What to Look For When Buying Used Rear Axle?

[Basilius]

I recently bought larger wheels and tires (225/70R16 --> 245/70R16) for my 1998 2.5L 4x2 Ranger. The speedometer is now way off, I need to stay in lower gears for much longer, and I also noticed that my current rear axle (86 - 7.5", 3.73, OD, 9" brakes) is very rusted and in bad condition. I thought that now would be a good time to install a different rear axle to get more torque, a LSD, and get the speedometer closer to accurate, and I've found some 2002-2004 R7 axles (8.8", 4.10, LSD, 10" brakes) in nearby salvage yards for good prices. However I've never done this kind of work before and I don't know what to look for when buying a used rear axle.

Would an R7 axle be a direct swap for my current 86 axle, and could I use my existing driveshaft? Is high mileage a big problem for these used axles? Many of the used axles that I've seen have 150,000+ miles on them. Also, what other things should I look for in used axles to make sure that I don't buy a lemon? I plan on buying new brakes and rotors so that shouldn't be a factor. thanks

 

[racsan]

I would just try to get the lowest milage axle in the ratio you want, If youre able pull the cover & look at the gears, look for any chipped teeth or excessive spider gear wear. Along with the brakes, replace the axle shaft seals.

 

[Basilius]

Thanks. Do you happen to know what type of axle this is? It's from a 2004 Ranger and the tag reads V333L 4L10 88 4C11, but I don't know if it's 28 or 31 spline, or an open or LSD.

 

[Dirtman]

8.8 4:10 Limited Slip.

You have to measure the axle tube diameter to determine if its 31 spline. 3-1/4" is 31 spline, 2-3/4" is 28 spline.

 

[scotts90ranger]

There's a step in the axle tube which I'm pretty sure means 28 spline, but I'm not familiar with the Ranger 8.8's

 

[4x4junkie]

Yep, 28-spline, and should have the Traction-Lok limited slip diff.

I've come across a few bent wheel flanges while looking at used axles. Definitely check that nothing wobbles when you rotate it (including the pinion flange) before accepting it.

 

[Dirtman]

Make sure it isn't haunted or cursed by a 13th century shogun warrior. They are almost impossible to remove and are just a constant headache. Simply take the cover off and if a smokey translucent figure of a sword wielding Japanese man appears, just walk away. I ran into this issue when I bought my 9" axle and I regret it ever since.

 

[Dirtman]

There's a step in the axle tube which I'm pretty sure means 28 spline, but I'm not familiar with the Ranger 8.8's

I think they both have a taper at the end of the tube, one is just more tapered than the other.

 

[scotts90ranger]

I was talking about the taper between the diff housing and the spring perch in the above pictures, unless I'm seeing things...

 

[Rimjam]

Another easy way to determine if 28 or 31 spline is to look at the drum brake backing plate nut spacing. Looking from the back side the 4 nuts form a rectangle on 31 spline, they form an inverted trapezoid on the 28 spline with the two lower nuts closer together than the two upper nuts.

 

[Basilius]

I recently found a 2004 FX4 level 2, 31-spline rear axle for sale at a local salvage yard for $150, but it has 300K miles on it. Is the high mileage a big problem and should I avoid the axle, and if not, what should I look for if I'm considering buying it? thanks

 

[scotts90ranger]

I'd jump on it at that price, if you go to look at it look for a wet pinion seal and while it's out I would replace at least the outer bearings (or at least pull the shafts and look at them) and the outer seals. If the pinion seal is wet it could mean the seal is bad or it could mean the pinion bearings are shot which gets more expensive, changing carrier bearings is less work and should be less expensive than pinion bearings...

 

[Basilius]

Thanks. I should jump on it even at 300K miles? The yard owner actually said that he doesn't want to sell me the axle because of the high mileage, which makes me nervous that there could be something dangerously wrong. Is there a way at the salvage yard to tell if the pinion bearings are shot, as the axle is already removed from the donor vehicle?

 

[pjtoledo]

where is that axle? I need some more stuff that I really don't need.

 

[sgtsandman]

Make sure they give you the axle you ask for too. When I was replacing the axle on the ‘98, they tried to just give me a 3.73 when I specifically asked for a 4.10. Then proceeded to try and convince me all I needed was the 3.73 when I confronted them on it. I ordered a 4.10, I want a 4.10.

I never went back there after that.