Questions on regearing

[RedNBlack77]

i know some discussion has taken place on this, but i have some newbie questions about regearing. when regearing, do you have to do both front and rear at the same time? what ratio is enough? i believe i currently have 3.55's, so 4.10 doesn't seem like a huge step up and 4.56 may be overkill, though i really have no idea. also, how does the gearing affect street driving? my xj is a daily driver, currently not even lifted, so i'm not sure how much i'd be wheeling in the near future (though i do plan to lift fairly soon), but i have a a chance to buy some 4.56 gears for my D30 and 8.25. the D30 is for low pinion, so i think i need a new carrier, but the person has olne from a yukon that he'd sell for $50. and with all this said, what does the labor of all this cost? any members know how to do this? thanks in advance...

-red-

 

[NomadJeep]

Yes you can do them at different time, however unless cash is strapped it is better to do them both. If you only do the rear, you will have to take out and LEAVE out your front drive shaft. If you drive with the different gears, it will blow things literally apart...

As for what gear, it is not based what speed you want to drive, it is based on engine RPM, speed, Tire size and what tire size you plan on running, fuel economy etc.. See the trick is, to plan for the tire size in advance. If you think you will stay at 33, then you gear for that, whether you have them or not.

I have a on-line chart that will let you know what is the best gear choice for our Jeeps

 

[jon]

Alright.... heres my spin.

you can change gear seperately just can't use 4wd until you have them matched. You DON"t need to remove your driveshaft, just keeps you from exploding things if you accidently put it in 4wd.

you kinda need to go with bigger tires and regear at the same time.
I have a set of 33 just waiting around for me to finally put them on.
Do you have a auto or 5 spd. that makes a difference as well.

if you have a 5spd and stock 28" tires you will be doing 58 at 2500 rpm in 5th. Not exactly a daily driver thing. with an AW4 automatic, you will get about 65 but that doesn't factor in any of the losses from the torque converter.

i beleive a 98 XJ had a reverse cut high pinion dana 30. so the gears WON'T work. if for some reason you have a low pinion they will work (not a big XJ guy nor a big dana 30 guy). you will need to swap the carrier to go from 3.55 to 4.56s in a 30, but this will not fix the gear cut and pinion issue.

 

[Josh]

you can change gear seperately just can't use 4wd until you have them matched. You DON"t need to remove your driveshaft, just keeps you from exploding things if you accidently put it in 4wd.

This is correct, I know from experience when I had a new axle put in with different gears in my old XJ.

 

[/dev/null]

Here's an excellent calculator:

http://www.tommyjeep.com/apps/ratio/index.asp

Go lower than you think you need (numerically higher), you'll dig the power.

 

[NomadJeep]

I think he has the XJ with Full time 4WD, and Part time 4WD... (=AWD)

 

[jon]

I beleive a 98 XJ had a reverse cut high pinion dana 30. so the gears WON'T WORK. if for some reason you have a low pinion they will work (not a big XJ guy nor a big dana 30 guy). you will need to swap the carrier to go from 3.55 to 4.56s in a 30, but this will not fix the gear cut and pinion issue.

 

[RedNBlack77]

so here's the email the guy sent me:

"The dana 30 gears will probably not work in your front axle. They are for a low pinion (TJ style) front axle that was used in '00-'01. It might be worth checking which axle you have though, the low pinion has the pinion at the bottom of the housing where as the high pinion has the pinion set at the top of the housing. Look where your driveshaft hooks to the front axle, if it is at the bottom its a low pinion. You will probably need a new carrier for the front axle, but not the rear, the dana 30 has a carrier break at 4.10. If your cherokee has a 4.0L, it probably has 3.55 gears and will need the new carrier. If it is a 2.5L, it will probably have 4.10 gears and your stock carrier will work with the 4.56 gears. The carrier I have will work for yours. The one I have is a Yukon, and I would probably sell it for $50."

would i be better off just waiting until i lift/tires and go with a kit from rusty's?

http://rustysoffroad.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=GEARSPECIAL825&Category_Code=

btw, i think i'm ready to lift soon if anyone wants to wrench fest it. i'm thinking like mid- to late december...


thanks everyone for the input...

-red-

 

[BrokenXJ]

The typical gear ratio's for XJ's are 4.10 for manual 5 speeds, and 4.56 for automatics. This will more than conpensate for 33" tires. You always want to go lower (higher numerically) than the tire calculators because of all the weight that you will be adding by bolting on all the stuff that Detour's is going to sell you.

If your front-end is high-pinion you are going need reverse-cut gears, otherwise standard gears are OK.

Go to a NAPA in your area and ask them who sets up gears in your area. These guys ussally have a pretty good idea, because they have a machinist who sometimes presses on the bearings for these shops.

Used gears are fine, as long as they are setup right. Installation goes from $300 to $500. Make sure they replace all of the races, and seals when they are in there. Put in some spicer u-joints in the front also.

 

[jeepgod]

Just had 4.88 w/ detroits put in the xj $250.00 an axle (labor only) replaced every single bearing seal etc.

 

[xjmark]

Just had 4.88 w/ detroits put in the xj $250.00 an axle (labor only) replaced every single bearing seal etc.

I'm going the same route with the 4.88's and detroits F+R. How's it handle on the street?

I'll be going to see Pete at CT Axle when I'm ready to build the axles.