Optimum racing suspension setup?

[rfields]

Trying to tap some of the community knowledge on the subject since I am new to the e30 scene. The car has absolutely no suspension work done yet. (you can see the build progress here). I know that the MacPherson strut/semi-rear trailing arm setups work together pretty well when tuned correctly, but I am hoping to go a little more in depth on what has been known to work or not in the past. I have looked at the Turner Jstock setup, the spec e30 setup, and a few others. So what works well?

The plan will eventually be to go racing in NASA GTS with an s50b32 swap and LOTS of downforce.

[Wanganstyle]

Ohlins is used by one of my diff clients with good success in GTS-4; exhaust blown diffuser and full aero
S54 is the gts weapon of choice nowadays; everyone is removing s50 euro's

[nando]

I can't really comment on the "ultimate" setup, but keep in mind Spec setups are made with cost and availability in mind, rather than all out performance (although they do work fine, if your options are open they aren't where I'd start).

[Emre]

The Turner J-Stock suspension works well for a typical E30. It's basically a copy of the proven BMW Gruppe-N race suspension. On my last E30 track car, I had J-Stock springs and dampers (custom-valved Bilsteins) plus camber plates, urethane bushings, and Ireland Engineering swaybars. I also used the little-known trick of decreasing front offset, while keeping the rear stock (i.e., reverse stagger).

Everyone who drove my E30 was blown away by the handling. It was so neutral; it would slip into a gentle 4-wheel drift that was a breeze to balance. I could keep up with much, much faster cars at places like Tremblant and the Glen.

However, that was with a stock M20B25 engine. The J-Stock stuff works great with underpowered cars because it's the one suspension that really lets you rotate the car under power in the dry. But if you're running an S54 or Euro S50, you won't have any trouble getting the car to rotate.

In your case, you'll want something much more compliant to keep the rear under control. Try to find out what guys like Mike Akard are running.

[FredK]

I also used the little-known trick of decreasing front offset, while keeping the rear stock (i.e., reverse stagger).

By how much did you increase the front track width? I'm just curious, as I'm not really at the point where this makes a difference in how I drive.

[djjerme]

Most PRO3 guys are running Coilover and double adjustable's these days. But if you just wanted to spend money for the sake of it, you go all out and remote reservoirs, aluminum control arms, relocated suspension points..etc.

My suggestion, take the extra money you are going to spend on "optimum suspension" and hire a driving coach.

Chances are, what ever you do to your suspension, your car will be capable of going faster than your abilities.

[jlevie]

Have you considered making the car into a Spec E30? There is a lot of very good racing in those fields and the cost is pretty low for a race car.

[Emre]

By how much did you increase the front track width? I'm just curious, as I'm not really at the point where this makes a difference in how I drive.

I tried a few different things. Settled on 30mm total reverse-stagger (i.e., 15mm H&R spacers behind each front wheel). But only in the dry. Keep in mind that I had bigger sways than most folks (Ireland Engineering).

Stagger is basically the very last bit of fine-tuning to be done after everything else is pretty well optimized. It's a subtle difference. But everyone who drove my car could tell something was different/better.

A couple of E30 M3 club racers running in the J-Stock class drove my car and were raving about the handling. One asked me to help set up his car. We were basically all running the same springs and (non-adjustable) shocks. The only difference was my huge sways and reverse-stagger.

[Bimmerman325i]

Define optimum.

Lots of people run the SpecE30 suspension or J-Stock, which are very good for their intended applications and purpose (good performance/cost), but are nonadjustable.

If you want single adjustability, look at Ground Control (forum sponsor), TC Kline, KW, AST 4100, JRZ RS1, Nitron R1, Bilstein PSS*, and (as-yet unreleased) Motion Control SAs. These vary from $1600ish (GC/TCK) to $3k range.

If you want/understand double adjustables, the same culprits offer kits, some with or without remote reservoirs. Budget $2500 - $5500.

By asking this question I'm guessing you don't have much experience with triples or higher, which is good, since those start at $6-7k and ramp up.

Personally, I have both TCK double adjustables and AST 4100s on different cars, and have run the much lower cost (and not optimized) Bilstein HD/Eibach Pro-Kit combination.

The Billy/Eibach was a great low-cost setup that allowed me to focus on my driving rather than tinkering with the car, so if you are new to the track/e30 game I would go with the SpecE30 setup (Bilstein Sports/H&R Race) and focus on driving.

The TCKs are amazing, and the double adjustable shocks are freaking sweet, allowing for great track handling and good street manners. The ASTs are also great, both the 4100s and 4200s. Are they worth the price difference? Depends on your experience level and willingness/interest in fine-tuning the car setup rather than seat time.

You don't need to spend a bajilion dollars on suspension to go fast, it's really more about the driver than the brand. HOWEVER: you do get what you pay for. Don't bother with the BC racing, Megan racing, etc crap for a track car. What the stance/hardparking crowd wants in a damper is super stiff springs with dampers attached, which is NOT what the track/racers want.

In your shoes I'd go with SpecE30 or GC SAs, and then just drive the piss out of the car. Once you have exceeded those limits, then upgrade.

[Roland H]

JRZ RS1. Best S/A damper I've experienced, ideally you want to start with an E36 though. Significantly better design and geometry if you want to have any chance at putting down power.

[Bimmerman325i]

JRZ RS1. Best S/A damper I've experienced, ideally you want to start with an E36 though. Significantly better design and geometry if you want to have any chance at putting down power.

not sure they're offered for an E30, though hell, half my list isn't.

[pandaboo911]

I tried a few different things. Settled on 30mm total reverse-stagger (i.e., 15mm H&R spacers behind each front wheel). But only in the dry. Keep in mind that I had bigger sways than most folks (Ireland Engineering).

Stagger is basically the very last bit of fine-tuning to be done after everything else is pretty well optimized. It's a subtle difference. But everyone who drove my car could tell something was different/better.

A couple of E30 M3 club racers running in the J-Stock class drove my car and were raving about the handling. One asked me to help set up his car. We were basically all running the same springs and (non-adjustable) shocks. The only difference was my huge sways and reverse-stagger.

What size rear sways did you run?

[Nsquared97]

What size rear sways did you run?

Wondering this as well, though about both the front and rear. Did you have the big kit (25/22)?

[rfields]

Wow, thank you for all the input. I absolutely respect all the suggestions to hire a driving coach and am lucky enough to say that is well covered. I guess I should have definied "optimum" in this case: I do not want to go more intricate than double adjustable, uses readily available components, doesn't require radical attachment point relocation (some is fine but if it gets too crazy, i'd just as soon fab my own double a arm), and doesn't require that I be Carroll Smith to tune pretty well. I know that no one system is likely to meet all those goals but a man can dream.

[rfields]

Ohlins is used by one of my diff clients with good success in GTS-4; exhaust blown diffuser and full aero
S54 is the gts weapon of choice nowadays; everyone is removing s50 euro's

I'm well aware of the aero side, we're hoping the euro can keep up. If it becomes too much of a deficit, we'll find a way to compensate. (read "go to Paul's Automotive for a blower")