Can I get away with this?

I'll be pulling the carrier on Thursday to get a better look at the pinion. The driver's side wheel hub bearing unit was cooked. Metal on metal... It was dragging the tru-trac for at least 200 miles or so.

I just pulled the cover and very little metal on the magnets and virtually zero in the fluid. There was some thick gummy residue at the bottom of the case. I was running about 1/2 qt low for most of the winter. This strength of the vibration is recent in the last two months or so. I did not have any issues in the fall driving back from Indiana.

The pattern on the ring gear does appear to be shifted outboard on the drive side of the teeth. The coast side looks fine.

Is it possible that this extra bit of vibration could be from cooked gear oil in the tru-trac?

How would you go about flushing it? Several oil changes after heating up the carrier? Petroleum distillate flush, clean and refill?

If the pinion shows nothing, I'm thinking I'll flush it somehow and refill: then send it. The bearings looked fine from what I could see.

Thanks!

Here is my 2 pennies and it's worth about half a cent. You never said front or rear, but mentioned the unit bearings, so I'm guessing front. High Pinon dana 30 from the pics. I must say, the prominent side of the ring gear teeth in the pics is the coast side. the drive side is the one hardly visible.. the flatter side of the tooth is the drive side. the side with the greater angle is the coast side. I do agree the wear is outboard "on the coast side" because the ring gear is "driving" the pinion gear. from what I can tell on the drive side ( where the pinion is actually driving the ring gear) the wear looks pretty even along the length of the tooth. Since you have the drive shaft off, here are my suggestions.
1. pull the tires and check the ring gear for out of round.
2. check your back lash at 4 different points on the ring gear.
3. check the carrier bearing bolt torque.
4 check pinion preload. this will be a little tuff because al the guts are in there. Sometimes just rotating the pinion flange and feeling for unusual drag can give you some idea if the bearing are too tight.

Good luck.

warriorsuspension said:

You might find that when you fix that unit bearing all your problems go away.

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I was hoping it would. Unfortunately, it did not. I had a couple units hanging out. They say that they should get up to 75k. They're only lasting 30-35. Timkin if anyone is wondering.

warriorsuspension said:

What do you expect from a dead dinosaur anyway

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Yup. That is the essence of the whole shebang. I've been looking for the right 76-77 or 81-83 Cherokee now for about a year. A sweet one just popped up in PA, but unfortunately way to far away for me to grab.

I am at the point of wondering what am I willing to put back into it. Getting close to retirement time, and do I sink more time and effort in correcting my mistakes.

Gluckmysock said:

1. pull the tires and check the ring gear for out of round.
2. check your back lash at 4 different points on the ring gear.
3. check the carrier bearing bolt torque.
4 check pinion preload. this will be a little tuff because al the guts are in there. Sometimes just rotating the pinion flange and feeling for unusual drag can give you some idea if the bearing are too tight.

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Gluck, thanks doc!

1. known to be slightly out of round already. The vibration has strengthened in the last few weeks.
2. a pinion tooth had a small nick in it that never got repaired. It raised one tooth about ~.001" to .002". I set the backlash initially at .008" thinking it would open up over time. The backlash does need to be rechecked before leaving.
3. This is what I am praying has happened. it would be the best scenario at this point.
4. this is also next up when the blizzard stops outside. I gotta get the wheels up in the air to check the tru-trac's function as well as the bearing loads to see if the axle is worth rebuilding. So far the answer is yes, and am leaning towards my anxiety being strong. The tru-trac seemed fine a few weeks back while driving in a blizzard. The unit bearings were rough on it over the last few months. The passengher side had a broken seal and was rough to spin, and the driver's side was metal on metal bad.

I appreciate the 2 pennies and help fellas.

Thanks!

It looks like it's the pinion bearings.

The carrier cap bolts were still torqued right, and the backlash opened up to .022" whenever the pinion large tooth engaged. The tightest spot on the ring backlash was .010". The carrier never moved side to side.

After snugging up the pinion nut, I'm gonna drive it and rebuild at home. I'm just gonna have to take it slow.

The truetrac is still operating as it should. I believe that the carrier is just fine. The fix won't be as expensive as I was afraid of. New ring and pinion with new bearings.

One last request for opinions:

Would you take out or leave on the driveshaft?

I'm leaning towards leave it on: less movement of the pinion. Thoughts?

The last of the photographs. I took several from around the ring gear at several points on the coast, drive, and pinion as best I could without pulling it.

I appreciate he help boys.

I tried one last ditch effort to tighten up the pinion preload, but it didn't help at all. SO, after a looong day of tearing it apart, I just decided to pull the ring gear. There still is an issue with the RGSB not being properly worn, and still getting vibrations but not as harsh as before. I did find the remains of a shaft seal spring in the oil when breaking it down. It was about 1/3 to 1/2 of the spring. It looked chewed up.

I am experiencing added vibrations to the ride from the truetrac. I am operating on the assumption that some of the tiny, little spring is caught up in the truetrac. I am hoping it eventually chews up what is left and the severity of the vibration dissipates. I've noticed the vibration goes away when turning 5-25 degree turn to the driver's side whist driving around moderate bends in the roads.

It is drivable, and the carrier bearings looked fine and well worn in. I believe I can drive it between 55-65 MPH with little issue. The out of roundness of the carrier bearings is an issue, but not as severe as before.

I'm packing up all of the tools for the rebuild and getting it ready to roll in the morning. It is time to order the clamshell carrier bearing tool and parts.

I appreciate the help.

How are things in your neck of the woods 4.3L? It sounds like the reservoirs are all filling up and that the drought conditions have stopped. Good news, at least until the spring runoff. Has the Oroville dam spillway been fixed? could make for a rough spring up there....

How are things around Pittsburgh Doc? That chemical fire in East Palastine has me concerned for everyone in that neck of the woods....