5 lug Toyota 8.4

Buddy Holly

Buddy Holly

Professional Amateur
Joined
Apr 6, 2014
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Mooresville
Way back when, Fourwheeler mag posted an article about swapping a Toyota rear axle in a tj that was 5x4.5 and 59” wwide from the factory. There really isn’t much reliable info out there online about them besides the minimal info in the mag article. About all I know is they are referred to as the 8.25 or 8.4 and the 5 lug variants came in v6 2wd Tacomas that did not have the prerunner option. The 8.4 was used in tacomas, tundras, and t100s. Possibly 4runners too?

I’m considering one for my xj but am concerned with aftermarket support. I need to regear to 4.10 and would like to add a limited slip or selectable locker. I found a couple threads saying the third member and gears in the manual trans trucks were unique and no lower gear options exist. The automatic supposedly is fine and can be regeared with standard 8.4 parts.

Anyone able to confirm or deny what I have so far?
 
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The 4-cylinder 2.7 tacos have the 5 lug rear ends in a deeper gear than 6 cylinders
 
5lug Axle Info

My 2014 4 cyl 5 lug taco has the 8.4 rear with 3.53s.
 
interesting....
What is your stock axle in the XJ?
Chrysler 8.25 is more/less equivalent to a Toyota....
unless
you want it for other reasons.....
 
yager said:
interesting....
What is your stock axle in the XJ?
Chrysler 8.25 is more/less equivalent to a Toyota....
unless
you want it for other reasons.....
Click to expand...

I’ve got the 29 spline 8.25 but the housing is trashed. PO ruined one of the housing ends and one of the side adjuster threads is messed up. The easiest thing is to find another 8.25 or swap in an 8.8, but what’s the fun in that? I like being different :D Really like the design of the Toyota stuff too
 
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Buddy_Holly said:
I’ve got the 29 spline 8.25 but the housing is trashed. PO ruined one of the housing ends and one of the side adjuster threads is messed up. The easiest thing is to find another 8.25 or swap in an 8.8, but what’s the fun in that? I like being different :D Really like the design of the Toyota stuff too
Click to expand...
I'll have a 8.25 available soon. Just needs new bearings. Let me know, I'll let it go cheap.
 
scrubber3 said:
I'll have a 8.25 available soon. Just needs new bearings. Let me know, I'll let it go cheap.
Click to expand...

Thanks but no thanks. If I’m gonna swap an axle in I’m gonna put something else in besides an 8.25. With my suspension I have to cut and move perches and shock mounts regardless of what I get, even if it’s a factory xj axle.
 
Buddy_Holly said:
Thanks but no thanks. If I’m gonna swap an axle in I’m gonna put something else in besides an 8.25. With my suspension I have to cut and move perches and shock mounts regardless of what I get, even if it’s a factory xj axle.
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Right on.
 
Yup, it only took me 30 sec, to hit ebay and bam there it was.....
4.5" AND 8.4(what ever they call it) :)
Swapping in the Toyota axles and stuff is laim,
or so Ive heard.... ;)
s-l1601.jpg
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s-l1602.jpg
 
paradisePWoffrd said:
Sounds like the later trucks have the same 8.4 internals as 6 lug axles.

Would be sweet to figure out how to get an elocker third in one.
Click to expand...

IIRC, the link I shared has some info about swapping an e-locker 3rd in.
 
paradisePWoffrd said:
Sounds like the later trucks have the same 8.4 internals as 6 lug axles.

Would be sweet to figure out how to get an elocker third in one.
Click to expand...

336wheeler said:
IIRC, the link I shared has some info about swapping an e-locker 3rd in.
Click to expand...

Swapping the elocker third in a non-eld housing is a pain (or so I’m told) but I wonder if the 5 lug shafts are the same lengths as the 6 lug elocker axles. It could be as easy as just swapping the 5 lug axles in the elocker housing. May have to give that a shot if I can find an elocker axle cheap enough.


Only thing that sucks is the 05+ axles are 64” wms. Was hoping for a 59-61” wide axle, but I can run spacers on the front to fix that issue.
 
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That easy to swap an elocker in...but why would you want to?
The 8.4 is like more better than a regular diff.
Elocker is a regular diff. With out the truss on the bearings....
But what do I know.... ;)
 
Buddy_Holly said:
Swapping the elocker third in a non-eld housing is a pain (or so I’m told) but I wonder if the 5 lug shafts are the same lengths as the 6 lug elocker axles. It could be as easy as just swapping the 5 lug axles in the elocker housing. May have to give that a shot if I can find an elocker axle cheap enough.


Only thing that sucks is the 05+ axles are 64” wms. Was hoping for a 59-61” wide axle, but I can run spacers on the front to fix that issue.
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That site states that the elocker shafts are 1/2" longer than others. Not sure how much that matters.

Also not sure it's worth the hassle if a autolocker will work fine in the 8.4 diff.
 
Probably would just install a Harrop Elocker or ARB anyways. The factory elocker is nice, but dealing with different length shafts is a pain.

Now, something else that I should probably consider is the difference between my factory 8.25 drums and the drums on the 8.4. The XJ uses 13/16” bore wheel cylinders, whereas the 8.4 taco axle uses a 7/8” bore for the 5 lug. Not sure if this will make a discernable difference in braking or not, but it’s something to consider. I read that larger bore wheel cylinders will increase braking force and cause the rear wheels to lock up before the front. I don’t know if the 1/16” larger bore cylinder of the taco axle is enough of an increase to cause this or not.

Parking brake cables are something to figure out too as well.
 
Yeah larger cylinder will increase force for each psi applied.. however, it will also require more fluid than a smaller bore to expand it the same distance.. whether it's enough difference to matter, I'm not certain. I'd try it and see.
 
a_kelley said:
Yeah larger cylinder will increase force for each psi applied.. however, it will also require more fluid than a smaller bore to expand it the same distance.. whether it's enough difference to matter, I'm not certain. I'd try it and see.
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My thought was if it has an issue I can add an adjustable prop valve to the rear line to dial the bias back in.
 
I have an 8.4 axle that I'm planning on running in my Sami buggy. The bolt circle diameter for the third is larger, and the mounting studs are larger too. I don't see how a standard Yota 8" e-locker third could swap into an 8.4 housing. Mine had an open third which is now welded.
 
You could check the bore on the original application and see how it compares to the one you're swapping into.. pretty sure they'll be closely sized however.
 
a_kelley said:
You could check the bore on the original application and see how it compares to the one you're swapping into.. pretty sure they'll be closely sized however.
Click to expand...

You’re referring to the bore of the master cylinder? The taco has a 13/16” bore and the xj is a 1” bore according to the catalog I’m looking at. Not a huge difference, but enough to raise concern in my mind. I guess the only way to know for sure is to actually do the swap and cross that bridge when I come to it.
 
If the xj bore is 1", I would think that it will move plenty of fluid, and that would be the only concern. You can always limit pressure to the rear, but you can't increase it without changing the master. Now whether or not the xj has a step bore and that's the larger dimension, I don't know. But sounds like it'll work just fine.
 
IIRC the prop valves from a zj with rear discs brakes will help. I believe that will keep you from locking the rear tires before the front. That’s an easy 10 minute job.


Sent from my iPhone using Tapatalk
 
paradisePWoffrd said:
How different are the width and diameter of the drums? Might be possible to swap the XJ drums and backing plates onto the yota axle? Or swap a ZJ/8.8 rear disc setup onto it?
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Could possibly buy weld on brackets and add 8.8 or eldorado calipers. May be dicked for ebrake that way though. The axle flange is completely different from the Jeep or Ford stuff. I don’t mind keeping the Toyota stuff, just have to make it work right. Probably less work to keep it yota rather than swap parts over from another brand.
 
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