Hi guys,

Ok so I have a really unique problem and I'm looking for some advice. The car is a Z51 84 that's LS6 swapped with a 4L80e and a Dana 44. Here in PA we have a foot of snow on the ground so I'm not driving the car any time soon, So after I got the new transmission in I decided to lower the front of the car. I got the basic kit with the rubber wedges and I pulled the factory spring out. The rubber was all shot. The spring looks ok though.





Here's the problem. When I did the LS swap years ago I used a Camaro oil pan. I had to notch the cross member to clear the oil pan. I welded in a 1/8" thick steel plate over the hole to fill everything in nicely. Well when I went to put the factory spring back in last night with the lowering blocks, it won't fit. Because of the shorter blocks It will hit on the plate I welded in. So this leaves me with a choice to make. I could pull the motor back out and re-fabricate the plate in a way that will allow the spring with the shorter wedges to go in. Or I could install coil overs.







I have absolutely zero experience with coil overs. I don't auto cross the car at all. I do enjoy some "spirited" driving and I love the handling of the Z51 spring with Billstien shocks. So if I did coil overs I just want something that would handle the same as what I had but would allow for adjustable ride height. I know that most coil overs won't fit on an 84 without work. I found an old thread here with this picture of what user rklessdriver did.




I like this idea. I could easily weld the mount on top like he did. I was thinking about a set of QA1 shocks and springs. 350 to 400 pound spring rate. The shocks are one way adjustable. The price of all the parts seems really reasonable. But will I get the same feel as I did before. What do you guys think?

 

You should be able to approximate the same feel with coilovers but you may have to tweak the roll bar. You lose some of the anti roll properties of the mono leaf removing it. But that being said a good set if coilovers should be as good or better imo.

 

That's what I was hoping. After a little more research I think this is for sure the route I'm going to go. A lot of people want the 84 Z51 front spring. They sell on ebay for way more than I thought they did. Also my Bilstein's on the front are still in good shape so I can sell those and the aluminum spring brackets I got from an 89. I could sell all this stuff and only spend around $100 out of pocket to do coil overs. Kind of nuts really.

Anyway I think I have a parts list

Shocks QA1 DS404
Springs QA1 10HT400
T mounts QA1 BAR350K
Upper mounts PRO-TEK SM3180

I might have to figure out a different sway bar mount but I won't know that until everything else is on. Nice thing is if I try out the 400 pound spring and don't like it, it's super easy to swap it out for something else.

 

I'm a little confused by the cutting and welding since I used the same pan and had more than enough room to pull the pan off the engine with it still in the car, but I guess its a little late for that.

Coilovers can be an improvement over the leaf in a lot of aspects, but it'll take the right amount of spring and adjustment to hit their potential.

 

I think the pan hitting was because of the motor mount adapters I used. They seemed to seat the motor a little lower then some of the other adapters I've seen. I saw a thread here a long time ago were a guy had the same issue. Then I've seen others that it fit fine without any cutting. Mine didn't hit by much. But it rubbed the pan.

The nice thing is I'm not super picky about spring rates or anything like that being I'm not racing. This is only a street car that sees an 1/8 mile every now and then. I just want it to feel close to stock and have the adjustability.

 

I just got off the phone with QA1. The tech talked me into a little stiffer spring. 450 instead of a 400. I might put together a build thread with pictures. Nice thing with using all off the shelf parts for this from Summit Racing is that if I measured wrong and something doesn't fit I can stop by and exchange whatever I need.

 

Just a little pointer I learned from my conversion.

Spend some time mocking everything up with the front suspension at various heights/travel. You will have to grind or cut the factory shock tower back a bit towards the top. The further you can angle the coilover back at the top the less it will rub on the upper A Arm at full droop.

I only barely ground my tower back at the very top and my spring rubs pretty hard on the A Arm at full droop.... it dosen't bind anything up and mine being a radial tire drag car the front suspension extension is limited anyway but it would be more important on a daily driver.

Also fully weld the tower to frame seams..... there's only a few spot and seam welds from GM.
Will

 

@LD85 did a very nice fabrication on an '85 and Will might have contributed. I've no idea where the snapshots went but you might reach out. It was a very nice fabrication.

Here's the thread and there's likely more


https://www.corvetteforum.com/forums...ck-towers.html

 

In my opinion restoring the cross member is the safe route. Pulling the engine is the main part of the work.
For street use, or even for racing, you have to invest some time and parts before you get a coil-over soluition that is 'better' than the stock spring and shocks.
To do the coil-over correctly you have to spend a lot more time designing and fabricating top shock mounts compared to just restoring the cross member.

Even if restoring the cross member it is still possible to do the coilover conversion in the future if you would decide to do that.

 

Maybe you just buy a used 'correct' suspension member, modify as needed, suspend the drive-line and lift assembled suspension to the car.

 

That's my thought when i see stuff like this, for an all around street car with even twice the power it had stock. the standard c4 suspension is pretty damn good. Not saying that it can't be improved for specific applications. but it is all a compromise. and the factory struck a pretty damn good balance. now if drag or auto cross track use is the plan then sure go for it.

the one c4 i rode in that had coilovers didnt impress me, and on the little road course we were playing around on it was not any quicker through the course. however, there were no professionals driving the cars. and the coilover kit was a vansteel kit i believe. the thing that stuck out to me was it was more twitchy at the wheel, the car had a tendancy to nose dive. and when on the throttle it didnt plant the rear tires as well as stock. in all fairness that could have been driver error. and definately far from optimal setup. the car was not weighed at all four corners or setup right after the coilover install. but riding in it, and seeing it run the overwhelming thought was "this guy spent over 2500 to install this and his car is the worst handling car out there. seems like if you want to go coilover youd best have one hell of a lot of chassis setup knowledge. and the collective resources of a race team to properly dial it in.

to just buy a kit, install it, and setup ride height and expect it to do better than oem is pretty unrealistic. it least from what i have witnessed. be prepared to do some testing, and preferably have the help of a chassis setup expert for whatever type of racing you plan to do with the car is my point. and if you cant do that maybe consider leaving it stock with better shocks, bushings, and some adjustable suspension parts to dial in what you have. especially if normal street use will be in the plans.