If you want to go all the way replace the front lower control arm bushings. They commonly wear and tear giving the car sloppy handling and may contribute to the clunks. There's no alternative to the OEM rear/verticals but bushings from the '88 - '96 BMW/M5 (E34) will fit in place of the Catera's front/horizontal bushings. They come in 2 flavors. Standard rubber, which are a little firmer than ours, or Polyurethane, which are much firmer. Both are better than GM's replacements in that they improve handling and braking stability but also last longer and resist the tearing common to ours. There's no poly substitute for the rear/vertical bushings but I'm still looking.
NOTE: When I say front or rear I'm referring to the location of the bushings on the lower control arm and not the car's axles.
Meyle Bushings BMW E34/M5 HD Bushings: part # 31121136607MY
http://www.germanautosalvage.com/services4.html
Heavy Duty rubber front horizontal BMW/M5 bushing for Omega/Catera.
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Meyle Bushings (Opel Omega)
Front Horizontal Bushing 58.5mm: part # 614 035 0016
Rear Vertical Bushing 48.5mm: part # 614 035 0010
http://www.meyle.com/Home/applicati...de=30713069069&mo=14201777488&ba=14201772640&
Rubber bushings for the Opel Omega/Catera. I have sent emails to Meyle and German Auto Salvage asking whether these bushings are Heavy Duty. No answer yet.
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Meyle Control Arms w/bushings & ball joints: part # 616 050 0017(Left) - 616 050 0018(Right)
New wishbones loaded with Meyle rubber bushings & balljoint.
http://www.meyle.com/Home/applicati...&de=6220321167&mo=14201777488&ba=14201772640&
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NOTE: Meyle makes a large range of replacement parts for the Opel Omega that we can use in our Cateras.
Use their search engine and leave the the last box default [select...(not required)].
Korman Autoworks:
BMW M5 (E34) Heavy-Duty Thrust Rod Bushings: part # 3112567
http://www.kormanfastbmw.com/m5m6susp.htm
Heavy Duty BMW/M5 bushing for Catera front/horizontal control arm bushing.
MOOG: part # K90137 (1993 BMW/M5 Thrust Arm Bushing)
http://www.rockauto.com/catalog/raframecatalog.php
BMW OE bushing for Catera/Omega front/horizontal bushing.
Bavarian AutoSport:
BMW/M5 Upper Control Arm Bushing: part # : 31 12 2 226 528
http://www.bavauto.com/shop.asp
BMW OE bushing for Catera/Omega front/horizontal bushing.
Bavarian AutoSport: BMW/M5 Upper Control Arm Bushing: part # N81368BAV (POLYURETHANE)
http://www.bavauto.com/shop.asp
Quote: "Our exclusive street performance bushings and mounts are made with a more forgiving urethane formula! During spirited driving, polyurethane bushings and mounts provide more responsive handling and maintain better control over suspension geometry than stock bushings. Along with this improvement in handling, though, comes a stiffer ride -- a welcome side-effect on a smooth race track, but much more noticeable on the streets. Our street performance urethane is formulated with a touch of polyester. This new compound is more forgiving than 100% urethane, so it’s better for street BMWs."
Powerflex BMW E34/M5 ('88 - '96): part # PFF5-601 (POLYURETHANE)
http://www.powerflex.co.uk
Polyurethane front horizontal BMW/M5 bushing for Omega/Catera.
RockAuto.com:
ACDELCO Front/Horizontal Bushing OE: Part # 45G9329
SPICER Rear/Vertical Bushing: Part # 5651329
SPICER/RAYBESTOS Part # 5071237 {Professional Grade}
Front Suspension; Left Lower; Complete Arm With Ball Joint & Bushings
SPICER/RAYBESTOS Part # 5071238 {Professional Grade}
Front Suspension; Right Lower; Complete Arm With Ball Joint & Bushings
http://www.rockauto.com/catalog/raframecatalog.php
INSTALLATION TIP: All rubber suspension bushings mounting bolts must be tightened after the wheels are supporting the car's weight. This ensures they won't be pre-stressed and wear out prematurely. Urethane bushings may be torqued while the vehicle is still raised.