nothingbetter

Time for a story.

I recently installed a new rear end in my truck. I bought the Front Range Off Road full float chunks, cromoly axles, an 85 housing, rotors and loaded ifs calipers, all used, from a guy for $800. I cleaned everything up, welded on my spring perches, painted it so it was pretty, and installed it. Brakes work perfectly, but I can't say the same for the axle.

Trouble shooting says I warped the housing while welding it. Oops. The internet says I'm not the first one to do that with these toy housings. I have access to a frame machine in the body shop I work at, so I "un-warped" the housing with some chains and a few tonnes of pressure. The axles sit centered in the spindles now instead of rubbing the bottom edge as they did before my un-warping.

Now my current issue only occurs at highway speeds. I'll be cruising along just fine, Then it goes clunk and we're back to normal again. Occasionally I get a bad growling from the rear end. If I engine brake it goes clunk and then everythings back to normal. And twice now it just loses power all together. I coast to a stop, Put the transmission in first, I can watch the drive shaft spin but the truck doesn't move. Its as if one of the hubs has been unlocked. Take them apart on the side of the road, everything looks fine, nothing out of the ordinary, no metal shavings. no wear marks. Put it back together, drives off like nothing ever happened.

I can make it not happen if every 30 seconds or so take my foot off the throttle just long enough for it to start engine braking then back on the throttle again. It also doesn't happen with my diff locked. Or with diff locked and one axle unlocked, either side.

I have had no issues with my rear end untill I swapped in this axle. I just unbolted the 3rd from my old 86 housing and put it in my 85 housing with the full float chunks on it. There are no signs of wear on the axles. All the splines look perfect. I've changed the diff fluid a few times to be sure all the nasties are flushed out.

I'm going to re check that the axles are centered, order some drive flanges, and wait for my arb bits to come in so it will stop leaking.

Any ideas?

nothingbetter

anyone?

RJR

So do I understand correctly that you now have locking manual hubs on your rear axle, similar to what many folks have on the front? If so, it sounds like the locking collar is sliding out of lock under continuous torque, and then when you release the torque (engine braking) the spring pushes it back into lock again. The growling is probably when it has slipped out of lock and the teeth are chattering against each other.

If those are new locking hubs, I'd contact the manufacturer. If they are used, the teeth are probably worn such that torque causes an axial movement driving the collar out of lock. It may be as simple as swapping the hubs from one side to the other, since then the torque (going forward) will be in the opposite direction and tend to keep them locked.(maybe). The problem would occur in reverse, then, but you probably don't drive long distances down the highway in reverse.

Drive flanges will probably cure it, since they can't come out of lock unless the bolts come out and they fall off.

nothingbetter

You are understanding it correctly Ron. And you are correct.

My drive flanges were ordered a few days ago. Its disconnected today and wouldn't re-connect, so I locked the rear diff, drive home in 1wd, pulled the hub apart and found that the lock ring had slid out. Why it doesn't re-engage sometimes...I'm not sure, Its probally getting wedged. I have to drive 2.5 hours each way this weekend so I'll find time to swap my front hubs onto the back and see if that works.