Which bushings: PolyGraph, Bronze, needle bearing,, or Delrin? Options

[airsix]

Ok guys, what suspension bushings/bearings should I be installing?

Options:
Poly Graphite (soft/hard)
Delrin
Bronze
Needle bearing

Most importantly what kind of life can one expect from each of these options before things start getting sloppy from wear? Since the car is dual purpose I am interested in ALL the pros & cons of each.

Car: (to give an indication of my personality type)
Dual purpose currently set up with:
21mm torsion bars
19mm adjustable front swaybar
Koni sport yellows on medium
180# rear springs
911 vented A's on all 4 corners
225's on 7" front and 245's on 8" in rear
EFI turbo 1.7 to be replaced with 2.7 six (once it's finished)

-Ben

[Mueller]

These are my feelings on this subject:

Bronze bushings:

Unless the inner diameter of the Bronze Bushing is perfectly matched to the OD of the
A-Arm shaft, one will experiance slop since the you will only have one point of tangancy between the a-arm shaft and the bushing (picture your crankcase bearings, without oil pressure you'd have the same problems)
Sure the bronze bushings can be greased and lubed, but the grease will be squeezed out while in use. The surface of the a-arms are not smooth by modern bearing standards...the smoother the surface the better. If the a-arm OD is too small, how do you build it up to get a better match on the Bronze Bushing ID?, for your average person, you cannot...the same is true if the a-arm OD is too large....you can file/sand it down, but can you accuratly get it perfect 360°'s?


Poly bushings (hard and soft) and Delrin:
Same issue as above, the ID of the Bushing, must be matched to the OD of the A-arm after the bushing has been installed in the factory bushing mounts.
Grease helps significantly, however, due to plastic wanting to form, the plastic bushing will eventually want to fill in the voids and dips on the uneven a-arm surface.
(Chris Foleys rear kit seems to be a good design since he does supply a precision ground bearing surface for his Delrin Bushings which currently, is only availble for the front A-arms with the needle bearing kits)(Is the Tangerine rear kit regular Delrin or Delrin AF? Delrin AF is has Teflon impregnated in it)


Needle Bearing kit:
Precision ground and hardened sleeve slides over the imperfect A-arm shaft surface
(unless JP is working on it, then nothing just slides together (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smash.gif) )
The Needle bearing has 35 individual needle bearings to be in contact with the sleeve at one time.
Is this 100% coverage...no, but it is many times more coverage than the bronze bushing...in fact at any one time, the bronze bushing can only have one point of contact with the A-arm sleeve. This point of contact will vary depending upon the movment of the A-arm. (top of bearing while at rest, who knows where else while in motion?)

The plastic bushings can have more contact with the a-arm shaft (and the trailing arm shaft) since it will want to give in to a harder surface...100% coverage? No and for these you wouldn't want that since it would mean the bushing would be squeezing the shaft...not a good thing for a near-friction free application.

Now back to your question:

For the "average" street/auto-x'r, I'd say that any of the engineered plastic products should be fine as long as they are installed correctly. (stay away from 100% Teflon...too soft)

Sorry for the ramble and I hope it makes sense (IMG:style_emoticons/default/mueba.gif) (IMG:style_emoticons/default/mueba.gif)
(under the influence of too many cold medicines right now)