Considering an FZJ rear axle for my 4runner (1 Viewer)

[WrenchTech]

I’m looking for some input from land cruiser community for my project. My goal is to create a full floating rear axle for my 1999 runner with selectable locking hubs so that I can flat-tow it behind my RV without burning up my driveline components. I am also looking to benefit from the 9 inch differential that will have to handle the torque of my TDI diesel, which should put out around 310 ft lbs at the crank. I also plan to run a reduction box between my transmission and my transfer case, so the torqhe applied to the Drive line down stream from there will be substantial greater than stock. I am also looking to benefit from the addition of disc brakes and the ability to retain the 4runner‘s ABS.

My understanding is that the Land Cruiser’s rear axle is 63 inches wide compared to the runner which has an axle that is 60 inches wide. I would cut 3 inches off the long side of the Land Cruiser axle, which will center the differential. Then I will need new axle shafts for both sides with the correct lengths and splines to accommodate selectable locking hubs, which I believe will bolt right up to the Lancruiser wheel hubs.

I am also thinking that a 9”Electric locking differential would be nice. My runner currently has the smaller version of the Land Cruiser locker. I’m wondering if the wiring will be plug and play?

 

[Feistl]

Couple of things...

do you need locking hubs or can you just put the transfer case in neutral?

secondly, rather than shortening the axle could you just run different offset rims?

Alternatively, swap the rear hub over to a 40/60 series. It’s a direct bolt on, but reduces the track width by just over 2” in total (1” track difference would still be fine).

 

[WrenchTech]

Couple of things...

do you need locking hubs or can you just put the transfer case in neutral?

secondly, rather than shortening the axle could you just run different offset rims?

Alternatively, swap the rear hub over to a 40/60 series. It’s a direct bolt on, but reduces the track width by just over 2” in total (1” track difference would still be fine).

The Transfer case at the back of my set up relies on a pump for lubrication. That pump only works when the input shaft is turning. Now you’ve got me thinking. If I leave the reduction box in neutral (it doesn’t have a pump, it just relies on a good old fashion oil bath and splash) and leave the rearmost transfer case engaged, the pump would work while being towed and the transfer case would be lubricated. I still would want to shorten the long side of the Land Cruiser axle though.

 

[leonard_nemoy]

Just buy an 80 series and be done with it......

 

[Broski]

I don't think running different off set wheels is a feasible idea. The swap you propose has be done before, ideally you would cut enough off the long side of the housing to run stock short side axles on both sides I'm not sure what width that would get you.
E-locker housings and non elocker are not the same and I don't think they interchange with a 4Runner e Locker

 

[Heckraiser]

Swap sounds totally feasible. I very much doubt the locker wiring is plug and play between the 3g T4r and the LC, but probably not too hard to figure out as there isn't much to it.

What size tire do you run? The 9.5 diff hangs down a lot lower than your 8" and will get hung up more if you're on 33's or smaller.

But I have to question the merit of the project as a whole. I'd rather unbolt the rear driveshaft (just the diff side) and strap it up to the frame. This is assuming you have an auto. If you have a 5-speed, I believe the 3g can be flat towed.

 

[cody c]

I think he’s referring to the front e-locker being the same as the 4Runner rear.

As per above, shorten the long side to run the short side shaft if you narrow it, but I wouldn’t, you want to be wider as you go taller and finding wheels with more back spacing is easy and saves a bunch of work.

also, with a full floater you could just pull the axle shafts for flat towing, you would just want a dust cover for the hub.

it’s possible a front hub and axleshafts with splines on both ends instead of a flange on one end could be found and you could install hubs in the back, but I’ll bet you would be into it for about $1k for shafts, hubs, machine work etc. Just pop them in or out while your filling tires or airing down. It’s simple and less parts to break or carry for spare.

 

[WrenchTech]

I was thinking of the benefits gaining disk brakes, retaining ABS, bigger gears, and doing it with salvaged parts for less money. The tires I would be running are 285 75 17 which are 34” tall.

As for the the idea of just getting an 80, I think about it all the time. These thoughts tend to involve a Mercedes om606 and an 6L80E or a NV4500.

 

[Grandlooser]

I agree with just pulling the shafts for towing. You are talking 10 minutes work and you dont have to worry about replacing hubs when they break.

 

[eimkeith]

My understanding is that the Land Cruiser’s rear axle is 63 inches wide compared to the runner which has an axle that is 60 inches wide. I would cut 3 inches off the long side of the Land Cruiser axle, which will center the differential.

I looked at doing this on my '96 4Runner as well - however, narrowing the FZJ axle ends up interfering with the stock 4Runner lower link mount spacing (I'm assuming you weren't planning on reworking the suspension link arrangement?)

If the rear hub swap to 40/60 series narrows by 2" (wasn't aware of that, but am certainly interested now) then that might be a better solution. Or just using the FROR full-float kit on your stock T4R axle... ?