Deckstripes

Advice please, I've modded myself into a corner.

97 Z28, wanted to freshen up the 70K suspension. Did some other mods with it as a group, so I went from totally stock, to where it is today. Lots of bracing and firming. Too stiff, I've lived with it for a year, and can't take it anymore. Spine shattering is a term that comes to mind. Not to mention I've got my work cut out with 10 new rattles to chase.

Edelbrock weld-in connectors, & chromoly tubular K member
Koni adjustables (full soft), Strano 35/22mm hollow bars
Tubular lower trailing arms w/poly bushings, poly torque arm mount
17" Z06s 275/40

The car handles great on smooth surfaces. Unfortunately, city of indianapolis hasn't seen fit to give me any of em, and the car's so jittery over bumps that I'm not sure it's effectively any faster.

So here's where I'd like advice- I've considered the following
#1- remove the bars and put the stockers back on

#2- get softer springs. V6 model? Custom aftermarket? Just not sure where to go. A little lower is better, but not a full inch lower.

#3- ditch the Konis, and go with something like a KYB gas-a-just that's a nice soft street shock, not a performance shock.

What would you do? I've ruined a car I used to love driving.

Thanks for any advice!

Greed4Speed

What springs are you running now?

Tire choice also makes an impact on ride.

hotpart

Before you do anything start with the basics. Check the alignment if you have toe out on the street it will cause a darting feeling. If the alignment is okay I would bumpsteer the vehicle to find out if you have toe out during bump. If the bumpsteer is OK I would recommend removing the anti-roll bars. The problem with bigger bars is it will tend to make the vehicle act more like a solid axle vehicle (you loose the advantage of an independent suspension) which is just fine on smooth surfaces but horrible on rough surfaces.

Dave K

yup... I've got a 35/25 solid bar setup (suspension techniques) and the car got pretty squirrelly on very rough surfaces after it was installed. I've contemplated going to smaller bars, or getting a couple to try out since it's pretty quick to swap bars out. In my case, most of my driving is on highways and interstates so the bars aren't a big problem, but if I lived in the city I'd have already gotten rid of em.

Deckstripes

The car still has the stock Z28 springs, and firestone wide ovals because I could get a deal on them. But it also rides terrible if I put the stock 16" bridgestones back on. I'm comfortable with the rim/tire difference, but something is inherently wrong with my setup for city streets.

Around here, they love to fix a crack by cutting out a 6" wide groove, and re-paving just that. Every time I hit one, the front and rear independently jump 1/4 inch to the side. Sometimes same side, sometimes not. And these frickin road repairs are every 40 feet.

Maybe this is another clue. The front struts are 3/4" lowering struts. The car is stock height up front, not lowered 3/4". Verified with before/after measurements. The only added weight was the connectors, and LS1 front brakes added a few lbs. But it also got the tubular K, and off road Y pipe, and SLP headers which may have removed upward of 50-75 lbs from the nose. Everybody says my car should still be lowered, that amount of weight loss won't raise it that much. I've made sure the A arm bushings aren't bound up, it's not that.

I question how soft the konis actually are on full soft. Also heard Z28s are oversprung to start with, wonder if I've just aggravated that with the bars & konis.

Still wonder if softer springs are the correct solution, or a band aid.

I'm not sure how to measure bumpsteer, but wouldn't it be the same since my car is stock height? Or could it be anywhere with my aftermarket K member and 98 spindles? The car did go to a competent alignment shop afterward.

Is it possible I'm just a sissy

Thanks & Please keep the opinions coming

PS- Hey hotpart Brian, I've got your trailing arms on the car, they're nice pieces at the right price. Thanks!

MeanGreen97Z

Those poly/poly trailing arms are doing it to you bad!!! I bet some poly/rubber bushings in those lower control arms would soften the ride a bit.

Greed4Speed

#1. leave the springs and Koni's on!!! You can also lower with the Koni's if you want, since you brought that up.

Give Strano a call and see what he suggests, but I'd have to agree with MeanGreen. Poly bushings are most likely the culprits. Do you have them in more areas than just the LCAs?

Deckstripes

Only poly bushings in the whole car are the trailing arms, and torque arm. They cured some funky dragstrip behavior.

Bud M

You didn't say what brand your LCAs are but if they are BMR, you can replace the bushings with rubber. BMR sells those bushings. They may very well fit other brands of LCAs. But first, did you properly grease all poly bushings including swaybar bushings? Did you use the correct type of grease?
I agree with Dave K about the ST bars. The ST 35 solid made the car react to every little irregularity in the pavement. I replaced it with Strano's 35 hollow and I like it much better now. I don't think those swaybars are your problem. It sounds to me like you have too much compression damping. In any case the problem is not that the springs are too stiff. But you have discovered the reason for a basic rule: do mods one at a time.

Lil Dog

Try some 16" wheels and tires...

OBE1 95Z28

If you read his posts, he already did.

What tire pressure are you running?

Sam Strano

Poly LCA's kill the ride. You shouldn't be running anymore than 32 front/30 rear in your tires. It's not the Koni's or the bars. Koni's at full soft are not very stiff, and the vast majority of folks run the fronts at least half-stiff, and I can guarantee you that if they caused the ride to be that bad, they wouldn't.

Do the two easy and FREE changes first, and watch the difference. If you start just changing parts without knowing why (and you don't) things are the way they are, you won't make things better.... but worse.

Deckstripes

OK then, sounds like tire pressure and reinstalling the stock rear arms should come before anything else. I'll give those a shot (individually), and if the weird launch behavior returns then it's time to search out some middle ground on the trailing arm/bushing stiffness. Thanks for the advice, I do appreciate everyone's help.

I know all at once isn't the best way to go. But with 4 project cars, 2 project bikes, the usual life/job/girlfriend stuff, sometimes you gotta go for the gusto. This was just the underside of that particular upgrade. I still think the overall package is very worthwhile, it just needs a tweak or two for me. Others would probably be happy with it. Thanks again

Sam Strano

That's part of the problem. You don't ever want to do changes with "gusto", if gusto means a lot of stuff at once. One reason is just what happened here. Suddenly the shocks and bars became the culprit, with nary a mention of all the other parts. Well, what happens when you remove what you thought was the problem, and realized that wasn't the issue? Now you have to re-install and start ripping other parts off.

There are other reasons as well. One is fixing what needs fixed, not randomly tossing parts at a car.

Deckstripes

You can call it randomly tossing parts at a car, but the combo was researched thoroughly. The struts were purchased from a knowledgable source, based on words to the effect that 75lbs off the nose would not allow the car to rise much because the springs were so close to uncompressed at ride height. Still believe the seller is an expert on the subject, but also know that every car is a unique individual to some extent. Please don't confuse a deliberately simple and lighthearted question for me being a novice. Group projects present pitfalls, but it's how I like to do it sometimes, this is about fun after all. Also have extremely, extremely high standards. Not uncommon to be unhappy with projects that others love, and redo em until I'm satisfied too. As far as fixing what needs to be fixed, the quest is called..........Hot Rodding

Please note that in no way have I implied the bars are bad products. Thoroughly believe a big chunk of it's improvement comes from them, and the fit is great. (the car is better in many ways) Whether or not they're ultimately right for my useage and preferences and the parts that surround them, is not related to quality and fit.