Any opinion on a Del-a-lum bushing vs. a poly one

Polyurethane is said to increase binding, of the suspension pieces. Global West says that customers of polyurethane are led to believe that the binding that they feel in the stiffer ride is "handling". Polyurethane bushings need to be lubricated, both at installation, and periodically with a special grease, it may be silicone based. The Del a lum bushings that G. West sells are lubricated via graphite, I believe.

It depends on where you put them. In the front, they are a great product, probably the best out there. In the rear, they would bind up even worse than poly, and ruin your ride, performance, and handling.

I'll go a little deeper into this now that I'm on my lunch break, and don't need to try to pretend I'm working. :D

Front Suspension: the control arm bushings rotate on only one axis. The bushing options are basically Rubber, Poly, Delrin/Teflon, or Solid.

Rubber: The bushing material is soft, and is bonded to both the inner and outer sleeves. When the suspension moves, it wraps the rubber up, which takes extra effort to rotate them. This is why you need to tighten rubber bushings at ride-height when installed. Rubber is very good at absorbing road-noise and vibrations, which is why they are still commonly used on new cars. Under cornering loads, they deflect, which means it will actually push the outside tire further into the fender well. This isn't too big of a problem on a front-steer car like a chevelle, because it will cause a slight understeer, as the steering is rigid, and the tire is pushed inward. On a rear-steer front end, like a first-gen camaro, this creates oversteer by actually turning the front wheels farther than the steering-wheel input.

Polyurethane: Poly is a decent upgrade here. It eliminates nearly all the deflection, and still can absorb some of the road-noise and vibration. The bushing material is not bonded to the inner and outer sleeves, so the inner sleeve actually rotates with the control arm inside the bushing. The biggest problem with polyurethane is that it is a sticky substance. Metal does not slide easily on it, unless it is lubricated, which is why it is known to squeak. PST has added graphite to the mix to make them less squeaky, but they cannot be greased after installation (need to be greased during assembly). Also, graphite actually causes the urethane to deteriorate, although they still will last longer than most of the rubber bushings.

Delrin/Teflon: Global West sells them as "Del-alum". Delrin is the material, Teflon is a trade-name for it. This is a bearing material, and slides very smoothly across metal. These use a steel sleeve, a delrin bushing (about 1/8" thick) and an aluminum outer shell that presses into the arms. They rotate freely, and do not deflect. The thin layer of delrin absorbs some road-noise, but not much.

Solid: Solid bushings work like the delrin, but need a little more attention with greasing, as it is metal-on-metal, and do not have any way to dampen the road-noise. When they wear out, they get noisy and vibrate.


Rear Suspension: The rear arms on a Chevelle chassis do not just swivel in one direction like the fronts do. With a solid-axle, and the converging 4-link suspension, the bushings need to allow articulation for the axle's range of motion. Imagine looking at the upper arms through their arcs if they were only connected to the axle, and not the frame. If they only rotated on the axis of the bolt connecting them, the distance of the frame mounts would have to get wider in compression, and narrower at droop. Obviously, the frame mounts do not move, so if the bushings don't allow the angle of the arms to change, then the stress (bind) is taken up by the arm's ability to flex. If you were to replace that flimsy stamped steel arm with a rigid boxed arm, and use poly, delrin, or solid bushings, then the twisting forces would be taken up by the frame, or the axle housing. Of course, you don't want that, and those are both pretty stiff, so the result is that the axle doesn't move enough, and traction suffers.

The only other good option other than rubber in the rear, is to use spherical bearings, which are available in either solid, or teflon bushed.

If you were to replace that flimsy stamped steel arm with a rigid boxed arm, and use poly, delrin, or solid bushings, then the twisting forces would be taken up by the frame, or the axle housing. Of course, you don't want that, and those are both pretty stiff, so the result is that the axle doesn't move enough, and traction suffers.

The only other good option other than rubber in the rear, is to use spherical bearings, which are available in either solid, or teflon bushed.


Derek... Hotchkis offers an adjustable upper rear arm with a locking nut, what if you were to back the nut off and allow the two peices to twist freely.
It would be impossible for the frame mount to unscrew itself regardless. Any thoughts?

The gotcha with that idea is that the bolt threads were never intended to bearing surfaces and would wear out, perhaps fairly quickly. There is also some amount of play in the threads which would get hammered by vibration and cause the threads to get flattened.

Derek... Hotchkis offers an adjustable upper rear arm with a locking nut, what if you were to back the nut off and allow the two peices to twist freely.
It would be impossible for the frame mount to unscrew itself regardless. Any thoughts?

Like "Vroom3440" said, the threads would wear out quickly. Not only that, but doing that would only take up one of the many angles that it needs to twist, so it would still be to rigid.

Here is a quote from Global West President Doug Norrdin in Car Craft magazine:
Car Craft: What is the least understood aspect of the products your company sells?

Doug Norrdin : People seem to think, based on the information we publish, that we are against using polyurethane bushings—especially in rear control arms for Chevelles and other A- and G-body vehicles. We’re not. We use polyurethane bushings in various applications ourselves. In fact, we build polyurethane control arms for the rear of Chevelles and other A- and G- body vehicles. It’s just that we only recommend them for straight-line applications, like drag racing. Why? Both polyurethane and our Del-a-Lum bushing will cause binding in the rear suspension if used in both ends of the control arm. Neither bushing allows the differential to articulate when the vehicle goes around corners or over bumps. The solution is to build rear tubular control arms with aircraft spherical bearings on the frame side of the control arm. The bearing provides the control needed and still allows the differential to articulate without bind.