Many of you have been following the series of articles on the restoration of our '41 Packard LeBaron Sport Brougham. In this series, we covered rebuilding the drive train, brakes, body work and steering and suspension (see the Archives section at www.southernwheels.com). The car is now mostly assembled, in primer, and we can have a little fun driving it on short trips while we finish the restoration. We decided not to align it immediately after finishing the steering rebuild, because the body was still disassembled and it would have involved towing and possibly leaving it for several days at the alignment shop. We wanted to take the car as togetheras possible, and have all alignment shims, thimbles and specifications ready before we took the car in. Before getting into the alignment procedures, heres a little about our '41's steering and suspension system:
During the '30's, many of the car companies were working on steering system innovations, converting from the straight-axle to independent suspension, which provided better handling and smoothness of ride. Packard introduced the Safe-T-fleX suspension system in 1935 on their new Junior Series 120, 8-cylinder cars, then added it to the Senior line in 1937; the Super 8's and 12s, continuing through 1942 on the non-Clipper cars. Safe-T-fleX was a front coil spring, king pin system, the left and right upper support arms of which were attached to each of the front Delco hydraulic shocks. These shocks were bolted to the left and right frame rails and the wheels supports were attached at the shocks by way of a rubber-and-metal sleeved bushing with a bolt through the top end of each wheel support and a pin and needle bearing/bushing at the wheel supports lower end at the lower support arm. Left and right torque arms attached forward at the lower control arms, and rearward near the cowl area at the bottom of each frame rail via a rubber ball bushing 2-1/2" in diameter, at the end of each torque arm, held in by a cover plate. This setup was designed to give protection to the alignment of the front wheels, and prevent the front end from twisting in the event of a rear-end collision.
The steering system was also re-designed to include a central control lever that conformed to the geometry of the new suspension system. Our first test drive, before any adjustments had been made, revealed three problems: wandering a steering wheel that wouldn't right itself after cornering, and, in a hard right turn, the rear of the right front wheel scraped the torque arm, although in a hard left turn, the rear of the left front wheel cleared the torque arm by over 1" We decided to do some alignment basics at our shop.
Before we started, we knew that all of the front end components had been restored and were not bent, and the front bearings were packed and correctly set. We began with the Toe-in. This is the adjustment of the front wheels, so that the distance between them is less at the front than at the rear. Toe-in is usually set after the Camber and Caster adjustment is done, but we wanted to rough it in now to get an idea of how all of our new parts were going to line up. We put the car on the lift, then put a piece of masking tape in the center of each front tire, drawing a line on the tape exactly in the middle of the tire tread. Using a measuring tape, we measured the distance from line to line, then rolled the tires around 180 degrees and measured from the back side. You can do this with chalk, holding it stationary in the center of the tire, then spinning the tire around, so that the chalk makes a center line all around the tire, but the tape system seemed a little more precise. Our Toe-in measurement was about 2" off! To adjust this, we loosened the clamps on the tie rods, then rotated each one while checking our Toe-in distance. (Rotating the tie rods lengthens or shortens them, depending which way they are turned.) We set our Toe-in about 1/16" less in the front.
Packards Toe-in specification is 0 to 1/16" measured at or as near hub height as possible. We also re-checked our wheel scraping problem. This time, when we cut the wheels to the right, the rear of the right tire cleared the torque arm by 1" and the same on the left wheel. Both wheels had a good clearance in the front. Its also a good idea to check the wheels for trueness. A bent wheel can scrape the frame sporadically as it turns, mimicking an alignment problem.
With the Toe-in done, it was a good time to finish our steering arm assembly. A piece called a Belville (spring) washer had come up missing. Our buddy Ron Carpenter found one for us and sent it, along with installation instructions. (Youve got to love the hobby!) The steering crank (arm) is mounted with one bolt and bushing in the center of the front crossover frame. It allows the arm to pivot. The mounting bolt components are: Main bolt with grease fitting and fixed nut at bottom, Flat washer, D-washer, Bushing, D-washer, Spring (or Belville washer--points upward), Flat washer, Castellated nut and Cotter pin.
The spring washer is crucial to the assembly because it automatically pre-loads the bushing and steering crank. Installing the cotter pin in the top of the bolt is difficult, due to the tight working space. We found that making a mark at the bottom of the bolt, in line with the cotter pin hole at the top, made installation of the cotter pin a lot easier. We were also able to adjust the steering rods, located at the end of the steering gear. First adjust the one at the steering gear end of the drag link by bottoming it out, then backing it off one full turn. Then back off the one on the opposite end two full turns.
All of our steering parts appear to be aligning up and working smoothly. We are now ready to take the car to the alignment shop to precisely set the Caster/Camber and re-set the Toe-in.
Heres how they will set the Caster/Camber:
CASTER: Is the backward or forward tilt of the steering pivot. In other words, its the tilt of the king pin or ball joint as seen from the side of the car. When the support arm tilts backward from vertical, its positive. When tilted forward from vertical, its negative. Its purpose is to improve steering stability (keeping the car from wandering, and helping the steering wheel to right itself after making a turn). Most pre-1974 cars had negativeCaster, due partially to the need to correct the positive Caster effect that the OEM bias-ply tires had on the steering system at higher road speeds. When putting radials on an old car, its a good idea to discuss with your shop the prudence of changing to a more positive Caster to help prevent wandering that can occur with original Caster angle settings combined with radial tires.
SETTING CASTER: The Caster angle on our car is set at ¾ degrees negative, but a minimum of 1 ¼ degrees and a maximum of ¼ degrees negative is permissible. To set the Caster, special tapered shims are inserted at the front ends of each of the torque arms, between the torque arm and spring perch. They come in two sizes: one-half degree and one degree*. If more than one degree is needed per side, you should look for bent parts.
CAMBER is the angle of the wheel in degrees when viewed from the front of the car.. If the top of the wheel is leaning out from center, it has positive Camber. If the wheel is leaning in at the top, it has negative Camber. Correct Camber provides for easier steering. our Camber angle is ½ degree. A maximum of 1 ¼ degree is permissible. Our Camber is adjusted by installing offset pilot thimbles. They are inserted on the inside of each arm of the front shock absorbers, at the steering support. The pilots are available in five sizes: 0, 1/16, 1/8, 3 1/6 and 1/4. A change of 1/16" in amount of offset changes the Camber angle 1/3 of one degree.
In addition to all of the above, there are other problems that can cause our steering wheel not to return to center. For example, bad or mis-adjusted steering gears, or steering bind (misalignment of the steering gear), but these are less likely to occur on a lower-mileage car like ours, or one that has not had the steering column or steering gear removed.
We will update you on all of this after the final alignment. We have other cars with Safe-T-fleX, and even though there is some extra work involved in getting parts and alignment, its worth it. These cars steer easily, handle great, and provide excellent stability with years of trouble-free service.
Include your old cars in your Thanksgiving holiday. We hope its a happy one, and remember, keep em driving!
*Caster shims and Camber thimbles are available from Max Merritt Packard Parts, 800-472-2573.