oversteer

I am considering installing the Pfadt Control Arm Polyurethane Bushings and Sleeves kit on my C6Z. The car is a street car but it sees a few track events per year (advanced/instructor level) and lots of twisty roads. The chassis is stock other than new DRM Bilsteins.

The goals for installing this kit are:

To increase the steering and chassis feedback + feel.
My car feels amazing up to 9/10th but right at the limit the chassis seems to move around on the suspension and it doesn't clearly transmit what it is doing. No doubt many drivers can post fast lap times with this feeling but it bothers me and I haven't experienced this in any other car I have tracked. It just doesn't have the pinned down feel of a GT3, M3 or F430 and while I appreciate that the C6Z is as fast or faster than any of them I want it all - the speed and the feel

To reduce the tendency for the car to change direction on and off throttle.
The engine has so much torque and the tires generate so much grip that getting on and off the throttle hard really makes the suspension move around (bushing deflection?). Even in a straight line shifting hard from 3rd to 4th or 4th to 5th causes the car to yaw a bit. My guess is this is caused by the rear toe change due to the bushing defection. Am I onto something here?

To be able to reduce the amount of static negative camber required.
My car is set to the Pfadt 'Performance Street' alignment settings with F -1.3 and R -1 camber but I get lots of outside tire wear. Hopefully the Pfadt bushings will reduce the outer tire wear by keeping more camber in the suspension under hard cornering.


Two questions.

Are Pfadt Poly bushing users happy with the performance improvement or is it not a good trade off vis a vis the increase in NVH and the potential circlip issues some have reported?

If you installed Zerk grease fittings which size fittings did use and can you please post some installation photos?

Lawdogg

My Pfadt poly set up does what you are looking for. I did have significant problems with the circlips coming off and the bushing pushing out of the upper control arms. Once I filed some of the bushing material off the inside of the bushings so that they wouldn't rub against eachother inside the control arm they quit knocking off the circlips.

I've had them on the car for two summers and about 12 track days.

el es tu

Im currently using the vette as a daily driver and am happy with the performance of mine - for 300 bucks you cant beat it. The slop in the suspension is greatly reduced and you can "feel" more of whats going on. Yes that translates to nvh, but its not annoying or tiring.

My only gripe is not going with their all metal kit instead; no matter how good it is, you always want more...

oversteer

Thanks for the replies.

Lawdogg and el es tu, prior to installing the Pfadt bushings had you also noticed what I call ' the tendency for the car to change direction on and off throttle'?

froggy47

I have them on my c5, never needed to drill holes for zerks, when I grease them (properly) they are good for 1-2 years at least. I take them apart to ck and the grease is still there.

Mine still dances a bit on a high rpm shift, that may not change much, but to me it's managable.

That may have more to do with tires & alignment. a6 doesn't dance as much as others (335's)

If your car changes direction with just on/off throttle you have something broken.

naschmitz

Are you talking about the car nosing to the right or left under throttle and then swinging back to center when you lift? You probably have something worn or loose in the rear that is changing the rear toe as you load and unload the rear. Or you need more toe-in in the rear because under load you have toe-out.

Bushings are the single biggest hit to ride quality, but they help immensely in track.

I've been through a set of Pfadt poly and really didn't like how sticky they are, even when greased. Got delrin on the car now and I love them.

oversteer

Yes exactly.

Everything checks out 100%. The car has 7k miles.

Maybe I do. IIRC the current setting is around 0.12 toe-in per side on the rear, so over .20 total toe-in. Isn't that enough?

Really that bad? Since the stock rubber bushings don't rotate (they twist) wouldn't well greased Polyurethane bushings remove a lot of friction (sticktion) from the suspension movement?

Delrin would be ideal from a cost and performance standpoint but I doubt I could live with the NVH on the street

McMung

I went with Pfadt's poly bushing kit and I installed zerks for each one.

I also went with tubes of the same poly grease that Pfadt specify, this is Energy Suspension Formula 5. It is extremely sticky, but does pump with a grease gun.

For the zerks, you basically want to cut a trench around the circumference of the bushing in line with where the zerk will be. You then drill several (e.g., 8, equidistant) holes through to the center of the bushing on that trench line and to meet up with each of the internal grooves in each bushing. This way, when you inject grease into the zerk it will flow around the trench, down into the holes, and along the internal grooves.

EDIT: You ALSO want to cut grooves on the FACES of each bushing so the grease has somewhere to flow out. If you don't do this you will find a battery or pneumatic grease gun will not have the ***** to pump through (and if you force it with a manual gun you might risk pushing grease between the bushing and the housing.)

EDIT 2 (Sorry! I keep remembering details...): Keep in mind that there is a large variance of bushing housing/bore sizes from the factory control arms, it IS NECESSARY to trim the faces of the two piece bushings so they do not smash into each other and create bind. If you think about it, the two piece design from Pfadt is ideal for the zerk setup also (since you can maintain whatever trench you want, and you dont need to drill holes... the grease will just freely flow around the center bushing pin and out of the interior grooves.) I'm fairly convinced most who complain about poly bushings being "too sticky" have this problem where the bushing is far too large for the bores of their control arms and it is causing the bushing to compress and "grip" the center pin with a LOT more force than would otherwise be the case. Make sure whoever installs checks this thoroughly.

I used generous amounts of isopropanol (e.g., http://www.goldeagle.com/brands/heet/) as lubrication while I was pressing the poly bushings into the bores. Some of the bushings are quite difficult to get in, and require just the right alignment and a stable press fixture. They will look like they're going to explode/burst/split, but they won't...

I did a lot of testing on one bushing to make sure the back side would be reached and it does work (albeit with a bit of waste on the "front side" (zerk side) of the bushing simply because of less restriction.)

That particular prelube/grease should last for a very very long time, if it ever starts making noise just give them all a quick hit with more prelube from the gun.

Very happy so far and the poly bushings provide all of the things you're looking for.

Re: spherical/steel bushings, Pfadt have been fairly clear here that these are not suitable for the street due to street use quickly wearing a pattern/groove into the ball & socket so you might not want to consider this if the car sees any street use.

If you do the work yourself, you do NOT want to have to do it again!

McMung

When I was assembling mine with upper and lower control arm on, both attached to spindle, I could raise with one hand and they would drop by themselves. A lower control arm would drop by itself, but an upper would not (they're just too light.)

How much less "stiction" do you really need? The car weighs north of 3000 lbs and the full unsprung mass of each corner is a lot more than this (combined control arms + bare spindle, no bearing)... it seems negligible at this point unless you have some kind of obsession going on.

naschmitz

Mine were never that loose with the Pfadt poly and I doubt yours will stay that way for very long. In changing front end alignments for street and track I would rotate the UCA pivots 180-deg. This would take a long screwdriver or crescent wrench to get enough torque to do this. With the delrin, I can rotate the pivots with my fingers even after a year of use.

I didn't notice any difference in NVH between poly and delrin -- both are much worse than rubber of course.

Bill Dearborn

Not sure you will get rid of the direction change due to going on and off throttle. Some of that is probably due to the thrust angle not being dead nuts zero, some due to the bushings flexing more on one side than the other and in corners most is due to transferring weight back and forth between front and rear which changes the steering at each end.

Bill

oversteer

That is a surprising observation. Delrin has essentially zero give or deflection while most Polyurethane bushings (80D) still deflect a fair amount which should lead to improved levels of NVH.

Are you using the Phoenix Delrin bushings? What other mods does your C6 have? Does it see a lot of street miles?

oversteer

Bill, interesting point with the thrust angle. I will check my last alignment sheet to see if that spec was noted. How close to zero is it possible to get?

I don't expect the poly bushings to get rid of all throttle steer but many other fast and powerful cars (911 GT2 & GT3, GT-R, M5, F430, etc) with stock rubber bushings don't exhibit the annoying and disconcerting throttle steer / yaw that my Z06 does.

oversteer

Anyone else out there with some thoughts on this bushing upgrade?

I am surprised that there aren't more forum members that want to offer their $0.02 on what surely must be a very common upgrade for C5 and C6 models.

argonaut

I recently removed the Pfadt poly in my C5 and am moving on to LG Monoballs. I did have the zerks installed and if you do so, then IMO you don't need the fancy Energy suspension glue...I mean grease. I think you can see in some of the previous posts the importance of the install. Mine, I think, were probably to tight and led to a lot of stiction. Custom fitting each bushing to its location is critical to minimize this. In the end I thought they were ok and probably an upgrade over stock (keep in mind that most people upgrading to poly already have worn out rubber, so they tend to rave about the brand new parts...duh.) but I had the extra money and was dissatisfied enough to go a different route.

T4Eater

I have read EVERY bushing thread on this forum through google searches and I'm still amazed that these cars have such a nightmare with control arm bushings. I've even chatted with Froggy47 through one of his youtube videos. It seems there's down sides to both kits. Mainly being that the VB&P squeek horribly and the Pfadt ones have fitment issues and bind. I spoke with Doug Rippe on the phone and he recommended the VB&P kit due to the fact that he has seen first hand peoples cars with radical binding issues with the Pfadt kit. I think Phoenix Performance wants nearly 1000 bucks for a delrin set lol

Edit:
Has anyone ran the P_S_T bushings ?