So I did a rear suspension rebuild on my 1996 GrandSport at the beginning of the summer. Replaced rear bushings with Prothane polyurethane. The only thing I left OEM was the bat wing and sway bar frame bushings.
I also did the half shaft u joints. The I moved to the front suspension. My lower ball joints were bad but everything else was perfect.
So I replaced the lower ball joints with Moog joints.
I did remove the lower control arms from the car to press the old ball joints out and new ones in. After I finished, the steering wheel was not straight anymore.
So I had a 4 wheel alignment (at two different places don't ask about the first one). The final place that aligned it spent 4.5 hours on the alignment. They aligned it as close to the Advanced Street Specs recommended by Vette Brakes.
Basically a little more negative camber front and rear. and toe very close to zero. The car is nice and straight going down the road. even road crowns don't upset the car.
But here is my question: The car does not seem as responsive as before. Example I used to be able to turn the wheel from left to right quickly (like race cars do to warm up the tires) and the car would respond to the wheel nice and flat. Now it seems as though the car sways a bit, not quite as flat as before. On a non related note I think my Goodyear GSC tires have hardened over the years so the back end does not stick as well.
The shop that did the alignment (the second time) checked my suspension over (just in case I missed something myself) and they said nothing was worn or needed replacement.
The car has the Z51 suspension and from day one (1996 when new) it handled great to me. Now I know it is 17 years old but I don't feel it handles as good as before. Anyone go through this after a suspension rebuild? And any suggestions?
Thanks!

 

It looks like you did a really good job on the suspension, but what shape are your shocks in?

 

I tried to bounce the front and rear on each side. The car hardly moves when i try to push down on it! No leaks at any of the Bilsteins but the car does sit in my garage for the long winters. I suppose they may be weak. Any way of really checking them other than the bounce test?
ThanksQUOTE=desertmike1;1585283272]It looks like you did a really good job on the suspension, but what shape are your shocks in?[/QUOTE]

 

"Example I used to be able to turn the wheel from left to right quickly (like race cars do to warm up the tires) and the car would respond to the wheel nice and flat. Now it seems as though the car sways a bit"

Did this happen right after the re-work.. or was it a problem all along?

 

If the tires are old and hard, you could chase your tail all day long looking for something amiss in the suspension.

 

Yes! Replace your tires before doing anything else....... you will be amazed at the difference in handling with new tires.

 

I had the front toe set at factory and the steering was slow to respond like you suggested.
So when I got home, I cranked out two flats each side for a touch of toe-out.
The steering was again crisp and tire wear unaffected.

Four hours? Geez did the guy take a lunch break?

 

What are "two flats"? And, I'm guessing the front tires are really supposed to have some visible toe-out? I remember noticing this before and probably asked about it years ago.

There is enough visible toe-out (on my just-aligned car that) you'd think the tires would wear more quickly. It looks like as much as 2-3 deg on each side. Maybe even a bit more.

A Chevy dealership did it as part of repairs after my recent fender-bender.

 

First thanks for all your suggestions. desertmike1 this started after I replaced my ball joints (after the rear suspension the car still felt pretty good).
My alignment specs are Left front Camber -.16deg, Caster 3.98 deg., Toe -.01". Right front Camber -.28 deg. Caster 4.72 deg., Toe -.01"
Rear left Camber -.27 deg. Toe .12". Rear right Camber -.20deg., Toe -.01".
The Caster came down from what it was (6.2) due to the alignment guys trying to get more negative camber. They took out several shims.
The thing I do not understand is that if it is an alignment issue why does the car not feel flat almost like sway bar is not connected (but it obviously is).
Tires felt ok during the hot days in the summer. Now that the temps. are in the mid 40s they are not getting much traction. They are getting close to the wear strips. Tires will be on my list for next season (as my car will be put away for the winter).

 

Gregg,
Your front tires should have just UNDER 1/4" toe-IN. -.220" is the
factory spec. With toe-out, you will tend to get some 'wander' of the front end. I've set my '90 to 0 and .220", my car likes the .220" better. You need a really good stretch of road to 'feel' the difference. Lately, all the roads in our country seem to be either full of potholes or patches. I was lucky to have a new section of I-10 just north of Tucson to test on.
Exactly how did you measure your toe-in? You need to scribe a line all the way around your tire in the tread area. Measure to this line both in front and behind your front axle. This will give you the total toe measurement. Visual cues just don't work for this precise measurement.

Mick

I spent two years in an alignment shop after high school, I"m sure the latest machines are light years ahead of what I learned back then.

 

I was wondering about that. Looks like he went home and got a long quikie.

The best place to get Corvettes align, is a place with Corvette experience. These cars, ARE NOT regular passenger cars.

 

The alignment shop spent 4 hours to try and get the specs as close to VBP Advanced Street specs. They also had to start off where the first alignment shop screwed up. They took their time but I did not want it rushed like the first shop. This guy has a 25th anniversary C3 Vette. His shop has had some nice musclecars that he works on. So I am pretty confident of their ability.I am just trying to figure out why my car handling has changed after all the work I put into it. I mean it still corners ok and it is very stable at high speed compared to when it was even new (since this last alignment). But the car has a bit more of a sway feel to it. No longer is the car flat when I turn the wheel and through off ramps. It is subtle but it has changed. I don't think tires are the issue as some have suggested. The shocks may be at fault. But I can't even push down on the car it hardly moves! That usually means they are good or am I wrong?

 

these cars a light enough and the spring rates heavy enough, that i don't think you could find bad shocks by a bounce test.

 

My opinion is that it sounds like your describing excessive roll. So look at your anti roll bars front and back at the end links, checking the bushings and check the mounting points to the frame. The end link bushings seem to degrade on these and need replaced. There have been multiple threads on these so you may be able to find out more with a search. When I got my 96 I had to replace the rear end link bushings, two were completely gone.

 

GSCs....seriously? Even if they're not the reason for the handling issue, they're a safety issue. Get rid of those things.

Based on your description, I'd consider the shocks. Push test won't work. Pull one off and see how easy it is to compress and also how quickly it rebounds.

 

Maybe not. Sounds like a good way to measure though...or just measure to the outside groove in each tire?

If I line up one tire so it looks parallel to the rear wheel face, the other side would clearly be pointing to the inside of the rear tire. It will be turned outward.

I've had it aligned 3 times in 14 years and it's always looked toed-out. I consider the body is tapered to the front when I'm looking at the lines. So, I look down the side of the car -- at the wheels -- and ignore the body line.

 

A typical fine measurement of turns.
A common nut or bolt has 6 flats.
1 flat equals 1/6 of a turn.

 

Mick

 

Whole heartily agree. The bounce test isn't good on these cars. When i replaced my factory installed Bilstiens last year with Z51 Bilstiens, the difference was amazing. My old shocks could be compressed with one hand. Essentially they were riding bottomed out and the only absorbtion was coming from the transverse springs.

Now it steers like it's on rails, almost no roll what so ever, and this with old bushings. Can't wait to get the bushings replaced and see what happens.

Get new shocks and tires, then go from there.

 

Thanks Guys for all the help. I will check the front shocks. The rears seemed ok when I did all the rear suspension work.
Just to clarify my tires are Goodyear GSD3 tires not the OEM GSC's as I mistakenly stated above, but they are about 8 years old!
If the front shocks turn out to be bad where do you guys purchase your Bilsteins?