Replacing rear air struts on 1988 Cadillac Seville
Jack stands (2)
WD-40 or your favorite penetrating oil
Coat hanger wire and/or plastic squeeze clamp
Air compressor for powering air impact wrench, and air hammer.
Torx 50? socket (depends on what struts are on your car)
7mm allen socket (depends on what struts are on your car)
½-inch drill bit and electric drill
3/8 drive socket extensions
3/8 drive ratchet
Jack car up using floor jack under the center of the rear suspension cross member. Stabilize car with jack stand under rocker panel pinch weld (use wooden block between pinch weld and jack stand).
Remove wheel center cap, lug nuts, and tire.
Install 2 lug nuts to keep rotor from moving.
Remove parking brake cable from caliper bracket (a pain to do but VERY helpful later.) I used a flat screwdriver and some twisting/pulling to pop the cable out of the mounting hole.
OK, here’s the hard part that requires decision making. The center shaft of the strut has to be held from turning while the big nut (should be 24mm) is removed. The top of the shaft usually has a Torx recess or perhaps an Allen recess or may be hex shaped (probably 10mm). In my case the strut had a Torx 50 recess. But the only way to get the Torx in to the tiny vertical clearance above the strut shaft was to punch and drill a HOLE in the sheet metal from inside the trunk (remove the carpeting from the wheel wells and you have easy access.
I didn’t want to punch holes in the sheet metal but there was no other feasible way to get a tool in that space. I suppose an “L” shaped doohickey could be fashioned somehow but I was not willing to go to all the trouble to make such a tool, when I know that a little sheet metal repair with JB weld and seam sealer will cover the hole perfectly!
I punched the hole from outside the car using an air-powered hammer and pointed punch. I then cleaned up the hole with a 1/2 –inch drill bit and a little more air hammering.
Once the hole was large enough, I placed a mirror above the strut top and confirmed that the recess was indeed a Torx. Your struts may be different! Please check yours before proceeding!
Anyway, I place the Torx socket in the hole as far as I could get it, and then used a hammer to knock the Torx vertical and seat it fully in the recess. I then inserted a 6” ratchet extension in the Torx socket from INSIDE the trunk, and held the socket from turning with a 3/8 ratchet. I used a 24mm open end wrench to turn the big nut until it came off. A liberal does of WD-40 helped the nut turn smoothly.
Next up: remove the brake caliper and wire it or clamp it out of the way so you can then lower the strut outboard.
Loosen the pinch bolt at the bottom of the strut but don’t back it out or try to remove it at this point.
Remove the air line if you haven’t already, and pull the top of the strut down and out. The strut has to be tilted outboard to allow for sufficient clearance to remove the pinch bolt completely.
Remove the pinch bolt. Return the strut to its original vertical position making sure that the top of the strut is seated in the hole at the top of the suspension member.
Now here’s where it gets a little tricky: you have to FORCE the bottom of the strut out of the pinch bolt mounting.
I put a jack stand under the control arm to stabilize the arm and put a little weight on the control arm by jacking it up with a bottle jack (thereby compressing the strut slightly), and then placing the jack stand under the control arm.
Then I removed the bottle jack and repositioned it UNDER the bottom of the air strut, and began jacking slowly upward.
The upward movement of the bottle jack forced the air strut to POP out of the pinch bolt with a jolt!
I then had to pull and twist the strut some to get it completely out of the pinch bolt mounting.
Time for a beer break!
Ok, installing the new air strut.
VERY IMPORTANT NOTE: there is a TAB on the LOWER PORTION of the strut and a corresponding NOTCH in the pinch bolt top edge. BE SURE these two items line up and seat fully!!!! Otherwise the shock can twist or God forbid, come loose!
Seating the new strut in the pinch bolt is the tough part. I greased up the bottom of the strut and place it in the pinch bolt hole, being careful to line up the tab and notch.
I then stood the shock up as straight as possible and alternated hammering on the two side “ears” to drive the strut down into the pinch bolt hole. This task was very slow but the shock finally seated. Lots of WD-40 and hammering evenly on both side seated the shock fully, with the aforementioned tab and notch fully mated.
Then some wrestling with the top of the shock got it seated in the top hole – you may want to inspect it with a small mirror to ensure the top mount is all the way seated in the hole (I had to finagle the shock with a pry bar to get it to seat fully).
One puzzle that came up for me: with the top rubber donut and metal washer in place, there was only 1 or 2 threads sticking up when the top nut was placed on the center shaft threads. I checked the strut’s seating several times and was finally convinced that it was fully seated.
I though that I would not be able to hold the center shaft from turning while tightening the 24mm nut – but happily I was wrong. The nut tightened enough with me holding the center shaft still with just the tip of my finger. Then I was able to hold it with a 10MM wrench and complete the tightening.
The rest of the task is buttoning up and reversing the disassembly steps – don’t forget to attach the air line!!!! And seal up the holes in the sheet metal!
Re: Tips for replacing rear air struts on 88 Seville
Great write-up! I've been planning to tackle this for a long time. One question: Did the leaf spring give you any trouble in the process or is it fully unloaded (and safe)when the vehicle is off the ground?
Re: Tips for replacing rear air struts on 88 Seville
Ok, the leaf spring is 95-100% unloaded when the car is jacked up, the top strut mount is free, and the the lower control arm is hanging down.
The only times I noticed the leaf spring coming into play was:
1) when I jacked the lower control arm UP to force the bottom of the new strut to seat in the pinch bolt
2) when I jacked up the old strut from the bottom using a bottle jack - the pressure of the jacking pushing up and the pressure of the leaf spring pushing down made the bottom of the strut POP out of the pinch bolt.
Since the car was supported on jack stands the POP of the strut releasing did not cause any danger.
Lastly, I did notice that there is a rubber pad? at the tip of the leaf spring. There was a little interference with that pad and the surface of the pinch bolt - but the pad moved into position at some point during the strut installation - I just didn't notice when!
Ed in Maryland.
P.S. In a week or two I will be replacing the air struts on my 1990 Cadillac Deville and will create a similar write-up of that project.