03 Seville SLS Rear Shocks
Posted: Tue May 18, 2021 8:05 pm
Customer states there's a banging in the rear.
This car is up to >180K on almost entirely OEM suspension. There were several variation on fancy suspensions in these Sevilles, fortunately the real expensive ones were only optional on the STS (ManaRide), which this one isn't. So it's conventional McPherson strut front and aid-assist shocks in the rear. It does have an auto leveling system which GM had been putting in many of their full size cars for a number of years (including the Fleetwood). This is a similar system to the older D-bodies with level sensors and a pump assembly. Conveniently, like the other G/K cars, the pump is located under the rear seat so other than an exhaust port it is never exposed to the elements which probably has contributed to the longevity.
We opted to get OEM 'Delco' replacements for this, mostly due to the non-standard design of the shock/bladder assembly and the internet providing mixed information on how compatible some of the aftermarket stuff was. The RH one is readily available, but the LH one is EOL. I did manage to find one at Summit, but it was a ~12% cost increase. In hindsight, the thing that makes these positional is only the relative alignment of the offset upper mount to the shock (180 out from L to R). The shock bodies are otherwise identical. Oh well.
The OEM stuff is branded Delphi, which isn't surprising, but the AC Delco replacement stuff is branded BWI, presumably after the airport? Probably not. I'm pretty sure the rear air bladders have never held air, mostly evidenced by the drastic increase in 'bound' ride performance of the new shocks. Also, the compressor now only runs for seconds after starting the car rather than several minutes (presumably on a timer). I am slightly surprised that there isn't a BCM code for this, but I haven't been paying too much attention.
Pics is attached. "Place inline" is missing? is that expected?
Regardless, the banging in rear. I think this was actually the upper mount, being exasperated by incorrect bound 'spring rate' due to the failed bladder. I was able to get vertical motion of the shock stud in the upper mount indicating it was either assembled on a Friday and not fully tightened, or the rubber degraded sufficiently to allow for motion of the mount before the rubber starting compressing.
Installation was so easy, I didn't take any pics. Something like:
1. Jack up your car
2. Remove wheel
3. Disconnect air line
4. Remove side trunk liner
5. Unbolt 2-bolt upper mount from inside trunk
6. Unbolt 2-bolt lower mount from lower control arm (like a B/D body or every GM ever shock)
7. Remove shock
8. Installation is reverse of removal
9. Repeat for other side.
The FSM says to not to fully put weight on the shock at first and cycle the air pump on to fill the bladder before ultimately lowering the car.
Great success. Now the only noise out back is the stuff in the trunk crashing around.
This car is up to >180K on almost entirely OEM suspension. There were several variation on fancy suspensions in these Sevilles, fortunately the real expensive ones were only optional on the STS (ManaRide), which this one isn't. So it's conventional McPherson strut front and aid-assist shocks in the rear. It does have an auto leveling system which GM had been putting in many of their full size cars for a number of years (including the Fleetwood). This is a similar system to the older D-bodies with level sensors and a pump assembly. Conveniently, like the other G/K cars, the pump is located under the rear seat so other than an exhaust port it is never exposed to the elements which probably has contributed to the longevity.
We opted to get OEM 'Delco' replacements for this, mostly due to the non-standard design of the shock/bladder assembly and the internet providing mixed information on how compatible some of the aftermarket stuff was. The RH one is readily available, but the LH one is EOL. I did manage to find one at Summit, but it was a ~12% cost increase. In hindsight, the thing that makes these positional is only the relative alignment of the offset upper mount to the shock (180 out from L to R). The shock bodies are otherwise identical. Oh well.
The OEM stuff is branded Delphi, which isn't surprising, but the AC Delco replacement stuff is branded BWI, presumably after the airport? Probably not. I'm pretty sure the rear air bladders have never held air, mostly evidenced by the drastic increase in 'bound' ride performance of the new shocks. Also, the compressor now only runs for seconds after starting the car rather than several minutes (presumably on a timer). I am slightly surprised that there isn't a BCM code for this, but I haven't been paying too much attention.
Pics is attached. "Place inline" is missing? is that expected?
Regardless, the banging in rear. I think this was actually the upper mount, being exasperated by incorrect bound 'spring rate' due to the failed bladder. I was able to get vertical motion of the shock stud in the upper mount indicating it was either assembled on a Friday and not fully tightened, or the rubber degraded sufficiently to allow for motion of the mount before the rubber starting compressing.
Installation was so easy, I didn't take any pics. Something like:
1. Jack up your car
2. Remove wheel
3. Disconnect air line
4. Remove side trunk liner
5. Unbolt 2-bolt upper mount from inside trunk
6. Unbolt 2-bolt lower mount from lower control arm (like a B/D body or every GM ever shock)
7. Remove shock
8. Installation is reverse of removal
9. Repeat for other side.
The FSM says to not to fully put weight on the shock at first and cycle the air pump on to fill the bladder before ultimately lowering the car.
Great success. Now the only noise out back is the stuff in the trunk crashing around.