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

[J P Stein]

Front, rear, both?
How much $$$$ do you want to spend?

I have the hard polygraphite in the rear. They've been in there for about 4 years. I just took the back apart.....they looked good. Lubed them up and slapped it back together.
Racer Chris has written about some mods he makes to the trailing arms to make the rear set-up work as I would like it to. I have an extra set of em'.....maybe next winter.


Muellers front needle jobbies work nicely, "striction" is nil. Longevity is an unknown. Bring money....... (IMG:style_emoticons/default/smash.gif)

[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)

[Bleyseng]

If cost is a factor stay with the plastic bushings, they are pretty cheap. Bronze and Mueller bearings cost $$$.
With the plastic bearings make sure you get the supplied grease!
Geoff

[echocanyons]

Mike,

when you gonna brew up some needle bearings for the trailing arms?

[Mueller]

Trailing arm bearing are on the way.....I'm just waiting for the rest of the prototype parts to arrive so that I can put them on my car to test them out.....as of now, my car is still not running so I better get on the ball and get mine running (again) or find someone elses car to install these on....oh nooooo (IMG:style_emoticons/default/smile.gif)

Geoff is correct, if cost is an issue, the plastic bushings are the way to go...even if money is not a big deal, I wouldn't recommend the Needle bearing to just anyone since yes, they will need to be inspected down the road....a year or two depending on miles and how hard the car is beat-upon....plastic bushings are perfect for those that want to "set and forget" about the parts installed on thier car.

[Brad Roberts]

JP,

We have several 914's (street and race cars) with complete roller bearing suspension that have been on the streets/tracks for 2+ years. These are cars that are done. Cars that get driven every week whether its too and from work or at the track. I would have NEVER asked Mike Mueller to dupe them if I didnt feel they could be slightly improved and used in every application. We also needed something that Joe Blow user could install at his house, not something that requires you to send me your control arm so I can machine and install the pieces.

I agree they are steep, but once you drive the car with the fornt and rear setup installed. You are SOLD on them 100%.

B

[echocanyons]

So am I right in saying with a little maintenence one could have roller bearings in the front and rear and use the car on the street in a daily manner?

how often should one relube the bearings?

[Brad Roberts]

It depends on how much you drive the car in rain. Drive the car in the rain for several months straight and you will end up lubing them every six months (same damn thing you would have to with Poly bushings) They come apart so easy that it wont bother you too lube them. The poly ones come apart just as hard as they go together. We started using silicon on the fronts...I wont check that car for another year.

B

[ThinAir]

Years ago I bought some new front bushings from Perfomance Parts or Automotion (Delrin - I think). I had someone else install them. I had a terrible time with loud "cracking" noises when going over bumps and the car would often stay stuck in a depressed suspension position after I got out of the car. After a couple of minutes there would be a loud "crack" and the car would jump up to "normal" height.

What can be done with these? If they just need lubricating, what is used for the lubrication?

[Dave_Darling]

Step 1--Take 'em all apart.
Step 2--File and hone and sand to fit. They all gotta fit proper.
Step 3--Use the "gorilla snot" grease that Weltmeister supplies. (Half grease, half velcro, an alllllll nasty!)

JP has been figuring out the "file and hone and sand to fit" routine for a while. I think he has some ideas for you.

Note that, with the bearings, there is zero "stiction" like you are noticing in your current setup.

--DD

[Brad Roberts]

They need lube. That cracking is exactly why we have gone to roller bearing suspensions. I am willing to bet your car road like wagon. The only way to lube them is to pull them apart. I never did determine what they sold with the kits..but I do know its is used in swimming pool installs. Its a very very sticky "lube".


I have several large tubs of it... so I havent bought any in years.

B