Hi guys I have a 85 bj73 with an ls1 in it and have totalled the rear diff just wondering as i have the chance to buy a cheap reco 80 series rear centre will it fit into my housing ratio is correct and will my axles fit any help will be much appreciated
80 series rear diff centre into bj73
- Thread starter bj73ls1
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I believe all of the non-factory locked 9.5" 3rd members are interchangeable in the 70 and 80 series non-factory locked housings. Their are some differences in the castings of the carriers over the years but they will not effect the compatibility.
Here is a pick of the diffs in my 1989 JDM BJ74. The black one on the left is the BJ74 stock unit (with an older style ARB RD-124 semi or full float locker) and the unpainted unit on the right is a newer style carrier I believe out of an 80 series (with a newer ARB RD-142 full float locker). You can see their are a few differences in the design of the carrier but either one will fit front or rear on my BJ74
Here is a pick of the diffs in my 1989 JDM BJ74. The black one on the left is the BJ74 stock unit (with an older style ARB RD-124 semi or full float locker) and the unpainted unit on the right is a newer style carrier I believe out of an 80 series (with a newer ARB RD-142 full float locker). You can see their are a few differences in the design of the carrier but either one will fit front or rear on my BJ74
The most common 80 ratio is 4.10. 41 tooth ring and a 10 tooth pinion. The earlier stuff would generally be a 4.11 with a 37 tooth ring and a 9 tooth pinion.
If this is the case here when 4WD is engaged the rear axle will "push" the front axle. Not a lot but on harder surfaces it could get a bit odd.
If this is the case here when 4WD is engaged the rear axle will "push" the front axle. Not a lot but on harder surfaces it could get a bit odd.
Good point Dan, I was not thinking about gear ratios in my earlier post as both my diffs were regeared to 4:56's. However a lot of older vehicles came from the factory with slightly different ratios. I had a 1970 Ford f250 with a 4.09 front and a 4.11 rear from the factory. I found this site below that claims if your ratios are with in 1% on road or 2% off road you will be fine.
http://www.wagoneers.com/JEEPS/tech/GEARING/myths.html
My self I wouldn't hesitate to run a 4.10 and 4.11 together. I'd just make sure to put the 4.10 in the front and not run high speed 4wd on dry surfaces
http://www.wagoneers.com/JEEPS/tech/GEARING/myths.html
My self I wouldn't hesitate to run a 4.10 and 4.11 together. I'd just make sure to put the 4.10 in the front and not run high speed 4wd on dry surfaces
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Thanks guys hey does it matter going from low pinion to high pinion it is a lifted truck not even sure if diff I'm planning on buying is high pinion just been reading up and thought maybe it is would it matter if it is mine is low now thanks in advance
The high pinion, or top pinion, is used in the front axle only and it is smaller. No-go in a rear axle.
I was simply noting that there is a difference. They are, afterall, not "the same". How much it matters is in the mind of the end user.
It is possible for a bind to occur. As I said "not a lot but it could get a bit odd".
I have been driving all sorts of 4WD vehicles since 1974 and perfectly matched ones will bind when there is "no difference". Building on that vehicles with a very slight difference could reasonably be expected to bind up a bit sooner and to a higher degree. It would depend on the settings on your butt dyno as to how you would experience it from the driver's seat.
I have been driving all sorts of 4WD vehicles since 1974 and perfectly matched ones will bind when there is "no difference". Building on that vehicles with a very slight difference could reasonably be expected to bind up a bit sooner and to a higher degree. It would depend on the settings on your butt dyno as to how you would experience it from the driver's seat.
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I'm not sure how your old age or the fact that all vehicles without a centre differential can experience driveline wind-up are relevant, but lets run with that.
You're saying that you believe that you (or maybe not you, maybe someone else) could, from the driver's seat, feel a noticeable difference from a 0.24% difference in drive ratios?
I'm a vehicle testing engineer and if there was the slightest, vaguest, smallest hint of a sliver of truth in what you were saying, I'd have let this one slide through the keeper, but let me make this perfectly clear Dan, you are wrong.
-Adam.
I'm sorry my opinions on a public forum have offended you. I will strive to do better.
By the way age has nothing to do with it. And I am offended that you would even bring that up.
By the way age has nothing to do with it. And I am offended that you would even bring that up.
I have to agree with dan here. After replacing the gearbox in my hzj75, I forgot to plug in the 4wd indicator wiring and whilst going for a test run, it felt like my brakes were stuck on. After some investigation I found out my tcase was in H4 which caused a bind. I couldn't get the tcase out of h4 on the spot and not wanting to risk more damage, I jacked a rear tire off the ground to release the bind.
This was with brand new tyres and 4.11's front and rear.
4.10 vs 4.11 would be completely imperceptible in every way.
Many many vehicles are sold brand newer with a larger differential from front to rear.
Many many vehicles are sold brand newer with a larger differential from front to rear.
Adam, you've gotta be the only Mudder in the history of time to utter these words to CDan, who's a renowned TLC authority, a huge contributor to Mud, and a well respected member of this community, AND you proceeded to do so with the attitude of a complete a******.
Post fail.
Delete.
Go ahead and log off, while you're at it.
Pretty sure you've an ego to stroke, anyway.
Huh?
What?
About time!
Now, the cauldron to witch up a diff spell for Adam, in true Shaman fashion!
Two words.
"CHOKE KNOB"
dang, look what you miss, and all 'cause of valentine's day.
I'm plucking down my dinar's and peso's on the oLd desert dweller.
when's the next round start? this cyber spectator assassin stuff is wierd.
I'm plucking down my dinar's and peso's on the oLd desert dweller.
when's the next round start? this cyber spectator assassin stuff is wierd.
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YUp im with these guys.
You gotta be joking I have had wind up several times with workshops leaving 4x4's in 4wd and leaving lockers on accidentally and yes you can feel it within 30 meters of driving out the workshop door. Even in the junngle on hard surface you can feel the wheels binding up if you strike a patch of concrete or bitumen or really really hard ground. Vehicles experienced on recently LJ77 BJ75 all running 35" sneakers. Oh and yeah a customer broke a front axle on my stock ISUZU pickup leaving it in 4x4 on the road accidently.