All,
I have been through this site several times and others to find the stock spring rates for my car 2013 S Vert w/32k mi.

I want to upgrade to BC CO's with Swift springs to get a correct (for me) ride height, but I LOVE the ride and handling of my stock S suspension. (and it is wife friendly) I want to duplicate the stock spring rate or maybe just a little firmer.

Can anyone help?

Here is the closest reference I have been able to find (IPL Coupe stock rate compared to Pro Kit progressives)


I have seen recommendations for 12 F, 10 R. But I can't tell if that is a Vert or Coupe and can't compare to stock S rates. This could be a track guy who prefers stiffer rates....Don't know. No Baseline...and that is over 100lbs/in higher than the IPL in front.

Here is a pick of my previous 2009 Base Vert. It came with Eibach springs and had the "saggy butt" (about 1/2" too low in rear). I solved this by buying a 1" rubber spring spacer and cutting it in half to create 2 - 1/2" spacers with a flat bottom and spring divot on top. used stainless fence ties to secure it to the bottom of the spring and...Vola!! PERFECT height. But it was too firm of a ride and bouncy in the rear. Not well sorted.



On the '13 new Vert, I have already installed 15mm spacers in front and 20mm spacers in rear to push the wheels out to the finder line. That helped. But I HAVE to get rid of the 1 1/2" gap between the top of the tire and bottom of the fender well.

Other related MODs I am going to do:

• SPC Adjustable Front Camber A-Arms (had these on the 09)
• Coupe Adjustable Rear Camber bars with shock mount welded to them (see below) For more adjustability than SPC bolts. (Thanks to another member here for the solution!)
• SPC Rear Toe Bolts
• Mich Pilot Sport A/S 3+ (245/40-19 F, 275/35-19 R)

Ready to pull the dang trigger on everything....just can't find my stock spring rates to ensure I don't dump a load of $$ and I and/or my wife is unhappy.

Please help if you can! Thanks!

 

I ended up with BC BR with Swift 12F / 10R and it's a great combo. The ride is alright for twisties (it's a heavy car), and the woman does not complain during longer trips.
I tried softer springs previously and while it was nice for cruising, it was not good on bad roads - too much sag. And if I tightened the compression, the car didn't feel good on bumps.

The only issue with the new setup is the deep joints (bridges) at speed. Going 60+ mph and hitting one of those swoopy dips pushes the rear down far enough for the wheels to hit liner. There are probably ways to get around that, but it doesn't bother me too much and only happens in very specific situations.
You don't need the arms for the rear, unless you are planning on tucking the tire or going with crazy camber. I used the spc bolts and the car is in spec with a bit of a negative in the rear.

 

Kiseliok, thanks for the reply and great info. Asheboro, SC. You are only about 1 1/2 hrs from VIR. That was my home track when I lived in Richmond. My Porsche club was one of the first on the track when it reopened in 2000. Was amazing being on the track back then....rustic, hidden away, all that history. After all the tracks I have been on, VIR is still my favorite and holds a very special place in my heart.

A few follow up questions if you don't mind:

1. Looks like your car is an S. How does your BC set up compare to the stock S suspension? (Talk about handling, ride quality, and wife factor please) Wife and I like to take this car out on the rural, two lane, back roads and get lost. These tend to be less well kept than the super slabs.
2. I see you have Hotchkis sway bars. How did that interplay with your stock suspension (if you added them before the BC's), and/or the BCs. Increasing sway bar usually means you can have softer springs and vise versa. If I keep the stock S sways, do you think that will work well with the 12F, 10R set up?
3. I don't plan on going "low." I want my fender bottoms to be at the top of my tires (like the picture of my 09 red car above. That said, the best i could get my rear camber to on the red car with SPC bolts was - 2.5 with that reasonable ride height in the pic. (rear camber spec is -0.8 to -1.8) While I use to race, and I still enjoy spirited driving from time to time, this is primarily a daily driver and I want to maximize tire wear. So targeting rear camber of about -1.2. This seems to be out of reach for SPC bolts which is why I was looking at the custom welded up set up. Maybe my alignment shop didn't know what they were doing. Is -1.2 attainable with SPC bolts?
4. Looking for about -0.7 on front. Do I need to buy the SPC adjustable A-arms to get there? I had them on the red car.
5. Is the bottoming out issue you described related to the top being down (ie more weight over the rear) or doesn't matter? How is the balance of the car? would 12F11R (or 12R) be better? Or would that make for too stiff of a rear end? (the Verts carry a lot of weight back there.

Sorry to hit you with all these questions, but you seem to have already walked point down the path I am going to travel. Teach me Obi Wan!!

 

I'll tell you one thing, most of the G know-how I posses is from this forum - there is A TON of information. The search hasn't been super intuitive so I used to just go through each vert thread and read up on everything related - I definitely recommend you do that. Folks on here have been graciously sharing info for years and I'm always super appreciative of what's already posted on this forum.

I'm in Charlotte, NC, but there are a few G folks from Asheboro area here. I've been to VIR a few times since about 2008 - very nice track. We used to watch GrandAM races there, when that was still a thing (mazda crews). My home tracks are Nelson Ledges (OH), Beaverun / Pittrace (PA), and Mid-ohio - spent quite a bit of time there, but I don't think I'd bother with a G on a track. It's a cruiser.

1. My BC setup is a bit stiffer than sport, but I messed with damping a bit to make sure she sticks to the road well regardless of the type of road. We also enjoy the 2 lane side roads the most, especially in Uwharree area. Just keep an eye on the bridge joints, as I mentioned in my previous thread.
2. I definitely would not got as far as saying that you can have softer springs with a thicker anti-sway bar(s). These two work in tandem. While you are cornering, the sway bar will help you will less body roll, so you could get away with a softer spring, but what happens when you hit that previously mentioned bridge joint with both front or both rear wheels? Sway bar is just hanging out not doing a whole lot at that point and your springs take the beating bottoming out your car. My reasoning for sway bars (I don't really know why I'm shortening the anti-*, since I'm typing out an essay anyway) was the sheer weight of the car (this roof is like 500lbs with a lot of the weight up top) and to keep it a bit more leveled while in the twisties. It definitely worked, but there was some noticeable loss of rear flex with potholes, etc. I don't think the woman noticed, but I know it's there.
3. I had the shop "elongate" the holes a bit and iirc my rear camber is at -1.3. Check out the description here: https://www.z1motorsports.com/suspen...ts-p-3981.html. There is also a full writeup on the forum somewhere. My height is right at the tire so I know it's doable.
4. Front is in-spec without arms. I think I still have arms in the box somewhere, actually. I don't remember all the details, but I don't think a lot of work was needed there. (Yep, should probably keep better documentation.)
5. I don't think the rear is bottoming out - there is not thud against the bump stops or anything else. The noise is just the liner. It doesn't matter whether the top is up or not, but I keep it down for the most part, especially when cruising in the twisties in the smokies. Personally, I wouldn't go over 10R as you might lose the ride quality, but if you are willing to experiment then try 11 (don't think it was an option when I was shopping - only 12).

 

Thank you for your time kiseliok. I sincerely appreciate your help! Sorry about the confusion about your location. I could have sworn I clicked on your profile and saw Asheboro. I must have mistakenly clicked on someone else's profile. (it was late)

I too have spent a LOT of time on this site and others. Great community, tons of information! That is how I found the welded rear camber arm solution, SPC front a-arms and rear bolts, BC with Swift springs Coilover option, and zero'ed in on 12F 10R as the most probable combination.

The last piece to my puzzle (mostly for my decision comfort and avoiding divorce papers) was understanding the 12/10 spring rate comparison to the stock S rate. Couldn't find the stock S rate anywhere! Thank you for filling in that missing perspective (at least from the seat of the pants data meter). Once I get these replaced, maybe I will find a shop to test the stock rates and post on here to help others.

Also, would be nice if I didn't have to buy the SPC front A-Arms, or modify a non-vert camber arm to get to my camber targets. Maybe the shop that did the work on my red 09 just didn't know what they were doing. I will try just using the stock front and SPC bolts on rear first and see where we get.

Here is the best they could do on my red 09 with SPC front A-arms and SPC rear bolts. I installed the bolts myself, so I know the slots were elongated and bolts would freely rotate to max adjustment.



Again, thank you very much for taking your time to help. Greatly appreciated!

 

So I decided to go back through the work that was done to the car as I'd feel awful if I misled you and sure as sh*t, the arms were indeed installed in the front.
I was thinking of the rear arms that did not fit initially - those, I think, are still in a box somewhere.
I'll PM you the picture links.

 

Thank you for the update and clarification Kiseliok!

 

Just saw your pm. In short. I used 20k rear spring rate helper spring in the rear spring bucket when I had coilovers on the vert.
.Would still bottom out on dips on bridge transitions or off ramp/on ramp transitions. Not run when running motordyne.

So I went air. And never looked back.

If air is not for you you can spend a lot and go for true style coilovers designed for the convertible.
D2racing makes some and maybe one other company. You'd have to search around.

Bc racing coilovers are for laying frame so not much raised height adjustment can be done. In short it will still sag a little. True style coilovers that eliminate using the spring bucket may be better. Someone has to buy it and try it. I've not seen any reviews with it on a vert. Get the highest possible spring rate if those are Adjustable at purchase time.

Good luck!

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