KCHOTBOAT

Looking to make some mods this winter on a 96 which is stock except for zr1 wheels which already bumped me to the BSP class.
I plan on adding R-D racing x frame and chamber brace this winter. Looking for other ideas and that people with more experence than I do have.

Solofast

The camber brace is legal in BSP, the X frame is not....

Get some offset lower front bushings so that you can get the car aligned to where you need to be as a first thing...and of course serious tires are a given.

Then you can think about serious shocks, as well as swapping out the springs and bars to, as a minimum Z07/Z51 spec parts....

At that point you can have a lot of fun with the car and still enjoy it on the street.

Then you can decide if you want to go whole hog and dedicate the car to autocrossing (gorilla stiff springs and bars) or keep it as a dual purpose toy....

Have fun...

astock165

Not to hijack the thread but...

Are single adjustables enough or would one quickly want to upgrade to doubles?

I will be at the point of changing springs and swaybars in the near future and have been struggling to figure out what rates and sizes to pick. My goal is to eventually make it a dedicated competition car (a/x and TTs) so the street is no concern. I don't have enough experience to comfortably make that choice myself. In that case, how would one decide what to go with?

With my 93, in the absence of any other info I would probably go with the Z07 rates & sizes (I already have the camber brace and do my own aligments).

Solofast

If you are going with the Z07/Z51 springs you can probably get where you need to go with a set of single adjustable Koni's. That is the "accepted" setup in A/S and those are the springs you are using. The compression damping in those shocks is a good match for those springs, and that would be a lot less expensive than double adjustables. I found for the later stock C4's I was, under some conditions, just about at about the end of the rope on front rebound adjustment, so maybe a set of custom valved singles with a bit more rebound would be the right thing. Also note that you are going to have bigger wheels on the front and more unsprung inertia, so a little more rebound damping may be required for that too.

If you go much stiffer than the Z07/Z51 in springs you are likely going to need to go up in damping rates and maybe that is where you go to a set of double adjustables, or get a set of singles custom valved with a bit more compression and a bit more rebound in the front.... With most of the serious BSP cars, folks tend to jump right to big springs and the doubles, but it is a big cost step, and it makes the car a lot less "streetable" so going that way is not to be taken lightly.

Depends how serious you are and wheather or not you are running nationaly or just locally, and what you want to do with the car.

astock165

That all certainly seems to make sense. I was looking at the C4 suspension chart and was wondering if Z51 springs would fit on a later C4, where Z07 was the stiff option package? I'm not sure if there were mounting point changes as well? It looks like in '91 the Z07 package had the same rates & sizes as the old Z51.

How much bigger in bars and stiffer in springs can you go than Z51 or Z07? I'm assuming they'll be aftermarket? I'd also assume that VB&P would be a leading vendor in this area.

Now all I have to do is pay off the new HVAC system in my house and get back to working on my car!

KCHOTBOAT

The below is out of the solo rules. Does this mean I can use a x brace since the convertibles have them. My real reason for using one is for taking the flex out when the targa top is off.

C. Equipment and/or specifications may be exchanged between
different years and models of a vehicle if (a) the item is standard
on the year/model from which it was taken, and (b) the years/
models are listed on the same line of Appendix A (Street Prepared
Classes). The updated/backdated part or the part to which
it is to be attached may not be altered, modified, machined or
otherwise changed to facilitate the updating/backdating allowance.
Standard factory installation methods, locations, and
configurations are allowed. The updating and/or backdating of

z28cp

You can add a FACTORY convertible x-brace, but NOT an aftermarket x-brace, like the R-D unit. I believe the R-D x-brace will move you all the way to the Prepared classes...

DaveZ

90pololt4

If you're interested I have some items from my C4 as a BSP car. These items were sold but the person never came through with the $.
I have the Z-51 F & R springs and the 30mm front & 24mm rear Z-51 sway bars with end links with poly bushings. I also have a set of Advance Design adjustable shocks. They were used one season and then rebuilt as a back up if needed. Let me know if your interested.

You may want to download the SCCA rules for SP if you don't already have them. You can do a lot of mods in SP.

KCHOTBOAT

PM sent.