Rear Diff.....

[wofat]

Drained the differential and lookie what I got:

 

 

Looks like blown out bearing races, this was the best shot I could get of the magnet after I swooshed it around in the drain bucket:

 

 

Big chunks, little shards...dayam!

A couple years ago I hired a friend's Dad to put a tranny in the car. After driving it around a bit I noticed some grindy/clunky noises coming from the rear diff (especially cornering). I picked up a JY diff to have the same guy install it and now I can't figure out WTH he did???!!! He was supposed to do brakes, shocks and swap the differential all at the same time. I did ask Him just to swap the pumpkin, he insisted that swapping out the whole axle would be easier. I dunno 'bout that.

I had drum brakes originally, now look:

 

 

I bled them yesterday, that's why it looks wet, but them are disc brakes.

When I picked the car up, I dunno, something just told me I better grab the pumpkin off the old axle just in case. I'm glad I did, it still had grease marks from the JY.

 

 

I think He just swapped out the axle shafts and called it soup.

 

 

I'm putting this one in a couple minutes from now, just wanna see if there's any words of wisdom You Nissan guru's can share with a Padawan like myself before I get going (including don't drop it on your head). I'll get pic's of the carnage inside the case, I think there's another magnet in the bottom of the diff. How am I gonna clean all the metal out??????

Look's to Me like just the four bolts on each axle shaft and pull 'em out a little, four bolts on the driveshaft and unbolt the pumpkin. Reverse for install. I couldn't find a gasket so I'll have to seal it up with black permatex.

Let Me know if You guys can think of anything pertinent for Me, I'll be checking back.

TIA

Edited May 25, 2010 by wofat

[silverton]

When I changed my diff fluid, I think my magnet had more crude on it than yours. It's just something that happens with differentials and limited slips, that's why the stock plug is a magnet to catch it all. Grinding noises should not be occurring though.

 

As for the original drum brakes and now discs, XE models came standard with drums, and SE's came standard with disc. If they work, keep them! Disc are so much easier to deal with than drums.

[wofat]

Thanks Silverton. I think this diff is past grinding anymore and the JY one looks pretty good. He put in a TON of lube, I dunno how he got it all in there (there's a little breather tube on top????). That probly quieted it down quite a bit.

I like the discs, that is a bonus. I thought the JY ones were drums but I guess I never looked that close. They forked it in the back of the truck at the JY and the mechanic had his helpers haul it out, I just figured they were the same.

If it's pretty normal to get a lot of shavings I guess I won't get too anal about cleaning it out, just the big chunks and change the fluid again soon.

Thanks alot, I'll keep ya posted.

[wofat]

Not gonna do it tonite. I hit two spinners on the axle shaft nuts, that means the calipers and discs need to come off and I don't have enough time to mess with it. I gotta drive it tomorrow so I tightened everything down and refilled the gearbox. I'll get it this weekend when I'm not rushed, that way I can get rebuilds for the calipers, new hoses and pads (they're real bad). I really wanted to see inside that diff, I got a hunch it'll look like a hand grenade went off in there.

Edited May 26, 2010 by wofat

[Precise1]

Not if you are still driving it.

 

Your story seems odd, but if it still works and it isn't howling, there is no way something major let loose. Some fuzz and bits is normal, I can't remember the last time I changed a diff fluid and didn't see something significant. Remember, it is the work horse of the drive line. It takes input and turns it 90 degrees both directions and is often ignored in maintenance.

 

B

[wofat]

I'm getting a lot of wobble on light braking, heavy braking is straight and solid. I went through the front end and fixed any iffy stuff so I figure I'm looking at a bad bearing (or now maybe a warped disc) in the rear. The outer bearings seem good but I want to repack and tighten them just the same.

It looks like the guy just swapped the axle shafts and left the pumpkin in. I put the old grease back in and had a little over a quart extra (even after I held back the crap with metal).

I hear what You're saying about diffs, I limped a Vega home once (back in HS) cracked open the diff and teeth fell out. It was missing a third of it's teeth and still ran, poorly but it did move.

Is there a way to test a differential out of the car? If I move the drive plate back and forth (on the JY one that's not in the car) I have about a quarter inch of play before it catches the gears to reverse itself. Is that right?

It's better for Me to work on them when I don't have time constraints, when I rush I make mistakes and it takes me twice as long.

I'll letcha know what happens.

Thanks.

[wofat]

Just had to put in new rotors and pads, all is well again now. No weird noises from the diff so I'm just gonna keep driving it as is. That was easy!

[silverton]

Glad you got it figured out the cheap way!

[jj big shoe]

You made sure both your original axle and the one the guy installed have the same gear ratio, right? Just checking.

[wofat]

You made sure both your original axle and the one the guy installed have the same gear ratio, right? Just checking.

He never swapped the diff, just the axle shafts. I think the grinding (from before he worked on it) was probly an outer bearing on the passenger side. He insisted that he swapped the whole transaxle even though I proved otherwise. Both pumpkins are from '88 autos, I wanna say 4.625?

I'd love to see how a 5 speed would do with that gearing, would highway speeds suffer too much?

[GrimGreg]

Most manuals had 4.3, so it should be better at highway speed on 4.6.

 

 

BTW, my 88 auto has 4.3, you might wanna double check.

Edited June 1, 2010 by GrimGreg

[Precise1]

Just a general FYI...

 

http://www.nissanpathfinders.net/forum/index.php?showtopic=20182&st=0&p=346830&hl=Trim&fromsearch=1entry346830

 

B

[87pathy]

that kind of material is not abnormal.

 

where there any "slivers"

[jj big shoe]

If you're sure he didn't swap the entire axle then nevermind. If there's a chance he did swap it and you have different gearing in the front axle than you have in the rear, that would be a problem. Just checking.

[wofat]

Just a general FYI...

 

http://www.nissanpathfinders.net/forum/index.php?showtopic=20182&st=0&p=346830&hl=Trim&fromsearch=1entry346830

 

B

 

46. Would there be a way to tell what the ratio is on the diff that's not in the car?

 

 

that kind of material is not abnormal.

 

where there any "slivers"

 

Yeah, there were slivers, kind of curly little things about 3/8" long. They don't show up in the pics very well, there's one on the magnet.

Edited June 2, 2010 by wofat

[87pathy]

open diff.

 

rotate tire 2 times, count the times the pinion rotates.

If it rotes just under 4.5 its going to be the 4.3

if it rotates just over 4.5 its going to be the 4.6.

 

If you have a locker, rotate it 1 time on the wheel, not 2.

 

 

JP

[wofat]

open diff.

 

rotate tire 2 times, count the times the pinion rotates.

If it rotes just under 4.5 its going to be the 4.3

if it rotates just over 4.5 its going to be the 4.6.

 

If you have a locker, rotate it 1 time on the wheel, not 2.

 

 

JP

 

NM, I figured it out a different way. I meant the JY one that's sitting on my garage floor, not the one in the car. I marked the ring gear and input, twisted the input until I got one revolution on the ring gear. It took just over 4-1/2 turns of the input shaft, so my money's on a 4.6.

This is the one I'm talking about:

http://i215.photobuc...0k/DSCF1228.jpg

It's got the junkyard markings on it, the pumpkin in the car has never been out so that should be a 4.6 as well. I tried to find any info on the case markings (ND496) and found nothing, the markings on the ring gear were equally useless (S378 AL821).

Thanks.

Edited June 2, 2010 by wofat

[beastpath]

it should also have a marking on the ring somewhere - i think on the outside circumference.

[wofat]

I revisited this last weekend after I heard and felt a light *thunk* in the rear end. The diff felt like it was dragging, grinding and had an elliptical wobble so I swapped out the other pumpkin. The drain pan and plug had a whole bunch more shavings and shards but I didn't see anything overtly blown apart on the old pumpkin, maybe the input bearing?

I compared old vs. new while they were both out, the old one turned much harder and had a lot more play back and forth when I turned them by hand. Anyway, newer one is in and the car feels much better. I drove into work (Seattle) all last week, much better mileage than was usual. Thanks for all the advice/info.

[OldSlowReliable]

Lol, bummer, I was gonna offer to buy the 4.6 new diff

 

How much did you pay for it if you don't mind me asking (j/y price of pumpkin and/or price of axle)

)

[wofat]

Full axle, rotor to rotor was $250. Kind of a screaming deal for Me since I got a disc conversion in the mix.

[tmoore4512]

When I changed my diff fluid, I think my magnet had more crude on it than yours. It's just something that happens with differentials and limited slips, that's why the stock plug is a magnet to catch it all. Grinding noises should not be occurring though.

 

As for the original drum brakes and now discs, XE models came standard with drums, and SE's came standard with disc. If they work, keep them! Disc are so much easier to deal with than drums.

 

I have an SE, has almost all the options with the exception of the adjustable suspension...and I think they may have been removed by the PO. My point is it has DRUMS...

 

Full axle, rotor to rotor was $250. Kind of a screaming deal for Me since I got a disc conversion in the mix.

 

On this same topic, I have found a lone pathy in a JY, that has a rear disc diff...in my past experience doing disc swaps, I have always had to modify the master cylinder portion of the system...to handle the rear discs. Does that not apply to the pathfinder?

 

Also I assume as long as the spline count is the same, third members should interchange...(this one is LSD)

[TrailChaser]

I think disc brakes were only standard equipment on the LE version. However they can be found on some SE's due to it being an option for the original owner. Maybe even the XE, but I've never seen one with disc in the rear.

 

The metal bits and shaving are pretty common in all rear diffs. There's lots of metal on metal action in there. You should see the plug from a diff with a mechanical locker.

[tmoore4512]

So nothing different to add disc to the rear of a drum truck?

[wofat]

 

Also I assume as long as the spline count is the same, third members should interchange...(this one is LSD)

 

The '87, 88 and 89 were all different, different bolt patterns on the pumpkin. What year is the one you're looking at? You might have to swap the whole axle and do some modifications, at least to the brake lines.

I put in a new stock master cylinder, haven't noticed any problems with it.