just orderd this set of rear coil overs for my 92 Z28.
this is a bolt in unit
http://www.summitracing.com/parts/ha...2332/overview/
) Double Adjustable Proma Star Shocks, (2) Springs, Mounting Brackets & All Necessary Hardware

anybody try them?
http://www.qa1.net/qa1_motorsports/d...sion-kits.html

on a side note the brand new ground control rear set up will be going up for sale...you can no longer order just the rear...

 

How much $ do you want for your rear GC set up?

EDIT: Sorry; PM sent...

 

I chose to get them from Spohn, because you get the plate to better space the load and strengthen the top shock mount area - VERY IMPORTANT. You could always make your own.
Looking into ways to lower the lower shock mount attachment point to get a little more piston travel when lowered. I might just go with transverse mounts and have the attach point lowered when I replace the rear end - but I'm balking on that price right now.



And my ride height

 

saw the older weld in ones years ago..this kit bolts in. and moves the shock over a tad.
placing it to clear the bumpstop wall (not there any more)
its been replaced with tire.
and setting the load more in the spring pad...ball park. it bolts up in place of the OEM shocks
and the lower mt has 2 bolts holding it to the axle tube. ya got to drill the 2nd hole about 2" above the oem hole

the pic summit has up is not the exact one.

saw them a few months ago in one of the chevy mags.. on a 3rd gen. they beat on.
have had the ground control set up set to go in on the back..and what the heck..ill give it a shot.

by the time i get done ill have enof parts left over to do a 2nd car...up grading even before i get the first set/style of parts in...lol

 

update with pics
this is the new lower shock mt


shocks

new upper mt

 

I like that lower mount. Are they available separately?

 

yes they are..if i remember they are proud of them! $40/$45 ea.

and there is a hole in the upper part to add a bolt to when ya drill the matching hole in the shock mt on your axle housing. (making 2 bolts to shock mt) the bolt ya see in pic..and 1 above that...

but it is a bolt in Kit now..
this kit was $700.97

but the single adjustable shock kits are $550

going to put the parts on a scale. but im thinking a 3lb ea side diff in parts. so its going to shave a few lbs off the car... (could be more)

did not even install the ground control parts i got...still upgrading even before installing...lol
more parts to pass on in the end!

 

Like the new kit

 

does the new mount lower the bottom of the shock? i had to fabricate new lower mounts and bring the bottom of the shock down about an inch and a half due to the shocks bottoming out.
Be aware that if you lower the car too much with the qa1's in the stock shock mount location they will bottom out because they are too long

 

here is a pic of what i made

 

Any time you lower your car. You are removing shock travel. And you can run into problems like that. But for us guys who have stock ride height cars this is something that we can play with and tune the car / suspension for track use.
because I'm sure with a lowered car you're not running 29 inch tall 13 and a half inch wide tires.

but they do make shocks. For a lowered application.

 

Are you saying that with a lowered car you cannot play with and tune the car/suspension for track use?

 

I don't really understand what you are saying here???
I actually use my car on the track and run 305 tires in the rear. I went with the qa1's for the purpose of using them to tune my suspension. They are too long and the shock mount needs to be extended...I am not the only one who has had this issue with them

 

and in case you were wondering on the ride height i run and if i really do run my car on the track here is a pic of my car after the faceoff at road america with optima batteries and speed channel.

at this ride height they will bottom out if you dont extend the lower mounts as you can see it is not too low

 

I dint know if you have a dif set of /part numbers then what they have now...what. but I talked to Q1A. before I posted my reply and ask them specifically about your problem.with the shocks bottoming out and that was the reply.for safety I always have bump stops on my rear shocks cause I don't have a bump stops from the factory..my shocks have over 6 inches of travel. But I have less than 5 inches of travel with tires so I don't know what to tell you except check your part numbers with what they have now

but it does sit lower then factory from the pictures. Mine sits the stock height and clears 29 inch tall tires but then my setup is brand new for this year

 

trust me the shocks are the same as yours i too talked to qa1....being i sell and install their stuff here at my shop, and they told me the same thing they never have seen this issue.. your car is at stock ride height so you probably wont run into this problem. 95% of the installs i do dont get set to stock ride height. the truth of it is if you want to lower your car a decent amout with their shocks for 3rd gens you need to lower the shock mounts they simply do NOT have the travel needed. My car was the EXACT same height it is now when i had Koni's and springs and they never bottomed out.
I saw you were installing these and was just tying to give you some advice from experience.
i still am happy with the way the shocks perform or else i wouldent install them on my customers cars

 

Like I posted. Have No info on anything other then stock ride height.I've never had to lift the back and I've never really been into dropping the car down...but on stock ride height cars they fit and work fantastic no problems....but on any shock I install bump stops.its just a safety thing for me.some companies sell over priced shock bump stops for like $55 each. But you can get really good ones even better than the over priced ones for under $15 each in the color of your choice

They just ride on the upper rod of the shock. Skidding down onto the shock.
Have you seen these?..

So the factory bump stops they still on your car.

And for street use ill bolt on a smaller tire 325/50/15 there only 28" tall.they are a full inch shorter then my sportsmen.
car sitting stock Ht. with tires on. thr QA1 bolt on coil overs work/fit fantastic.

jack was used under rear end. to lift and place back on Jack stands.
tires are 29/13.5/15 sportsmen pros. all under car...no GM bump stops.
before fender rolling(just to be safe)

 

Would you be willing to provide a link or part # to these? Thanks.

 

When I get home today (I get off early on Fridays..) as I put in... hrs in the week to do so..as I want my 40...ill post a link. It will be on speedway Motors site.. or see if you can go to there site now...under dirt track cars/parts.

 

Thay have a few.
http://www.speedwaymotors.com/Pro-Sh...umper,852.html
http://www.speedwaymotors.com/Speedw...ium,33270.html
http://www.speedwaymotors.com/Speedw...-Soft,830.html

and even more
http://www.speedwaymotors.com/search...y=SHOCK+BUMPER

sorta kewl.if a need them..
http://www.speedwaymotors.com/QA1-BC...ing,23506.html

 

This will be my last post on the subject; Thank you for the links. I almost purchased the $50 ones, but the AFCO/speedthane bump stops appear to be the real deal and are a little less $.

 

Tell me about it..I shop for parts just about every day..some times i can keep the price in the 50 percent difference..

glad I could help you out. A lot of us guys who have big money into their Race Cars like to do that...