2002 Ranger FX4 axle 31 spline?

[stx4.0]

I am looking to buy a rear axle from a 2002 Ranger FX4 and I believe it should be the 31 spline unit but am not totally sure.I can get it cheap but dont want to alert the person selling it into thinking its special.So my question is were all the FX4s 31 spline.I think the Level 2s with the torsen differential were the only 31 spliners but I dont know what years these were built to be sure of what it is.I know it is a 5 speed with manual transfer case which I am also considering purchasing.Any help with axle ID is greatly appreciated!

 

[4x4junkie]

If it has the Torsen limited slip diff (which all '02 FX4s had), it's 31 spline.

Also, 31 spline axles will have 3.25" dia tubes (28 spl is 2.75" measured next to the leaf perch)

 

[stx4.0]

Thanks for the info!That was where I was stumped.I didnt know when ford started building the FX4s and also level2s.I know I have seen rangers with the FX4 decal on the bed and then seen some with FX4 and level 2 which I know had the torsen and 31 spline axles.

 

[gw33gp]

2002 was the first year for the FX4. It is the equivalent to the FX4 Level II which came out in 2003. The 2003 and later FX4 Off-Road did not come with the Torsen and 31 spline axle unless by special order in the later years.

The early 2002 FX4 had a recall on the Torsen differential but only with the 5-spd manual transmission. If it had the bad differential and has a manual transmission, it most likely had the recall replacement. Mine was replaced under recall. You could check the build date. Mine was 11/01. If the build date is after 1/02 it probably did not need the recall. They put a freeze on the sales of the 5-spd manual FX4 Rangers sometime around 1/02 until they replaced all of the differentials.

 

[Fx4wannabe01]

As noted above, 2002 Fx4 Off Road and 2003+ Fx4 Level II all got the 31spline narrow ranger 8.8". Ford stopped offering the 31spline when they ditched the Fx4 trim package in '09. In '08, they ditched the Level II package, and made many of the Level II specific goodies optional on the Fx4 Off Road....like the 31spline torsen and the Ranchos.

Best way to determine if it's an Fx4 31spline is by seeing the shock mounts and spring perches. Are they spring over? Pop the differential cover off and you'll see this....Torsen T2 differential...

If you don't see anything like that, but you see a spring in between the two side gears that looks like an " S ", you've got a tracloc. Could be 28 spline, could be 31spline. I've heard some dealers replaced the recalled torsens with traclocs.

Another way you can tell too is by the tube diameter. Measure your existing axle(or whatever 28spline 8.8 or 28spline 7.5) at the spring perch. Do the same on the 31spline. 31spine is significantly bigger in circumference and diameter(same thing. lol). I used a string with a sharpie mark to compare...also used a tape measure. You'll also see visually a sharp difference in diameter on the 31spline out by the outer bearing/brake flange. See this pics....

28spline

31spline...note the big 'notch' or 'step'. This is because they both use the same sized bearings.

Ideally, you want as new as possible for low miles. Getting a 2002 with a manual trans is a risky business IMO. Just those give the Fx4 axles a bad rap because of the recall and them blowing up on even auto trucks of early production.





*note: my 08/09 years are a little foggy...I'm not entirely positive on the model year year regards to the Fx4OR and Fx4LII packages.

 

[Sasquatch_Ryda]

We have 2010 fx4 rangers on the lot right now.

 

[Fx4wannabe01]

^^Yeah, because in Canada, it still is an available option package. Not here in the states anymore though. 09 was our last year and I tend to spit out US specs. No disrespect of course, but you knew that. lol.

*Fwiw, I'm totally jealous of you guys up there....you had the super duper uuuuber rare '02 Fx4 reg cab twin stick tan interior!!

 

[4x4junkie]

This is because they both use the same sized bearings.

The bearings in the 31 spline axle are much larger. This is the primary reason why you can't just swap 31 spline shafts into a Ranger housing (using a 31 spline diff), they have to be custom-made for it.

 

[Fx4wannabe01]

The bearings in the 31 spline axle are much larger. This is the primary reason why you can't just swap 31 spline shafts into a Ranger housing (using a 31 spline diff), they have to be custom-made for it.

I'm talking about the outer bearing. But I'm pretty sure you got that.

The housing OD right there behind the brake flange are the same size. The ID I see being different given the different sized shafts but where the bearing and seal rides could be the same size. It's been a while since I've had both 28 and 31spline shafts sitting in front of me. But the pics show what I'm talking about.

But who the hell wants to run 31spline shafts in a 28spline housing when they've gotta run custom cut, custom length 31spline shafts!?!?!???

 

[4x4junkie]

The wheel bearing is what I was referring to.

31 spline shafts have 1.625" bearing journals on them, the 28 spline is 1.4".

But who the hell wants to run 31spline shafts in a 28spline housing when they've gotta run custom cut, custom length 31spline shafts!?!?!???

Someone who was hoping it would be easier to simply stuff a set of shafts and a diff into their existing housing rather than replace the whole thing and have to weld new perches on it (or hope to find a rare Torsen axle). Unfortunately it's not that easy, but the question does get asked pretty often.