Replacing pinion seal on R8 31-spline rear axle.

[2008DangerRanger]

My current ranger is a 2008 fx4 with the 4.0 V6, 5-speed manual, and 4 wheel drive (this combination supposedly didn't exist this year but from tracking the vin and previous owners it used to be a fleet truck up in canada). The rear axle code is R8 which from reading other forums is the much sought after 8.8 inch differential with 31-spline and a torsen lsd and 4.56 gears. In desperate need of a rear pinion seal I pulled the drive shaft and did the universal joints while I was there and now that I am about to pull the old seal out just for gits and shiggles I spun the drums and counted turns on the pinion to see if the gear ratio really was 4.56. Low and behold it isnt they are really 4.10 gears. Im wondering if someone swapped out this rear end at some point or if this is part of the weird factor that you couldn't get the R8 rear axle on a 4wd in America in 2008 probably because the 4.56 gears would require a different front differential too? I really don't know and haven't pulled the flange off yet to even see if the pinion is actually a 31-spline. This is where my questions come in before I order parts and take it apart. While doing the pinion seal Im wondering if I should do the companion flange as well because it has that plastic ring that appears to ride in the pinion seal as well. I would rather not have to replace it if I don't have too just cause they are about $130 and I cant even find the 31 spline version of the companion flange to begin with. I will not be pulling the axles out of the differential and replacing crush sleeves when I do this as I will just be marking the threads and retightening the pinion nut a few degrees further than before and maybe checking the drag is within the 8-14 inch lbs of resistance while spinning. Thanks for any help in advance.

 

[2008DangerRanger]

Forgot to also add that the R8 axle code is shown in the door but due to the heavy rust on my truck (being from Canada) the diff cover has been replaced and there is no tag on the axle.

 

[lowspeedpursuit]

8.8 gears are gears. The spine difference is in the axle shafts. There's a bunch of resources on ID'ing the 31-spline axle, like whether the tubes neck down at the ends. You have an LSD if you spin one rear tire in the air and the other one rotates the same direction. You'll be able to see if it's a Torsen in 2 seconds if you pull the cover.

Pinion preload spec is without the carrier, etc. It's not going to be spec with all that shit. I guess you could see what it is before you take the nut off, then confirm you match that afterwards, but I don't know if there's a point.

I don't know if I've ever replaced a pinion flange. Yokes I broke, yes. Flange, no.

 

[pjtoledo]

31 spline axle shafts had larger outer bearings, so the axle tubes are also bigger.
I don't have the numbers at hand right now, they are on the Forum someplace.
the plastic shield snaps onto the backside of the yoke/flange. it does not seal anything, it flings some mud off is all.

if the seal is leaking the bearings may be worn. there should be no play in the pinion bearings.

 

[2008DangerRanger]

if you spin one rear tire in the air and the other one rotates the same direction

if the seal is leaking the bearings may be worn. there should be no play in the pinion bearings.

Thank you for the clarification. Yes it does have an lsd in it, as both tires spin the same way. Also, there is no end play in the pinion bearings although I do have a quite a bit of rotational play in the pinion being able to spin it a few degrees back and forth without moving the axles. I'm now seeing some people with the 31-spline axle with 4.10 gears so I guess the forum I found saying they were 4.56 gears was wrong. I'm not trying to rebuild my entire axle but cant seem to find anyone who had a good experience with replacing the seal without taking apart the entire axle. First I thought I could get away with marking the threads/ counting rotations and tightening a few degrees more to put a little bit of compression on that used crush sleeve when I reassemble it with the new seal in there. Then I saw a few people saying that doesn't work great so I thought I could get a bar style torque wrench and see how much drag it has before disassembly and tighten it to the same drag when I reassemble. However, a lot of threads I am reading say that both of those methods are not reliable and I will end up having to rebuild the axle in a few months due to bad bearings etc. Is there anyway I can do this without pulling axles, ring gear, etc and replacing the crush sleeve? Im not too confident in my abilities to do this and am on the college student budget lol.

 

[lowspeedpursuit]

If you don't have the time/money/space/skills to take it all apart, you don't really have much choice but to pick the seal out and spin the nut back where it was.

If your bearings are already toast, they're already toast. If you kill the bearings putting it back wrong, taking it apart in 6 months isn't any different than doing it the hard way now. But if you do it the easy way and it works, you're done.

 

[2008DangerRanger]

If you don't have the time/money/space/skills to take it all apart, you don't really have much choice but to pick the seal out and spin the nut back where it was.

If your bearings are already toast, they're already toast. If you kill the bearings putting it back wrong, taking it apart in 6 months isn't any different than doing it the hard way now. But if you do it the easy way and it works, you're done.

Fair enough. I'm just gonna send it with probably both methods checking the drag before hand, marking the nut, tightening back to the mark, then checking drag, then 1/16-1/8 turn further and checking the drag again. Hopefully all goes well if not I will probably be back in 6 months lmao.

 

[bobbywalter]

if you have to redo it....

incorporate this.

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