Shock recommendation

[jeffandre]

Now I wish I waited, oh well, I will use my new Bilsteins for a while. I look forward to any updates you have as I was leaning towards the Varishocks but wussed out at the last minute...

We need some video of your car carving corners or cones. You really should look into getting it on a track someday!

[Jeremy]

Just to update my findings in case it will help anyone with a VBP setup.

I had run as high as 7 C 12 R and the front was very tight, but it was no where near matched to the rear. The front did not want to roll and the back did. From the driver's seat I could feel both ends fighting each other. Over dips it felt like there was no suspension movement and the corner hitting the dip would drop harshly.

This got me thinking and I backed off the rebound to 10. I then started paying attention to dips. On the front side of dip, the nose would drop and follow the dip and really want to hit hard on the back side coming out of the dip. I would then drive my wife's Taurus through the same dip and the nose would stay level. I started thinking that the suspension may not be able to drop fast enough with the shocks so tight on rebound. I then remembered my research on transverse springs that they don't store energy like coil springs. I figured that this meant they may need less rebound damping.

Since the shocks are easily adjustable, I tried 7 C and 7 R. You could actually feel the difference going into dips. The nose stayed more level and things were much softer. I tried 8 C and 6 C and the suspension followed the road even better. In turns now, the front and rear feel a lot more balanced. They seem to roll? the same or a lot closer now. I can actually drive the car harder this way with a lot more confidence.

There is no more bouncy feeling left. I think it feels a lot like a factory engineered car in its ride and handling. I'll see how I like my current settings after a longer time, but if they hold, I can see why the system never worked well with off the shelf shocks as I understand they generally run soft compression and high rebound.

[Jeremy]

The shock settings are holding true in that the setup likes more compression control than rebound. I moved the spring to the middle setting and am running 13 C and 8 R and it rides incredibly well.

I got a chance to drive a c6 convertible today to see how close I was coming in the ride and handling. I drove both on a 20-25 minute drive on a mix of city and highway driving.

The owner recommended the competition setting and that is where the car was set for the drive. The ride was very nice but I felt the rear was a little more skittish. The vette seemed a little choppy over one section of road that my car was smoother on. Big dips that hit both front wheels the same, the vette was a little more composed than my car. The steering on the vette was a little heavier than mine and both tracked equally well. Both tended to follow some road ruts/crown slightly.

Turn in was very similar between both cars, although the vettes may have been a hair quicker. I think I can improve in this area with a more agressive alignment.

Brake performance is nearly the same, although the vette feel is much better than mine, particularly in the initial application of the brakes.

Wind buffeting in the vette was much worse than my car with the T Tops out. Much over 70 was annoying to me in the vette and I can cruise 85-90 in mine and the wind doesn't beat me up nearly as bad.

Around town it is easy to feel the difference in torque. My car required much less thottle input to get up to 45-60 in traffic. Part throttle response was better. Full throttle, however was a different story. The vette really comes to life. It was an automatic and the gear splits were perfect. It picked up speed quickly. I was suprised at how much weight it transfered as the front end really picked up adding to the sensation of speed. In a 1/4 mile run I would probably say the vette would get me at the end of the track. Around town it was more fun to drive my car with the great torque.

I know I got a little off track comparing all aspects of the vette and my old TA. I meant to just compare the suspensions, but I thought others might enjoy the comparison. The VBP system seems to get a lot of criticism but I was amazed how close it comes to the c6 in terms of ride and handling on real world streets/driving. On a track it may not be as close, but I don't think I'll see any track time. On normal roads with other traffic present it equals it well.

It was also gratifying seeing my work come close to vette performance for a lot less money (more if you count my time).

[Jeremy]

I thought I would share my latest finding on the VBP setup. I removed the jounce bumpers and it was such an amazing difference that I had to start all over on my shock tuning.

The ride is getting very soft and the handling is amazing. I am also amazed at the lack of rattles now with nothing more than removing the bumpers and re tuning the shocks. I even stepped back up to the middle spring rate and it is still softer than it has ever been.

I covered everything a lot more in depth over at Nastyz28.com. With the jounce bumpers removed I would be curious to see how an off the shelf shock would work now.

[jeffandre]

What are the jounce bumpers? The hard rubber that cushions between the upright bolt and the spring eye and lower control arm? I gotta check the Nasty28 site out, haven't been there in years.

Do you still have your Hotchkis Bilstein's? Try them out for us!

[Jeremy]

They are the triangle shaped pieces of rubber bolted to the top of the lower a arm. They are supposed to be a progressive rate to keep the arm from bottoming. With the spring rates this setup runs, I don't think this is a concern.

I don't have the Bilsteins anymore nor my Edelbrocks.

[Marcus SC&C]

I`m not typically a big fan of totally removing jounce bumpers but I DO like replacing them with more modern non rubber versions. The newer ones are made of an orange almost foamy material (softer than the old rubber ones) and tend to be much more gentle and progressive in nature. The ZQ8 jounce bumpers GM designed for the factory lowered S10 ZQ8 Extreme are direct fit for most older GM cars and work really well. GM PN#15989674 or 15956547, the second number should be slightly firmer. When installed these should almost touch the frame at ride height. They`re only about $10ea. so you don`t have much to loose by trying them. Mark SC&C

[Jeremy]

Thanks for the #'s for different bumpers, but the way the bumpers mount to the arm is not like any other I have seen. The top of the outside edge of the arm is threaded for 1/4 inch bolts and the bumper has a slot on each side of the rubber for the bolts to pass through.

I have really been playing with shock settings since removing the bumpers and am down to 0 C and 3 R and it rides great. It feels a little "heavier" but there is no springy feeling and no bounce at all. Handling is very confidence inspiring and I find I am driving faster than I think.

There is one on ramp that used to get the car pretty bouncy before and I was hitting it hard in fourth and by the time I glanced at the tach I was at redline (105 mph). It was pretty stable for the way the road is contoured and much faster than I have ever felt comfortable at before.

I also drove down the entrance to Lowe's which is about 300 yards of real bad washboard. No bouncy feeling at all. This used to bring out in bad motions in the suspension.

There are only two bumps that I have found now that I can't seem to get perfect suspension motion over, but it is controlled, just not as smooth as I would like.

[Jeremy]

I've continued to play with it as it felt a little heavy and numb at 0 C and 3 R. Where I have ended up is 1 R and 13 C. The car is very responsive and smooth over all road surfaces. There is no bounciness and the front end stays as level as the rear.

I am extremely pleased with the set up. With such soft rebound numbers, the inside front of the car wants to lift slightly transferring weight to the outside. The rear follows suit and it is very predictable and confidence inspiring to push. If the rebound is higher than 5 the car gets very tight on front and just not easy to drive. The steering feels heavier and the turn in is slower.

I strongly recommend anyone looking at the setup, figure on double adjustable shocks for the front as mandatory.

[jeffandre]

Jeremy,
How is the car doing? What settings are your front spring and shocks currently at? Did you do anything about the rear yet? I finally got my front suspension done, but still have the Bilstein's. It moves so easily I will move the front spring stiffness to the middle setting for now. Rear is very stiff, without shocks! I have the rear Bilstein's too, but need to modify my upper shock mount to give them more travel.

[Jeremy]

I've been running on the stiffest spring setting for over 3 months now and am really pleased with the ride. I have shock settings now at 0 compression and max rebound. There is no sense of vaulting and I haven't found any bumps that upset the car anymore. It is very stable and planted feeling. Turn in is very crisp, yet it tracks very well.

I may try the middle spring setting again for a comparison but am very very happy with the front end the way it is now. My wife really enjoys riding in the car and agrees that it feels pretty soft.

For the rear, I have added 150 pound VBP springs and am using Edelbrock IAS shocks. The rear springs were well worth the money as they ride improved nicely and it added some more spring rate. I think I need a little more shock but it isn't bad at all.

Overall the car kinda scares me, not in how it handles, but in how fast I catch myself going. It has more capability than I can safely explore on public streets. If I don't pay attention, I find myself going way too fast. The suspension is very composed, even over rough roads. I probably need to upgrade the brakes now to better match them to the speed potential of the suspension.

Overall I am very very happy with the system now. It took some time to get it to this point and shocks definitely make or brake the system. Who knows what would be possible with different start points for the valving in the varishocks. I would like to try even softer compression settings and stiffer rebound settings. With the range of settings more tuned to the VBP system, it may be possible of even more. From what I have found, the compression settings may not be soft enough for the lower spring rates and I can't tell if I need more rebound on the stiffest as I can't go any farther.

[jeffandre]

Jeremy,
Cool update! One of your posts below said 1 R and 13 C (from 7/26) and it had me really confused. I kept bouncing my suspension without the shocks installed and knew it had to have less compression and more rebound, so that is one of the reasons I asked for an update. It must have been a typo, whew!

On the front I am on the middle setting now, but with the GW bushings and having my front sway bar chassis mount bushings lubed it moves so easily it is remarkable. I will move it to the stiffest setting. I have the 200# rear VB leafs, which are very stiff.

I have the Hotchkis Bilstein's up front and went back to my Koni rears as they have less compression and a firmer rebound (when adjusted all the way) than the Hotchkis ones.

Good point about the adjustable shocks possibly needing more range. I guess when I am finally ready to buy them I will have to look into the actual compression and rebound data for all of the adjustable shocks out there.

What are your current alignment specs? How does it feel at freeway speeds?

[81Nascar]

Jeremy ,glad you upgraded to the rear springs. Night and day isn't it? They have to be experienced. Mine are someof thefirst ones so I'm sure your's are much improved. You have taken things much further than me. I just might have to update the nascar to the front system. I think you stiffening up your car has helped alot as well. Way to go.

[Jeremy]

It wasn't a typo. I had tried everything including a lot of compression and no rebound. That's why it was so important for me to keep a log and drive the same roads at the same speeds to get accurate results on the changes. It was one little dip that kept me going as I never, until now, get it dialed in.

My alignment specs are:

Camber

[Jeremy]

My current alignment specs are

Camber -.4 L and -.2 R

Caster 2.7 L and 2.8 R

Toe .03 L and .02 R

It tracks nicely and I find myself cruising on the interstate at 85 - 95 before I realize it. To get any more caster I'll have to get different arms.

I love the fiberglass rear springs. The ride is soo soft and the lack of noise is truly amazing. The poly bushings in the shackles squeak but I would say that is because I am using the factory shackles which are cupped. I need to make some new ones that are flat and I bet that will help a lot. I had to use 1 inch lowering blocks to get the ride height back where I wanted it, but that may have something to do with using first gen springs (too good of a price to pass up).

I would like varishock double adjustables for the rear at some point. I am done for the time being on the suspension as I have some maintenance projects to do (replace heater core, fix the dome light as it doesn't come on with the switch and opening the driver's door, some paint chips, etc).

Mostly I am driving it and enjoying the heck out of it.

I would agree that the chassis stiffening probably helped a lot and made it easier to tune things as the suspension was doing more of the work than chassis flex.

[NOT A TA]

edited