Facts About the Bushings & Spherical Rod Ends Griggs Racing Employs

Is there an option for polyurethane ends instead of rod ends? My car is a fully daily driven car so noise, longevity with minimal maintenance is very important to me and it seems poly ends are a much better option than rod ends.

Design Parameters

Handling performance, accuracy and reliability are our priorities, as our market is those that want to make either a superior sports car or a race car out of a Mustang. Installing our system will do that, at some sacrifice in NVH. However, we do make parts for different purposes and some of them do use poly urethane bushings.

All of our lightweight street only application lower control arms have a urethane bushing in one end to help insulate road and drive train noise from entering into the passenger compartment. However, they offer little compliance and therefore will alter NVH factors to the level of a sports car. For the rear Lower Control Arms (LCAs) to function properly without roll bind a spherical rod end must be utilized at least at one end of the arm. You may notice that opposite most of our competitors practice, we choose to place the spherical rod end in the chassis bracket end of the LCA instead of the axle bracket, to reduce the load on the thinner sheet metal of the chassis bracket, which would be more expensive to repair should body roll induced loads damage it.

Durability of Rod Ends:

Our rod ends last a very long time. They are not only PTFE lined, but manufactured here in the US to our unique specification with a pre-load on the ball. This precludes rattles and ensures long service. Calls for replacements are rare and usually on systems that have been in use over 100K+ miles and years of track use.

Note: When new they have about 5ft-lbs of break away torque which does cause "stiction" in the chassis, however they soon break in and have proven to fill the need better than all others we have tried.

NVH:

On our street systems we employ a urethane bushing on one end of the rear LCAs which reduces noise. We do offer what we call Quiet Watts Links, which use a single rod end mounted to the bell-crank on the axle, and a urethane bushing on the end that bolts to the Chassis mount. However in truth, subjective testing in many, many cars shows little if any difference in noise transference between the two with our rod ends, if the drive train is functioning as it should such as the gears in the rear axle are set up properly so they don’t whine. For that matter, there is very little noise transference with the standard double rod end unit anyway. Since our latest design Watts links utilizes a high strength aircraft aluminum bell-crank pivoting on Delrin Bushings which are materials with higher impedance to sound energy than steel, it seems the Quiet Watts version may become a thing of the past.

With that said, at the time of this writing, we just last week installed only a TorqueArm, street LCAs (bushed one end), and standard double rod end Watts link (not the "quiet" unit) on an otherwise stock track-pack equipped 2014 GT500 for a customer that stated he is very sensitive to noise. He said the car now "makes a faint sound back there, but it is not intrusive, and actually it is just different than before." And he can't believe the improvement in the car's performance. Further, I use the standard double rod end Watts link on my own street car.

Coil Over Shocks:

Shocks themselves can be a source of noise and certain damping rates can create harshness, depending on which shocks are used and their mountings. Coil overs need ball mounts both ends to preclude lateral loading that can cause premature internal wear, and ball mounts are a performance advantage as they eliminate excess hysteresis from flexing bushing mount joints. What this means is rubber or urethane mounts allow the wheel to move some without movement of the shock during low amplitude wheel high velocity displacement, which means a lack of damping and therefore control. Both the Koni and GRV Coil over units we currently offer introduce some sound into the cockpit, but very few customers find this significant. Still we are working on a mounting isolator for street use to hopefully preclude this sound intrusion as well. But, then there are those customers that prefer to hear much of the mechanical sounds that the car makes. To them it is all music.

Maintenance

Rod ends:

As stated above in normal street or track use our rod ends require very little maintenance. However, if they do ever require replacement, no special tools are required. Realignment is not even necessary if the installer simply counts the turns on the threads of the old part as it is removed and installs the replacement units the same number of turns. Mush less labor expense than pressing in bushings and dealing with the gooey lubricant.

Urethane Bushings:

The urethane bushings in our rear suspension are also known to last a very long time. However the lubricant will dry out over time and therefore disassembly and re-lubrication may be in order. Since these parts do wear, and are very inexpensive, replacement at this time is recommended. We do not install grease fittings on our parts to lubricate Urethane Bushings for a reason. All surfaces inside and out of the bushings must be thoroughly coated to both function properly and prevent wear. This cannot be done with a grease gun while assembled as the grease simply follows the path of least resistance to where it squirts out without fully coating all surfaces.

Urethane requires special purpose water proof high viscous extreme pressure synthetic grease. We supply such in our kits.

Delrin Bushings

Delrin is a hard plastic similar in characteristics to Aluminum, but with much better friction, ductility and wear characteristics when used as a bearing or bushing. Compared to Urethane, Delrin has very little deflection and can be fitted loose for less friction in the chassis. Our Watts link bell crank pivot and some of our front lower control arms use Delrin bushings. These parts have proven to last a very long time and after decades of trying to get feedback, we have no data to provide as to a service interval. Our own cars have never replaced Delrin, but Urethane? Yes. Some have had Delrin parts installed for many, many years with no maintenance. However we consider it good practice on a track car driven to service by disassembling, cleaning and lubricating Delrin at least once a year to assure proper friction free chassis performance.

We do not install grease fittings on our parts to lubricate Urethane or Delrin Bushings for a reason. All surfaces inside and out of the bushings must be thoroughly coated to both function properly and prevent wear. This cannot be done with a grease gun while assembled as the grease simply follows the path of least resistance to where it squirts out without fully coating all surfaces.

Delrin requires a good high pressure waterproof synthetic lubricant. We usually supply very high pressure synthetic grease with our bushing kits. However if the need arises to service the bushing, a quality copper or graphite based Anti-seize lubricant such as offered by Permatex which can be found in any auto parts store will suffice. Anti-seize contains solid compounds that will continue to lubricate long after the oil in it has evaporated.

If there are other questions regarding service and durability, please contact us directly at support@griggsracing.com .