Replaced Tcase and Now Rear Tires Drag

[Qban]

I replaced the 242j tcase in my 98 XJ with a supposedly "rebuilt" one from craigslist. I got everything on and then went for a test drive, however it was short lived as my rear tires (both of them) would just drag, it would go for a few feet then bind up, BTW, I was driving in a straight line. I was able to get back to 2wd and drive for a little but, but when I got it into 4wd again the rear wheels would just drag yet again.

The tcase had been sitting in the guys garage for a while with no fluid in it. So I think the difficulty in shifting could be caused by fluid not being completely circulated yet

So I put it up on 4 jack stands, 2 on each axle with the tires in the air. I put a line of tape on the top of each tire.

In 4 part time the front tires rotate faster than the back 2 tires.

Is it safe to assume that both front and back should rotate at the same speed in this configuration (being on jack stands and in 4 part time)???

I'm wondering if the nv242j in the xjs ever had different ratios for front and back?

Any help would be really appreciated, I think I'm a bit screwed at the moment =)

 

[sidewaysstarion]

Sounds like you have different ratio gears in each of your axles, which could explain why your old tcase failed.

Shift your t-case into neutral and put a white line on the front drive shaft and count how many turns it takes to rotate the tires one turn and the do the same for the rear and see how far off your gear ratios are.

 

[Qban]

Sounds like you have different ratio gears in each of your axles, which could explain why your old tcase failed.

thanks sidewaysstarion! So I measured both front and back 2 different ways. Once with both tires in the air, and once with one side of the axle down and letting the tire make 2 rotations instead of 1 (i read that this was a tad more accurate and it made sense).

The results were:
Front -> a bit less than 3.125 shaft rotations to 1 tire rotation
Back -> a bit more than 3.5 shaft rotations to 1 tire rotation

This is my first XJ and first 4x4 for that matter (i bought this used), so forgive my ignorance. This differential gear ratio doesn't seem right does it? Shouldn't both of them be the same? and should an NV242J tcase give a 1:1 ratio between the front and back output shafts?

Thanks a lot!

 

[Devilfrog]

looks like you have 3.07 front gearing and 3.55 rear gearing ... that'd bind your driveline something fierce unless you drive on ice.
The transfer case has a simple 1:1 ratio fr/rr in high range and no difference in output speeds. In 4 part time the front and rear out puts are physically locked together.

You could try putting tires that are 13.5% smaller on the front and it should solve your issue ... as a temporary solution (unless you like the hot rod look) ... that'd be 31's rear and 26.8's front.

 

[Qban]

You could try putting tires that are 13.5% smaller on the front and it should solve your issue ... as a temporary solution (unless you like the hot rod look) ... that'd be 31's rear and 26.8's front.

Thats actually really funny, and yet not funny at the same time =) hee hee

so... I guess this makes sense because I bought it used from someone and he had an accident causing front right bumper and fender damage. He said they replaced all the front suspension but he failed to mention that they replaced the front axle with different one having a different gear ratio.

So this is really a project for me, and that was the original intent. In the meantime I'll just drive it 2wd.

Do I have to replace the entire front axle? or can I just change gears or differential, or something like that?

Thanks for the sad truth, I think I'll become a naxja member just because of this help =)

 

[scoobyxj]

You could do either (gear only or whole axle), but it would be easier for you to just swap the axle. More than likely the front one came from a 4 cylinder Wrangler.

 

[ParadiseXJ]

Much easier, waaay cheaper and faster to swap in a 3.55 axle in front. If you had everything on hand it could be done in a few hours, and that's coming from a shade tree guy.

 

[sidewaysstarion]

I'm sure if you threw a WTB post up in the socal (assuming you're in socal) section someone would have a front axle for cheap.

 

[Qban]

Sweet, well that sounds like a plan then. I guess I'll start doing my research to find a suitable replacement. Do you guys have any suggestions on where to find one aside from the junkyard, ebay, or craigslist?

 

[Qban]

I'll definitely do the WTB

 

[GrimmJeeper]

where in CA are you located?

 

[Qban]

I'm in Long Beach

 

[Qban]

Is their any indication on the outside of the rear differential about the gear ratio? I measured a little over 3.5 which some members here said is more than likely 3.55, but I also heard some rear axles have a 3.56.

 

[Devilfrog]

They should be 3.54 for a Dana/Spicer axle ... this is not a difference to be concerned about. As long as the ratios are close (max 2% difference) it will be ok. If the stock tag is missing from the diff cover then you'll have to pop the cover and count gears.