Service slants

Motor, Mar 1998 by Juran, Ken

Dodge Truck

Steering shimmy. If your shop is in a rural area or you work on fleet trucks, this applies mostly to you. Dodge says there are a bunch of heavyweight 1994-96 Ram pickups out there that suffer from a self-- sustaining vibration or shimmy in the front end after hitting a bump or pothole. The specific rigs this applies to include 4x4s with a 10,500 GVW (sales code Z8A) or an 11,000 GVW (sales code Z8B), and 4x2 chassis cabs with an 11,000 GVW (sales code Z3B), all built before 5/15/96. Here's the lowdown:

Although there's already a steering damper in the front-end assembly, Dodge has come up with a kit that replaces the original damper and track bar (if necessary), and adds a second damper. The part numbers are 52038276 (updated damper), 4856304 (auxiliary damper kit), 4796791 (22.8mm/.897-inch track bar) or 52038795 (29.5mm/1.16-inch track bar). Start by replacing the existing damper with the updated version and checking the torque on all the front-end suspension and steering components. Retorque as necessary to factory specs.

If the truck was built before 7/5/94, install the appropriate new track bar. You can determine which of the two to use by measuring the thickness of its frame rail bracket. If it measures 22.8mm, use the smaller track bar; if it measures 29.5mm, use the larger one.

If the truck was built after 7/5/94, simply loosen the track bar-to-axle bolt and retorque it to 140 ft-lb. Next, inflate all the tires to the factory specs and get the truck on an alignment rack. Dodge says to pay particular attention to the toe settings, and to the orientation of the tie-rod alignment bar. Make sure the bar clamp and adjuster clamps all hang straight downward and that the bar clamp is positioned on the passenger side.

On to the auxiliary steering damper Attach the kit's axle bracket on the passenger side against the axle tube sleeve with the large U-bolts, flat washer and special Nylock nuts. Torque them to 20 ft-lb. Attach the smaller bracket to the drag link as shown in the illustration using the small U-bolts, flat washers and, again, the Nylock nuts. But don't tighten things up just yet. Use the supplied retainers and bushings to mount the large end of the damper to the axle bracket. Apply Mopar Thread Adhesive Lock 'N Seal or equivalent to keep the nut from walking. Tighten it down until the bushings expand to the diameter of the retainers.

Next, extend the damper rod out and assemble the bushings and retainers on that end. Tighten down the rod nut. Then, with the wheels pointing straight ahead and the rod extended exactly 4.5 inches from the damper body, tighten the small bracket clamps to the drag link to 12 ft-lb. Make sure there's no binding or contact between any components when you turn the wheel full lock to the left and to the right. If there is some binding or contact, reposition the brackets as necessary.

Finally, undo the rod end of the damper again so you can slip the boot into place. Use the supplied strap to fasten the boot to the damper and snap its end over the washer on the rod. Remount the rod to the bracket, lock the nut in place with the thread goop and you're done.

GM

Chuggle or surge. Should you get a 1993 Camaro or Firebird with the 5.7liter V8 (VIN P) that chuggles or surges somewhere around 1500 to 2000 rpm at 50 to 60 mph while accelerating lightly, know that there are new PROMs available to cure the car. They all apply only to federal emissions, so look elsewhere if you've got a California car.

The three possible PROMs available are called out by the axle option code and tire option code. So try to find the options sticker on the car before heading down to a dealer for the chip. If the car has no such sticker, you may need to have the dealer parts man decipher the car's VIN in order to determine the correct PROM to use.

For a GU2 axle with QMT tires, get PROM Part No. 16216377 (broadcast code BNXD). For a GU5 axle with QLC tires, get Part No. 16216379 (broadcast code BNXF). For a GU2 axle with QLC tires, get Part No. 16216990 (broadcast code BPBD).

Ford Truck

Lumpy idle. Ford explains that some 1994 Ranger 4x2 Supercabs with P225 tires, a 3.08:1 or 3.55:1 axle ratio and the 4-liter V6 may develop a hunting idle after a cold start in 50deg to 90degF temperatures and an extended idle period. What happens is that the engine management system enters closed-loop too early. The fix is to replace the PCM, but it's applicable only if the engine has calibration code 4-58E-R10 stamped on it. Installing the updated PCM with any other calibration is an emissions violation. The new PCM leaves the truck in open-loop an additional 20 seconds.

The new PCM part number is F47Z 12A650-CRA. Its new calibration code is 4-58H-R10. For reference, the old PCM part number should be F47F-12A650-- ANB. After the fix, describe the repair on an Authorized Modifications Decal and stick it underhood for future reference.

Jaguar

Engine knock. A knocking noise may emanate from the engine bay when the climate control is working on some 1995 XJ6, XJR and XJ12 models built between VINs 720001 and 939750. Jaguar says this is caused by the heater valve mounts and requires three revised mounts (Part No. MNA 6730AB) in order to correct the condition.