turbodremz

iTrader: (18)

Hey CL differential guru's, came across some info and looking to get some confirmation on it.

I have been hunting for an LSD that will hold up to anything from drifting, to hard 3500+rpm launches on drag radials. I recently found a thread on yotatech stating that the Toyota 4Runner uses the same 200mm ring and pinion setup as our SC's, and that in theory the internals could be used in most of the 200mm cased Lexus diff's. This lead me to look to see what LSD options may be available for the 4Runner that might fit in the stock SC pumpkin. And I found a Eaton Differentials 187SL61B Detroit Locker Differential for less than $700 shipped. Based on the specs listed below, does anyone see any reason it wouldnt work?

P/N: 187SL61B
Detroit Locker Differential; 30 Spline; 1.30 in. Axle Shaft Diameter; 4 Pinion

Also Eaton has a Truetrac differential even cheaper, but different specs, so Im assuming this would be for the front third member, but still questionable at $600

P/N: 911A445
Detroit Truetrac Differential; 27 Spline; 1.10 in. Axle Shaft Diameter


I have had Eaton lockers in the past and broke drive shafts and u-joints in a 550+rwhp K5 Blazer before hurting the diffs, and with the sub $1k price tag, this may be something to look into. If these are compatible, they would be a solid alternative to the TRD and Auto TT diffs.

CatManD3W

iTrader: (18)

I like the idea....I could imagine it would be able to hold the power since the diff have no problem with powering massive tires....Interested to see

turbodremz

iTrader: (18)

The same thing crossed my mind. Most 4Runners I have seen are normally on a 31" tire, and watched a few video's with them on 35" and up rock crawling with the Eaton Lockers with ease. Just have to do the research to see if it would fit properly.


First thing I need to do is check spline count. The Locker and Truetrac have 2 different spline counts, and I think this is where the problem is going to be. Does anyone know what the spline count is on the stock SC differential side shaft? (pictured below circled in red) I have searched but getting mixed info on 30 and 35 spline




IF by chance its a 30 spline to match the Eaton unit, this should be a direct swap and provided the bearings have the same inner diameter also. Only solid info I have found so far with spline count for the side shaft was from SupraForums, and it had the following listed:

A Series dimensions
-------------------------------
Differential Case OD 123mm
Element Gear Length 57.1mm
Spur Gear OD 33.3
Worm wheel OD 30.5mm
Side Shaft OD 33.70mm
Side Shaft spline count 30

t2d2

iTrader: (8)

Definitely interested in following your research on this.

CatManD3W

iTrader: (18)

Would be sick to put an air locker in.....Then you could leave it unlocked for regular driving....but have the ability to lock it up with a flip of a switch....

I have a 99 tacoma with rear diff locker in it....it should be the same diff the 4runner uses

Vrank

iTrader: (4)

Which year 4runner? Detroit locker is the absolute ****! I loved mine in my 82 4wd Toyota pickup. If this works, it'd be the only diff I'd use, ever in these cars. They're strange gettin used to driving at first, make a clunking noise during engagement, but your driving style will change and it will become seamless after awhile.

turbodremz

iTrader: (18)

From the little time I have had to look into all of it, the 4Runner and Taco's use different series differentials depending on the year, but they do make air and e-lockers for the Runners so it might be something to look into down the road. If I looked correctly, only the 96 and earlier year Taco use the same differential...but not sure on all the details.

So far it seems just about any year 4Runner will theoretically work provided its the 200mm/8" rear end/Series A. And yeah they do have a different feeling. I recall thinking I broke my rear axle doing a burnout in my K5 after putting the locker in.

As of now Im pretty sure that the SC side shafts are 30 spline, and I have found that the Eaton locker uses a 45mm bearing although not sure if thats ID or OD. I have emailed a few vendors that sell the Tomei and TRD units for the SC's to try and get some details on them, and going to contact a few places to get full dimensions of the Eaton locker.

Eaton also has a full locker/spider replacement unit for $344 for those with track only cars, which is another option if all this checks out.

If anyone has a diff laying around and can take some measurements for me/community, it would be excellent. I just cant take my diff out at the moment

Bflatsharp

iTrader: (18)

spline is a 30
bearing is a 50mm ID 41301a

turbodremz

iTrader: (18)

, thanks for the info! Im going to contact Eaton or a distributor today and confirm the measurements. If there is a 5mm difference in the bearing size, Im sure that would be an easy obstacle to overcome.

Only thing left now is the axle size differences if there are any, and then the physical size from side shaft to side shaft.

Candela

iTrader: (1)

Hey turbodremz

I did something like this throughout this summer, It struck me too that the ring gears are same size, same splines, and also 10 bolt. I regret to tell you that it just isnt going to work, I bought an LSD for a T100 from auburn gear, I have a bunch of pictures because I documented everything. I ended up returning it, getting my 500 almost 600 back, saved up a little more, and purchased myself a tomei 2 way lsd.

I know the reputations 2 way lsd's have, but let me tell you, If you drove my car and did a U-turn and hard city corners, you wouldn't know there was an LSD in there, mostly due to the tomei fluid and the transX additive.

Let me know if you want me to post all the pics I've taken.

Candela

iTrader: (1)

Also, the T100, Tacoma, Pickup, 4Runner, all those old school toyota trucks use the same size diff, all interchangeable, 8" 10 bolt 30 spline, it's just what I ran into is that it was too narrow for the SC pumpkin, thus the bearings would not sit in the bearing cups. Also, the 10-bolt actual bolt pattern was different from the SC ring gear, Splines fit great, but since it was too narrow the axel shafts wouldn't slide all the way into the diff, thus sticking out from the pumpkin and not sealing.

turbodremz

iTrader: (18)

Well huge thanks for chiming in with the info. That is a big bummer though, was really looking forward to having a true locker. Guess the Tomei unit it is.

Candela

iTrader: (1)

I gotta pick up my parents from JFK which is going to be super fun, then I gotta help my sister move upstate tomorrow, I'll post pics tomorrow or monday of everything.

turbodremz

iTrader: (18)

Sounds good, thanks. Glad you chimed in cause I was a few hours away from ordering one and toying with it

Candela

iTrader: (1)

This shows how the axels do line up with the splines but don't evenly slide in cause they end up touching each other





Here you can see the big difference in length





This shows the difference in the 10-bolt pattern. Our diff on the right has the bolt holes closer to the center, the toyota truck diff has them further out





This was me attempting to make it fit by adding extra bearing cups, needless to say you can see it's still too small, and the axel would stick far too much, which would not allow the diff to seal from the sides

I'll upload some pics of the tomei install next