mountainbiker2

This is what prompted me to get them.
http://forums.corvetteforum.com/auto...trol-arms.html

Car: C5 FRC #2684 Hoosiers A6's. 335/315

I took my car out to a 12 lap autocross practice. Just a heads up, I was not driving well all day, plus the track was not to my liking. Basically the bearings did what they suppose to do. Let your car absorb bumps and let the suspension work properly. I did NOT find that the camber could be less by using these. Of course, I'm coming from poly bushings. What I did find out was, that all your suspension setup is useless now. The car will rock and sway all over the place. Bad for now, great for when I get it figured out again. Spring change or stiffer sway bars for sure. Back to adjusting the shocks too. When I get it all figured out again, I'm sure the car will be more capable. Just one step closer to what the competition already has, but like usual, they will out run, out spend, and out think me for the hundredth time. I just might put the car up for sale and return to Super Stock.

Steve A.

Z06phile

I guess they meant less camber vs stock rubber??? Comparing the deflection of poly vs bearings would be minimal, so maybe .1-.2 deg less static. It's hard to believe the bushings stiffen things up that much, but I've never tried moving the arms with everything disconnected either.
Are you still on leafs?

Since you've ran both. Are you as happy (fast) in a "stock" car? You know... hands shaking after a run type of happy

torque*is*cheap

Hey Steve,

Sorry about the teething problems with the bearings. Are they so free that you're missing the extra "spring rate" from binding bushings?

One step backward before two steps forward....I'm sure the setup will sing when you get it sorted out.

--Doug

froggy47

I think there is still friction in the Pfadt poly's and maybe next to none with spherical. That's could be why the car is moving more.

Check out my thread about ACS roval & let me know what you do re: down shifts.

mountainbiker2

If you don't grease your poly bushings all the time, believe me they hardly move. Plus that's with no load on them. I have coil overs. I get shaking hands no matter what car I'm driving.

I believe the poly bushings caused a lot of unpredictable spring rate.

Steve A.

fatbillybob

That's why I always liked delrin. But delrin needs to be milled to size vs. ploy which I think can be molded. But I'm not sure on that. Anyway with delrin you get very very close to spherical bearings with about as much maintenance. Last set of delrin bushings I cut cost me 50 bucks in material and a few days to do the job.

dvandentop

i think phoenix is selling delrin bushings for $1200```

mgarfias

Thats because they're having to cut them to fit each car.

trackboss

Try cutting cutting just one pair of bushings (or anything to spec for that matter) on a manual lathe and you will realize that is a more than fair price

Aaron Pfadt

Steve,

Thanks for putting those parts on your car. We certainly appreciate you choosing Pfadt components.

As you have learned, spherical bearings are a game changer coming from poly. The main benefit to these is going to be reduced friction versus poly. The deflection will be removed also, but in terms of what you are feeling, the friction is the major player.

The car will feel softer because of the reduction in 'damping' (bad damping at that) from the poly. These bearings will give you the opportunity to put that damping back into your suspension strategically. This means you can add stability to the car without hurting mechanical grip. I would start with the old shock tuning method of setting damping soft, and increasing it incrementally until you see slower lap times. Keep in mind that rebound damping - in general - is the enemy of mechanical grip, so keep that soft and increment the compression damping (low speed primarily if you are running 3-ways) until you get good stability in the car. Again, you will know you have gone too far after you see lap times go away.

On a more fundamental level, you also have the opportunity to increase spring rates to reduce overall roll/dive/squat while still allowing the car to react well to bumps. Again another benefit, but that you can tackle down the road. Theoretically, the overall roll in a steady state corner will be equal with poly or spherical bearings, but practically there is enough stiction in the poly that you probably saw less overall roll.

Dynamically you will see faster roll rates with the sphericals, so in any turn that you transition out of before you reach steady state the roll amoiunt will be higher than it would be with poly. You can dial that back with shock damping, or you can add roll stiffness with spring or anti-roll bars.

The tuning may be a little work, but it will certainly be worth it. That spherical bearing kit will eventually make your car much more precise, and increase mechanical grip levels significantly.

Feel free to call or write if you need any more guidance on the points I talked about.

-Aaron

mountainbiker2

Thanks Aaron for the detailed response. I called your shop yesterday and got the same response. If I wanted to put on stiffer springs, how much do you think I should go? I have 600 front, 550 rear. Keep in mind the weight of my car. #2684. I have an autocross this weekend again. I put on a 32mm front sway bar coming from a 28.5. I also added a rear one. 25mm, adjustable. I didn't have a rear one on at the time.

thanks,

Steve A.

Aaron Pfadt

Steve,

I probably would not up the spring rate right now. Again, mechanical grip is key, and springs are not adjustable. With spring rate, you can not adjust the rate at which the tires load up, with damping you can. If you keep the springs softer (your rates are not unreasonable) and control the loading with damping, you can make adjustments between runs and sessions. This will allow you to put a lot of firmness and stability in the car on a course or track that has high grip levels, and soften it on a low grip course. If you put on very stiff springs, you are stuck with that load transfer and can not adjust as much to suit the course conditions.

If you were to change springs, I would move the 600s to the rear and put 700s on the front.

Also, you could consider a set of our Pfadt Light Rate sway bars which will give you some spring rate in cornering (roll stiffness only) and also a bit more tuning capability for overall balance. Those will still allow good weight transfer for acceleration out of corners.

The system is multi-faceted and has too many variables However, you have a great starting point and a lot of flexibility. Try things and take good notes. Once you understand how your car reacts to changes, you will have the ability to adjust quickly to suit any course.

-Aaron