Getting my ducks in a row

[Trail X]

Glad it's all done Jeff. You'll just have to pass the knowledge on sometime. I think you, Mario, and Bacon should get together and hammer out this how to on the front diff, since you all used roughly the same method.

[Shdwdrgn]

Ugh I don't even want to think about it for a few days. Everything above the waist hurts...

But yeah, we'll have to get something put together. Since I had to buy a few tools to add to my set, I think I have a good handle on what 'specialty' tools are needed... 15, 18, and 21mm deep-well sockets and box wrenches are critical. I also had to get an extra-deep 21mm (2-1/4" depth inside the socket) to get to the nuts that hold up the steering rack. And of course you need a 35mm axle socket. Longer and shorter socket wrenches are useful, plus a long pry-bar -- there's a lot of bolts that need persuasion (a good impact air wrench would be the better option). The craziest piece was trying to reach the 8mm bolts on the disconnect actuator... I ended up making an 18" extension using extenders for my spade drills, and a 1/4" hex to 1/4" socket adapter.

Let's see, useful tips... Using one of the PCM bolts to thread into the intermediate axle shaft (plus a fender washer to give a better grip) - I just had to wiggle and pull for a couple minutes to get it to pop out. Using the large screwdriver on the ledge of the tripots to get the axles snapped back into place. Oh, and for some reason the axle on the driver's side was really tight going back in -- it took two of us to pull the pieces back in line to reassemble the upper ball joint (I kept expecting a clunk of something settling into place when I rolled down the driveway, but it never happened). Also, As I went along I either put bolts back in the pieces they came from, or made individual piles with the brackets they came out of -- there are quite a number of different sizes and lengths of bolts, you don't want to get them mixed up.

If you've never done this before, and you're working by yourself, allow 2 days for the project. Most of that is just trying to figure out how things come apart, and trying to break the bolts free. By the time you are finished, you will know everything you need to pretty much repair ANYTHING in the front suspension and drivetrain.

At this point I'm just watching for any oil leaks. I had a bad one in the old diff, and was down to only about 1/4 cup of oil that I drained out (I just refilled it this Summer). I also found my oil leak during the project... the oil filter was loose. Half a turn and it stopped dripping. While in 4WD, the pinch from turning too sharply seems a bit more pronounced with the new gears, and more likely to break a front wheel free. I've run the 4x4 actuator several times, both at a stop, and while rolling -- no problems at all, seems to be slipping in smoothly every time. Once I getl a new alignment done, I should be all set for the coming Winter.

[Shdwdrgn]

I should also mention that in order to get enough clearance, I had to remove the motor mount nuts on both sides, then jack the engine up against the firewall.

Now what would have been *really* smart is having someone take a picture, or even a short movie clip, when I went to put the new diff back into the truck. As Bacon said, the damn thing just slipped right up into place, even though removal required prying it out. When I picked up the diff, it literally took about 10 seconds to push it up through the slot, get it over next to the engine, spin it 180 degrees into position, and set it in place so I could start attaching bolts (and then I had to pull it back out of position so I had room to put the steering rack back in). Its almost as if the truck is fighting you to hold on to the diff that first time, but once you do get it out, it stops fighting and suddenly there's all kinds of room to move it around.

[bgwolfpack]

[Shdwdrgn]

"Wait, where does THIS bolt go???" Underneath the truck, trying to break loose a bolt, and I hear another bolt hit the floor and go bouncing. What is this bolt? Its too clean to have come from underneath. Its too small to be anything I've been working on. WHERE DID IT COME FROM???

<wait and hour>

Oh yeah, that's the bolt I put in the fan pulley to try and take off the fan. When I removed it, I laid it on the front bumper.

Some day my sanity will return, but in the meantime I will shoot anyone who tells my TB-driving friends that I know how to do this... Ugh I don't even have the energy to clean up my tools.

[Shdwdrgn]

Fine you pic'y bastards! Here ya go!

First shot... Pull the upper ball joint, the lower joint in the spring tower, and the link for the sway bar. With a little downward pressure, the axle has just enough room to come out.


Underneath, you need to pull out these two brackets. The medium-sized bolts at the bottom of the image go through the sides of the larger bracket. Drop all six bolts from the smaller beam first (it sits on top of the frame, so it won't fall on you), then start pulling the rest of the bolts from the underside of the larger bracket. These bolts are 15mm and 21mm.


There is one large bolt through each end of the steering linkage (21mm bolt and nut), plus one bolt underneath the rubber boot that connects the steering wheel to this linkage (15mm). With the steering linkage dropped down, and the front drive shaft tucked out of the way, its starting to look like I might be able to get the diff out. But no!


After removing the drive shaft, I unscrewed a T-bracket from the driver's side wheel-well that holds the top of the power steering fluid lines. This gave me room to pull the steering rack down, then rotated the passenger side of the rack straight out to the front of the vehicle.


Here you can see how I tucked the steering and fluid lines back out of the way, pushed up against the frame. The diff has been rotated around, and is very close to dropping here.


The final trick was to rotate the diff around so the cylinder part that fits into the oil pan was facing towards the driver's side. That part slipped down into the slot left behind by the steering rack. This puts the driver's side axle seal of the diff right against the oil pan. A light pry on the driver's side of the diff (I think it got hung up on a bolt head, I didn't see this part) and the diff fell on the floor (my sister's arm broke its fall).

The new diff, ready to go in place. Three of the mounting holes are unused. The short bolt goes through the back end of the diff. These bolts are all 18mm. Don't forget to make sure the drain and fill plugs are loose BEFORE putting the unit into the vehicle... just in case there's a problem!


During reassembly, you will also need the proper size hex key that fits inside the ball joint for the sway bar. I had a standard size that happened to fit, but no idea what size it really is.

[Shdwdrgn]

Got my four-wheel alignment done today. I'm not sure what all the numbers mean, but they said the front was quite a ways out of whack. I know the rear was also out, because it's been drifting since I replaced the rear axle, but this doesn't look like they actually changed anything on the rear? Anyway, feels a lot better now. I also told them what all I did, and asked that they double-check the bolts for tightness, and he said it all looked good.



One thing I didn't realize was that in taking off the steering rack, it changes the alignment. I guess I assumed the rack was somehow fixed to a set position when you tightened down the bolts, but apparently not. Good to know, in case I ever need to remove the front diff again for some reason.

[Trail X]

There's nothing to adjust in the rear.

Your toe wasn't really out of range either, it just means that the steering wheel was turned some when they did their first measurement - or as you said, the rack became positioned slightly differently.

Looks to me like you didn't really need an alignment that bad.

[Shdwdrgn]

It needed *something*... like I said, it's been pulling noticeably since I replaced the rear axle, but now it goes straight down the road again.

[jonbo2002]

as JD said there is no adjustments that can be made to the rear unless you buy the Massive control arms. Our factory rear cannot be adjusted, so if you paid more for the 4 wheel alignment you got bent over with no lube

[Shdwdrgn]

So... STILL no luck in getting my system reprogrammed for the new gears. The best I've been able to find is that IF someone can find a GM tech willing to do the work, a new PCM build can be made and uploaded. The problem is that apparently most GM techs aren't willing to do this...

So if anyone has a lead on a tech that I can contact, I have someone with a tech II scanner that is willing to upload the build.

[RyansTBLS]

isn't Walt here on ORTB a GM tech, might want to try PMing him

[v7guy]

Yup, WaltV, I'd PM him and see if he has any input.

[Shdwdrgn]

I still haven't gotten a reply back from Walt, so this morning I dropped off my truck at the dealership. I originally talked to them on the phone, and they basically said they didn't know what it would take to get the system reprogrammed, so I've been doing research. I went in and talked to them on Monday, and one of the actual techs was standing at the desk, so when I explained what needed done, he said yep, that's exactly the procedure. I have a little more confidence now since it appeared he was familiar with what I was talking about.

Anyway, we'll see how its doing when they call me back. They have all day to work on it, so crossing my fingers. Also this should be rather interesting to drive it home again with the computer completely back to stock. I've been driving with a custom tune much longer than I ever drove it stock, so it may be rather funny to see how it drives. Then I'm off all day tomorrow, so I can start working on tuning the programming again.

Since the thing has so much torque now, I'm thinking about adding some of the torque management back in again. Not sure if that will help prevent breaking the wheels free from a stoplight, but it might be worth trying.


[UPDATE] Just heard back from the dealership... GM has informed them that the 2004 models were not offered with 4.10 gears, and therefore GM is unwilling to send a new program with that gear set. The dealership did some checking of their own and were unable to find anything else that would actually fix the problem.

SOMEBODY PLEASE SAVE MY SANITY

[v7guy]

That's encouraging... especially since I have an 04. I think you're down to one of two options, see if one of the tuners with EFIlive might have any luck or swap to a newer/older pcm.

[Shdwdrgn]

I've actually been debating swapping to the P12 PCM... seems like there's a lot more options available on that unit, but I have no idea how much work the actual procedure would be (or if its possible). Alternatively, I can try and find a PCM from another TB that has similar RPO codes, drop that in, and see if it "just works".

You know, it's funny... I'm looking online and finding all kinds of GT5 rear axles for sale for 2004 models (TB SWB and EXT, as well as SWB Envoys). So what's the deal here? Was the tech at GM just being a dick because those gears didn't come stock on MY vehicle?

Fortunately the tech at the dealership was real cool. I asked if he could punch the computer back to the stock tire size, since changing to the smaller wheels had made my ABS problems even worse. He did one better, hooked up his scanner and we went for a drive. He checked the readings for the front and rear wheels, then changed the tire size up to 265/70/16 (which is what I actually have, and apparently is the largest size available in the computer), and found that the abs now thinks the wheel speeds match. So we're going to leave it there and see what happens. At the worst, the ABS problem was infrequent with the stock settings, so hopefully it will be less of a problem now.

[Shdwdrgn]

Ah even better... I found a listing from another Chevy dealership for the same model I have -- 2004 LT 4x4 SWB -- and that one has the 4.10 gears. Not only that, but they were kind enough to include the VIN in their listing, so I can go back to my dealership with proof that yes, the 2004 models DID come with the 4.10 gears, and more importantly, they paid for a call to the GM tech line and were outright lied to.

[RyansTBLS]

Hope this all works out for you!. keep us posted!

[Shdwdrgn]

So an interesting update... I mentioned before that the dealer changed the ABS system to match my actual tire size (265-70-16) and I have not had an ABS warning on the dash since then. Well today we finally got snow on the ground, so I was able to test the ABS in front of the house. BIG SURPRISE! The ABS system actually worked just fine! I had to run some errands, and slid on a few spots, and even on the road it still worked as expected.

The 4WD took a second to kick in first thing. When I first hit the gas, the back end spun out like I was still in 2WD, so I stopped all the wheels, gave it a second, then took off again, and this time 4WD was engaged. After that, no problems at all with it, guess it just needed a second to warm up.

So it looks like at this point the speedo and odometer are the only things not working correctly. At least now I don't have to worry about driving on ice!

[Trail X]

Your 4wd shouldn't need to warm up. That sounds like a disconnect that has some wear in it. Or - did you just pop it into 4hi and mash the gas without first driving forward and wiggling the steering wheel? I'm so glad to be rid of that problematic assembly.