Cool bushing photos

[Aaron Pfadt]

Think the stock bushings on your Z are up to the task of a track day? Think again!

I was doing a once over on our C6Z after two intensive days of track testing a bunch of existing and new suspension products at Reno Fernley last week (watch for results and video soon)and found some bushing carnage.

We were testing the Z in a stock configuration and adding suspension components to determine some lap time deltas. With that we retained the stock control arm bushings for all the testing because of the difficulty of changing bushings at the track.

Both of the front upper control arms had severe slippage of the bushings. The interesting thing is that is must be from rotor torque. The upper control arms are both pulled forward on the chassis. I would have expected them to be pushed back (toward the rear of the car) from holding the car back under braking. Instead the torque on the upright assembly under braking rotates the upper control arm forward.

Here is a little video of the spindle under braking also. Look at the rotor glow! I'm in the market for some new rotors






I'll post a full write-up on our testing very soon. It has lots of interesting data.

later,
Aaron

[DJWorm]

Aaron:

Correct assesment. This has been documented here before on competition cars. Especially on AutoX cars that experience a high degree of lateral turning forces, hard acceleration and hard braking.

The previos fix was to replace the bushings with either a harder Dur rubber (as in the T1 bushings), Urethane, Poly Graphite, Nylon, Delrin or full race metal bushings.

The Urethane fix was a carry over from off-roaders. The down side was they are very noisy and squeak.

Better yet were the Poly Graphite bushings offered by VB&P. These are essentially Graphite impregnated Urethane which self lubricates the bushings and eliminates the noise and squeaks.

The full race metal & Delrin are too harsh except for a dedicated race but even more effective.

I noticed that you guys have come out with new Urethane bushing for the C6 Z06 (presumably the solution your post is setting up). I just wonder why you did not use a graphite impregnated Urethane instead of straight Urethane in your new C6 Z06 offering. Please address these concerns.

[No Doubt]

They're probably Polyurethane, not Urethane. Urethane (Ethyl Carbamate), despite the name, is not a chemical component of Polyurethane, although you will see the two words used interchageably quite often.

Graphite particles can be impregnated in Polyurethane to act as a lubricant, as you said. Hence the term "Graphite Impregnated Polyurethane".

[Aaron Pfadt]

Originally Posted by DJWorm

The full race metal & Delrin are too harsh except for a dedicated race but even more effective.

I noticed that you guys have come out with new Urethane bushing for the C6 Z06 (presumably the solution your post is setting up). I just wonder why you did not use a graphite impregnated Urethane instead of straight Urethane in your new C6 Z06 offering. Please address these concerns.

The polyurethane used in our bushing kits has graphite impregnated in it. It has become 'standard' in polyurethane bushing components. It certainly does have properties that reduce friction and promote quiet operation.

The real measure that we use for keeping our bushings quiet is a specially formulated lube. It is extremely tenacious and thick. It gets in the grooves in our bushings to provide lubrication over a long period of time. The other aspect of our kit that is important is that all of our bearing surfaces are machined aluminum for low friction. The factory rubber pieces are basically bonded to the control arms and sleeves so that any relative movement takes place through the twisting of the rubber. The poly kits become bearing surfaces where the poly is fixed to the control arm, but has a sliding interface with the sleeve. The surface finish of both of those parts is important to noise and wear.

I am always careful about recommending the poly bushing kits for customers, because even if they do not squeak, the poly is denser and transmits more vibration through the suspension. It is minor, but you will notice the difference. The plus side of the equation is improved response, less deflection and not blowing apart under track use like the stock parts. It is a nice upgrade.

If you are racing, look for our full spherical kits to be launched very soon. They are no compromise track pieces.

-Aaron