Bravada jerks when backing up

[buciou]

My 2000 Bravada makes a jerking motion when backing up or turning tight. What might be the diagnosis?

[Chris Stewart]

Originally Posted by buciou

My 2000 Bravada makes a jerking motion when backing up or turning tight. What might be the diagnosis?

There's a clutch pack in your transfer case that sticks on some folks Bravada's.
note: The rear differential reference does not apply to shudder in reverse.
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Here's something from Chcknugget.

chcknugget []
AF Enthusiast



Joined: Oct 2004


Status: offline
Posts: 749

12-02-2004, 10:15 AM Re: smart trac help (Post #15)
It's actually not an additive like I thought, it's the actual fluid that goes goes into the case. It's a "blue colored fluid" called AUTO-TRAK II.

I found this in a the astrovan forum and thought it might be of some interest, however your car is a different year and I'm pretty sure its case uses different fluid anyways (check and see if you have the same transfer case p/n).

Bulletin No.: 99-04-21-005B

Date: September, 2002

TECHNICAL

Subject:
Transfer Case Shudder
(Flush and Replace Transfer Case Fluid)

Models:
1999-2003 Chevrolet Astro (AWD)
1999-2003 GMC Safari (AWD)
1999-2001 Oldsmobile Bravada
with All-Wheel Drive (NV136) Transfer Case (RPO NP4)

This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 99-04-21-005A (Section 04 - Driveline Axle).

Condition

Some customers may comment about a vibration (shudder) during tight turning maneuvers on dry pavement at vehicle speeds less than 8 km/h (5 mph).

Cause

This condition may be caused by a slip-stick of the clutch plates in the transfer case clutch pack. On 1999 and newer models, the preload that is designed into the clutch pack may contribute to the condition. In addition, contamination of the fluid may interfere with the friction modifiers.

Correction

Flush and replace the transfer case fluid on affected vehicles using the following procedure and the part number listed below.

Perform the following diagnosis prior to flushing and replacing the transfer case fluid in order to properly identify the shudder.

Diagnosis

1. Verify the shudder in the vehicle. The vehicle needs to be at operating temperature (driven at least 5 miles) for proper diagnosis. After the vehicle is at operating temperature, drive in a tight circle just short of steering wheel lock, at a speed less than 8 km/h (5 mph) in order to identify the shudder.

2. Identify what rear axle type the vehicle has.

^ If the vehicle has a standard rear axle, then proceed to step 3.

^ If the vehicle has a locking rear axle, remove the front propeller shaft. Refer to the Propeller Shaft subsection in the Service Manual. Drive the vehicle as outlined in step 1.

^ If the shudder goes away, install the front propeller shaft and proceed to step 3. Refer to the Propeller Shaft subsection in the Service Manual.

^ If the shudder does not go away, the locking rear axle may be the cause. Review the owner's records and determine if the rear axle was serviced at the first scheduled oil change. If records indicate that the axle service was done, then revaluate the condition using diagnostic information in the appropriate Service Manual. If the rear axle was not serviced, service the rear axle.
INFORM THE CUSTOMER THAT THE AXLE SERVICE IS AN OWNER'S MAINTENANCE ITEM NOT COVERED UNDER THE VEHICLE'S WARRANTY.

^ Install the front propeller shaft. Refer to the Propeller Shaft subsection in the Service Manual.


3. Flush the transfer case with the blue colored fluid (AUTO-TRAK II) using the procedure and part number listed below. Perform the flush procedure even if the transfer case contains the blue colored AUTO-TRAK II fluid in order to remove any possible contaminants. The AUTO-TRAK II fluid contains an improved friction modifier that should correct the slip-stick condition. Refer to the Transfer Case subsection in the Service Manual for information on draining and filling the transfer case.


Flush Procedure

Important :Refer to Corporate Bulletin Number 99-04-21-001, dated April 1999, for important information on removing the transfer case drain and fill plugs.

1. Drain the transfer case fluid.

2. Refill the transfer case with 2 L (2 qts) of new fluid, P/N 12378508 (Canadian P/N 10953626).

3. After refilling the transfer case, drive the vehicle a minimum of 8 km (5 mi).

4. With the transfer case at operating temperature, drain the transfer case fluid again.

5. Refill the transfer case with new fluid.

Important :The vehicle may require approximately 160 km (100 miles) of driving before the condition is completely corrected..

[Taylor44]

This may be a stupid question.. But here it goes... Does this mean if the vehicle is out of warranty, the dealer will still make the repair at no charge?? Or is this just the procedure the dealer must go through for a billable repair?

[Chris Stewart]

My limited knowledge of a Techinical Service Bulletin (TSB) is a problem and a factory way to fix the problem. After the warranty time is up, there's no recourse except maybe a court case.
The dealer may or may not use the TSB instructions as things and procedures change.
Recalls are something else but I don't know if there's a time limit even for those.
Some repair procedures found by a mechanic never make it to the TSB stage but are time saving/money making tricks for him just the same.
I work part time with a guy who was a Line Mechanic at the local dealer who eventually found enough shortcuts to do a job on a '65 or '66 Pontiac heater core replacement rated for 4 1/2 hours in 45 minutes...he really didn't want to recommend a TSB on it as it was a tough job nobody else wanted but paid him great. He made good money on QJet carburetors when they first came out too...still does.

[ericn1300]

Originally Posted by Chris Stewart

He made good money on QJet carburetors when they first came out too...still does.

LOL, anybody who can make a QLeak carb work right must have the same genetic and mental disorders as the guy who designed it in the first place. Who needs cloning when we can just depend on inbreeding.

As far as gettinging your shuddering problem fixed, Taylor44, i doubt it would be covered under warranty unless you bought an extended one. Doesn't sound to be to expensive of a job, take it to a reputable tranny shop and be sure to give them a copy of the TSB. They might already be aware of the problem and have a quick fix for it, like Chris said.

[Chris Stewart]

You're right Eric, a QJet is a challenge. Pay$ good too.