Grenaded front diff! Now what?

[Cruiserdrew]

Is there oil in the diff?

Is the drive shaft correctly phased?

Wheelbearings?

Seriously could be anything. Have your mechanic look at it asap.

 

[Desert100]

I have this part, if that would help...

I sourced it here, described as:

"This is a 4 pinion front carrier out of an 07 100 series. It was replaced with an ARB so there was nothing wrong with it and it has been stored well."

I was assured it would replace the 2 pinion front carrier in my 98 LC (I eventually went with a new front ARB and compressor instead).

I'd be happy to sell it for the same $100 +$25 shipping I paid for it.

 

[bhicks]

Is there oil in the diff?

Is the drive shaft correctly phased?

Wheelbearings?

Seriously could be anything. Have your mechanic look at it asap.

I will take it in tomorrow. that is the earliest I can get it in. Could you explain what you mean by "drive shaft correctly phased"? Never heard that phrase before.In regards to your questions. Oil is in the diff. All bearings were replaced during the rebuild. I installed new CV boots since mine looked worn and I was already in there so labor was next to nothing to reboot all 4 spots. I see zero leaks visually. No noise of any kind on acceleration or even braking. The noise seems to only occur during coasting and is worse when coasting down hill.

 

[bhicks]

I have this part, if that would help...

I sourced it here, described as:

"This is a 4 pinion front carrier out of an 07 100 series. It was replaced with an ARB so there was nothing wrong with it and it has been stored well."

I was assured it would replace the 2 pinion front carrier in my 98 LC (I eventually went with a new front ARB and compressor instead).

I'd be happy to sell it for the same $100 +$25 shipping I paid for it.

thanks for the offer, but my front diff has already been replaced. Now I have to deal with the whining/humming noise.

 

[Skidoo]

Could be the gears are not meshed correctly. 100 diffs can be tricky. CV may not be seated in diff.

 

[bhicks]

Could be the gears are not meshed correctly. 100 diffs can be tricky. CV may not be seated in diff.

Well I will have to tear it all apart tomorrow and get it figured out. I will let you guys know what we find. Hopefully something minor and easily fixed.

 

[46/71 Hybrid]

I'm guessing either the pinion bearing pre-load or too much backlash. Did the shop take a photo of the pattern before they put it all together?

 

[bhicks]

I'm guessing either the pinion bearing pre-load or too much backlash. Did the shop take a photo of the pattern before they put it all together?

I have no idea what they did. I didn't really question anything they did since they have done gears for me in the past with zero issues. I will be talking with them and asking the questions I should have to start with. They open in 45 minutes.

 

[2001LC]

I thought my updates/questions were over but unfortunately the story continues. I picked up the 100 about an hour ago. Mechanic said he drove it around and everything sounded perfect. I paid for the work and started the drive home. Everything sounded quiet and worked normal. I started the long drive up into the mtns. where I live. Most of the driving is up hill so I was on the accelerator most of the time. There is one section that is down hill and my problem began. As soon as I took my foot off the gas as I began the down hill part I got a weird humming sound. Sounded like a mixture off really knobby offrorad tires and an exhaust brake from a desiel. If I stepped on the gas the sound immediately went away. I continued to drive up the hill then decided to head back down and the sound remained. The faster I was going the louder it was. At 65mph down hill coasting with zero acceleration, it sounded horrible. At 25-35mph coasting to a red light it's barely noticeable. So what did the mechanic do wrong? I'm assuming something has been tightened down too tight. Maybe the torque on the main bearing that is up against the 3rd member where the driveshaft enters? I will definitely have to take it back but the shop closed early today due to the holiday. It will have to wait until tomorrow. I had confidence in this shop because they did the gears on my TJ and XJ a few years ago with zero issues. The TJ with 4.88s has almost 100k on the gears they installed.

Could this be issue:

For a cheap fix you can get any take out 4.10 gears from an 80 series. You just have to be aware setting up used gears could lead to gear whine. I would still prefer Toyota oe gears over aftermarket.

 

[bhicks]

Could this be issue:

I didn't end up going with used gears. These are new in box Nitro 4.10 ring and pinion from JustDifferentials. Also used the OE rebuild kit. They come from the same plant that the OE gears are cut. From all of my research there is no difference between the two other than cost. If I am wrong then someone please step in and correct me. I am basing my info off old threads I came across. I read a bunch of old threads on Nitro gears but it seems like everyone has been happy with them and couldn't fine someone with Nitro gears and the bad whinning noise. Maybe I should have researched a little longer.

 

[bhicks]

Time for the final update. She is back on the road and running nice and quiet. After tearing things apart and opening up the diff we found nothing wrong. The gear pattern that had worn onto the new gears was absolutely perfect. We put it all back together and the noise persisted. We then focused on the axle shafts and new boots but everything was perfect there. Finally we focused on the drive shaft and sure enough we found the issue. It had zero slip movement in it. There was zero grease in the shaft and it was binding up since it was fully out. The binding would occur on deceleration creating that humming/whining noise. We replaced the u-joints and greased everything really well. Everything is back together and nice and quiet. Lesson here is to make sure your u-joints and driveshafts are well lubricated.

 

[PabloCruise]

Time for the final update. She is back on the road and running nice and quiet. After tearing things apart and opening up the diff we found nothing wrong. The gear pattern that had worn onto the new gears was absolutely perfect. We put it all back together and the noise persisted. We then focused on the axle shafts and new boots but everything was perfect there. Finally we focused on the drive shaft and sure enough we found the issue. It had zero slip movement in it. There was zero grease in the shaft and it was binding up since it was fully out. The binding would occur on deceleration creating that humming/whining noise. We replaced the u-joints and greased everything really well. Everything is back together and nice and quiet. Lesson here is to make sure your u-joints and driveshafts are well lubricated.

Wow, that is a great lesson there! It takes a definite skill set to set up gears, that is for sure.
Amazing how basic things, like regular maintenance can impact things!
Thanks for closing the story!