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Reduce that pogo on your lowered Grand Prix
The reason for doing this mod: Just about everyone that lowers their Grand Prix with Eibachs, Progress, B&G etc springs and retains stock struts or KYBs or Monroe aftermarket struts faces the problem of pogo, a sometimes violent bouncing of the car up and down over bumps that at best causes unpleasantness and at worse can be dangerous if an emergency maneuver is required. But there is now a mod that will greatly aid if not eliminate pogo!
How this mod works: The top strut mount on the front fenders have a retaining nut along with a retainer cap; this will hold the strut rod, which comes through the center of the mount, in place. With the stock springs, this retainer is in direct contact against a rubber cushion underneath it, this is what directly connects the strut to the mount. With lowering springs, this retaining cap is raised up about a quarter to a half inch, so the strut is no longer firmly secured against the mount! What this means is that the spring can bounce up and down this tiny bit before the strut even begins to act on it.
The fix comes right from GM! When you go in, ask for P/N 10203412, which is the retainer specified for 97-03 GPs for the lower cradle assembly. You are greeted with a much more shallow design. This new retainer will firmly press against the rubber cushion, even on a lowering spring!
Notice the difference in depth of the cup on the retainer when comparing the new ones on the outsides to the OEM one in the center!
Parts you need:
2 of GM P/N 10203412 (or 4 if you want to do the rears, which I did.) An air impact gun with a 19mm or 21mm socket (19mm or 21mm wrench and allen wrench for the rear struts...These need to be done by hand.) This mod will take all of 2 minutes to do up front (about 10 for the rear struts).
Benefits: Greatly reduced pogoing with lowering springs That BANG you get on potholes seems less violent as well
The procedure is very easy. Set yourself up with an airgun and a 19mm or 21mm socket, deep if possible. With the car on the pavement (and not raised!!!!), remove the top nut from the strut.
You can then remove the retainer cap and set it aside.
Grab the new retainer you bought from GM and put it in place on the mount, then take the retainer nut and zip it back on with the airgun until it is tight. Move to the next side and repeat and that's it! Notice how well the new retainer cap mount sits on the rubber mount cushion.
Disclaimer: While the author uses this modification on his own vehicle with success and would recommend it to others, he cannot be held responsible for any mishaps that may occur on other vehicles the result of following this tutorial. You perform this modification at your own risk.
Special thanks to Will Rishworth ("Overkill" on ClubGP) for the excellent pictures.
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