What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[SpareParts]

Got the transfer case apart today and it is in pretty good shape really.
After getting it apart and checking out the forks and bearings the only thing it really needed was a new chain. Could have just cleaned it and run it though.
I have ordered new bearings, chain, seals and output bushing.

 

[SpareParts]

After reading and more vid watching it looks like my rear case needs to be replaced.
The rear most snap ring that holds the bearing in place is groved pretty bad. Being groved allows the gears to work back and forth wearing out the shift forks.
My shift forks are good, disaster averted.

 

[SpareParts]

Here are a couple pics. One shows what a new case looks like and mine with the worn snap ring grove.

 

[Fless]

Here are a couple pics. One shows what a new case looks like and mine with the worn snap ring grove.

View attachment 480997View attachment 480998

Do those transfer cases experience the same pump rub as the NVG/NP246?

 

[Doubeleive]

Do those transfer cases experience the same pump rub as the NVG/NP246?

I don't believe so

 

[SpareParts]

Yup.
Mine had the little clip that GM installed in the later years but it only helped a little. After a while it would break and rub over a larger area.
I ordered a case saver.

 

[Doubeleive]

I guess I stand corrected, lol

 

[Fless]

I guess I stand corrected, lol

One time you thought you were wrong, but were mistaken.

 

[SpareParts]

Gotta say. Im more excited to switch axles then changing my engine. There are two places i could not go because my truck would almost power out and front would start spinning.
Low range and 4x4 should do it and a lot easier + more transmission friendly.
Really looking forward to it!

 

[Joseph Garcia]

Gotta say. Im more excited to switch axles then changing my engine. There are two places i could not go because my truck would almost power out and front would start spinning.
Low range and 4x4 should do it and a lot easier + more transmission friendly.
Really looking forward to it!

Many more smiles per mile coming your way.

 

[j91z28d1]

will be interesting to hear the difference 4lo makes

 

[Charlie207]

Front diff is always an open diff weather it is AWD or 4x4 diff
When the 4x4 diff is put into 4x4 mode then the diff is still an open diff but the pass side axle is locked into 4x4 mode and along with the two speed transfer case power is supplied to both front wheels.
I guess i assumed when i said front diff locked it would be automatically known i was talking about 4x4 mode and with an AWD transfer case it should act like a normal AWD front diff because an AWD diff is basically always locked in 4x4 mode.

The reason why 4WD (when in 4-HI) Yukons get the low-speed chatter in the front-end when turning sharply, and the AWD systems don't is because there is a planetary gearset on the ouput shaft of the AWD tranfer case, which lets the front driveshaft rotate at a different speed than the rear driveshaft.

4WD Yukons with the AUTO feature achieve this (although not nearly as well) is because in the AUTO setting the 4WD actuator engages the clutch with a small amount of preload... something like 10% of what switching into 4-HI will do. This is why the AUTO setting is so fast to react when the front wheels slip (fast being relative): The front differential is powered, and the passenger axle is locked to the output of the open carrier (same as when 4-HI is turned on).

AWD front diffs. are always connected between the driver & passenger axles, and there is no electric actuator.

The main takeaway is the AWD transfer case has a planetary gearset that does some mechanical calculus 100% of the time, whereas the AUTO 4WD system does the same thing with clutch slip, and why you shouldn't really leave your 4WD truck/SUV in AUTO all the time. You can feel a slight dragging (not quiet binding) when you are in 4WD-AUTO vs. 2WD in parking lots with tight turns.

 

[Doubeleive]

The reason why 4WD (when in 4-HI) Yukons get the low-speed chatter in the front-end when turning sharply, and the AWD systems don't is because there is a planetary gearset on the ouput shaft of the AWD tranfer case, which lets the front driveshaft rotate at a different speed than the rear driveshaft.

4WD Yukons with the AUTO feature achieve this (although not nearly as well) is because in the AUTO setting the 4WD actuator engages the clutch with a small amount of preload... something like 10% of what switching into 4-HI will do. This is why the AUTO setting is so fast to react when the front wheels slip (fast being relative): The front differential is powered, and the passenger axle is locked to the output of the open carrier (same as when 4-HI is turned on).

AWD front diffs. are always connected between the driver & passenger axles, and there is no electric actuator.

The main takeaway is the AWD transfer case has a planetary gearset that does some mechanical calculus 100% of the time, whereas the AUTO 4WD system does the same thing with clutch slip, and why you shouldn't really leave your 4WD truck/SUV in AUTO all the time. You can feel a slight dragging (not quiet binding) when you are in 4WD-AUTO vs. 2WD in parking lots with tight turns.

I have ran the silverado in auto for 50,000 miles so far, beating on it far worse than most people, with no ill effects thus far.
this prevents me from doing daily burn outs which happen when in 2wd only. works for me.
not saying the wear isn't or doesn't happen but the auto function works out for me.

 

[Dirty looks]

Been there but not by my doing. Did it lock up the wheel every time you braked?

Yes, with just a touch of the pedal.

 

[Dirty looks]

148ft lbs clyde

I replaced the pad well over a year ago, must have only cracked it to 147lbs..

 

[Dirty looks]

When that happened to me I was driving my dad’s late 70’s w200 dodge EC. He was a heavy equipment mechanic so he had a utility bed packed with enough tools and tid bits of parts and nuts and bolts and such.

His lf caliper did the same thing. Bolt fell out. I’m was able to macGuyver it using what was on board to get going again. I was a teenager.

Mine came apart 2 blocks from home.. very lucky.

 

[Charlie207]

I have ran the silverado in auto for 50,000 miles so far, beating on it far worse than most people, with no ill effects thus far.
this prevents me from doing daily burn outs which happen when in 2wd only. works for me.
not saying the wear isn't or doesn't happen but the auto function works out for me.

I know the person who owned my Yukon ran it in AUTO all the time. One of these days I'd be interested in opening up the transfer case, and looking for premature wear. I bought it was 150k miles already on it, and had to replace the front end (too lazy to rebuild existing) due to bearing wear/sparkles.

 

[Doubeleive]

I know the person who owned my Yukon ran it in AUTO all the time. One of these days I'd be interested in opening up the transfer case, and looking for premature wear. I bought it was 150k miles already on it, and had to replace the front end (too lazy to rebuild existing) due to bearing wear/sparkles.

I probably wouldn't do it if transfer cases were more costly to replace but there are tons of used ones out there for cheap in relative terms, but so far so no issue's and I like the extra road grip.

 

[Dirty looks]

Ordered some more ridiculous over priced parts today. This long travel suspension game is absolutely crushing to the bank account.
B.J Baldwin has my respect.

 

[Charlie207]

I'm not sure I fully understand why that steering kit is so expensive, but those control arms sure
are sexy.