Steering/Suspension - Lead or Pull Diagnosis
NUMBER: 02-008-00GROUP: Suspension
DATE: Dec. 15, 2000
SUBJECT:
Vehicle Leads or Pulls
OVERVIEW:
This bulletin covers the diagnosis and repair information for vehicles that have a constant pull or lead condition.
MODELS:
2001 (LH) Concorde/Intrepid/LHS/300M
SYMPTOM/CONDITION:
Vehicle has a constant lead or pull on a flat non-crowned road.
DIAGNOSIS:
To assure correct diagnosis, it is important to follow the steps outlined below in the order shown. Road test the vehicle before and after each step to verify that the lead condition has been corrected. When evaluating a vehicle, always drive the same road in both directions to get a feel for the effect of road crown and cross wind. A neutral vehicle will exhibit a small amount of drift on both right and left crowned roads (normal crown sensitivity). A vehicle with pronounced lead/pull may have one or more of the following conditions:
1. UNEQUAL TIRE PRESSURE - Adjust tire pressure to the pressure stated on door placard. Make sure the tire pressure is equal on all four tires and evaluate the car. Also note that the tire size and type are correct and match each other. If the car still has a lead condition go to step 2.
2. TIRE CONICITY - Excessive tire conicity is one of the more frequent causes of vehicle lead. Cross switch the front tires and evaluate the car. If the car still leads in the same direction or gets worse, return the front tires to their original position, and go to step 3.
3. SUSPENSION ALIGNMENT - Check and record the vehicle alignment settings including caster. Non symmetrical front caster or camber can sometimes cause a lead condition or can be used to fix a lead condition. To bias the front suspension caster and/or camber alignment settings to correct or minimize a lead condition perform the Repair Procedure. If the car still leads after the alignment bias procedure, go to step 4.
4. STEERING GEAR VALVE IMBALANCE - Steering gear valve imbalance can sometimes cause a vehicle lead. Although there is no quick test or measurement that can be performed to verify a good or bad steering gear valve, generally the steering efforts will feel much lighter in the lead direction and heavier in the opposite direction with an unbalanced valve. Replace the steering gear only as a "last resort" to solve the problem. To replace the steering gear follow the procedure in Group 19 of the 2001 Concorde/Intrepid/LHS/300M Service Manual (Publication No. 81-270-1040).
PARTS REQUIRED:
REPAIR PROCEDURE:
1. CASTER BIAS
a. On a vehicle that leads left, create more caster on the left than on the right. On a right lead vehicle, the procedure is opposite. Try to get at least 0.8 degree of cross caster, but do not exceed the maximum specification of 1.0 degree.
b. Loosen the four engine cradle to frame bolts. Rotate the cradle forward on the side that you need to increase the caster. Tighten the engine cradle to frame bolts, 163Nm (120 ft.lbs.).
c. Center the steering wheel and set toe (toe must be reset before doing another caster sweep). Verify that the lead is corrected. If vehicle still leads, continue with the camber bias procedure.
2. CAMBER BIAS
a. On a vehicle that leads left, create either more negative camber on the left or more positive camber on the right. On a right lead vehicle, the procedure is opposite. To minimize uneven tire wear, try to achieve the same amount of camber bias on each side. For example, if the car leads left, compensate by setting the front left camber to -0.3 degrees and front right camber to +0.3 degrees. Do not exceed cross camber maximum specification of 0.7 degree, or individual camber specification of -0.6 to +0.6 degrees.
b. Raise the front of the vehicle until the tires are not supporting the weight of the vehicle and remove the wheel and tire assembly.
c. Remove one of the strut clevis to knuckle bolts and loosely assemble a reduced shank bolt, p/n 06505362AA, and nut, p/n 06505363AA in its place. Loosen the other strut clevis to knuckle bolt to provide for adjustment. In severe cases where a wide range of adjustment is required, replace both upper and lower clevis to knuckle bolts with reduced shank bolts.
d. Install the wheel and tire assembly. Lower the vehicle until the full weight of the vehicle is resting on the suspension.
e. Adjust the front camber to the preferred setting by physically pushing in or pulling out the top of the wheel and tire assembly as required. When the camber is correct, tighten both strut clevis to knuckle bolts, 217Nm (160 ft.lbs.). Set front toe to specifications.
POLICY: Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
FAILURE CODE: