128 rear suspension refresh - Koni Reds, new A arms

Agnelli

Agnelli

True Classic
OE NOS Koni Reds. There is a sleeve at the top of the shaft strut to transfer off the original blue Fiat struts. Otherwise fit appears correct. Top bushings at the upper body mount were in serviceable condition.
rear koni.jpg

This is the left side A Arm. It according to service records had been replaced due to a prior owner's mishap. Might have gotten away with leaving it in place, but the bushings were starting to fade so while in there went for the swap. The new stock Fiat arms required pressing the metal sleeves on the outer bushings away from the Koni strut to enable enough clearance. Accomplished that with the large socket / bolt method, using a spare head bolt. Before disassembly performed string alignment measures to get a baseline. Plan to adjust the body spacers at the inboard mounting points to make toe in correct. Existing A arms had the lowering kit already, to be moved on to the new arms. The right side arm bushings were fully perished. Most likely 44 years old.
A arms.jpg
 
Swapped the right side arm and strut this morning. The two rear struts were dissimilar (no surprise given the old damage to the left side). The right side strut lacked the detachable sleeve at the top of the strut rod. Fortunately, I had prepared for that and had some brass sleeves ready from McMasters Carr. These make the fit to the upper rubber bushes to the body accurate. I did have to ream out the brass sleeves with a Dremel, but it went well in the end.

The right arm was a bear to uninstall. The large lower bolt that secures the strut to the arm was completely seized. The worst section being seized to the hub carrier/upright. Finally capitulated drenching with PB Blaster, then hitting it multiple times with an electric impact wrench.

One side of the inboard mounting point of the arm, the end facing forward, appears bent. I will try to upload a photo later. Thinking this could easily have effected alignment. The other issue as stated earlier was completed perished bushings, particularly the inboard bushings that mounts to the chassis pivot.
 
Here are the old arms. Top is the left, likely original, and appears to be slightly bent. Bottom is right, replaced at some point more recently.
old arms.jpg

Koni instruction booklet and old box for your viewing entertainment.

koni box.jpg
 
Agnelli said:
Here are the old arms. Top is the left, likely original, and appears to be slightly bent. Bottom is right, replaced at some point more recently.
Click to expand...

This is a common occurrence in my experience. I went through a pile of maybe 7 used arms to find two straight pivots for my coupe. I've seen photos of some race cars with tie bars between the left/right pivots to share the load. And some that employ a torque reaction rod or trailing link to keep the arm from moving around. When the bushings get old you can grab the tire and force toe change by hand so you're right to replace the bushings while you're at it :)
 
Thanks Courtney. Next challenges with completing the job:

(1) The large lower bolt that goes through the arm end bushings, lower strut mount, and hub upright is now too short. The new arms must have longer bushing sleeves. I need to source longer bolts on both sides.

(2) The transverse spring on the right side is not quite far enough outboard to seat properly on the rubber perch.
 
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