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New rear shocks

I’ve been driving the car more this summer since I’ve addressed a lot of the problem areas. The next item on the punchlist was getting it to ride more comfortably. The suspension felt very stiff, particularly in the rear, and going over potholes or train tracks felt like the car was going to shake apart. kaBLAM!

I didn’t want to change the ride height, so that actually limited my choices. Most of the springs/spindles/shocks available are for 2″ drop, not stock height.

After asking on, I bought a pair of Bilstein AK2073 rear shocks. That was not the right part to order it turns out. It’s not clear on the Bilstein website, but AK2073 is for monoleaf applications, while AK2074 is for multileaf. The difference is that the multileaf has a taller spring pocket under the differential to accommodate the multileaf spring. That puts the shock mounting plate under the spring lower, so the shock needs to be a little longer.

But first…

Way back when I first got the car and was redoing the brakes, I noticed that the right rear shock upper bracket was broken, so I decided to fix that. The setup was not stock, there was a mount point extender that was bolted to the upper shock mount, and the shock was mounted to that. The extender is commonly used to adapt the shorter monoleaf shocks to a car with multileaf shocks. Moving the upper shock mount position lower meant the shorter shocks would work with the lower multileaf shock mount.

I gave it a good pull with a breaker bar, but the bolts were not moving. I sprayed it down with some penetrating oil, and gave the bolts a try and more oil every day for about a week. I felt them start to budge and cranked harder…only to have the bolt snap and the head twist off. It turned out that the extender was aluminum, the bolts were steel, and they had corroded together so there was no way they’d ever come apart.

The rear upper shock mounts are two pieces. A thick plate inside the trunk with threaded holes, and another thinner plate under the car that is attached with bolts into the threaded holes in the thick plate, sandwiching the trunk floor in between. I ended up drilling the bolts out of the thick plate and cutting it away until it let loose. Not a fun job.

I could not find a similar design shock extender, so I ended up with a version that screws onto the top stud on the shock that makes the stud longer. Different design, but same effect. I put it back together with replacement upper shock mount brackets, and the stud extender on the original shock.

Back to today’s shock replacement: Remembering how difficult it had been to remove the right one, I was not looking forward to doing that same job on the left rear upper shock mount, but it had to be done. It took me 3 hours to get the mount bracket off, but I did succeed.

Removing the bracket…


The old shock turned out to be a no-name model marked “20818” and “POF22MC1R”, neither of which seem to turn up as the correct shock for a 1st gen F-body. It was a little shorter than the new shock, but not by much, maybe 1/2″. I had checked the travel in the new shocks, and it was about 7″

Once the new upper shock mount bracket was bolted into place, I started to test fit my new Bilstein shock, and discovered that the lower mount had been bent to fit the narrower lower eye mount of the old shock. I was able to bend the bracket back into shape. It was around this time that I discovered that my stud extender piece had a fine thread (as did the old shocks) but the new shocks were coarse thread, and probably also metric. That meant the extenders weren’t going to work on the new shocks. I decided to check the length anyway. With the car supported under the shock mount, it was at the normal ride height. I had to compress the shock about 3″ to get it seated, which worked out to about half the overall travel, which seemed correct.

Then I looked closer at the spring pockets on the diff, and realized they were for monoleaf springs, which means a) the springs aren’t properly installed, but also b) I didn’t need the longer shocks with my monoleaf setup.

Given that the old and new shocks (fully extended on the workbench) were about the same length, and the new shocks had about 7″ travel, I think the 3″ shock extenders were putting the old shocks near the bottom of their travel limit. When the car hit a big bump, the shock would compress until it bottomed out…which was likely a major cause of the rough ride.

The right side was much easier since I had already replaced the upper mount.

After I got it put back together, I took it for a test drive on some bumpy roads. The roads were still bumpy, but at least the car doesn’t sound like it’s coming apart when I hit those bumps. Much improved!!!