Hilux Diff Centre - JZA70 Torsen Installation

[Pure_In_Sanity]

Hey Guys, Thought i'd share some hassles i've been having trying to install a jza70 torsen lsd centre into my hilux diff. Maybe it will save someone else going through the same problems.

I've searched old and new forums and havent found much info on whether these are compatible with each other. General perception is "G-series - G-series, It should fit straight in"

When first comparing the 2 carriers, the ID of the bearings is different, The jza70 having 50mm items, hilux having 45mm. This was sorted after a trip to the local bearing supplier and picking up a pair to suit.

When fitting the centre into the housing, it appears the offset of the pinion is different in the supra irs housing. To adjust the backlash, one adjuster ends up wound in all the way, the other wound out. Also, the side of the carrier ends up binding on the housing.



The difference in offset is about 3mm. To try and rectify, a 3mm thick spacer ring was fabricated for the crownwheel. Once fitted, all was starting to look much better.



Backlash can now be set, but it turns out the smooth section of the torsen carrier hits the top of the pinion as it turns around.



I dont think its going to be possible to machine material off the end of the pinion, as this is just going to mess the teeth contact up.

Does anyone have any suggestions?

I think i might just have to go for a Tru-Trac centre.
Ah Well

[joecoolmk2]

is it just scraping or is it definately hitting?

what i mean is if you take say0.5mm off will it clear?

that much won't hurt anything.

[Pure_In_Sanity]

It would need a bit more than 0.5, probably 1mm. It completely jams up.

[joecoolmk2]

i reckon it'd be fine without that 1mm, it's up to you though.

if it was me i'd shave the 1mm off to save the hassle of buying a new diff and selling the one you've got.

[gianttomato]

I knew about the need for a spacer ring and the different bearings when we played with a GZ20 LSD centre and a Hilux carrier. The "plate" to which the crown wheel is bolted to is about 3 or 4 mm thinner than the non IRS centre. In one of my final posts on the old forum, I think I mentioned this somewhere. Other than that it was all OK.

Looks like the Torsen centre is slightly more bulky again.

Now from memory there are multiple different pinion bearings that can be used (IIRC maybe 4 or 5) with the Hilux diffs. They all have different heights. I'd suggest using a slightly less tall one but that's still going to mess with the tooth contact isn't it?

[Pure_In_Sanity]

Yes, different pinion bearing is going to change the tooth contact. I'll take the pinion back out and have 1mm machined from the top. This should give clearance, and there is still going to be plenty of that taper left at the top.
I haven't really got much to loose.
Worst case scenario - I'll buy a complete 4pinion lsd hilux centre for time being and order a tru trac later on.

[cambelt]

i can help out with the proper 4 pinion hilux lsd if u need 1 .
dave

[Pure_In_Sanity]

Hey guys.
Interference was by approx 0.8mm, So i ended up having 1.5mm taken off the pinion. I wanted that extra bit of room incase things shift slightly under load.
Pics are a bit dodgy, the camera didnt want to focus well inside the diff.
BEFORE

AFTER

The pinion should probably be re-hardened as i've been told the case hardening only penetrates .030"
But i'll see how it goes for now, the gears i have (4.3) are probably going to be a bit short anyway, so they might get changed in the near future.

So there you have it... jza70 torsen centre does fit into a hilux housing, but its not a straight swap. The extra time, parts & machining brings the total close to a Tru-Trac torsen, even closer if you're paying for assembly labour.

[joecoolmk2]

you don't need to worry about re-hardening it, as the end of the pinion doesn't(hopefully ) come into contact with anything.

[madmont]

I fitted torsens to my hilux 4wd diffs front and back . I used a spacer slightly less than 3mm.
The diffs were old 5.28s and I dont recall having any clearance issues with the pinions. As you can see from the flanges one is old the other real old.I discarded the locking tabs and used loctite on the threads so as to gain thread depth in the crownwheel. They have not come loose and i have a 1UZ in it

[Pure_In_Sanity]

Hmm. Maybe my pinion is slightly longer or just sits higher than the average hilux gearset. The teeth contact has been set correctly though.
Your torsens were from JZA70 supras?
Thanks for the info and good pic

[emp?]

it depends what hilux diff your trying to put it in, i think the early ones have this problem, but once you started getting to the late 80's early 90's diff you wont have the same problem

[The Witzl]

shite.... and here i was going to buy a JZA70 torsen centre for my RN27 diff.... oh poo

[Pure_In_Sanity]

Ok makes sense. Mines an RN41 hilux diff so maybe they changed in the 50series?

[07XTC]

it depends what hilux diff your trying to put it in, i think the early ones have this problem, but once you started getting to the late 80's early 90's diff you wont have the same problem

Thats correct. Later model ones and (in 5 stud 2wd) fitt straight in no modifications.

Hope this helps out....and hope it doesnt piss anyone off that bought an older style hilux thinking its straight forward.

James