I have a 98 3/4 Ton 4x4. It only has 67 original. As far as I can tell, it has never been used for hauling. The original owner was an elderly man who passed away so I don't know any of the history of the truck. It was immaculate as the miles would suggest but the reality is that this beast has been a money pit for me, first the torque convertor, then the tranny and now the rear end. When the truck is under load and I turn the corner, I can feel some grinding in the rear end. Any ideas? Also is this something an average skilled mechanic can do? I have done plenty of engine work but never drive line work. Thank you.

 

Do you have a limited slip diff? You'll have to crawl under and find a label or tag.

 

If it sounds bad, have someone watch you on a dry parking lot, turn in the tightest circle you can.

If they hear clunking, or tires dont go around fluidly, chances are your ring and pinion was not shimmed correctly.

I had that on an chevy of mine, opened the pumpkin and one side had 1/8" gap on one side.

Not even sure how ours are shimmed , havent had mine open.

 

Take a look at the sticker under your hood and see if you have a factory limited slip. If you do your rear diff might not have enough additive in it. Get some limited slip additive if you have it and add it to it, as well as check the fluid level. Do some figure 8's after adding a little at a time until the chatter stops.

 

As others have siad, if its a limited slip, and it bothers you, add Friction Modifier. If you don't mind it a lot, leave it, the less Friction modifier you use, the more grip the clutches in the LSD have...i.e. better traction.

If I were you, I'd pull the diff cover, and check what's in there. From the sounds of it you may have a locker in the rear end, Lunchbox or Detroit, they all make some odd noises. If you end up pulling it, check to see if the oil looks metallic, throw a magnet in it and check for chunks. Then replace the oil with some 80W140, it'll keep your noise down a lot.

 

I second the friction modifier. Thats cured my hopping in tight turns. Ive seen a few of these rear ends go bad on friends' trucks. You can often times find a good used axle from a wreck and use that instead of a rebuild. Keep an eye on that magnet, it will give you an indication of if theres damage still occuring in there once you change the oil.
The transmission and front end are known money pits. Best to spend the big bucks up front and get good aftermarket parts for it. Youve got mass diesel next door if you dont mind driving out to eastern MA. He'll do differentials, but any good local driveline shop can set you straight there.

 

Thanks for the advice. I have the hytech rear end cover and when I pull out the magnet there are some fine shavings on it. I guess I had better get it in before some major damage is done.

 

There will always be a little REAL fine looking metal sitting in the bottom of the rear axle.

 

I would not trust the sticker under the hood to determine if you have a LS diff or not, look at the tag on the diff itself, take the numbers and call a shop. The difference is that when Dana built the diff, the tag they put on the housing says exactly what it is. When Dodge builds the truck, they pull the complete axle from the parts bin and install it. My friend insisted (from the hood tag) that he had a LS diff, but he tag on the housing said it was a open diff. The housing tag was right. Dodge goofed up, they put in a open when the build sheet said it was a LS.

 

Good Point Baja, it never hurts to be exactly sure of what you have.