1982 Avanti Front Suspension Rebuild, Improvements and Alignment

[ronmanfredi]

I recently purchased an 82 Avanti with 97K miles on it and have started working on the car to bring it up to speed.  The car drove terrible, wandering at all speeds and needing constant attention when steering.  As an old auto technician of many years ago, I decided to tackle the front end.  I bought some inexpensive turntables, a caster/camber gauge, a 3/4”-16 threaded adapter to mount the gauge on the spindle and a Toe Bar. I did an alignment check and wrote down the measurements:

Drivers side:       Caster -7/8 degree          Camber -5/8 degree

Pass side:            Caster + 1/4 degree        Camber -2 degrees

The passenger side tire was definitely tilted in at the top and the Caster readings explained part of the wandering drive.  Now with that being said, the Studebaker suspension being from the 50’s was designed for bias ply tires and no power steering back then and this explains some of the settings, but not all.  So, I started disassembling the front suspension. I replaced all bushings, the shocks, rebuilt the bell crank, and replaced the King Pins/ bushings/ bearings.  I found one King Pin with a frozen grease zerk which would not allow grease to pass through it and it had rusted needle bearings due to a lack of grease over the years.  Once all components were rebuilt, I reassembled the front end and made the following adjustments:

Lower Control Arm:  Using the crossmember mounting portion of the lower control arm, I made 2 plates out of 3/16” thick mild steel to shim the rear most arm mount on both Arms to increase the caster.

Upper A Arm eccentric pins:  I adjusted them for maximum + Caster and maximum + Camber before I connected the King Pin to the lower knuckle.  This is done with a 1/4” allen wrench through the rear grease zerk fitting.  You are basically moving the top of the King Pin as far towards the back of car and outward as possible.

Upper Control Arm assembly:  I mounted the King Pin to the lower knuckle and determined that I needed a 1/8” thick washer placed under the front Upper A Arm mounting bolt to offset the caster shim that I used on the lower control arm.  It was a perfect fit.  The A Arm mount is offset to where you can increase the camber by mounting it one way.  (Mine was already mounted with the offset favorable for + Camber).

Next was a test alignment check and the numbers were better but the Pass side Camber was still way off.  In looking at how to correct this, I decided to slot the Upper A Arm mounting holes so I could slide the A Arm outward to fix the Camber.  I did this 3 times before I got the Camber where I considered it good based on previous readings.  By the time it was over, I had slotted the OEM mounting hole over 1/2", which is a lot.  After some consideration, I decided to add a 1/8” steel plate under the Pass upper A Arm that I could tack weld into place once everything was torqued to specs, so as to prevent the upper A Arm from ever slipping back into it original place.

And here are the final readings:

Drivers side:       Caster +1 degree              Camber +1/4 degree

Pass side:            Caster +1 5/8 degree      Camber -1/8 degree 

Toe:  Set to 1/8” in.

The car now drives great without all the wandering that it originally had due to the increase of positive Caster.  The steering is tight and the only play in the steering is being caused by the hydraulic power steering control valve.  The Passenger side tire now has the same distance at the top of the tire to the fender edge as the Drivers side tire.  I consider this a really good end result.

There was one thought that was passed on to me about making a bracket to adjust the camber with shims at the upper control arm.  After looking closely at this, I don’t see how it will work since the A arm mounts are at an angle to the wheel and in attempting to do this with a bracket would force a caster and camber change at the same time, beyond the King Pins ability to take the caster change.  Slotting the frame while concerning to some, is the only way that I can see to bring the camber close to specs.

Ron Manfredi

 

Edited August 26, 2023 by ronmanfredi
spelling

[Zedman]

Hi Ron- I will be installing my reconditioned suspension in the next month or so. I think I understand your comment to mean you flipped over the Upper Control Arm inner Shaft to gain more +ve camber ?... 

The A Arm mount is offset to where you can increase the camber by mounting it one way.  (Mine was already mounted with the offset favorable for + Camber). 

I have always wondered whether to 'Flip' or not but looking at you figures, I guess I ought to turn 'em over. Looks like you replaced your original bolts with class 8's. Did they fit really closely? If I remember correctly the originals had a slight thickening of the diameter to fit the holes in the Shafts very neatly. 🤨

[ronmanfredi]

5 hours ago, Zedman said:

Hi Ron- I will be installing my reconditioned suspension in the next month or so. I think I understand your comment to mean you flipped over the Upper Control Arm inner Shaft to gain more +ve camber ?... 

The A Arm mount is offset to where you can increase the camber by mounting it one way.  (Mine was already mounted with the offset favorable for + Camber). 

I have always wondered whether to 'Flip' or not but looking at you figures, I guess I ought to turn 'em over. Looks like you replaced your original bolts with class 8's. Did they fit really closely? If I remember correctly the originals had a slight thickening of the diameter to fit the holes in the Shafts very neatly. 🤨

The grade 8's fit perfectly.  The Upper A Arm mounting shaft has offset drilled mounting holes so you can mount it 2 different ways on the frame for camber.  They are supposed to be set from the factory with offset positioned for maximum + camber, which mine already were.  (wheel tilted out at the top)