Question about my rear end. ;-) Mechanical question.

bambihunter

Not what you are thinking.

I have a 1998 K1500 4wd Chevy Z-71 truck with the G80 limited slip 3:73 rear end. I've had the rear differential fixed a few times replacing the ring and pinion gear replaced twice. Lately it has been making a different noise. Not like the gear whine, but when turning and big bumps. I put it up on my jack stands to check a few things out. It seems the noise I am hearing is side to side play in the axles. It makes the same sound when I push from either side. Makes me think it is just the axle bearings.

But, this part really confused me. When I spin the wheels by hand while it is supported with tires off the ground, they spin and spin. They do not rotate the drive shaft so they never hit the park pin. Is this because of the axles not having a pre-load on them? Or, is that a sign of something else?

The shop that I have had to the rear diff has been in business for 30 years and that's all they do, rear ends and CV's on FWD vehicles. A place doesn't stay in business that long if they don't know what they are doing. The owner and his son are the ones that do the work.

Could it be something about this rear housing that makes it keep doing weird stuff? Out of tolerance, bent, etc?

Thanks in advance

Also, if anyone is still reading, this is a minor issue but one I can't figure out and I am electrically inclined. About 3 months back, I moved my truck out of the shop to get the mower out. I mowed, put it back, and when I went to pull the truck in, the battery was dead. Stone dead. Not even a faint glow on interior lights. I charged it over night and it fired up the next day and has worked fine since. Except, when that happened, my interior dome lights don't work automatically (but will if you manually turn them on). At the same time, my remote transmitter to lock/unlock quit working. And, the drivers lock/unlock switch will do both doors, but the passenger will only do the passenger door. I have checked all the fuses and relays I can find. I did the transmitter reprogram procedure multiple times without success. I am wondering if the BCM has flipped out on me. Any other out of the way places there might be another fuse besides drivers side door area, and drivers side engine bay?

bustedknee

My wife would tell you your truck is haunted.

I lean more towards a mouse/chipmunk chewing on some wires - something shorted - intermittent.

A service manager at a dealership told me recently they are having terrible problems with mice chewing the insulation off wires. Apparently they used soy, or something similar in the insulation....

jimdeere

Another vote for mice damage. 

Nanuq907

I was going to say...

But reading how you know about jack stands and lug wrenches maybe I'll shut my yap.   

Check the connections on your ECUs (computers, that's what they call them on Land Rovers).  The computers need "clean" power to function and corrosion in the plugin contacts will make "noisy" power, and make them do weird stuff.  They need good grounds too.  Does your automatic dome light just blink on/blink off, or does it ramp up and ramp down?  Likely it's computer controlled.
I chased weird electrical issues for 3 years with my Land Rover until I pulled apart the fuse block beneath the bonnet where the heavy leads come in to the 100A fuses, cleaned the metal with a pencil eraser, smeared some Vaseline for protection, and reassembled.  Under the bonnet they were experiencing heat cycles, and water spray from the front tires.  Since then no trouble.

Now about your rear end (cough).  If it's got a LSD and the wheels will spin my guess is you have a broken half shaft (again a Land Rover term, I don't know what GM calls them).

toad67

Maybe Kasey can come over and look at it....

dunbarboyz

YouTube! Understanding limited  slip differential. Would like to here the noise.

chiefr

Have rebuilt enough of them to know you have a problem and the only way to tell what's wrong is to do a teardown. Pinon wear and not engaging the ring precisely or bearing wear. Timing the ring and pinion to mate perfectly must be precise, if offset in any way, both gears will wear and wear out quickly.
If you had it done twice by the same shop it sounds to me like they failed to setting the backlash, and bearing preload etc. I would not be taking it back to them unless they guarantee their work.   

Correctly set up ring and pinion should outlast the truck provided your are not drag racing or heavy towing.

 On some axles, you can stack a flexible borescope thru either the fill or drain plug to inspect the ring gear.   

TRAP55

chiefr beat me to it. That Gov Lock differential was a good idea from GM,...for daily driving. If you had to have the R&P replaced twice, it wasn't set up right, or something is out of spec from the factory. Either way, who ever did the work, isn't as good as you think they are.

88-98 K1500 rear axles had all kinds of problems. OEM axle bearings/seals was one, the other was the spider gear shaft bolt. It was either over torqued to the point the head of the bolt was almost completely broken off, not torqued at all, or not torqued and no LocTite on the threads. One of two things would happen, either the head of the bolt just fell off, and went through the differential, or the bolt fell out allowing the shaft to slide out.

That's what mine did, just as they backed it onto the lift. There nothing left to salvage inside that axle housing. Thank God it didn't let go on me driving 65 on the freeway! The pieces hang on the wall of shame at West Coast Differential. I was going to have a Detroit Locker installed, but they were out of stock for my truck. I went with an Auburn Posi, and glad I did. More streetable than the GM unit, and locks up tight when you need it.  That was 80,000 trouble free miles ago, and it's still working like it's supposed to.

bambihunter

Thanks guys for all your input.

I'll see if I can answer all the questions.

Nanuq907. My truck is old enough that the lights just has on and off. No delay, no fade up or down. I am puzzled by what it was that caused that initial electrical event. I have had squirrels get into my truck a couple of time back 5-6 years ago when it was usually parked outside. But, I've replaced all that. These trucks have two battery trays for the versions that have diesel engines. Mine is gas so just has one battery. They loved to build a nest on that other tray. They've chewed the wires to that headlight, blinker, and windshield washer pump. I've fixed all that. I've not found anything any further damage then or now.

Chief and Trap:

My truck has the 350 / 5.7 engine, and we used to have a lightweight 24' tongue pull camper that I'd pull, or my 18' boat. Not even close to the GVWR. It is now getting up there in miles, I am at 230k, but the body and frame are in great shape. The motor is still running just fine. Every time I start looking at another truck, I come to the realization that I won't get something I like any better until I get up to the 30k mark. It's odd to me to even consider buying a truck with the same miles as mine, that might cost over $20k just because it is newer.

The rear diff issues started maybe 6-7 years ago. It started with a major leak on the front seal. They put a new piece in there. I later looked at it and realized they replaced the input shaft part instead of just the gasket. Why? Because they didn't have a gasket tool. I wasn't going there again. Especially because I could have bought a decent tool for the difference. I've got a lot of back issues so even though I have a good base knowledge of how a lot of these things work, what I did know/do was 20 years ago.

Then, several years ago it started whining on the way home. Just as I pulled in the driveway, it clunked and locked up on me, blocking my narrow driveway. That is when they did a complete rear and put in a new carrier. I don't have the receipt in front of me, but I think it was a different carrier than the factory GM "clunk" lockup design. I believe it is more of the spring pressure plate idea.

Could it be something in the housing is out of tolerance after seizing up? I mean, it was on gravel, and probably only 10mph. I wonder this because years ago, I had a 700r4 transmission that would work for a while after a rebuild, then it'd lose over drive. This went on for a couple years, we tried all kinds of transmission shops. Finally met a guy that ask if we had ever tried a different core. So, he put the guts from mine into a different chassis. I drove it for another 100k miles and some of that was a little light to light racing so not near as good as I have been with this vehicle.

The best way I can describe the sound it makes is if you have any lawn equipment. You push it side to side above the axle. You'll hear it hit the hubs on each side. The tone is different on smaller wheels, but it sounds like that.

Just to clarify, the complete 'free wheeling' I noticed is NOT normal correct? I can't say I've ever tested that before, but it sure seems to me something isn't right for there to be enough tolerance for it to spin freely while the vehicle is in park and on jack stands.

cbxjeff

Darn Bambihunter, I didn't see who posted this before I started to read.  I was hoping it was from remotegirl.