Pinion threads destroyed :(

[blistovmhz]

I beat the snot out of 4.56's in a D30, they were beat on prior to me owning them and the current owner is beating on them harder than I did.

4.56's in a D30 is just fine.
4.56's in a D44 is not even a question.

Yea, all the crying about 4.56 destroying a d30/44 didn't make sense to me. I'm sure that you might run into issues with a bigger power plant and 37+, but 33 and the 4.0L or even a 4.7L I6 I can't imagine causing a lot of stress.

That said, either this will be my first attempt at setting up gears, or I'll be paying some alcoholic redneck to do the setup for me (he charges $150 per axle, which seems both expensive and cheap at the same time), so I've no idea how confident I'll be with the resulting install/setup.
Anyone in Vancouver, BC want a LOT of beer for an install ?

Not quite completely off the subject but...

If you do decide to re-gear, I can attest to the combination of 33" (P285/75R16) tires and the 4.56:1 gear set. The combination gives a 10% mechanical advantage over stock which is to say that the engine will be turning 10% faster for any given road speed.

This 10% is not a calculated value, it is a measured value.

As I run a Supercharger, I had to install a F/IC to manage the larger injectors and to retard the ignition under boost. I use an AEM F/IC 8 which provides the capability to calibrate the speedometer by altering the VSS signal.

The correction required to get the speedometer to a less than .5% error is, -10.1%. thus, the 33" tire and 4.56:12 gear combination results in a 10% advantage. Whilst not exactly accurate, I am willing to live with the 1/2 percent error... Yes, this is sarcasm alright.

My fuel economy is not a good one to use for reference as it heavily depends on just how many times I get frisky on the skinny pedal. If I keep it out of boost (yah, right...) the Heep gets about 16 to 17 in town.

In boost, it gets 12. But..... It is a very fun 12......

IMO, this tire/gear combination is just about the optimal selection as it still allows for highway speeds. Also IMO, you need the mechanical advantage as soon as the rig is lifted and larger tires fitted. I know this is obvious but, larger tires take more torque to turn and lifted rigs suck aerodynamically...

The XJ is a Brick On Wheels to begin with and then, we lift them to create Brick Walls on Wheels....

Yea, I did the same calculations. I'm coming from 4.10, so not as huge an upgrade in torque, but should at least restore a little pedal power and hopefully make driving on the highway less embarrassing. (As it stands now, I have to pull over to let grandma and grandpa pass on a regular basis, and went from 20mpg with the 31's to avg. 16-17mpg with the 33's).

 

[O-Gauge Steamer]

Again this is just my opinion but......................

4.56:1 are about as far as the D30 can go and still be reliable. At 4.88:1, the pinion gear has what? two teeth on it? (yes, even more sarcasm)

The 4.10:1 gear set will run forever as long as they are properly setup to begin with. After all, Jeep installed those gears for the 2.5 Litre 4 banger...

IMO, same thing goes with the Chryco 8.25 axle. 4.56: 1 is the practical limit.

Of course, there are those that will argue the point and they are entitled to that opinion. For me, If I were to go shorter than what is currently installed, a new front axle will be required. I run a Currie HP 9" out back so that axle is just dandy...

 

[kastein]

4.88s are fine in an 8.25, I have never heard of any real issues with them. 4.56s are as deep as I would go in a 30 that isn't street driven by a pansy though.

Also, 4.56s were available from the factory in a high pinion 30, just so you know. They came with the 4cyl + 4 speed automatic w/ OD drivetrain generally. I know they existed as late as '90 and have heard claims of them lasting into the OBD1 era. Never seen or heard of a verified set in an 86 or earlier.

 

[WB9YZU]

I don't know about that Ken. Pretty sure the lowest ratio on a stock XJ was a 4:10.

My 2000 runs a locked LP d30, and though I beat it like a red headed stepchild some days, I didn't expect to shear 5 teeth off the ring gear climbing a wet sandstone ledge. I would have expected the stock shafts to get eaten first. When I was removing the ring gear so I could make it home, a number of folks indicated that their 4.56's had died in a similar fashion and that they carry hubs with stubs just for the occasion. Perhaps it is a LP thing ...

 

[87manche]

it is, cause LP is on the coast side.

lots of HP 4.56 d30s living just fine. I have watched bloose destroy a few 4.88 gearsets though.

and 4.56's did exist in the very few 2.5L-AW4 combo jeeps. There's been pictures taken and a few bellhousings sold in the clasifieds.

 

[kastein]

I don't know about that Ken. Pretty sure the lowest ratio on a stock XJ was a 4:10.

My 2000 runs a locked LP d30, and though I beat it like a red headed stepchild some days, I didn't expect to shear 5 teeth off the ring gear climbing a wet sandstone ledge. I would have expected the stock shafts to get eaten first. When I was removing the ring gear so I could make it home, a number of folks indicated that their 4.56's had died in a similar fashion and that they carry hubs with stubs just for the occasion. Perhaps it is a LP thing ...

Well, I do. That's why I posted about it

AXLE ASSEMBLY, Front, With Disconnect ***
Without System Sentry
8350 3567 1986: 4.56 Ratio, Tagged 8953003497

AXLE ASSEMBLY, Front - w/Disconnect Front Axle ***
1987-89
8350 3567 4.56 Ratio, Tagged 89 53 003 497

1990
5252 968 4.56 Ratio, Tagged 53 005 579

Direct from the Jeep parts catalog for that year range.

You can tell it was all old AMC stock planned for use in those years because of the "Tagged" notes followed by old AMC part numbers.

I can find no evidence of there being a 4.56 stock ratio available in 84-85 or 91-later, however.

And like Nate said, it was *only* available with the 4cyl/4spd auto combo, unless the buyer/dealer specifically requested it when ordering a vehicle built to custom specs.

I personally know a guy who saw two 4cyl AW4 4.56 geared XJs in a pile of junk vehicles at a local scrapyard and verified the gearing himself. And 'gollum' (I think - might have the username wrong, guy from Michigan) had a 4cyl AW4 MJ with 4.56s for the last few years, too. I believe 'thechief86' (again, not sure on username, one of the SEC guys, from TN I think?) had a 4cyl 84-85 that had 4.56s, but based on my parts catalog info, I suspect they were swapped in or upgraded later. It may have been an 86, too, I forget.

There was a guy up here in CT (name is Will I think?) who had a 4cyl AW4 Comanche as well, but unfortunately it was 2wd and had a d35 rear as I recall. So sure, the rear probably had 4.56s, but who cares?

 

[conejocherokee]

I think that before I spent money on new gear sets for my rig, I would pull out my angle grinder and lose a couple threads and see if that will settle it. Then I would seriously look for a Ford 8.8 rear with disks. (I just regeared to 4.56 with 33"s and the D44/D30 and wish I had gone the other route.)