Regearing my 97 ZJ 5.2L w/ 33s - JeepForum.com
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post #1 of 9 Old 09-19-2019, 11:26 PM Thread Starter
RepBolt
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Regearing my 97 ZJ 5.2L w/ 33s

Highway driving has been sluggish and gas mileage is horrible. My ZJ has the 30/44a axles. I'm looking to regear to 4.56s or 4.88s. Which would you recommend?

I'm not familiar with this process at all. Anyone with experience, what parts do I exactly need to complete this other than the new gears?

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post #2 of 9 Old 09-20-2019, 01:59 AM
Kolak
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I would recommend 4.56. RPMs will be good on the highway and you'll have better tooth engagement on the D30 vs 4.88.

You need the front & rear ring and pinion sets along with master overhaul kits.

The master overhaul kits will have carrier and pinion bearings, seals, shims and crush sleeves.

We can enlarge the D44A ring gear from 8.5" to 8.8" for added strength. Fits in the housing perfectly.

I have everything you need available at great pricing. You can PM me here on the forum or email me at [email protected] and we'll chat.
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post #3 of 9 Old 09-20-2019, 09:37 AM
Timo_90xj
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4.56 for highway mileage and if you need to go +70mph. Towing, heavy trail use and max. 70mph I'd go with 4.88s if there wasn't a turdy up front.

I chose 4.56 for 32s when I did my axles anout 7 years ago. Since then I went to 33s, and I also had 285/75 R16s BFG AT KO2s as street tires (they were about 1" larger in diameter compared to my ~30% worn 33s).
Power and highway mileage-wise 4.56 with the 5.9 and engine upgrades is good; for trail use I might want to go 4.88s, but with the D30 pinion gear engagement - or the lack of it - with 4.88s is not that good of a thing.
RPMs @ up to 85mph are very reasonable with 33s and 4.56 gears and you will like how you get your power/ torque back. 3.73s with 33s is simply apalling..

Like Kolak mentioned, if you install JK Rubicon rear R&P, you get the 8.8" ring gear compared to 8.5" on the D44HD. JK D44s use the same pinion bearings and have the same pinion diameter as D44HDs. Difference is that D44HD uses the same 29-spline D60 pinion spline, where the JK uses the JK- specific IIRC 24-spline.




No matter which gears you choose, I do very highly recommend drilling out your ring gear bolt holes on the carrier from the 3/8" to either 7/16" or even 1/2" - depending on which bolt diameters your ring gear has.


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1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #4 of 9 Old 10-12-2019, 08:39 PM
Rallyrs
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Great thread!

I am a noob poster here and just picked up a 98 5.2 -3.73 -Quadratrac -rear D44A LSD- ZJ as well.

Will probably go for 4.56 gears, as I see on multiple forums people donít think the 4.88ís are a good idea with the D30.

But just curious, is this based more on theory?

Or are we actually seeing more jeeps breaking their front axle parts with 4.88ís then those who are running 4.56ís.

And Iím not trying to say itís untrue or be a jerk or anything. Just curious, as I would love to have the extra acceleration of the 4.88.

But if itís at the(real world)expense of more likely breakage in my Dana 30 -forget it.

Assuming reliability and durability, max acceleration is my priority.
Although I suppose I donít want to be screaming too much at 75.

Mpgís I donít care.


Jeep was bought primarily to run on my local run -what -you-brung short course track.


But the interior is in pretty good shape, I donít think I can bring myself to gut this one.

So I think itís going to be my weekend Four Wheeler as well for a bit.
And it might supplement my daily driver a bit.

If I donít wad it up.

To tide me over until I get the two door JK manual trans Rubicon that I would like to pick up in the next year or so.

It came with a brand new 30 x 9.50 15 Firestone destination ATís and I think Iím going to run It like that for now.

Should haul butt with either the 456s or 488 with that short of a tire I think.

Biggest I think I might supplement the 30ís with (for weekend wheeling and DD dutiy)would be a 33 inch tire.
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post #5 of 9 Old 10-13-2019, 12:34 PM
Rallyrs
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Great thread!

Would 33ís and 4.88 be OK if I went to a late XJ high pinion Dana 30?

Better tooth engagement right?
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post #6 of 9 Old 10-13-2019, 02:38 PM
Timo_90xj
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Same amount of tooth mesh on an LP D30 and a HP D30 - the only difference is that HP D30 is stronger when driving forward, LP D30 is stronger in reverse.


4.88 gears on a D30 leaves you with very little tooth engagement between ring gear and pinion.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #7 of 9 Old 10-13-2019, 03:44 PM
Rallyrs
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Quote:
Originally Posted by Timo_90xj View Post
Same amount of tooth mesh on an LP D30 and a HP D30 - the only difference is that HP D30 is stronger when driving forward, LP D30 is stronger in reverse.


4.88 gears on a D30 leaves you with very little tooth engagement between ring gear and pinion.
Copy that. So still a bad idea I guess.

I suppose 456 it is. Thanks!
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post #8 of 9 Old 10-14-2019, 10:16 AM
LordHobbit
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upgrading to the HPD30 is still a good idea.

93 red ZJ 196k 4.0. Spent more money than I should have ...
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post #9 of 9 Old 10-14-2019, 10:48 AM
Timo_90xj
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Yep, it sure is. Gives better ground clearance for the DS and a slight increase in gear strength when going forward.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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