Rear End Locked Up

[USAFLong]

Was driving home from work and slowing down for a red light when the rear end locked up. Truck would roll backwards but not forwards. Tried to drive it forward because a cop told me to clear the intersection and it snapped off the driveshaft at the rear end after the u-joint. Finally got it towed. The guy said he will do the labor for $200 to swap a good rear end under it. The closest rear end I can find is in Kentucky with no price listed.

What year rear ends work for this truck? I would prefer to just swap a good used one in from drum to drum since it would probably cost more to rebuild mine than I can find a used one for.

This is how I feel right now

[wideblock]

why swap the whole rear end??? id be willing to bet the problem is in the third member. you can go to the salvage yard and swipe a 3rd member from almost any dodge/chrysler/plymouth with an 8.75" rear and put it in your truck useing your housing and axles. vans, trucks, mid size cars and the full size cars from the 60's and 70's will supply what you need. just check the gear ratio, dont want to wind up with a big long legged 2.76 gear like i did.

one other thing, some of the car rear ends have a smaller u-joint, but napa and o-riely sell a hybrid joint that has the big size and the little size in the same joint to make the swap easy.

[USAFLong]

It will roll backwards, but when pulling it forward with a winch the right tire locks and drags and makes the truck hop.

When it locked up on me I thought it was the trans, like it went into park or something because it locked up and hopped really rough till it skidded to a stop.

[BigBlockDodge]

I would highly doubt that the problem would be anything other than something that gave way in the center of the rear. But like wideblock said, replacing the center "chunk" would be the easiest way to go. Basically, the axles unbolt from the outside (5 bolts per side behind the drums), and then the center can be unbolted (once the drive shaft is off), and it will come right on out of there in one piece! And those things are pretty heavy!! So if you found a good complete used 8.75 chunk you could put it back in there and go! And now would also be a great time to possibly swap gear ratios if you werent happy with your old one.

[Nuthinbutmopar]

I concur with everyone else about the problem being in the carrier. With the driveshaft broken and out of the way, you can have the carrier sitting on the ground in about 15 minutes if you have a good impact wrench.

I went to www.car-part.com, put in the vitals on the truck and searched for carrier in Ohio and came up with 5, though no prices listed. I've got a 3.55 sure-grip sitting in the garage, but I'm about a 4 hour drive north of you...

[USAFLong]

Well if i can replace the internals and re-use my axles, that might not be too bad. How much would you want for the 3.55 suregrip setup? I don't know what ratio I had, but I can go over to where my truck is and look this weekend. I am from MI originally. Might be able to run up and get it from you.

[wideblock]

wen you get the old one out the ratio should be stamped in the ring gear. or if the rear is original to the truck it will be on the data plate. a 3rd member is usually not more then a couple hundred unless its a posi with a desirable gear ratio. the 3.55 would be a great one. id run 3.55 or 3.23 if you could.

[USAFLong]

My truck turned 2600 rpm at 70 mph. Not sure what that ratio would be.

[BigBlockDodge]

My truck turned 2600 rpm at 70 mph. Not sure what that ratio would be.

Sounds like 3.23's to me. I have 3.55's with 31inch tall tires and I turn 2650 at 65mph. This is assuming that you have smaller tires than I have. If not smaller by much, then you probably have 3.55's. But this is just a guess. Like wideblock said, the best thing to do is check your old ring gear to see what ratio it is. Sometimes there is a tag on the rear that is held on by one of the bolts that holds the chunk in. This tag will tell you the ratio also. but the only way to know for sure what ratio it is, is to check the ring gear.

[wideblock]

my money is on a 323. my 355's were doing 3000rpm at 70 with tall tires.

[Nuthinbutmopar]

Checked my spare out, it's a 741 case 3.55 sure-grip. It came out of one of my dad's derby cars 20 years ago, and one ear is broken off of the yoke I'd have to have $250 for it. If you go onto MOPARTS, in the differentials for sale there is a 3.23 open in Ohio for $125 that might get you back on the road sooner and cheaper.

[mopardwh]

Did you get yours out yet? Haven't had time for mine.

[USAFLong]

Not yet, my truck is at a shop in the ghetto lockup up behind a fence.

I had 275/50/15's on the rear, so I think they are not 31" tall. Maybe I did have 3.55's.

I'll look at the moparts site and see. 3.23's would give me a little lower cruising RPM on the highway which couldn't hurt.

[elacruze]

I don't think you have an axle/differential problem, it sounds like your brake shoe has come loose and jammed up in the drum. Before tearing everything out and spending, have a look inside the brakes.

[USAFLong]

hmm.... well now that the driveshaft has snapped off.... need to replace the rear pinion gear or whatever connects to the rear end. The driveshaft still has the rear u-joint on it and then it's broken off at the yoke.

[mopardwh]

I don't think you have an axle/differential problem, it sounds like your brake shoe has come loose and jammed up in the drum. Before tearing everything out and spending, have a look inside the brakes.

That's true. I've heard othe members with the same complaint. Mine is without a doubt the diff though. Won't turn with the drums off.

[elacruze]

Ouch.

[USAFLong]

Hoping to get my truck back tonight or tomorrow.

The rear end I got from Backwoods had the bolts and seal on the front side of the rear near the yoke/flange. I could have sworn my old rear end had the removable back plate like most truck rear ends I've seen. Could it be that I got a smaller /6 rear end instead of the 8 3/4" rear end? Or did all D100's have the 8 3/4" rear?

My truck is a 1970 and the rear end I bought came from a 1967. Maybe they just changed the housing design?

[elacruze]

Sounds like you may have had a Dana 60 and got back a 8-3/4.

http://www.moparmailinglist.com/photo.p ... =15&page=1

If you're not putting huge slicks, pulling a huge load, or keeping a numbers-matching correct vehicle, it doesn't really matter.

[USAFLong]

Could have been. Truck used to pull a 5th wheel trailer as a farm truck (possible a big horse trailer).

I just got a call from the guy doing the work, he said they got the rear end in, but now the trans slips in 2nd and whines. God damn it.