I'm looking to replace my rear trailing arm bushings with polyurethane but have a few of questions.
Does anyone know the shape of the center bar that goes through the bushing? I have a set of Prothane bushings designed for the 2000-2006 Focus that may fit (there's a previous thread on using bushing sets for that car on our cars) but it requires one to reuse the center bar (dogbone) from the old bushing and the bar has to be round in the middle. Before I go cutting the old ones apart and burning off the rubber it would be nice to know if they are round and will indeed work with the new bushings. Looking at it on the car and images of OEM replacement bushings makes me think the bar is flat or oval shaped as it goes through the bushing.
Second question also relates to the Prothane poly bushing and the dogbone. I notice some replacement poly bushings come with new dogbones with larger diameter rings on either end to keep the bushing centered. Since the Prothane reuses the original dogbone it won't have these and thus the bushing will be free to slide side-to-side on the dogbone and I am wondering if this will create a problem. I thought initially the pocket where the bushing sits in the body when mounted would keep it centered but in looking at it on my car it looks too wide to accomplish this.
Third question pertains to whether it is a good idea to replace the trailing arm bushing with polyurethane or not. I've read some discussions on the Focus sites that the 'give' of the trailing arm bushing is a specific feature of the rear suspension having to do with 'passive rear steer.'
If I can't use my Prothane bushings I think I'm going with the Nolathane REV114.0036 bushings (suggested by avenger09123 in another thread) since they come with new dogbones, appear not to be solid poly so they may still give elements of the passive steering, and they can be installed without a press. I only paid $17 for the Prothanes so not a big loss if I can't use them.