GrantB

Long story made short: I've tried both and recommend Pfadt's bushing kit over VB&P's.

I had VB&P, and the rears were making noise from day one (the lower left rear seemed a bit oversized for the crossmember). After 6 months or so the front uppers started to make a TON of noise too. So I ordered Pfadt's, and swapped them out. They are only one week old, but are making no noise whatsoever and the control arms moved more freely (especially that left rear, which I think was causing handling issues).

Pfadt's bushings have grooves on the inside of the bushings where they rotate around the sleeve. When I pulled out the VB&Ps, most were very dry, so I think these grooves are important. They are also a bit lighter than the VB&P, being aluminum instead of steel. Of course, there is nothing stopping you from cutting your own grooves in the VB&P bushings.

The only issue I have with the Pfadts is the upper rear bushings appear to be slightly oversized for the sleeve. I don't know if this was intentional, or if the polyurethane will deform on its own, but after install they were more difficult to move than the other arms. They didn't make any noise, though.

The VB&P product feels like its a higher duromoter material, or that may just be because they'd been installed for a while.

Of course, it may be that after 6 months the pfadts will start making noise and binding too... If so I might just pull out the rest of my hair and install spherical bearings with some dust boots for street use.

fatbillybob

I am not sure why manufactuers like polyU. They always squeak and customers always complain. Once I raced a car that had a race bushing kit that was $4000! So being cheap I bought a $400 chinese lathe and $50 stick of dupont delrin and cut my own bushings and reused the OEM shells. It took me a week to learn how to use the lathe and cut all the bushing parts but it was worth it. I got no suspension noise and amazingly long wear as in I never changed them after many years of use and sold the car with them on. Delrin is self-lubricating I found out and does not make squeak noises. You do get more impactish noises closer to what you would get with monballs but still not the clunk of monoballs. IMO delrin is the happy medium. Delrin is between polyU and monoball for material hardness but easy to live with for daily driving.

doje

Does anyone make delrin bushings for the C5? I have the VBP kit myself and the noise is TERRIBLE.

gkmccready

Delrin doesn't really work on C5/C6. Not very many of our bushings stay square due to how you adjust alignment...

FWIW, my Pfadt bushings don't make any noise...

GrantB

Well, the uppers should be do-able, and the lower fronts if you don't mind giving up caster adjustment.

How long have you had them in for?

gkmccready

I think they've been on the car for a couple thousand miles or more now. The were a forced issue when one of the stock front uppers walked too far to be able to put the dogbone back over the stud kit...

As for the delrin, yeah, rear uppers and front lowers you could do. Worth it? Dunno. You wouldn't necessarily lose caster adjustment, you can still do that with the front uppers where you'll be adjusting camber, anyway.

fatbillybob

I'm not sure what this means. I think there is only one bushing in the rear that kind of pivots as opposed to rotates. I have not looked into the issue at all since it violates my class rules to change from T-1 or stock. But if monoballs can be made and polyU can be made I bet delrin could be made to work too. Even if you made 75% of the bushings in delrin could we say that 75% reduction in noise could be had?

ghoffman

It is not just a noise issue, it is a friction issue with all poly. If I disassemble all of the bushings, grease them liberally, my car tracks and handles very, very well. Now, if I go say a month without re-greasing them, the stiction is so bad the car hunts and darts around alot. I have had 3 brands of poly including the 2 brands mentioned here and I think they all have this issue. Do not confuse friction with damping, they are totally different.

0Randy@DRM

These haven't had greese on them in a long time. The lower bushing in fact didn't have much because I washed the hell out of the crandle and the greese went with it.

Randy

meldog21

When I swapped out my stock for Pfadt bushings I noticed that the control arms did not move at all with stock bushings. They were locked and spring loaded into the normal weighted position/ride height. When I raised or lowered the arms they were hard to push and sprung back to their original position. With the new Pfadt bushings installed the suspension moved easily and dropped in freefall with almost no friction. The bushings are not supposed to cause drag on suspension movement. The shocks are supposed to do the damping. Noise or not, any brand of poly's are going to work better than the rubber stock bushings.

Dog

ghoffman

Sorry to have to disagree, the stock rubbers add spring rate, but have zero friction because they are in shear and have no sliding action at all.

gkmccready

Not sure I follow, Gary. The rear uppers on the non-C6Zs have the bushings shoved in pretty tight, the poly does seem to slide in the clevis better than the stock rubber did. Isn't that friction as the rubber needs to slide over the steel?

ghoffman

No, the rubber does not slide at all, it is a flexure. It has zero dynamic friction (perhaps some hysteresis). I am just going to have to do this correctly, since nobody else seems to want to. Maybe Obama can bail me out and I can get some money to fund new projects!

gkmccready

Oh! My brain is having a real hard time imagining the upper control arm moving all the way through it's range of motion simply with the ends of the bushing staying still and the rubber inside the arm twisting, though.

GrantB

Gary is right, the OE bushings and bored in and basically stuck to the inner sleeve and control arm. The rubber just twists. This is why its a good idea to loosen the clamping load on the inner sleeve when you lower a car.

However, the friction added by the poly bushings seems to be very low. Aside from the left-rear, my VB&Ps moved very freely, even the ones that made a lot of noise. My experience is the same as Randy's, basically.

I've always been told that Delrin wears out, becoming oblong. Is this not correct?

BTW, I asked Pfadt if they ever installed grease zerks on the arms. They said they didn't, and would be worried about adding a stress riser. I didn't put any on, but have heard of people doing so with Mustang control arms.

froggy47

When one of the rubber bushings has moved (like c5z front/upper/rear bushing especially) does it , thereafter, have some slippage inside the metal of the arm, or just "stuck" in a new orientation.

I'm on my 2nd set of oem & it's moved. Stock rules require the oem.



I may mark it with a paint pen & see if I can find slippage.

drivinhard

the ones I've used on other cars tended to cold flow over time.

probably not an issue if you are replacing them often

ghoffman

No Delrin does not cold flow, but certainly there are materials that do. The poly bushings on my car have massive friction, like the whole assembly will NOT do what is shown in Randy's video, rather they will stay up, unless they have been lubed recently. I do not want to say where they came from because they were a professional courtesy prototype set that were no charge. However, they do not work very well. I will do something else as soon as I am done with other projects. I have the plastic prototype 3-D pieces in next week that are done on a Dimension uPrint 3D printer. Really cool technology that allows me to go from Solidworks to a plastic (ABS) part in minutes. You cant run on it, but it is great for fit check parts.
http://www.dimensionprinting.com/3d-...ng-uprint.aspx

drivinhard

I'm not an ME, maybe cold flow is the wrong term.

What would be the correct term for a material that compresses (and becomes loose, needing constant re-torque) under a given stress over time?

ghoffman

No, not at least with what we use. I have stopped giving out what alloys we use on these forums, too many copy cats out there with no honor.