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View Full Version : Weird Ring Gear Wear


rover67
11-30-2009, 08:27 PM
Ok, please don't laugh... I noticed a big oil leak at the airport this morning coming from my rear diff cover so when I got home I yanked it and put it back together with a new gasket. The old one had squished out causing the leak.

It still had probably 2 quarts in the rear end so I'm pretty sure it didn't run too low.. but when I took it apart I noticed the ring gear was funky. So the don't laugh part? My picture... I threw it back together in a hurry and the camera was inside, so I drew what I saw.

Basicall I can describe it as wear on both the drive and coast sides that looks like rough lines along the tooth face. the lines are pretty rough and catch a finger nail. The teeth did not look like they were super worn (no big step near the heel) but the faces of them seemed way too rough with no real pattern on them. The edges of the teeth were also sharp on all "external" edges.

The pinion has a lot of backlash (more than it seems it should.. but what the heck do I know?) and the pinion nut has come loose a few times in the past. The rearend seems quiet, but there are all kinds of noises that might be drowning it out.

I'm pretty sure it's toast. Can the more seasoned folks comment? I just haven't seen enough to know what the heck I'm looking at and I'm curious what caused it. Yes, the oil had lots of metal in it. Lots of fine metal.

(Farnham, I just posted this to make you feel better.. you're not the only one with diff troubles.)

can you guys get a feel for what they looked like from my sketch? This is the stock diff that was rebuilt with new bearings 50k ago. it has a total of 280k on it now.

all of the healthy diffs ive seen had much prettier wear on the gear faces. I just don't know what i'm looking at here.. I've got no experience in rearends.

rover67
11-30-2009, 09:02 PM
it almost looks like the teeth are too soft.

nuclearlemon
11-30-2009, 10:02 PM
so the entire face is worn? not just a section int the center?

60wag
12-01-2009, 05:35 AM
Its got 3.73 gears in it right? It shouldn't be too tought to find a complete third member to swap in. Is there a lockright or an ARB in it?

rover67
12-01-2009, 06:51 AM
so the entire face is worn? not just a section int the center?

yeah, the entire face is worn evenly and completely. Maybe the pinion being loose and being sucked into the ring gear?

rover67
12-01-2009, 06:52 AM
Its got 3.73 gears in it right? It shouldn't be too tought to find a complete third member to swap in. Is there a lockright or an ARB in it?

Yes, 3.73's. This might not be a bad time for things to need replacing honestly. little pressure from the gods to go ahead and do the ARB and regear.

farnhamstj
12-01-2009, 07:35 AM
Thanks Marco, Maybe Santa and VISA will visit your house too. You on the naughty or nice list?

rover67
12-01-2009, 08:08 AM
Part of me hopes I'm on both lists! I'll put pics up for real when I take it apart again.

corsair23
12-01-2009, 11:47 AM
I just don't know what i'm looking at here.. I've got no experience in rearends.

Sorry, I'm absolutely no help but this made me :lmao: - yeah, obviously my mind was in the gutter :D

timmbuck2
12-01-2009, 11:52 AM
Sorry, I'm absolutely no help but this made me :lmao: - yeah, obviously my mind was in the gutter :D

almost as good as Beater's quote...

Rzeppa
12-01-2009, 04:50 PM
Loose pinion nut = bad joojoo. Might be toast, might be okay for another 500k miles. I'd R&R the 3.70 myself. I'm sure there are a bunch of folks with a spare 3.70 laying around. I'd offer you one but all of mine are 4.11 coarse spline.

rover67
12-14-2009, 07:48 PM
OK, so I pretty much figured this thing was toast, but now it has to be...

So I'm under the truck doing my yearly pre Memphis trip inspection and I notice the rear pinion flange is loose. pop the drive shaft off and lo and behold the pinion nut is loose. Like not even finger tight, like totally loose. I unscrewed it with my fingers. I tightened it up wicked tight and hammered the stake back down.

so I have two questions now...

Why the hell does it keep backing off??? This is the second time since i've had the rearend rebuilt that this has happened... it keeps bypassing the stake...

Second, how tight is too tight? I tightened it waaaay tight with a big breaker bar and now the pinion is tight. Like hard to turn the driveshaft with both hands tight.

I don't have time to pull the diff before the trip to memphis, but I guess I can make time. The diffs I have to replace the rear have 5.29's in them and I need to regear to 4.88's before installing them (I got the axles that were up for sale here a few weeks ago).

Should I run it and cross my fingers? It's 1100 miles each way. Are the pinion bearings gonna fry? I guess I have a "spare" in the front axle if the rear diff grenades.. God i'd hate to be doing that job on the side of I-70 in kansas. Input please...

AxleIke
12-14-2009, 07:58 PM
Personally, I wouldn't run it. Just me though. You'd likely be fine. Robbie would be the guy to tell you what to look for.

It seemed to me, that when Robbie was setting up my diff, that the crush sleeve was REALLY hard to crush. As in, Robbie, huge guy, took almost all his strength to crush down on the sleeve to make the preload come out correctly. He was using at least 18" of breaker bar, maybe 24.

However, "hard to turn" sounds kinda bad.

Not sure how cash is right now for you, but Robbie can set up diffs really quickly. With the warm weather this week, I'd bet he could fix you up in a day, as in: you drop your diffs one night, and are reinstalling the next.

RockRunner
12-14-2009, 08:11 PM
I would change them, busting gears at speed can do a lot of damage DAMHIK:o. You say you could use your front if need be but what if you grenade the axle housing? Or any other parts that could get stuck with gear parts.

Don't forget if you lock up the rear end......................on ice:eek:

Take Isaac's advice and call Robbie :thumb:

rover67
12-14-2009, 08:14 PM
I'd need to source 4.88's and install kits in a day. I guess the writing is on the wall..

farnhamstj
12-14-2009, 08:38 PM
I had a rear pinion 78FJ40 nut back off and the pinion jamed into the ring gear violently. The rear tires skidded to a standstill on dry pavement. Fortunatly I was only going like 10mph. I would get it fixed before you go.

wesintl
12-14-2009, 08:43 PM
do you need a 3.73 diff to use until you do whatever swap your doing?

rover67
12-14-2009, 10:09 PM
do you need a 3.73 diff to use until you do whatever swap your doing?

I don't know yet.. do you have one? I still can't figure out what is the best/easiest thing to do.

I think my rear driveline angles being off may be causing the nut to back off... I measured and they are off. the pinion is up 6 degrees, and the transfer flange is down 3. I knew it and have been putting off fixing it since it is not too bad but does cause a vibration. I think this has to be the cause.

Does anybody know what gears MAF sells? I am placing a big order from them for delivery to memphis that I was planning on picking up while I was there. I could add these to it and do the regear while I am there assuming I can make it. here is the link:

http://www.man-a-fre.com/parts_accessories/ringandpinion.htm

I am gonna drive the snot out of it tomorrow and see if the pinion loosens up..

thefatkid
12-14-2009, 10:33 PM
The amount of torque you applied to the nut just over torqued your pinion bearing preload. Do not drive it, bearing failure will happen very fast now. You need to tear down the differential and install a new crush sleeve and possibly bearings.

Rzeppa
12-14-2009, 10:34 PM
If someone's got a spare 3.70 lying around that would be pretty quick and easy. An hour or two if you have everything ready to go.

60wag
12-15-2009, 05:47 AM
Do you know if it has a crush sleeve or a solid spacer? If its stock, I think its old enough to have the solid spacer. Crushing a sleeve takes some wicked torque, crushing a spacer is darn near impossible. If you have to take the 60 to Memphis, I'd swap the diffs and let the former front diff do all the work while the questionable diff fills up the big hole in the front axle - or borrow a replacement diff for the rear.

rover67
12-15-2009, 08:10 AM
welp drove it to work since it was too cold to bike. I was hoping the pinion would loosen up a bit but it's still tight as hell.

I thought about it and I need to try and keep 4wd in case the trip turns into an ice skating escapade like it has in years previous so I'm looking for a 3.73 3rd if anybody has one to just get me to memphis. I'll do the regear in memphis and come back on 4.88's hopefully. Does anybody have one sitting around? If not I can pull the one out of my 40, but i'd rather not do that just because it seems like more work right now and I only have a few days to get it sorted. I guess it's basically a wash though since it seems like it might only take an hour or so to pull the 3rd out of the 40.

Hey, at least I have options though. Kinda neat that the 40 stuff crosses over.

subzali
12-15-2009, 08:33 AM
benefits of getting a later model 40...flanges match up too?

RicardoJM
12-15-2009, 08:57 AM
benefits of getting a later model 40...flanges match up too?

If everything is stock, he should be ok. This diagram (http://www.cruiseroutfitters.com/tech_flange.html) outlines the differences.

DaveInDenver
12-15-2009, 09:01 AM
I thought about it and I need to try and keep 4wd in case the trip turns into an ice skating escapade like it has in years previous
It does seem like invariably one of the legs of our trips back to St Louis for the holidays ends up in a ground blizzard and snow packed highway from Burlington to Salina going 35 in 4wd-high.

wesintl
12-15-2009, 10:50 AM
i have a 3.73 but i'm all the way the hell down here. you can just return it after your trip.

MDH33
12-15-2009, 11:25 AM
benefits of getting a later model 40...flanges match up too?

Pretty sure 40 and 60 diff flanges are different.

rover67
12-15-2009, 01:13 PM
So I think the best plan for me is to yank the diff out of the 40 and stick it in the 60. I am just worried about overtorquing the pinion nut like I did on the 60 diff last night since it sounds like I'll need to swap them.

Do these diffs require setup blocks to set the pinion depth or can you measure from the pinion face? Just wondering if I'll need any special tools to set up a new one.

Red_Chili
12-15-2009, 02:29 PM
Pinion depth is already set by shims 'twixt the bearing and pinion. No touchee backlash. Do you mean pinion preload? If you have a crush sleeve, and need to replace the companion flange, you just need to install the changed companion flange (and maybe pinion seal for good measure... cheap insurance while you are at it). Then tighten a NEW pinion nut gently until the flange seats on the outboard pinion bearing, you will feel it. Since the bearings are used and preload with that sleeve was likely 0 by now, torque JUST A BIT (fraction of a turn), and stake the nut. This snugs things up without appreciably changing preload. Personally I do not find Lock-Tite to be overkill. Red. An air wrench will have no trouble with removal when the time comes.

Of course if you have a spacer, damn the torpedoes, full torque ahead. You won't change preload.

HTH. Most easily done when installed in both cases.

wesintl
12-15-2009, 03:26 PM
I have a pair of crush sleeves if you need them.

rover67
12-15-2009, 04:10 PM
Wait, so I can just throw a new crush sleeve in there and use a new nut and be done? My original crush sleeve "over crushed"?

Yes Wes, how can I get it from you? I'll PM you..

wesintl
12-15-2009, 04:12 PM
or you can come down tonight. I'll be up til 11

i'm sure even christo is closer and has crush sleeves but i thought i'd offer since i have had them for 5 years and never used them when I swapped my 3.73 for fine spine 4.11's

rover67
12-15-2009, 08:36 PM
Quick update, I think I've got it to where it'll make it there.

Thanks to everybody for the input, advice, offers for parts and parts.

I got a crush sleeve from Kevin and a new seal from napa and with advice from close friends on preload got it sorted. The pinion bearing nearest the flange looked OK even though I used the limping truck as a parts runner/get to work truck with the wicked tight pinion. I just didn't understand what I was doing when i cranked on it.

Phew.

Now to throw all the tools in the truck for the drive.. hoping i won't need them.

Thanks again all, you're great.

:beer::beer::beer::beer::beer:

rover67
12-15-2009, 08:40 PM
Pinion depth is already set by shims 'twixt the bearing and pinion. No touchee backlash. Do you mean pinion preload? If you have a crush sleeve, and need to replace the companion flange, you just need to install the changed companion flange (and maybe pinion seal for good measure... cheap insurance while you are at it). Then tighten a NEW pinion nut gently until the flange seats on the outboard pinion bearing, you will feel it. Since the bearings are used and preload with that sleeve was likely 0 by now, torque JUST A BIT (fraction of a turn), and stake the nut. This snugs things up without appreciably changing preload. Personally I do not find Lock-Tite to be overkill. Red. An air wrench will have no trouble with removal when the time comes.

Of course if you have a spacer, damn the torpedoes, full torque ahead. You won't change preload.

HTH. Most easily done when installed in both cases.



Now this all makse sense... I over torqued it the first time...

Red_Chili
12-16-2009, 08:27 AM
It's gonna be almost impossible to install a new crush sleeve while the diff is in the truck... if it is anything like a minitruck diff. But if you did.. you did. Goodonya. The only difficulty I see is the near impossibility of determining pinion preload torque without a
1) dial inch/lb torque wrench, and
2) removing the diff from the housing, and
3) removing the carrier from the diff.

My opinion only, I defer to 'Da Boyz':
However you may be able to redneck it if you carefully crush the sleeve until you only just eliminate any play you feel, then crush just a bit more. You won't (shouldn't!) have enough backlash to really measure the pinion preload, but you may be able to tell by feel. Maybe.

I would not run the resulting assembly across country though. Pinion bearings like some preload but get fussy about too much or too little and will leave you 'in a tight spot' and shed bits all over, which makes a lot of noise and screws everything else up. I rather suspect they are female in nature. They definitely spin around fast, that must be it.

Carrier bearings must be male. Crank the hell out of the preload, give em appropriate quantities of fine fluid, and run them forever until everything around them falls apart. Then they die. Yep... Male.

AxleIke
12-16-2009, 09:48 AM
It's gonna be almost impossible to install a new crush sleeve while the diff is in the truck... if it is anything like a minitruck diff. But if you did.. you did. Goodonya. The only difficulty I see is the near impossibility of determining pinion preload torque without a
1) dial inch/lb torque wrench, and
2) removing the diff from the housing, and
3) removing the carrier from the diff.

My opinion only, I defer to 'Da Boyz':
However you may be able to redneck it if you carefully crush the sleeve until you only just eliminate any play you feel, then crush just a bit more. You won't (shouldn't!) have enough backlash to really measure the pinion preload, but you may be able to tell by feel. Maybe.

I would not run the resulting assembly across country though. Pinion bearings like some preload but get fussy about too much or too little and will leave you 'in a tight spot' and shed bits all over, which makes a lot of noise and screws everything else up. I rather suspect they are female in nature. They definitely spin around fast, that must be it.

Carrier bearings must be male. Crank the hell out of the preload, give em appropriate quantities of fine fluid, and run them forever until everything around them falls apart. Then they die. Yep... Male.

Bill,

I chatted with Marco a bit about this.

Agreed that a set up needs to be done on the bench, but this diff is done anyway. From the amount of backlash he was talking about, its not good.

He's getting them rebuilt in Memphis with his new gears, and, I believe, a new carrier.

I told him exactly what you said, IE tigten it down until there is not play, then just a hair more. Not too far. It sounded like he got it.

Figured it would last for the next 1000 miles or so, enough to get to memphis. Or at least across the snow belt and he can swap the front in if needed.

I guess he'll see. We may see a post up on mud asking for help with a beige FJ-60 with a blown rear end needing a tow somewhere in the middle of kansas... :D:D:D:D:D

As I told marco though, I'm certainly no expert. I've read a lot, done a couple, and paid Robbie to build one and explain everything to me as he did it. Still feel like I just BARELY know whats going on in there.

Figured, if he didn't punch it, and baby'd it as much as possible, he'd get there.

rover67
12-16-2009, 10:35 AM
The pinon has about a quarter of a turn of backlash so there is actually enough to feel the preload. Oddly enough the gears are quiet still... it's had a lot of backlash for a while now.

The new crush sleeve was easy to replace, just un screw nut, pull of flange, pop seal out, dig bearing out, and slide off crush sleeve. new went back in opposite. I tightened it down to crush the new sleeve (which was fun) and once at "zero" added just a touch more. I still gotta go measure it, but just past no preload is I think the consensus.

I think it'll make it with enough confidence to throw the whole "family" in the truck and go for it. we'll find out i guess. Like Isaac says... if you see a post on mud.. :)

Anywho, I am having everything I need to get it done right (gears, bearings, gaskets, ect.)shipped to my old shop in memphis. My old boss at the first place I worked who has built lots of rearends for everything from road race cars to dump trucks is ready to help me build the rearends on Tuesday. My Christmas present will hopefully be my safe arrival and rebuilt axles.

If it makes it there I should be good to go.

I have lots of spare parts i'm taking with me including a rearend (with the wrong gears... but it's a spare), all the tools and spare axles.

Red_Chili
12-16-2009, 11:32 AM
1/4 turn backlash... wow.
Sounds like you have it handled, good luck on your trip!!

rover67
12-16-2009, 11:34 AM
1/4 turn backlash... wow.
Sounds like you have it handled, good luck on your trip!!


you should see what the ring and pinion look like...

rover67
12-19-2009, 06:11 PM
Just made it! Truck actually did great.... I bet it could make it back no problem.

15mpg average at 75mph with the Goodyear MTR's at 35 psi. It only took us 16 1/2 hours.

Thanks again for all the input... I walked in the door here and tripped on a big box from Kurt at cruiser outfitters with two yukon 4.88 gear sets and two pinion install kits. Tuesday will be good to the cruiser...

nakman
12-19-2009, 10:04 PM
That's great news Marco, nice job. We missed you at the party tonight. :party: :beer2:

corsair23
12-19-2009, 10:37 PM
That's great news Marco, nice job. We missed you at the party tonight. :party: :beer2:

x2...but we all drank a :beer: for you and I think Tim dranks your shots :eek: