In my quest to find a front-end suspension noise I have decided to replace my worn factory sway bar bushings. Unfortunately, the only option we have is to buy the rubber ones from GM. If you have the 28MM sway bar, the best price I have found is $20 each. With the 30MM bar you can get away with $7 each.
If you haven't looked, the bushings and the sub-frame are a little unique. Instead of using a flat bottom bushing, the sub-frame has an indentation where the bump on the bottom of the bushing rests. This design keeps us from using stiffer polyurethane bushings available as aftermarket upgrades.
I stumbled across a post in the Aurora forums where a member was upgrading to a STS sway bar and they decided to use polyurethane bushings from Energy Suspension. However, they have the same sub-frame indentation that we have. To get around this problem, the OP cut a small piece of steel that sits above the indentation and allows you to install the improved (and cheaper) aftermarket bushing.
The first thing you have to do is figure out if you have the 28mm bar or the 30mm part. I think the rule of thumb is that the SLS usually has the 28mm and the STS has the 30mm. However, I have also read that it isn't always the case so you should check to see what you have. Amazon has the Energy Suspension bushings for $24.
28.5mm - 9.5170G (Black)
28.5mm - 9.5170R (Red)
30mm - 9.5171G (Black)
30mm - 9.5171R (Red)
According to the manufacturer, both colors are just as hard. The only difference is that the black version is graphite impregnated. I chose black in hopes that the graphite will help to prevent squeaks.
Cover the Indentation
You will need to make two small parts to cover the sub-frame indentations. I used a 2ft piece of steel from Lowes (aprox $6). You can use a hacksaw to cut two pieces that are just a touch more than 4 1/2" long. The steel bar should be 1 1/2" wide. I painted mine to prevent rusting.
1. Jack up the front end, put it on stands, and remove the tires.
2. Remove the sway bar end links. You will need to use a wrench or locking vice wrench on the top nut and a 14mm socket.
3. Remove the two 13mm bolts in each bracket holding the bushings in place.
4. Take the two brackets that you removed from the car and use them to mark holes for drilling out the steel pieces that you cut. You will need to drill those out so that the 13mm bolt can pass through.
5. Attach the new bushing and bracket to the sway bar. The 4 1/2" x 1 1/5" steel mounts will sit between the sub-frame and the new bushings.
6. Reattach the end-links. (I got new poly end-links from Moog)