OK, I will try to keep this short...
Had the rear end out to do a 3.91 swap and thought, what a good time to do some poly/shock upgrades. So I did Z51HO shocks, Rear poly conversion kit and front/rear sway bars too. I followed all torque procedures including using ride height for the necessary points and used lots of lube.
Issues:
1)*** end riding high; 5 fingers between tires and fenderwell (front is 2). Was aprox 3 fingers before work. Got 10" bolts which only lowered it 1/2" at the most. Was advised of 12" bolts availavle for $60
2)Ride sucks! Over smooth pavement or slightly bumpy at speed it is fine, but slow speed bumps like intersection humps, driveway entrances, speedbumps will literally throw me up and the seatbelt chinches on me to keep my head from hitting the celing. Turning through intersections needs care to not spin the car as the rear bounces and loads/unloads the tires.
I thought it may be the Z51 shocks, so I put the old ones back and there is little difference in ride and ride height.

SO

Where do I go next?
-Put rubber bushings back? Which ones contribute the most to ride, as I'd like the idea of a responsive suspension.
-Try the longer bolts to lower the ride height (decrease the spring rate as the rear is lowered, and correct alignment from raised rear end).

I don't know what to try next, but it is unacceptable as it sits. It rides worse and can't hold a line in a corner with bumps nearly as well as stock comfort suspension with 65K miles... It almost seems like it is binding up and not allowing the correct amount of suspension travel.

TIA for any direction you can provide me.

 

Poly bushings should not affect the ride height much if at all. Mine actually sits slightly (1/2") lower with the poly presumably because they don't bind up like rubber does. They also shouldn't affect ride quality nearly as much as you're describing (excluding the shock change). You will feel small bumps a little more, but that's about it.

Sway bars will affect ride quality, but mostly on uneven surfaces. Shouldn't be anything as severe as what you're talking about, though.

Sounds like swapping back to the old shocks didn't help much.

For comparison, I have a '96 with stock (soft, non Z51) springs, stock shocks, 30mm solid anti-sway bar front, 26mm solid bar rear, poly bushings on everything with the exception of heim joints on the rear camber adjustment bar. The ride is definitely stiffer than stock, but not bone jarring by any means. Very comfortable on the highway. Only gets unsettled when I go through some major potholed streets in the city.

It almost sounds like the suspension may be binding. That would explain the high ride height as well as the stiff ride. With the spring unhooked (car jacked up), and poly bushings, you should be able to move the suspension through it's range of travel by hand -- OK, both hands. If you can't budge it, something is binding.

 

I thought it might be binding, so I loosened and re-torqued all the bolts. It seems like they are very tight though. Some are as tight as I can get them with the torque specs for Helm. I was also thinking to loosen the bolts again and re-tighten them less than before. Maybe they don't need to be as tight with the poly. I'd be really ticked if I put the rubber back and it didn't change it...

 

Check to make sure you didn't install your sway bar upside down in the rear.

Shot showing correct swaybar mounting

http://www.pnwzr1.net/Jeff/Coilover/IMG_5420.JPG

 

I know the rear will ride high after it's been unloaded, but this is exceptional.

 

everything needs to be torqued down at proper ride height. The manual states that pretty clearly. Otherwise, I suspose you may experience preloading.

It says something about not torquing below rebound. It's difficult without the wheels on there... or difficult with the wheels on there, depending on which way your looking at it......

 

You can use a jack to pre-load the rotors before tightening.

 

I don't think poly's need to be torqued at ride height - they rely on the sleeve rotating in the poly as opposed to rubber bushings that rely on rubber deflection.

You did drive it around after tightening everything and it still didn't settle down?

 

FWIW, I had chromoly poly bushings put on my rear suspension along with new Bilstein's...the shocks were the regular model, not the stiff ones...my rear rides high as well..people even comment on how it looks "wrong"...the ride is awful..if I hit any of those reflectors in the pavement it's like a gunshot going off...speed bumps are rediculous...

All the work was done by one of the most knowledgable vette wrench's in the country and torqued perfectly (I watched)...the owrst part is it was my bright idea to put them on...oh well...

 

I torqued all the bolts at ride height according to the Helm and it made no difference.
I just went out and loosened all the bolts and re-tightened according to my hand meter (basically what feels right with the ratchet). They are considerably looser than the specs call for. We will see, a quick spin didn't seem to change much. I was thinking some of the brackets were binding up due to the torque, this will eliminate this factor. Ride height is at about 4 fingers to the body edge. I am wondering how much the raised ride height has on the spring rate. How much does it soften with lowering? I wouldn't figure much.

 

BINGO!

 

For anyone else reading this, another cause can be the bushings binding.

If the width of the installed bushing including the shoulder thickness is wider than the inner sleeve, the bushings can bind. I found the fitment on my Energy poly bushings to be a mediocre fit. I'm guessing this wasn't a problem with the stock rubber since it's so compliant.

You should torque the bolts to spec, then try and pivot the suspension parts.

In fact, if the sleeves are too short, the bolts won't load up against them, and you have to tighten them more to get your torque. I solved this by actually grinding the suspension eyelets thinner. (Yeah I'm crazy, but it was easier than arguing with Energy Suspension over and over or trying to cut the bushings down.

 

Your welcome Go enjoy the ride.

 

Are you saying the sway bar(s) was upside down?

Edit: woops! looks like that was the case.

 

Went out and peeked through the rim and the edge of the bar was resting directly on a frame mount. Thats why I didn't feel compliant, it couldn't move!
Just got done re-installing the bar, put the Z51 shocks back in and retorqued it all back to spec. Lowered in down and it was way too low, so I screwed the bolts in an inch and went for a quick ride and it seems great. Loving the forum tonight! I was ready to pull my hair out!
Thanks Jeffvette!

 

And how did we know about this??

 

Hasn't happened on my car. Came across it on another car a few months ago.

 

I love happy endings!! BTW Jeffvette, nice hood ornaments you got there!

 

I am installing Prothane bushings on my '96 LT-1 CE. The rear sway bar link bushings have the same raised edge profile of the other bushings which are 2-piece. Well, these 1-piece bushings will not fit into the sleeves without cutting off one of the raised edges. Is this the right way to do this? If so, which edge to cut? How did you install yours?

 

Sent you a email, mine were able to be squeezed in using the vice even with the raised edges, though they are contoured edges. Lube it up and squeeze it in...