Can tire change damage real differential?

[StealthRabbit]

Originally Posted by acespeed

Thanks guys. I just send the car to the Chevy dealer and they confirmed it is the rear differential problem. The repair bill will be $2-3K. I just do not have that much cash to repair it.

Garthur:
This is where doing your own work really pays.

Any shop will tell you that the differential is bad if they find that the lubrication is low. A home mechanic will first add lubricate and see if that corrects it, if it doesn't then further work is necessary. ...

>>>> Check level of oil in diff<<<<
1) establish a benchmark for noise and vibration (only under acceleration... on smooth road...all gears...) (Vibration is often first seen using your mirrors and seeing if headlights behind you blur when noise is prominent)
2) check for play / backlash in yoke (turn input shaft, back and forth while in neutral, wheels on ground
3) Check temp of diff (after a long hard run) with an IR gun ($30 and handy for lots of things)

if no vibration and minimal noise, consider running it for another 100k

4) Drain the diff into a magnetic catch basin
5) Observe oil for shavings and color and smell
6) Replace with a GOOD synthetic rated for your diff (Castrol, Royal Purple, Amsoil...)
7) Recheck temps, vibration, noise


Keep your eyes open for a replacement (wrecking yard)

Installing new Ring and Pinyon is not trivial and chance for doing it wrong is worth just getting a salvage replacement.
https://www.ringpinion.com/Technical...r_break-in.inc

[acespeed]

Thank you all. It is very helpful to see all the support. I am still driving it with noise. No vibration yet. Will keep an eye on the junk yard for a rear axle. There might be a problem to find one with correct gear ratio. The PRO code in the glove box showed me this code GU4, which means "GU4 : AXLE REAR, 3.08 RATIO". It seems to me that other GM SUV and trucks are using higher gear ratios. Am I right?

[StealthRabbit]

3.08 is pretty common in light service SUV / trucks

[NY_refugee87]

Fair warning.

If you go the junk yard swap route, you'd better be getting it from a reputable salvage yard...

I've had many customers who decided to go that route and get rear diffs in worse shape than what they started out with all in the name of saving a buck... Typically dismantlers are hacks that have been fired from every independent and dealer due to butchering. I've seen vent hoses cut off allowing water to fill the diff that's been sitting for months/year(s) ruining the bearings.

And the junk yard not want anything to do with replacing another assembly due to shady "guarantees/warranty" policies...

Personally, I'd suggest having the rear diff overhauled by the dealer...
1. If you're rear diff is howling because of bearings due to say leaky seals or water intrusion, and there isn't excessive ring and pinion run out and back lash due to wear, I'd just throw new bearings and races in.
2. Complete overhaul all new bearings seals ring/pinion dealer warranties the work for a year sometimes longer depending...
I'd only go that route if I planned on keeping the truck though...

[StealthRabbit]

simple solution for wrecking yard... use one of the newer / indoor parts storage / bar-coded operations with guarantees.

most of the sketchy yards have been bought out by the chain stores.

No problem if you want the 'dealer to do it'.. #1, they will replace the assembly (for a price), cuz certainly NO ONE working standard shop rate in dealer will know how, nor can afford the hours to set up your specs correctly. A DEALER will certainly not be willing to stand behind a mechanical task like that. Dealers use 'modular' factory replacements, whether it is engines or ECU's they are NOT gonna dink with something technical with specs and micrometers and indicators and remove and replace shims till you get the preload correct. Ain't gonna happen.

[NY_refugee87]

Originally Posted by StealthRabbit

simple solution for wrecking yard... use one of the newer / indoor parts storage / bar-coded operations with guarantees.

most of the sketchy yards have been bought out by the chain stores.

No problem if you want the 'dealer to do it'.. #1, they will replace the assembly (for a price), cuz certainly NO ONE working standard shop rate in dealer will know how, nor can afford the hours to set up your specs correctly. A DEALER will certainly not be willing to stand behind a mechanical task like that. Dealers use 'modular' factory replacements, whether it is engines or ECU's they are NOT gonna dink with something technical with specs and micrometers and indicators and remove and replace shims till you get the preload correct. Ain't gonna happen.

Really? I overhaul them in the dealer... Use a dial indicator, caliper, micrometer, seal drivers, all supplied by the dealer (if they aren't and the dealer were to be audited by the manufacturers they'd have to get those tools ASAP)

Shims, clutches, bearings, races, crush collar (most newer ones are crush collar not shimmed) and all. Takes 3-5 hours start to finish on a standard solid rear axle, independent rear suspension varies due to how the diff assembly is mounted to the vehicle. Only time I've ever replaced a whole assembly was when either the shock mount was busted off due to hitting something tearing the axle tube or if the tube was bent from a side impact. From an 8.8 mustang/F150 to a Dana/Sterling full float 10.5 to the 9inch on steroids F250-F550. Some new mustangs with IRS have a wicked vibration due to a warped ring gear. Can set a dial indicator up and spin the pinion by hand and see excessive runout. Acts just like an out of balance driveshaft.

If a dealer had only access to modular replacement warranty expenses would sink the manufacturer...
Pinion seal leaking, yeah just replace the entire assembly window motor burned up, replace the whole door, trans shudder/slip replace the whole transmission, ac is weak replace the lines evaporator condenser compressor for a leaky o ring

Guess you'd really flip over replacing a piston and ring set for piston slap instead of replacing the engine, finding that by measuring the cylinder and piston diameter, run a hone to clean that bore up file the new rings for proper end gap press the new wrist pin with the piston to the connecting rod and gasp reuse the same rod bearing... Replaced rods that bent in 4.6-6.8 from leaky fuel injectors that hydro locked the engine. Or if an electrical concern was present to overlay a circuit or repair a ground or chafed wire instead of replacing a $1200 module... Only time modules have ever been needed to be replaced was due to water intrusion from a leaky windshield (GEM/Fuse panel/BCM), someone pressure washed their engine bay in the winter, and water got into the fuse panel and froze inside the fuse box causing the bus bar to snap cutting power off to the interior fuse panel and PCM, a burned bulb not replaced ASAP burning the driver circuit out of the BCM, or a kid who went mud bogging ruining a TCM. Rarely do we replace entire harnesses be it CP or warranfree.

Only time I've replaced engine assemblies were when a 6.4 went Fukushima/Chernobyl and melted pistons leaving just a rod and wrist pin and the bore not salvageable pan filled with debris oil galleries filled with debris, and heads were damaged, or a rod made an exit during a run away event, or when the 6.7 ate glow plug tips wrecking pistons cylinder walls valves and heads. Be very costly if ford had to replace an entire engine assembly for a bad head gasket/EGR-oil cooler failure in the 6.0 or an entire engine for a 4.6/5.4 HLA failure/top end knock... Or tearing a torqshift transmission completely down to replace a leaky/torn reverse piston instead of replacing with a reman unit.

Only assembly that's replaced is the PTU in their AWD car/SUV lineup. It isn't serviceable.

By the way the dealer does stand by the work. If they didn't they run the risk of getting their franchise pulled.
Not all of us techs are from puppy mills like UTI.

Some of us actually know how to fix stuff.

[acespeed]

Thanks guys. Do you guys know which model of GM truck uses 3.08 gear ratio? I had a hard time to figure out which model should I look for. Thanks a lot