QuasarDecimari

Are you running oversized tires from stock? If I remember right, the stock tire size is 29", anything above that is going to change the way your transmission shifts. When I put on my 33" tires, before installing the speedometer chip to tune my tranny shift points, it would have a really hard time anywhere above 65 as well, and I'd have to force it to shift by letting off the gas slowly until it was basically choking the engine for those RPMs, and it would finally shift hard.

This is a really cool idea. Let me know if you get around to it and if it was simple, I’d like to try and do this myself Sent from my iPhone using Tapatalk

Very curious about this myself. I always thought the clutch couldn’t be disassembled, and I’m certain the bearings on my AC compressor clutch are going out. It’d be lifesaving if it’s possible to fix, rather than buying a new $500 compressor... Sent from my iPhone using Tapatalk

I was considering something like this. How are you planning to go about the design? Are you going to also lower the control arms about an inch or so, if that’s possible? I was worried that by dropping the differential down any further, it could hit the control arms, and the driveshaft angle would be bad. A transfercase drop isn’t all that simple either, given that the engine would need to be lowered, I assume. That’s not the bad part, I think the line-up of the engine bay and everything connected would be an issue... What’s your plan? I’m very curious!! Sent from my iPhone using Tapatalk

EXACTLY what I think was going on. I feel lucky nothing else was damaged as far as I can tell. That sort of thing could have easily damaged my diff or transfer case.

My dearest friends, I would like to proudly announce to you that this incredibly annoying issue has finally come to a close. In combination with the very worn differential bushings, the tire size differences in wear made all the difference in the end. Those bushings definitely needed replaced, and drastically reduced the front end vibrations, but the main cause of the issue actually boiled down to the tires themselves. Since I got these tires before winter, I never needed to use 4WD on paved roads, and when I used it, it was at low speeds on the trails. I never would have guessed that the issue actually resided in the ratios in which all of the drivetrain must maintain. Without a nearly 1:1 front to rear rotation ratio for the tires and driveshafts, the transfer case struggles to output the same speeds with the tires under load and rotating different distances. This, in turn, likely caused the front differential to behave strangely, with the driveshaft and axle shafts not exactly cooperating at the same speeds, causing harmonics to shove the differential back and forth on the bushing mounts, wearing them faster and causing the terrifying vibrations. With the tires properly rotated, as to maintain a proper ratio as close as possible between the front and rear differentials, the issue vanished. The spider gears in the differentials put up with the fractional differences in rotations between both sides of the front and rear, allowing the power to be distributed properly and everything to rotate evenly. This, in turn, also fixed the transfer case shifting issue. With the front tires matching the rear tires in speed, the transmission-like setup of the transfer case can sync up the speeds and properly engage and disengage on the fly, without damaging anything. HUGE thanks to everyone that cracked down on this issue with me. As stupid simple as the conclusion was for this, I think it teaches me a lot about how important tire wear is, and possibly teaches us all how far the limits go for our vehicles and their gear tolerances. I'm just thankful that I limped it around in 2WD all winter instead of gritting my teeth and hauling it around while it was shaking, as something was likely to break. I hope this thread sticks around, this should be very helpful for anyone out there with the same issues!

Ohh okay makes sense. Wonder if the FSM has anything on the brace, even as part of the body diagram. Sent from my iPhone using Tapatalk

From inside? Sent from my iPhone using Tapatalk

Aaaaaand back to square 1.I DID swap the tires to even things out, aired them up and hit the road before class. On my way home tonight, I’ll kick it in 4Hi and see what happens. Sent from my iPhone using Tapatalk

Same, but gotta kill every variable haha. Sent from my iPhone using Tapatalk

You know, since I'm going through college for mechanical engineering, I really should be trying to solve that sort of issue mathematically myself haha. But hey, doesn't hurt to skip reinventing the wheel (no pun intended). That makes perfect sense, though, since the spider gears will put up with the slight difference in revolutions between the two sides of the vehicle, but in the end, ratios should balance out as 1:1 for the front and back. Redoing my math from earlier (wrong mm conversion), if the front tires are traveling 101.89" per revolution, but the rears are traveling 101.52" per revolution, that puts the ratio at 0.9964:1 rear to front revolutions. For the ring gears, at 233mm (doing 28.82" per revolution), the ratio is the same, meaning the rear ring gear rotates at 28.72" per revolution, while the fronts are rotating 28.82". There's a 10th of an inch rotation difference between the front ring and the rear ring, meaning the driveshafts are also rotating at SLIGHTLY different speeds, and so on with the rest of the transfer case. Alright guys, time to bust out the jack stands, impact, and torque wrench... the moment of truth awaits!

What do you mean specifically by "locked center diff"? I have the original differentials for the pathy, LSD 4.363 gearing. Differentials are made to withstand small variances in tire wear, of course, but it's unclear how far those variances can be. I'll be throwing the rear tires on the front today, and if I have time, I'll crack down on the math behind the ratios for the gearing.

I may have a new one for you guys. I was looking at rotating my tires, and as I was checking out the treads, I remembered something. I bought my tires used, and I suppose you get what you pay for sometimes, but here's the thing. I looked up the original tread depth (mm) for my tires, which brand new tires are 18.5mm deep. I grabbed my digital caliper, and took some measurements. My front tires are sitting at 9.2mm deep (50% worn), but my rear tires are actually at 6.2mm deep (66% worn)... That makes the rear tires about 33% shorter than my front tires. If my tires were brand new, they'd be around 803.6mm in diameter. My front tires, therefor, are approximately 794.3mm. Converting that to circumference in inches, that's 101.85" traveled per revolution on the front tires. Rear tires: 791.3mm, so 101.47" traveled per revolution. That's a difference of 0.38" of travel from the front to rear. Of course, to figure out the revolution differences this would make in the differential gearing all the way through the rest of the drivetrain and transfercase, there'd need to be a lot more math done... I guess the major question here is, with the difference between the two tires being within a third of each other, could this be causing binding along the drivetrain? I don't hear any grinding, the transfer case doesn't make any noticeable sounds, and the diff fluid shows no signs of shavings since my last fluid change... Regardless, I have absolutely no idea why I let the tire shop get away with putting the much-more worn tires on the rear... The rear tires are going to wear much faster than the front.

That would make sense. I tried a lot of things to get it to stay but nothing did it. I wonder if that support may be possible to find through the ceiling of the interior. I’m not all too geared toward pulling my headliner out, but I’m sure there’s no other easy way.

Phone posted this multiple times. My apologies everyone.

(2001 Pathfinder LE) This isn’t a major deal, of course, but wondered if someone with a bit of hardbody experience had any ideas. I was helping a buddy move out of his apartment, and put a lot of stuff in the back, and strapped the mattress on top of the car. Well, the mattress was a couple pounds too heavy for the metal roof, and con-caved the roof panel inward, making it impossible to open the sunroof now. Looking at it, you’d have no idea it was pushed inward, but I can take a big suction-type dent puller to it and pop the whole panel upward. As soon as the panel is back where it should be, the sunroof doesn’t jam, and slides back with ease. The smallest touch of the roof will pop it back down, and the sunroof won’t move. I have a roof-rack up there right now, but that can be taken off to try and fix this. Does anyone have any suggestions for how to pop it back up permanently? If it’s not gonna happen, I’m not hurting about it.

Huh, but all is well with your 4WD? No vibrations seeming to be influenced by that? That looks like about how much mine moves. I let my buddy borrow my GoPro but I got it back today, so I’ll get it under there and try some different angles.

Ah, fantastic. I might raise the rear axle and unlock my front hubs, put everything in 4LO and just watch the front driveshaft spin, see if there’s any wobble at that point. I’m thinking it couldn’t HURT to do that bearing, given how simple the removal and installation is, and how cheap the bearing is for me. Sent from my iPhone using Tapatalk

They WERE rotated and balanced before winter, but now that you say that, I haven’t thought about the fact that there was no use for 4Hi on the roads since most everything was slow 4WD on the trails. I might go ahead and rotate them real quick. Sent from my iPhone using Tapatalk

I’m assuming the “Mainshaft Front Bearing” specs is what I should look at. I’m just curious if I need to measure that with a feeler gauge with the flange off? Sent from my iPhone using Tapatalk

Aaaaand continuing on my list of ways to troubleshoot this BS: I’m waiting to get ahold of that dial indicator, but in the meantime, I made YET another discovery (which will likely disappoint like the rest of mine). I decided to push around on the driveshaft, checking for play, and while it was nice and solid, I went down to the differential pinion flange. All was good, no play, solid. Move up to the transfer case output flange, and I could wiggle it around a little. Maybe about 1mm or so of movement side to side, or up and down. I can get ahold of the output shaft bearing for about $9, and it’s no difficult thing to do at this point, but what do you guys think? Anyone want to shake theirs around a little and convince me it’s normal? Sent from my iPhone using Tapatalk

Awesome. Seriously thanks for all your help, this thread blew up to be bigger than I thought, but I’m hopeful that some unfortunate soul that gets the same issue as me can use all this to find the problem too. Sent from my iPhone using Tapatalk

I just skimmed that in the FSM this morning, and I was curious about doing that. Not sure where to get ahold of one, but I work directly across the street from a Nissan dealer. I’m tempted at this point to see if they want a spin at it. Sent from my iPhone using Tapatalk

No play in the slip joint thankfully, only maybe a few hundredths of a mm for spline play, which is totally normal as far as I can tell. I pulled some driveshafts off the shelves at work to compare to. I did go ahead and grab my grease gun and pump it full of grease, as that’s potentially never been done since the car left the factory in 01. Sent from my iPhone using Tapatalk