A weird thing happened. I was loading fliers into the trunk of the Z tonight to bring to an event I was holding, 150 lbs worth to be exact. On the way back to the event I had to take the 10 West in Los Angeles, a road that normally causes my Z to porpoise at speeds in between 40-80mph. This time though, things were different. Immediately upon entering the freeway I noticed that the ride was completely smooth, then onto the 5 freeway North (the section between the 10 and 110 freeways) the ride was even smoother... SO, what i've decided is that by compressing the rear springs the ride of the Z is 200% smoother. I thought that possibly the extra weight could've smoothed out the ride but it was only about 150 lbs worth. So what i'm thinking is that if lowering springs were put on the stock car the springs and shock compression/rebound rates would be better matched to reduce the porpoising the stock suspension causes. I can't wait till aftermarket suspension comes along and I can test out that theory.

 

This is the 2nd part of my post... I know it sounds counterintuitive that by compressing the rear springs you get a smoother ride, but I figure the spring rates are better matched with the shocks once they are pushed down and at a higher rate. Didn't someone do suspension testing and find that the stock shock in the rear is too strong for the stock spring? Can someone give a technical analysis of my experience?

 

interesting, hmm maybe if I installed a JL W7 that would almost be the equivalent of the extra weight you had in the rear, maybe putting extra weight in the car is not that bad of an idea...

 

I'll have to try this. I guess I can load 150lbs worth of the weight plates on top of the spare tire. Probably put some packing sheets in between the plates so they don't rattle around.

 

I have made two long trips with the Z loaded to the gills and agree that the weight does eliminate what I consider a bounce, nothing even close to what I would say resembles Porpoising. I will not carry an extra 150 lbs to eliminate this problem.

Glenn

 

And no one should have to. However, this is a good way to prove to your dealer that a problem exists and to convince them that a fix needs to done to the rear suspension to rectify the problem. A simple spring swap or combination of spring and shock could greatly improve the ride, while keeping the handling of the car the same, if not making it better. Be sure to check out the other post on this issue "Bouncy Ride Anyone?" for more info.

 

Sounds to me it is just a bit too stiffly sprung in the rear, kind of like an unloaded pickup truck. I'm not sure it is neccesarily the compression of the springs, but the added weight compensating from a bit too much stiffness.

150 lbs can make a lot of difference in a smallish car when directly over the suspension or behind it (to create a bit of leverage), as what you are describing sounds like. I don't think lowering springs are necessarily required, but slightly softer springs or revised shocks might fix this.

 

Does the Z have progressive rate springs??? If it does then I can see why the extra weight would help. If it doesn't then I think it may be something else. My guess is that the Z does have progressive rate springs, it being a sports car and evertything. Can someone confirm this.

 

I'm happy with the feeling of the Z..but probably the springs are not compressed with a single rider and no extra weight and others feel this to be a problem.

For example, while riding my Honda CRV '00 by myself, I do notice harshness and feel the road a lot more. As soon as I put in 2 passengers in the rear seats, the harshness goes away...and I feel I am riding in a very soft suspension car.

I have no idea about springs and such, but maybe a solution is to have 90% of the spring the same as it is now, and then the remainder 10% of the spring being the softer and latched on to the primary spring. This will in effect smooth out the ride further and possibly provide the cussion people seem to be needing.

I'm happy with the feel of the Z .... th