Rear Differential Whining- Hope its bad carrier bearings...

[mastacox]

Well the trifecta is complete. First, axle seal goes bad. Take things apart to find one of the wheel bearings is bad. Now, the rear differential is whining. :tapedshut:

SO the story goes something like this- On the way back from labor day off-roading festivities, I notice a slight high-pitch whine while driving on the highway at about 60 mph. It is independent of engine RPMs and gear selection, and it only occurs when the 4Runner is accelerating or maintaining speed; the sound goes away while coasting. It also get higher-pitch when I go faster and lower pitch for slower speeds. Additionally, it only starts to be noticeable at about 35-40mph, at which point it is a low-pitched gear sounding noise.

Over the past week the noise has been getting progressively worse until it got me worried enough to park the 4Runner until I found the source. Hoping it was a u-joint, I bought a new one and crawled under the 4Runner to inspect. The U-joints are tight and seem fine. However I can move the diff flange about 15-20 degrees before the gears engage (sounds like way too much backlash to me, or severely worn gears which I doubt).

SO I decide to do a dangerous but necessary (IMO) diagnosis- don't try this at home kids. I put the rear axle on jack stands along with the frame, chocked the front wheels, and start up the engine shifting into drive and set the cruise at 40mph. The wheels quickly free-spin up and overspeed to about 50mph, and then decelerate to about 35 and accelerate again, in a loop going between about 35mph and 50mph. Every time the wheels accelerated the rear differential makes the noise I've been trying to pinpoint in the cab. The noise is definitely coming from the 3rd member, not from the driveshaft or outer wheel bearings.

Noise from the 3rd member is definitely bad... Fearing metal chunkage of the ring gear I drained the gear oil which was dark (after only about 600 miles on it, Amsoil Severe-Gear Synthetic). No large metal chunks but the magnetic drain plug had thick magnetic grease on it (small metal particulates in gear oil).

So I think it's obvious something is VERY wrong with my rear diff. I'm going to have to pull the 3rd member and inspect the ring gear for damage. If I'm lucky I may only have to replace the carrier bearings... If not, well I might have to try finding a 3rd member in a junkyard or suck it up and get a new ring and pinion. How much would it cost to get a new R&P set up by Zuk if I provide the 3rd member?

[JOSHH]

Don't know how much he charges, but I've only heard good things about Zuk.

[mastacox]

Well, Zuk is going to save my bacon. Sounds like I'll be replacing all of the bearings (carrier and pinion) with new cryo'd ones, and while we're at it we'll do a freshen up with inspection of the ring & pinion, and a solid pinion collar. I'll be pulling the 3rd and shippping it off in the next couple of days.

:wrenchin:

[4x4mike]

Well, Zuk is going to save my bacon. Sounds like I'll be replacing all of the bearings (carrier and pinion) with new cryo'd ones, and while we're at it we'll do a freshen up with inspection of the ring & pinion, and a solid pinion collar. I'll be pulling the 3rd and shippping it off in the next couple of days.

:wrenchin:


Cryo'd bearings? I didn't know there was such a thing. Hope it all works out for you. I guess you're lucky if the gears are ok.
I had to laugh at the running the 4runner, on cruise at 50 mph, while on jack stands. I could totally see my self doing that but having something go terribly wrong and having difficulty explaining my story.

[mastacox]

Cryo'd bearings? I didn't know there was such a thing.

Yeah i didn't know about them either until I started reading about some of Zuk's installs on his website. Apparently Cryo-treated bearings are stronger and hold preloads longer, and are a good idea in high-torque applications (like a supercharged 3.4).



I had to laugh at the running the 4runner, on cruise at 50 mph, while on jack stands. I could totally see my self doing that but having something go terribly wrong and having difficulty explaining my story.


I will be the first to admit it is a terribly dangerous thing to do, but I was pissed off and wanted to narrow down where the noise was coming from IMMEDIATELY. I was able to tell that the noise was definitely coming from inside the rear diff and not the T-case, tranny, driveshaft, or axle bearings; so I'm going to call it mission success :ban: :asshat:

[ZUK]

Hello Brian,Josh, and Mike....post #1 :) I'll charge the batteries on my Camera and post a ton of pics for you to look at.... ZUK

[mastacox]

Hello Brian,Josh, and Mike....post #1 :) I'll charge the batteries on my Camera and post a ton of pics for you to look at. ZUK


Thanks for coming over Zuk ;) UltimateYota is the new cool place to be :love: :wrenchin:

[mastacox]

On an interesting related note, if I ever did explode my ring and pinion, I guess I'd be going to 4.56's because 4.30's are not available from aftermarket manufacturers, and a R&P alone from Toyota would be about $537 at wholesale prices! :spit:

I guess the 4.30's are kinda like the factory 4.88's in 2nd gen 4Runners... except that the carrier and 3rd on the factory Toyota 4.88's is different too.

[ZUK]

$537....I just found out that was with the "old" part number .....the new superceded part # is 41201-69466 and the price went UP, of course......to $595.56! That's with the 30% wholesale internet price also. Yikes.

Going to 456 gears was something I forgot to mention to you.....I have some new MOTIVE 456 gears if, for some reason, we ever decide to go that route.

I didn't know about this board....I just bookmarked it.
ZUK

[mastacox]

Unfortunately since funds are tight and I'd have to re-gear the front diff to 4.56 too, I think we'll probably have to save re-gearing for another day farther down the road. I don't think I can afford another master install kit, plus 2 new sets of R&P's, plus a little more labor for the front...

[mastacox]

Hmm, so I think I may have stumbled upon a cheapish way to "regear" the front...

http://www.yotatech.com/f11/4-56-4runner-front-rear-thirds-guaging-interest-154576/

I would think this diff would just be a straight swap for mine. I guess the real question is do I want to go through all that trouble for an extra 6% in gearing? It would basically get me back to "stock" in terms of power and speedo reading.

[mastacox]

Just a little update-

I'm not going to bother regearing, I like my 4.30's just fine. I'll be driving to Tucson on Friday for a wedding, so I'm taking the 3rd member and dropping it off at Zuk's personally, and then hopefully picking it up on Monday when I drive back as long as everything goes as planned.

On a semi-related note, if anyone in the Arizona area wants an almost-new set of 33x12.50r15 Interco TrXuS M/T's on 15x8 Black Rockcrawler Steelies with Discount Certs they should get in contact with me because I could drive them down too.
http://www.ultimateyota.com/index.php?option=com_smf&Itemid=26&topic=5562.new

[mastacox]

So I pulled the 3rd member and am taking it to Zuk tomorrow. The pinion preload is completely gone, and and I measured the backlash at about .014" which is a bit out of spec. Sounds like the pinion bearing(s) gave up the ghost.

Happily with cryo'd bearings and a solid crush sleeve things ought to put up with some abuse and last a long, long time. :thumbup:

[mastacox]

Nother update-

Got the 3rd member rebuilt by Zuk with the cryo bearings and solid crush sleeve. He set it up as "well as it could be" with the used ring and pinion. Because the pinion bearings were going bad and the pinion preload was pretty much completely gone, under power the pinion was moving slightly to the outside of the ring gear causing an irregular wear pattern. Now that things are back to where they should be everything is good. I will have a slight whining noise until the R&P wear into the new contact pattern, which will take a few hundred to a few thousand miles.

Someday in the future, I may end up going with 4.56's, but for now everything is happy again.

Overall, Zuk is awesome and of course highly recommended :bowdown:

[mastacox]

Zuk's writeup is now online- 1998 4Runner E-Locker makes noise on acceleration only (http://www.gearinstalls.com/brian2.htm)

The history of the 4Runner is not 100% accurate in the writeup yet (the whine hasn't "awlays been there") but basically the carrier bearings showed evidence of overheating and there was black sludge from bunt oil. One of the carrier bearing rollers was self-destructing, and all of the races showed signs of pitting and irregular wear.

http://www.gearinstalls.com/brian2/7.jpg
http://www.gearinstalls.com/brian2/8.jpg
http://www.gearinstalls.com/brian2/26.jpg

When the diff might have overheated I'm not sure, I don't think I've done anything to overheat the diff like that, but it's possible maybe :headscratch: Zuk thinks it might have been due to running with no oil a long time ago, but the fluid level has always been good while I've had the 4Runner. The only thing I can think of is I did tow a very full U-haul 6x12 trailer about 600 miles from Tucson to Santa Fe. The trailer probably weighed a good 1500-2000 lbs so maybe that was too much weight when paired with an old diff that had old bearings...

Anyway, depending on whether these old gears are able to "wear themselves back in" I may end up having to go to 4.56's in about a year.