Sorry to hear.

You can try the Haynes manual and see if it's descriptive enough. I have the shop manual, but unless you find one cheaper on Ebay, it's over $100.

You have to support the engine and get the oil pan off to replace the diff. A lot like top end work. Nothing I'd want to do myself outside a nicely heated garage.

Depends on if it's your only vehicle, and how much downtime you can tolerate. A junkyard diff with the right gears can cost $500. And you have a few other bad parts as well.

 

Thanks Bill.

I'll check out the Haynes manual. Do you know if the public library system has shop manuals?

I agree a heated garage would be nice. Not the most enjoyable thing to do outside right now but I've done it before.

I was able to borrow my grandfather's truck, so I do have some time. Hate spending Christmas doing it though. Better than taking off work though I guess.

Is there any way to get a warm fuzzy feeling about a junkyard diff?

Thanks!

 

Pop off the fill plug, take a look inside at the oil level, oil color and quality, and take a look at the gears as best you can.

 

Since he posted: The casing around the axle near the differential was blown apart and it smashed the power steering lines., something tells me there will be little oil to examine. And perhaps few gear fragments. Here's what I found inside my rear diff after I blew my G80 up.

 

You can find used front differentials on eBay and at salvage yards for under $500, its the labor that's going to kill you. (If you need a CV shaft, they're under $70 for a new one). The cost of the diff depends on the gearing, 3.42 gears are easy to come by, 3.73 and 4.10 less so.....actually the 4.10 unit is out right difficult to find and more expensive.

What I haven't figured out is why you need to pull the pan off the engine to replace the front diff? - Yes, I know it bolts to the pan, but why isn't it possible to simply unbolt the diff and slide it out the back side using the space occupied by the removed half shaft to maneuver it out. I've done the fluid change, yes its tight, but it would appear that if the half shaft wasn't in the way, there's a good chance it could be removed raising and supporting the engine with pan removal. Has anybody tried it w/o removing the pan?

 

When I get around to putting my front gears in, I plan to try just lifting the driver's side of the motor. Seems like it should slide out the back... or maybe even twist and come out the driver's side wheel well...

 

Thanks guys.

"ylab" mentioned how hard it was to find some of the diffs with odd gear ratios. As I mentioned before, I am a newby on 4WD and suspension. If I don't find the exact model/year/style of TB is there a way to determine the gear ratio from the outside?

Thanks,
Rick

 

Look in the glovebox at the codes. GU6 = 3.42, GT4 = 3.73, GT5 = 4.10. Look at yours, then go find one with the same code.

 

Don't use this as a how to, but it'll give you an idea of the front diff. Just don't separate the body from the chassis, you're only doing a diff, not an engine swap lol

http://www.youtube.com/watch?v=YSukLMLZy48

 

Thank you ! Thank you !

You guys are all unbelievably helpful. This info makes me feel like I can take this job on if I can find a garage to use. Gotta get to work on that.

I'll try to take good pictures and write this up for future generations.

Thanks so much guys.

Merry Christmas!

PS - "wardak33" I'll try not to take the body off too. But it'll be tough. That looks like fun.

 

I am right near you. There is a rebuilt front diff on CL for 400 I believe right now. Let me know when and where you are working on it and I can try and help.

 

Ok....so just reading this thread and I believe I have the same problem.

Driving the Envoy on the weekend in crappy weather, threw it into 4HI. Suddenly the most awful noise, and now all 4WD is crunching and grinding. We have been driving the truck since the weekend in 2WD, but there is an awful whining noise during deceleration. Seems to be getting worse.

Took it into the shop, and they advised front diff is screwed. It was bone dry of fluid, and whatever fluid they could find was the nastiest sludge that stunk horribly.

They wanna charge me $1800 to install a used/rebuilt diff. I think we can do it ourselves. We have access to a heated garage with a hoist.

Question is.....where the hell to find a used/rebuilt diff in Ontario.

HELP!

 

Ebay or car-parts.com. Somebody's gotta ship to Canada or be there already.

Sorry to hear yours was dry. How many miles total, and how many since the level was last checked? Always curious if they dribble out quickly or slowly once they get older.

 

Well, there's about 148,000km on it. Bought it used 2 years ago with about 115,000 on it. Have never checked the fluid (first mistake, I know)....but on our last oil change, we noticed some serious oil/fluid leakage evidence. Figured it was engine oil. Now I'm assuming is was diff fluid.

 

I'm sure you'll have new-found enthusiasm for maintenance now, but let me save a bit of time and recommend also changing the transfer case fluid (required every 50K miles) and the tranny and the rear diff.

Lots of items in the Owner's Manual for the 100K mile service at this time, and matching how-to threads here on trailvoy to assist.

 

Definitely! Thanks a billion!

Still can't seem to find a front diff assembly though. I tried ebay etc. No luck.

 

Ok, so I've actually found several possible ads on Kijiji.....just want to make sure I'm looking for the correct one....

There is talk of 3:73 (should I assume this is a gear ratio?).

ie. 2000 CHEVY/GMC 1500 front differential assembly complete with solenoid, ready to install... 3.73:1 ratio

Would this work?

Also found this one.....sounds like it could be the same part...

Fits vehicles with the AWD GT4 option.
Fits from '99-'06 chev/gmc trucks and suv's.
3.73 ratio

$900 cash.

 

Hmmm. I may have answered my own question (I think).

RPO sticker says GU6. I believe that means it's a 3.42 gear ratio. Assuming I shouldn't try replacing the diff with a 3.73?

In case you're wondering, yes, I'm a woman, so gimme a break! I'm trying here....lol

 

In case you're wondering, yes, I'm a woman, ...

Not really wondering. Your member name had me convinced you were a normal guy who just neglected maintenance. Happens a lot. :tiphat

 

No, you MUST buy a front diff off a GMT360 (aka TrailBlazer, Envoy, Bravada, Rainier, 9-7X, Ascender) as we have a 1 off diff. I believe the Colorado/Canyons have a similar setup, but I wouldnt try using anything but a GMT360 diff.

Only way you could replace the front diff with 3.73s is if you want to swap the rear end gears too, with 4WD it would bind and you'd break more stuff running mismatched gears as each end of the truck would be trying to turn at different RPMs.

 

I would be down for helping out on a replacement as well. Lets just call it educational study preparing for the upcoming replacement on my wife's diff. She had the same issue and failure as yours.

For a short time solution, pull the half shafts. That way you can hopefully avoid any further damage or issues. Plus you will have a drivable 2 wheel drive truck.

 

Being that it is your front differential then you can have any gearset that is available with a little additional labor and expense. The rear differental replacement is far less involved than the front differential. It seems most ofter that people inquire about doing this is after blowing the rear and decide the front is too time consuming. Your case is much different from others.

 

Hi Guys,

I finally found a garage to work in. It's not heated, but it is certainly better than the driveway.

I have a question for you guys. There is what looks like a splash plate under the back half of the oil pan. The main part is about 3 feet wide and 2 smaller plates are mounted over the ends. These 2 smaller plates have a couple of huge bolts holding them in. Since I am laying under the truck with no hoist or anything do I need to worry about taking out those bolts? They just seem too big to be holding just those plates.

Thanks again. I've got plenty of pics to use for a write up when I get done.

Rick

 

Regulator will be around tomorrow afternoon and I can help after I get marks new prototype lift in tomorrow night. Might help to have extra eyes or hands

 

Hi Guys,

I finally found a garage to work in. It's not heated, but it is certainly better than the driveway.

I have a question for you guys. There is what looks like a splash plate under the back half of the oil pan. The main part is about 3 feet wide and 2 smaller plates are mounted over the ends. These 2 smaller plates have a couple of huge bolts holding them in. Since I am laying under the truck with no hoist or anything do I need to worry about taking out those bolts? They just seem too big to be holding just those plates.

Thanks again. I've got plenty of pics to use for a write up when I get done.

Rick

Yes Rick, I am currently doing the front diff and I went that route.(remove The oil pan) It is a huge PITA and I was using a hoist. I know what your talking about and yes those bolts need to come off. Those two plates your talking about are actaully all one cross peice that needs to come off. Its held on by those four large blots and I think 6 15m bolts. Once that peice is off there is another cross peice....that comes of as well. When those two are off it will give you a lot more room in there to pull out the steering gear assembly. The steering gear assembly looks scary but it wasn't as bad as I thought it would be. If you have any more questions Ill help you out. I'm all most all back together so I know what you are going through rick. :crazy:

 

Please Please Please take pictures and try to detail this rebuild. I have to tackle it in the spring on my wife's Bravada, and any and all info would be helpful and appreciated.

 

!

Witt's End-----><-----ME

Still working on getting the differential out!

Splinned disconnect broke off on the passenger side. Argg! See first pic. So I am trying to get the oil pan and diff. out in one piece. Spent 2 hours prying and swearing yesterday but I cannot seem to get it out.

So my question is, any idea on how to get the shaft disconnected from the diff. (see 2nd pic)? Is the end of the shaft threaded? Can I put a bolt in there to hold it while prying them apart? Any ideas would be greatly appreciated.

By the way, Happy New Year!

Thanks,
Rick

 

I haven't done this, but the end of the intermediate shaft is reported to be threaded. Metric of course. So you can use a slide hammer on it.

Other folks have reported broken disconnect housings. Was it cracked first, do you think, or did you pry on it and it broke too easily?

 

There was nothing easy about it. Used slide hammer for about 2 hours. Then had a friend help by prying as well. After another 30 minutes it finally broke. I didn't expect this kind of a workout!

Any idea how to find out what size the hole is in the end of the shaft?

Thanks,
Rick

 

The shop manual just says to use super-special-and-expensive GM slide hammer J6125-B and adapter J45104.

You can buy those sorts of things from Kent Moore company:

KMTJ-45104
http://www.handsontools.com/Kent-Moore-J-45104-Adapter-Slide-Hammer-_p_33124.html

in this case for $30, but their web site has no indication what thread is on the adapter.

Just get an assortment and try 'em.