do it for you.