investinwaffles

So, this just started a few days ago and I'm not sure why. I had gears installed about 8k miles ago and it's been super quiet ever since. Did a full master kit on the rear, carbon fiber FRPP LSD clutches. Haven't done any hard wheeling in the last 2 months at least.

Only does it when hot, like after a 20+ mile drive in the Florida heat, and only when turning at slow speeds.

I did the break in procedure slowly and carefully. Changed gear oil at 500 miles to 85w140 (Chevron Delo Heavy Duty), then 2000 miles later with the same, both times with the Ford friction modifier.

I only have 6k miles on the old fluid which isn't that much (especially for Delo ESI). But I did drive 2000 miles while towing ~4k lbs so it might have sheared out of grade (though Delo ESI is spec'd for semi trucks)

Anyone know what might be causing this? I am going to dump the fluid and pull the cover off tonight and take a look see, hope nothing is scored or damaged!

00t444e

You may need to add some more friction modifier, the noise is probably coming from the clutches since they are supposed to slip when you go around a turn.

investinwaffles

I actually wasn't able to make it to the Ford dealer to pick up the specific friction modifier. So I'll need to wait till tomorrow

Last time, I put 3 quarts in the diff, plus one full bottle of the friction modifier, but the gear oil didnt have any modifier on its own.
I just bought 3 quarts of Valvoline Dino 85w140 which does say it has LSD modifier in it, but I assume I'll still need more friction modifier so might as well have it on hand. I'll throw it in tomorrow and see what happens

So I think your theory might be right
​​​​

00t444e

You can get friction modifier at most auto part stores.

investinwaffles

Ok dudes, I need some advice from peeps with actual gear/differential experience.
I changed out the gear oil with zero change to the issue. Varying quantities and mixtures with/without friction modifier, definitely not lubrication related.

The noise is 100% isolated to the rear axle. I eliminated the driveshaft and rear brakes from the equation.
I now think that it is the spider gears causing the clicking noise. It clicks enough to see it in the driveshaft (you can see the shaft turning freely, and it pops forward when the click occurs).
Without removing the cover, I am pretty sure the clicks are in short enough succession that it is not a specific tooth causing the issue.

What could cause the spider gears to "loosen" up to the point where they have enough play to click like this?

And depending on that answer, should I change out the spider gears? No clue if they were changed when my diff was "rebuilt" 10k miles ago

EDIT:
I do have a Ford dealer right around the corner, and they should have the spider gear kit (which I think is THIS KIT )

The Jeep is my Daily Driver, and none of my other cars are close to in driveable shape. Do you think it is going to cause any major damage by driving it in the meantime? Only seems to do it when it's hot after driving for 30 mins or so

00t444e

Worn out clutches can cause the spider gears to be loose.

investinwaffles

I haven't really offroad that hard, but its definitely possible. I hate having people perform work on my XJ, I have no idea if he actually replaced the clutches or not. They should be in good condition if they only have 10k miles on them
I guess I need to pull the spider gears and clutches out and measure thickness.

Uugh, I guess I will try to tackle that tomorrow so I can get parts from the dealer if they are worn out. Hopefully not the case, but at the same time it's an easy fix if it turns out to be the issue

00t444e

It could also be that the clutches weren't shimmed tight enough or one of the thrust washers is missing.

investinwaffles

I think the clutch packs have a minmum and maximum thickness but I dont think he would have checked before installing. Only way to know is to pull it apart which I will do tomorrow

I also did about ~2000 miles of towing cross country with no issues. This honestly just started out of the blue one day after driving it from Tampa to Orlando and back to help my friend pick up a set of wheels (like 350 mile round trip)

tinytrax78

open cover and verify problem , im gonna say worn pin and spiders and or broken s spring

investinwaffles

I pulled the cover again and took more detailed pictures. What do you all think about these spider gears? They definitely don't look new like the ring and pinion gear, they have plenty of pitting and surface discoloration. Some gouging on the surface of the gears, but I didn't see any huge chunks missing or anything.
One of the small spider gears has about 1/8" of play up and down on the center pin, and I think that is what is causing the noise. The clutchpacks feel pretty good, they grab hard so I think he did actually change those. It doesn't look like the Ford Racing clutchpack though, he probably bought the cheapest one and pocketed the cash (I had him buy all the parts)

Should I go ahead and change the spider gears and see if there is an improvement? I checked to make sure the S spring was well centered around the center pin.

investinwaffles

Also, I made a video which came out pretty good. Its hard to hold the camera steady and rotate the tires by myself (and even harder to put some tension one one of the tires to get the clutches to grab and spin the spider gears)

Came out pretty good though

00t444e

Those spider gears look a bit rough from the pictures, changing them wouldn't be a bad idea and make sure there is thrust washers on the two spiders that the center pin runs through. Also the S spring is just there to put a pre-load on the clutch packs so they grab when less torque is being applied, it doesn't have anything to do with how tight the spider gears are, you can run it without the S spring and it would be fine, it just wouldn't have as much pre-load.

00t444e

Just watched your video, something definitely isn't right I bet if you removed the center pin those spider gears would roll right out, since they are so loose, when properly shimmed with all the thrust washers installed and a good set of spider gears it should be a bit of a fight to get the spider gears in and out. Your in luck though the Ford 8.8 is a popular axle and there are several YouTube videos on how to work on the limited slip and set the proper clutch pack thickness.

investinwaffles

Dude u da man, thanks for the sanity check. I just am not that well versed in diagnosing issues. I have actually installed clutches on an 8.8 before. Without a bench vice it was a PITA to compress the s spring.
It was a long time ago, but I wasn't really sure how much play was too much

Luckily now I do have a small bench vice, hopefully it'll get the job done. If not, off to Harbor Freight