A while back I struck pick-n-pull GOLD. I found a locker equipped 4Runner. This never happens, the parts-pulling elves somehow manage to snag those immediately, every tie. It's even really rare to see an open diff. Anyhow, *SCORE*, pulled it, 45 minutes and $45 later and I had a spare.
Fast forward about 10 - 11 months, and the original diff in my factory locker equipped 5 spd 99 started making more noise. Not bad, just a bit of a bearing noise. I'd replaced the wheel bearings a year or two prior. Carefully checked and listened, and it was def. coming from the pinion bearings. Not sure why? Roughly 220K miles.
So I looked over my spare diff. And found it was in excellent shape. Beautiful smooth feeling bearings, no sign of leaks from the pinion seal, great looking gear wear patterns (and lack of wear). I verified that it was 4.30 ratio, since I was *SURE* that's what mine had on it (that's called foreshadowing, there), and spent a weekend morning swapping it in.
Sweet! Nice quiet diff again. Took it wheeling several times and never noticed any issues. Only issue was during our summer trip to Colorado/Utah, it was making a few more tire chirps on some of the bare rock sections of Elephant Hill (Canyonlands Needles district). Not a LOT of tire chirps, just some. And you normally get some tire chirps here and there on slickrock, regardless. About the only issue I noticed is that I *always* had to back up to shift back into 2WD. Driving forward in an S pattern didn't work. But backing up just a foot or less? That worked.
This started me to thinking...why was I so sure I had 4.30 to begin with? Because most locker equipped 4Runners are 4.30. But they're almost all automatic, mines a manual. I was too lazy to crawl under it and count driveshaft rotations on the front, so I jsut shited into 4Hi in the driveway and shut it off, then put it in neutral and jacked up the driver's side and started rotating tires. And... the rears turned a bit more slowly than the fronts.
<--D'oh!!!
Went to the basement and dug out my noisy diff to verify - yep, I had 4.10 gearing. So now I have a 4.10 on the front, and a 4.30 on the rear.
Obviously, I need to get them to match. Probably a 4.30 on the front. Maybe just get the bearings replaced in my 4.10 rear and swap that back in (it's easier to swap a rear diff than a front). Or maybe get both swapped to a 4.56, or a 5.27(?? or whatever that ratio is), it's got 33's on it now (well, 32.8?), might go bigger in the future, possibly.
BUT: The funny thing is, I've been wheeling with it since I discovered this issue, and even knowing they were off, and looking for any issues while wheeling it around for a day, I don't see any. Perhaps I'm putting some stress on the drivetrain doing this, but it's a low traction environment, and it really doesn't seem to load up or bind up at all. And, perhaps I'm just imagining this, but it really seems to turn better in tight turns, where it would generally tend to push a little wide. And I'd swear the front end hops up on ledges a little better. Is it possible that having the fronts turning a slight bit fast er than the rear, so the front end pulls a bit wherever it's pointed, is not an entirely bad thing?
I'm def. going to fix it at some point, just thought it was interesting how small the issues it creates is, and that it almost perhaps does a tiny bit better off road than it did with matching diffs.
Fast forward about 10 - 11 months, and the original diff in my factory locker equipped 5 spd 99 started making more noise. Not bad, just a bit of a bearing noise. I'd replaced the wheel bearings a year or two prior. Carefully checked and listened, and it was def. coming from the pinion bearings. Not sure why? Roughly 220K miles.
So I looked over my spare diff. And found it was in excellent shape. Beautiful smooth feeling bearings, no sign of leaks from the pinion seal, great looking gear wear patterns (and lack of wear). I verified that it was 4.30 ratio, since I was *SURE* that's what mine had on it (that's called foreshadowing, there), and spent a weekend morning swapping it in.
Sweet! Nice quiet diff again. Took it wheeling several times and never noticed any issues. Only issue was during our summer trip to Colorado/Utah, it was making a few more tire chirps on some of the bare rock sections of Elephant Hill (Canyonlands Needles district). Not a LOT of tire chirps, just some. And you normally get some tire chirps here and there on slickrock, regardless. About the only issue I noticed is that I *always* had to back up to shift back into 2WD. Driving forward in an S pattern didn't work. But backing up just a foot or less? That worked.
This started me to thinking...why was I so sure I had 4.30 to begin with? Because most locker equipped 4Runners are 4.30. But they're almost all automatic, mines a manual. I was too lazy to crawl under it and count driveshaft rotations on the front, so I jsut shited into 4Hi in the driveway and shut it off, then put it in neutral and jacked up the driver's side and started rotating tires. And... the rears turned a bit more slowly than the fronts.
<--D'oh!!!
Went to the basement and dug out my noisy diff to verify - yep, I had 4.10 gearing. So now I have a 4.10 on the front, and a 4.30 on the rear.
Obviously, I need to get them to match. Probably a 4.30 on the front. Maybe just get the bearings replaced in my 4.10 rear and swap that back in (it's easier to swap a rear diff than a front). Or maybe get both swapped to a 4.56, or a 5.27(?? or whatever that ratio is), it's got 33's on it now (well, 32.8?), might go bigger in the future, possibly.
BUT: The funny thing is, I've been wheeling with it since I discovered this issue, and even knowing they were off, and looking for any issues while wheeling it around for a day, I don't see any. Perhaps I'm putting some stress on the drivetrain doing this, but it's a low traction environment, and it really doesn't seem to load up or bind up at all. And, perhaps I'm just imagining this, but it really seems to turn better in tight turns, where it would generally tend to push a little wide. And I'd swear the front end hops up on ledges a little better. Is it possible that having the fronts turning a slight bit fast er than the rear, so the front end pulls a bit wherever it's pointed, is not an entirely bad thing?
I'm def. going to fix it at some point, just thought it was interesting how small the issues it creates is, and that it almost perhaps does a tiny bit better off road than it did with matching diffs.
