Switched to autotrac II last night

[GunsOfNavarone]

Recently traded my 1997 Bravada with 205,000 miles for a 1999 with 62,000 miles. Had the shutter that is often described on this forum. I was dissapointed that the fluid was not changed- simply because the Bravada I bought was a 1 owner vehicle- owned by a 81 year old man who had all the maintenance done at the dealer he bought the Bravada from (and kept every record). I talked to my wife lasty night about why the dealer didn't perform this simple and easy service bulletin- and she asked me what was the cost if it was not performed... and I found my answer. Likely a few thousand for the dealer.

A few notes from the fluid change:

need a 1/2 wrench for the drain, 15mm wrench for the fill

used about 1.3 quarts

definelty have a hose to fill the fluid. I hooked up a can (like a bucket with a opening in the bottom that one can connect a hose to) to the top of the hood and ran a clear hose from the can to the filler opening in the transfer case. My hose was a small diameter and took about 30 minutes to fill because no air return and the fluid is somewhat thick.

[Chris Stewart]

Good work! Now we can see if proper maint. on the transfer case firsthand since you're here regular. Are you planning to do it again after a few hundred miles?

[GunsOfNavarone]

Yes, I will change the autotrac II fluid next week. I am driving about 400 miles this weekend (assuming I get the rear brakes fixed). Will keep the forum posted. I really like the Bravadas and am hoping intensive preventitive maintenance will keep the transmission and transfer case from failing.

[GunsOfNavarone]

Changed the fluid after 400 miles/ 5 days. Some of the shutter returned prior to the second change, but only a slight amount. After the change drove 50 miles and no signs of shutter.

Bottom line- seems the second change is critical.

Only used 3 quarts for 2 changes. Little under 1.5 quarts per change on a 1997.

[GunsOfNavarone]

Made a huge mistake. I changed out the front differential fluid instead of the transfer case fluid. I put trac II fluid in the front differential.

Funny thing- this corrected the problem. But for how long and at what cost. After discovering my error I immediately went to GM and got the front differential lube ($15 a container and it took 3 containers). and also picked up more trac II for the transfer case.

I discovered the transfer case did have blue fluid in it.After changing both fluids, the Bravada does not have the chatter problem. The Bravada did have the chatter problem prior to putting trac II in the front differential. This is very concerning.

A few thoughts-

Old fluid in the front differential can also cause the chatter problem commonly identified as a transfer case/ autotrac II problem

Autotrac II may need to be replaced on a regular basis in the transfer case.

Guess I will be changing the front differential fluid soon to make sure all the autotrac II is flushed out. Another $45 to the local GM dealer. The bottle for the front differntial stated it was GM's advanced product and the [art number is different from what the owners manual states- the parts guy stated this is a newer lube developed for better performance.