[ScarabEpic22]

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.

 

[hardtrailz400]

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.

 

[the roadie]

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

 

[regulator1175]

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.

 

[DZP]

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.

 

[rickmmmmm]

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

 

[Kristis Dad]

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?

Pan does not need to be removed for front diff.removal. I saw a guy do it in less than 1/2 hr. iirc, remove lower motor mounts nuts, raise engine a little and also he used a small strap/come-along to slightly pull front of engine assy.towards the RF side. It would still take me 8hrs. even w/out a lift...lol.

 

[hardtrailz400]

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

 

[Iamwildman]

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:

 

[regulator1175]

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.

 

[rickmmmmm]

!

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

 

[the roadie]

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?

 

[rickmmmmm]

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 roadie]

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.

 

[rickmmmmm]

Thanks Roadie! As always you're a big help.

I'm working in a friends garage and he doesn't have tools, bolts, etc. Otherwise I would have tried that yesterday. If I can just secure it to the other side of the oil pan I'm hoping to pry it out of the differential.

I was hoping there was a better way. So many things have gone wrong on this project (broken parts, broken tools, etc.) that I wanted another opinion before doing something silly.

I'm still taking pictures for a big write up.

Thanks,
Rick

 

[Iamwildman]

For The slide Hammer I just bought a Peice of 1/4" #20 threaded rod that fit in to the end of the intermediate shaft. I just use some washers and nuts on one end and slid some large heavy duty sockets on on it. Pulled the Shaft out no problem.

 

[Coupe]

Ill definately be paying attention to this thread

My differential is stipped out as well but no outside damage.

My question is why are you removing the disconnect and oil pan if you dont have to? Some said its possible to get out without taking off the oil pan. This would be my route Im going to try. GM isnt the brightest but I cant imagine having to go to all that trouble to replace a differential that are known to eventually break or make an easy removal to change up the gears.

My best case scenerio would be to remove the drivers suspension, all the crossmembers needed, motor mount bolts, and try to get that carrier out the drivers side fender or downwards. Only thing is that shaft to the disconnect probably isnt going to allow it to drop right down after looking at that youtube vid.

Also everyone only talks about finding a used differential. Why not rebuild yourself so you KNOW its good? It cant be killer expensive I wouldnt think. If I go to all the trouble to get that thing out I want it to be good as new ready for another... uh... 70k miles lol.


I bought mine broke but after reading peoples common problems Im guessing the transfer case fluid wasnt changed and or the encoder motor wasnt working properly and caused the awd to be like welding spiders together and broke the gears. Probably turning a corner. Ive read alot of people complain about that problem with these awd ones. Also my differential drain plug was loose so who knows how much fluid is in there.

I cant believe no one has done a writeup on this R&R before with different ways of doing it, oil pan or not. Lets figure it out! I do write ups and help out people daily on other car forums from repairs to engine swaps. This site Im the one needing the help for once LOL.

 

[rickmmmmm]

First of all, super thanks to Iamwildman! I ended up prying the shaft out with a crowbar and a 1/4" #20 threaded rod. Yes, it will still come out if you break the splinned disconnect off in the oil pan.

And Coupe, I would have loved to have tried to take it out without removing the oil pan. I believe it can be done. But I do not have a lift and I am working with the truck on jack stands. The last I want to do is start shifting the engine around. Maybe I'm chicken. :no:

Anyway it is finally out. Now for my next questions.

Does anyone have a good method for removing the leftover bits of the splinned disconnect from the oil pan?

If the RPO codes are:

GU6 = 3.42, GT4 = 3.73, GT5 = 4.10 (credit to SparkyJJO)

...what is a G80? I found a site that lists them and it had "G80 : AXLE POSITRACTION, LIMITED SLIP" So what gear ratio is that?

I have a friend that I trust to help me find the parts but I need to have good part numbers or something to give him. Do I tell him a Positrack, Limited Slip Diff.?

As always thanks for all your help. You guys (and gals) are lifesavers.

Rick

 

[Coupe]

First of all, super thanks to Iamwildman! I ended up prying the shaft out with a crowbar and a 1/4" #20 threaded rod. Yes, it will still come out if you break the splinned disconnect off in the oil pan.

And Coupe, I would have loved to have tried to take it out without removing the oil pan. I believe it can be done. But I do not have a lift and I am working with the truck on jack stands. The last I want to do is start shifting the engine around. Maybe I'm chicken. :no:

Anyway it is finally out. Now for my next questions.

Does anyone have a good method for removing the leftover bits of the splinned disconnect from the oil pan?

If the RPO codes are:

GU6 = 3.42, GT4 = 3.73, GT5 = 4.10 (credit to SparkyJJO)

...what is a G80? I found a site that lists them and it had "G80 : AXLE POSITRACTION, LIMITED SLIP" So what gear ratio is that?

I have a friend that I trust to help me find the parts but I need to have good part numbers or something to give him. Do I tell him a Positrack, Limited Slip Diff.?

As always thanks for all your help. You guys (and gals) are lifesavers.

Rick

Good work! Im like you, I worry about cars on jacks so I use lots of jackstands along with jacks under there for backup and bricks under the tires lol.

Im having a hard time finding a differential also. Mines 3.73, not the most common. A guy here in nebraska is parting out a TB and wants $275 with a 30 day warranty for his differential. He hasnt told me what gearing it is yet though. Thats a great price.

 

[hardtrailz400]

G80 is code for rear locker not gears. There is a rebuilt 3.73 front diff on craigslist for 400.