HZJ70 Rear LSD Rebuild & Possible Front LSD Swap ?

[flo17]

Hello everyone,

I own a 1999 HZJ70(HZJ70LV-MNW) set up for bivouac / overland camping, mainly used for travel and off-road trips.

I recently installed a Harrop / Eaton E-Locker in the rear axle. Originally, the vehicle was equipped with a factory rear LSD, but it was showing clear signs of wear and reduced effectiveness, which is why I decided to replace it with a locker.

Someone I know told me that it is possible to install the original rear LSD into the front differential, which is currently an open diff on my vehicle. He mentioned that he has done this conversion on several vehicles in the past.
Is this actually feasible on the 70 Series? Are there any known limitations or things to watch out for?

Before considering installing the LSD in the front, I would obviously like to rebuild and refresh it properly. I opened the LSD to inspect it and measured the thrust washer thicknesses, which are as follows:

• 1.95 mm
• 1.94 mm
• 2.25 mm
• 1.96 mm
• 1.97 mm
• 2.37 mm

The free length of the preload spring measures 33.18 mm.
My main concern is that all workshop manuals I can find show 4 thrust washers, while my LSD only has 3. Because of this discrepancy, I’m unsure whether my LSD is:

• a different factory configuration,
• an earlier or market-specific version,
• or possibly already modified in the past.

Have any of you ever seen a factory Toyota LSD with only 3 thrust washers?
And more generally, do you have experience with rebuilding these LSDs or swapping them to the front axle on a 70 Series?

Any feedback, photos, or part number references would be greatly appreciated.

Thanks in advance!

 

[flo17]

To illustrate

 

[HZJ75 FARMER]

Is your crown wheel 9.5 inches or 8 inches?

 

[flo17]

I didn’t think to measure the ring gear diameter when I disassembled the axle.
The axle code on the engine bay plate is K085. I’ve attached two photos taken during disassembly.

However, I’m a bit confused: isn’t “K” supposed to indicate a 9.5-inch differential?
Since there are 10 bolts on the ring gear, that would normally indicate an 8-inch differential, wouldn’t it?

 

[HZJ75 FARMER]

I have never heard of a 1999 HZJ70, we didn't get them in Australia.

All I know, is the HZJ75 series, in Australia, have a 9.5 inch rear diff, and a smaller front diff. Therefore not interchangeable. I don't know if yours will be the same, but your model number indicates you have the 1HZ engine.

The older HJ75 series with the 2H engine, had the same size diff front and rear.

 

[JuanJ]

Hello,

Your truck seems to be a late model HZJ70, just before it was replaced by the HZJ71.

Your front axle differential diameter should be around 9 in. It changed from 9 1/2 in. in the early 1990s. Your rear axle differential diameter should be 9 1/2 in.

Chances are it is not possible to do the swap. However. it is worth measuring to confirm.





Juan

 

[flo17]

Yes, exactly I have a 1HZ engine.

I found some very interesting manuals:
https://toyotamanuals.gitlab.io/toyotamanuals/

In the manual dedicated to the HZJ70, the exploded view clearly shows the 5 components (3 thrust washers and 2 clutch plates) :
https://toyotamanuals.gitlab.io/RM0...0584e/repair2/html/frame_rm00000318p000x.html
This matches my setup exactly, and the tolerance values on this page also correspond:
https://toyotamanuals.gitlab.io/RM0...0584e/repair2/html/frame_rm00000318r000x.html

Hello,

Your truck seems to be a late model HZJ70, just before it was replaced by the HZJ71.

Your front axle differential diameter should be around 9 in. It changed from 9 1/2 in. in the early 1990s. Your rear axle differential diameter should be 9 1/2 in.
Chances are it is not possible to do the swap. However. it is worth measuring to confirm.

Is it possible to reuse the front ring gear on the rear differential, or are the internal mountings / fixations different?