I have QA1s on my 96 CE LT4 set @ 3 in front & 2 in the rear and it's quite a bit more pleasant than the FX3 Bilsteins on my 89FX3 Coupe.

My 96 CE LT4 originally came w/ the Delphi F45s which cost a small fortune if you can find them and weren't all that good to begin with.

 

The roads in Ramona are pretty decent. It's in San Diego Like Mira Mesa Blvd. and Ranch Bernardo Center Drive to 4S Ranch is where your car is really tested.

I'm looking close at the KYB shocks. After all the discussion and interpreting what what you guys have said it seems these shocks might make my commute a bit easier on these pot holed roads plus allow the car to corner decently.

I opened up this thread to start a discussion to see if there were similar complaints. There were. It also educated me as to the pros and cons of different shocks. I won't get Bilsteins, Monroe or Edelbrock. My first look will be KYB then Gabriel.

 

I am with mondo. A few years ago, I would have had the same sentiments as many have in this thread; If you want a smooth ride, buy a _______(fill in the blank). However, now I feel differently and here is why: My first 'Vette was an '06 Z51. It rode very nicely. Too nicely IMO (For a "Z51"). It had too much body roll and not enough shock damping at all, which resulted in a ride that was much more "comfortable" than I thought necessary...but allowed for the "Whoopty-whoop" over transitions and breakovers, that were unacceptable IMO. My 2nd Corvette is the one I have now; a base '92. Now it does have a "soft ride"...i.e. the suspension is not stiffly sprung and the shocks arean't overly dampened...but the OP is right; it "Crashes" over sharp-edged features, and looses all of it's grip and composure. Not good. As long as the road features are "rounded", the suspension soaks them up w/ease. But hit a raise man hole cover, or an expansion joint, or a RR crossing...and the car can't cope.



I've given the above a lot of thinking, b/c I'd like to fix it. My car too, has the Bilstein HD shocks. I don't think that the problem is the shock at all though. I THINK that it's two things:
*the flexible chassis.
*The point of contact for the spring on the lower arm (up front)

Aurora40 is right in his observation of the chassis stiffness; I HAD the '06 which was significantly stiffer than the '92, and I now have an '05 CTS-V which is significantly stiffer than both. The V has "stiff" suspension, and big sways...but it's ride is never "jarring". Yes, over "rounded bumps" you body is moving up and down in the seat...but it is controlled and tight feeling. And hitting sharp-edged features...is nothing. Don't feel it. Car doesn't care. It rides on 18" wheels and 35 aspect tires. So I'm convinced that chassis stiffening is absolutely critical to improve the quality of the ride in the C4.

On the C6, the leaf springs (and the shock too) contact the lower arms (front and rear) all the way out by the lower ball joint. This puts the load as close to the ball joint as possible, and impacts loads (sharp-edged features) are directed almost completely, into the spring and shock. On the C4, the shock mounts far out on the arm (like the C6)...but the spring contacts the arm only about 2/3 of the way out to the ball joint, from the pivot point; the lower arm bushings. That means that shock loads are focused into the spring, AND fulcrumed through the lower arm into the cross member. The lower bushings don't deal w/the shock loads, as well as the spring would, IMO. And why would they? They aren't designed to.

It is a theory of mine, that coil-overs would improve the ride quality of a C4, for no other reason than that they move the point of contact of the spring, further out on the lower arm, thereby putting all the loads into the spring, and very little through the lower arm bushings. I had asked PLRX for a detailed report on that right after his coil-over swap, but never recieved a meaningful reply, unfortunately.

Going forward, for MY car, I'm focusing my efforts on stiffening the frame, and see what that does. W/o any feed back on the coil overs, I can't spend the money on them. For the OP, I'd recommend verifying what shocks you really have, and lower your tire pressure down to ~25 PSI for a more compliant ride over sharp-edged features.

 

There are a few differant Bilstene shocks
reg / sport and extreme. I have AC/Delcos . I need something stiffer , preferably more rebound in the rear .
Looking for the Extremes , rear

 

People generally comment that the ride is more "european" or compliant with coil-overs. I figured it was because some of the stiff anti-roll behavior of the leaf spring is removed, and because people generally go with lower spring rates than stock. The pre-'92 front spring rates were something like 550 in-lbs base. It seems like coil-overs people go with are more in the 400 range. Plus I think the geometry of the coil-over means the spring moves less than the leaf did, but I'm not sure about that.

So I always figured that the reason they were more compliant is that people, sort of unknowingly, reduced both the spring rate and the anti-roll rate. So it's no wonder the car rides better.

As to stiffening the frame of the C4, I wonder how hard that would be to make large improvements to (without adding large weight)? If I recall, Corvette from the Inside lists the natural frequency at like 17Hz, 14.5Hz with the top off. That's pretty crappy. In '95 the Aurora had a natural frequency of 25Hz, in spite of being a much larger car with a much longer wheelbase. While certainly there are things that stiffen it up some, do they make more difference than top-on vs top-off?

Curious about your V. Do you have FG2 shocks? I've test driven a couple and I thought the base shocks were softer than I would have suspected. It was still sporty, but the ride had a lot of movement. I guess that doesn't mean the movements were not quickly damped, but it didn't strike me as much of a sacrifice over something like the 'roara. I should get a chance to experience one much more personally here soon, though.

 

Mundo, your first post is confusing. Did you just replace the shocks on your C4 with new Bilsteins??

 

Can you really set the tire pressure to 25 Psi? The door jamb sticker says 35 psi, and I have reduced the pressure to 32 psi and really noticed a difference. I know reducing the tire pressure even more will soften the ride, but what is the tradeoff? Do the tires wear faster or does handling suffer?

thanks,
Howdo

 

I can't see why not. I'm running 25 lbs right now. Watch tire wear, and if it's acceptable run it. Keep in mind, the larger the tire (for a given car weight) the less tire PSI you need to carry the load. Later Corvettes w/a 245 tire call for about the same 35 PSI...as my 275 front, 295 rear. That doesn't make much sense. Of course a larger tire, with the same pressure is going to ride more harshly.


Ours does have the FG2 shocks. I think the ride/handling compromise is fantastic. In fact, if the C6 rode and handled (subjectively) as well as the CTS-V does, I'd still own the C6. It's sad, but the V is what the C6, and ESPECIALLY the Z51...should have been.

Good data you posted on the C4 frame. I've had a tough time finding C4 frame data. I have a plan, which I believe is pretty good, for dramatically stiffening the frame, roof on or off, w/o sacrificing ground clearance and only adding about 80 lbs.

My biggest "problem" is figuring out how to measure the improvement. I was thinking of trying to strap the frame down and use a jack and dynomometer (strain gauge) to measure lbs per degree of torsional stiffness.

I don't know about your coil over theories. If true, you could get the same results w/a lower rate transverse spring. Go look at where your leaf interfaces the lower a-arm. Then look where the shock is bolted, and think about controlling the mass of that unsprung weight over sharp-edged bumps...

 

GM did not make the FX-3 shocks, Bilsteins did. The only difference between the shocks is the original GM say GM on them or Delco, but have no warranty. I had taken off my original FX-3 shocks and sent them to Bilstein in San Diego a few years ago and they lost them. Bilstein did replace all four with new ones, but did not say GM/Delco on them.

 

I should have said "GM offered such a shock"... The point being that what he was looking for, an adjustable shock that is soft on the road and stiffer at speed, was an option GM made available on the Corvette. Yes, Bilstein developed and made the shock.

 

I bought the car with yellow Bilsteins, soon to be replaced by KYBs.

 

Try replacing the front tires with dunlop direzza 101 tires. My 86 bounced over everything. It was really hard to control the car in a turn bouncing through the apex of the curve when the tires weren't touching the ground. I could get air just going over railroad tracks at 30 mph.
Installing 85 z51 sway bars made it worse.
i replaced my aging wheels with C5 wheels, and used the Dunlops, and you can't believe the cornering that I gained, and a soft pliable ride.
I still have the habit of tensing up for uneven pavement, and the car just absorbs the shocks instead of bouncing.
I think we tend to let our tires get old, even though the tread is still pretty good. A lot of the time, people buy tires that someone else says is great, and neglect to buy tires for the purpose at hand.
Also, there are more tires for 17 inch wheels out there than there are for 16 inch in our sizes.
The tires I am using now suits the roads where I live, not really bad, but distorted by the heat and lots of traffic at high heat periods where the asphalt is soft, and the mating to concrete causes a ridge.
I can't tell you how much I enjoy the ride and how fast I can corner now!!!!

 

My tires were brand new, end of last summer. Still, any sharp-edged bump completely upsets the whole car.

 

......
Going forward, for MY car, I'm focusing my efforts on stiffening the frame, and see what that does. W/o any feed back on the coil overs, I can't spend the money on them. For the OP, I'd recommend verifying what shocks you really have, and lower your tire pressure down to ~25 PSI for a more compliant ride over sharp-edged features.[/QUOTE]

Let me know what you do to stiffen the chassis & what difference it makes.I have the underbody X-brace as well as the targa truss on my vette to stiffen the chassis.The targa truss made a night & day difference but not so much with the X-brace.The best thing to do(my opinion) would be to tear the car down to the bare chassis & stitch weld every joint,add some chassis connectors or reinforce the chassis,reinforce the steering column,adding the camber brace to connect both upper control arm towers,& having a targa truss or something similar installed when the top is off.To me,my 1994 would be my dream car or close to it if it had a solid/stiff chassis like a newer vette or ideally as tight as a Mitsubishi Evo(2002-current).Thats one of my favorite cars due to how stiff the chassis is as well as the 4g63 engine-those chassis's are TIGHT as they are stitch welded percisely at the factory.Their Rally cars,so the chassis has to be stiff as hell.I remember a guy I worked with that Rally raced his 2002 Evo(imported) & said that some cars that raced(non-professional) had to be stiffened considerably & would still crack their windshilds or bend their chassis even from going over small jumps.The Evo guys never had those problems.I do hate it when I have to slow down to almost a complete stop when going over railroad tracksSorry I got on a rant but my car is amazing on smooth pavement but loses its composiure when turning while going over bumps.THE C4s' WOULD BE ONE OF THE BEST SPORTS CARS EVER MADE IF THE CHASSIS WAS STIFFER!Email me on what you plan on doing to fix the C4s only weakness(my opinion)-Jriderkelly@yahoo.com

 

The factory bilsteins are only sold by an authorized gm dealer for alot of $$$$. This shock is a little softer than you can buy in the parts house. Bilsteins makes these for dealers only. (I was told this info by bilstein)

 

Well I have a Jeep Cherokee so my 91 actually feels like a fukin cadillac compared to that truck. So if your driving cars that feel like they are driving on marshmellows ther is the problem. get a real rattle trap and then drive your vette and youll feel like you just stepped into a caddy. I will say though that the car jumping on pot holes is crazy

These cars are stiff like this for performance any added damping will take away from cornering etc. I took my vette out today for its madden voyage and I loved it. The car cooks. I never thought Id like an automatic as much. I adjusted that tv cable and man what a shift..............wheeeeeeeeeeew baby, nice.

 

Boy, was that post awesome. You "get it". Especially the part about the C4 w/a stiff frame; it would be one of the best, most fun cars made, IMO.

I'll email you what I'm working on. I'm glad that you're interested!

 

Let me know what you do to stiffen the chassis & what difference it makes.I have the underbody X-brace as well as the targa truss on my vette to stiffen the chassis.The targa truss made a night & day difference but not so much with the X-brace.The best thing to do(my opinion) would be to tear the car down to the bare chassis & stitch weld every joint,add some chassis connectors or reinforce the chassis,reinforce the steering column,adding the camber brace to connect both upper control arm towers,& having a targa truss or something similar installed when the top is off.To me,my 1994 would be my dream car or close to it if it had a solid/stiff chassis like a newer vette or ideally as tight as a Mitsubishi Evo(2002-current).Thats one of my favorite cars due to how stiff the chassis is as well as the 4g63 engine-those chassis's are TIGHT as they are stitch welded percisely at the factory.Their Rally cars,so the chassis has to be stiff as hell.I remember a guy I worked with that Rally raced his 2002 Evo(imported) & said that some cars that raced(non-professional) had to be stiffened considerably & would still crack their windshilds or bend their chassis even from going over small jumps.The Evo guys never had those problems.I do hate it when I have to slow down to almost a complete stop when going over railroad tracksSorry I got on a rant but my car is amazing on smooth pavement but loses its composiure when turning while going over bumps.THE C4s' WOULD BE ONE OF THE BEST SPORTS CARS EVER MADE IF THE CHASSIS WAS STIFFER!Email me on what you plan on doing to fix the C4s only weakness(my opinion)-Jriderkelly@yahoo.com[/QUOTE]

Only weakness ? cough brakes ....cough

 

I took a look at the book to confirm, but can't find a mention of the C4's natural frequency. I did find Dave mentions the light/stiff suspension moved wheel hop to 14.5Hz, and he mentions this is close to the top-on frequency of the chassis. So it's in the ballpark. The specific numbers may be in there, I just couldn't find them.

 

Yeah, the brakes suck...but no worse than any other sports car for under 70k from that era. The frame however, definitely doesn't stack up well against the frames in the same price range of say:
3000GT/Stealth
Supra
300ZX
RX7
Even SN95 Mustangs are better in this area.

I sure wish there were a place to find mroe tech data on the C4 frame.