Energy Suspension Master Bushing Kit

[Jeff G 78]

Leon, you'd be amazed at how much recession is designed into modern cars. It's one of the reasons that the ride is so much better now than on older cars. One way of reducing the bump steer effects is to allow the whole subframe to recess. That way, the steering gear and suspension geometry stays the same when the system "gives". Most luxury cars have very soft subframe bushings in the longitudinal direction while stiff laterally. That way, they don't allow much deflection while cornering.

I will be testing your theory when I swap the rear TC bushings for rubber. That's what I have in the race car and the ride is far better than my street car. It's hard to really tell though with the race car since there aren't many frost heaves on the track. The back-to-back test with my street car will be a better test.

Your altered analogy is pretty much what I was trying to say, but I wanted to make it more drastic for clarity. And yes, the suspension deflection amounts aren't huge relative to the vertical deflection even on fixed subframe cars.

[LeonV]

Leon, you'd be amazed at how much recession is designed into modern cars. It's one of the reasons that the ride is so much better now than on older cars. One way of reducing the bump steer effects is to allow the whole subframe to recess. That way, the steering gear and suspension geometry stays the same when the system "gives". Most luxury cars have very soft subframe bushings in the longitudinal direction while stiff laterally. That way, they don't allow much deflection while cornering.

I will be testing your theory when I swap the rear TC bushings for rubber. That's what I have in the race car and the ride is far better than my street car. It's hard to really tell though with the race car since there aren't many frost heaves on the track. The back-to-back test with my street car will be a better test.

Your altered analogy is pretty much what I was trying to say, but I wanted to make it more drastic for clarity. And yes, the suspension deflection amounts aren't huge relative to the vertical deflection even on fixed subframe cars.

Okay, that makes sense, regarding the subframe bushings.

As far as putting in the rubber TC bushings, you'll notice a reduction in harshness which would be proportional to the spring rate change. You'll get a bit less noise, but I don't think the change in actual ride harshness will be drastic. I would try to devise a way to measure harshness and do back-to-back tests (accelerometer(s) perhaps).

[Jeff G 78]

Leon,

What I will probably do is the same thing I did on the 260Z which is to reuse old rubber bushings on the rear while keeping the poly in front. If I'm happy with the results, I will order a new set of OE rubber and use 1/2 the set on the 280Z and the other 1/2 on the 260Z. My only worry with the rubber rears is that I already rub badly when turning and backing up. Softer rears will likely make that condition worse. I need to modify my OE valence to eliminate the issue. I already modified my rear fender lips to keep the rear tires from rubbing, but that's a different story.

If I can come up with some data aquisition equipment, I might try to do some analytical NVH analysis.

[LeonV]

Leon,

What I will probably do is the same thing I did on the 260Z which is to reuse old rubber bushings on the rear while keeping the poly in front. If I'm happy with the results, I will order a new set of OE rubber and use 1/2 the set on the 280Z and the other 1/2 on the 260Z. My only worry with the rubber rears is that I already rub badly when turning and backing up. Softer rears will likely make that condition worse. I need to modify my OE valence to eliminate the issue. I already modified my rear fender lips to keep the rear tires from rubbing, but that's a different story.

If I can come up with some data aquisition equipment, I might try to do some analytical NVH analysis.

That's exactly what I did on my 260Z. I'm using poly in front and the old rubber in back for the TC rods. I also don't have rubbing issues, but I have a lower air dam and not the factory valence. I was pleasantly surprised that I had zero rubbing with my setup, which is similar to your car: 16X7 Panasports with 225/50-16 rubber and Eibach springs. The ride is stiff and harsh, but that is mostly due to the very small amount of bump travel available before hitting the progressive bump stops and also the valving of the Tokico HP dampers.

Some NVH analysis would be cool, I haven't seen that done with a Z!

[SC240z]

The poly bushings stiffen up the ride a bit. On my 73 the rear bushings at the wheel had to be shaved to fit. Getting the old bushings out was the hard part after 30 years.

[Zguy91]

I love my coupe and I definitely know after having a bunch of z cars I definitely wouldn't compare the ride or handling ha ha. What can you do about the bumpsteer I know msa has a bumpsteer kit

[lmcguffin]

Read up on the spindle pin extraction before starting the rear wheel outer bushings. I ended up making my own extraction tool for a bushing replacement on a 78. Lot of threads related to spindle pins.