Ground Controls - Let's discuss spring rates...

[dinanm3atl]

1988 325iS
Ground Control w/ Koni(Shortened)
ST Sways
225.45.16 Tires

Vehicle will not be a daily. It will be driven quite frequently though. It will also see Auto-X as well as HPDE/Track Days/Potentially Drift. Just my 'motorsport' vehicle and fun vehicle to drive around.

What kind of spring rates should I be looking at? What spring rates do you run? What ride height with that rate? IE3 is 325/515 is I remember and I don't consider it stiff at all. Many are hinting I should be looking into 600ish front and 800ish rear. I know the rear of the E30 loses ~50% of the rate at the wheel due to the rear suspension design. Seems at that point with 600ish front rate would need more like 900-1000 in the rear if wanting to keep it more 'even'.

I am more experienced with an E36 in this type of setup so may thought could be off/incorrect and looking for guidance. Stiffer is not a problem. I just want it to stick, be fun to slide around and have a semi decent ride. Maybe the spring rates that I have been told or recommended are also too high. Maybe 550/750? So open to a discussion/reviews/etc. Seems that some reading on R3V that the 550/650 ballpark might be a much better starting point.

Thanks!

[SkinnyVT]

What weight reduction have you done? Removing the tar from the trunk really effect the handling of the car. I'm running 525/600, ST front bar, no rear bar with a 54/46 weight distribution. Car has a little push in slow corners so 650 rear or a light rear bar would probably be perfect. While these rates are fairly soft I don't have any significant body roll on the track and the car can actually absorb bumpy autox courses.

[E30Kaiser]

I run almost the exact same as Skinny, and I daily it, so I would say go stiffer if it is going to be mostly just a track car.

[dinanm3atl]

Thanks guys. I am not really looking into weight reduction. I like the full interior. I like it all being 'stock' with the go fast goodies.

[drumad]

I'm in the same boat as you and just received a 550/750 gc conversion set up. Hopefully it's what I'm looking for.

[SkinnyVT]

I'm in the same boat as you and just received a 550/750 gc conversion set up. Hopefully it's what I'm looking for.

that should be proportioned pretty well with the 50lbs of tar in the ass end, just fine tune it with bars (probably no rear or the stock one).

[z31maniac]

My S52 car (no PS/AC, sound deadening or trunk tar carpet, finish pieces in the trunk, but still a full leather sport interior), I was running 550/750 with a 22mm UUC bar up front and no rear bar.

Turn in was good, steady state was good and the car was easily rotated with the throttle.

[Erick]

My M30 car is running 650f/950r, and with the proper shocks, the car is quite a blast to drive. Jay at GC did make me promise him that I would never drive this car on the street though :p

[Cronus]

My M30 car is running 650f/950r, and with the proper shocks, the car is quite a blast to drive. Jay at GC did make me promise him that I would never drive this car on the street though :p

Though I see the point that those rates are pretty god damn high why couldn't you drive that on the street? I know s13 guys that run rates like that on the street. they say its stiff as hell and uncomfortable as a rectal exam though.

is it just the comfort thing or is it something else?

[Erick]

Probably the comfort, however either I am immune to crazy stiff suspensions (possible) or it's really not that bad.

[evil_twin]

erick, mine is I think 650/800? It's not that stiff, but... i'm still running stock tires lol.

[Erick]

Yeah tires are a huge factor in comfort. My old 318iS with 205/40/17 nankangs & shocks/springs was millions worse than my M30 E30

[drumad]

Though I see the point that those rates are pretty god damn high why couldn't you drive that on the street? I know s13 guys that run rates like that on the street. they say its stiff as hell and uncomfortable as a rectal exam though.

is it just the comfort thing or is it something else?

Yep. Tis is true. Cheap taiwan coilovers for S13s have shitty spring rates and even shittier dampers. Ask me how I know. ;)

[e30:)]

how do you know?

just kiddddding

i have 550/750 and its perfect for me, street only i wish it was stiffer but i will be with better shocks and tires

[dinanm3atl]

Sounds like I have the ballpark I need to work with.