Optimum racing suspension setup?

[Emre]

What size rear sways did you run?

The big one. I don't remember the numbers off the top of my head.

Did you have the big kit (25/22)?

That's the one. We set the front to the middle position. The rear didn't have fixed positions; you had to slide the mounts back and forth. We set it so that just under 1cm was sticking out of the bracket.

With TMS J-Stock springs and dampers, 15mm H&R spacers on the front wheels only, camber set to -2deg in the front, and 225/45/50 tires on 15x7" ET25 wheels (TDR ProRace 1.2) the car was perfectly neutral and gripped like mad in the dry. The engine was a stock M20B25 and the diff was a medium-case 4.10:1 LSD from an E30 M3 rebuilt to stock specs.

You could make the car do whatever you wanted and place it wherever you wanted on the track. It rotated like a good mid-engined car: think Lotus Esprit. It seemed to pivot around the center of the car. Tricky to control in the wet, but unstoppable in the dry.

[nrubenstein]

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")

Why are you building an E30 for GTS4? The chassis just isn't going to keep up with E46 M3s. And you can buy an E46 M3 for what an S50B32 E30 is going to cost you. Trust me, I have both.

The only reason to build an E30 race car is to run SpecE30. Building an E30 for GTS is a fool's game.

[rfields]

Why are you building an E30 for GTS4? The chassis just isn't going to keep up with E46 M3s. And you can buy an E46 M3 for what an S50B32 E30 is going to cost you. Trust me, I have both.

The only reason to build an E30 race car is to run SpecE30. Building an E30 for GTS is a fool's game.

Well what setup do you run on your swapped e30?

GTS (probably not 4) is the eventual goal but this car will serve many more purposes over it's life. For instance, at this very moment, it is being used by the other owner as a daily driver after being acquired for only $600. Find me a running e46 (or any!) m3 for that money and I will GLADLY buy it and follow your advice. For now, we're just building a toy out of a car that we like with an engine we like and, with guidance from this thread, hopefully a suspension we like.

[nrubenstein]

Well what setup do you run on your swapped e30?

GTS (probably not 4) is the eventual goal but this car will serve many more purposes over it's life. For instance, at this very moment, it is being used by the other owner as a daily driver after being acquired for only $600. Find me a running e46 (or any!) m3 for that money and I will GLADLY buy it and follow your advice. For now, we're just building a toy out of a car that we like with an engine we like and, with guidance from this thread, hopefully a suspension we like.

In my testing, a stock suspended E46 M3 has roughly equivalent handling characteristics to my S50 E30 on a Ground-Control Street/Track setup.

Putting an S50B32 into an E30 will run you $6-8k if you are doing all the labor yourself. Putting a blower on that and tuning it will run you about that much IF everything goes perfectly and you don't blow the motor up. E46 M3s can be had for as little as $10-12k these days.

Do what you want with the E30 to make it fun, but pick a fun end point. A GTS E30 will also require a shit ton of expensive bodywork to clear tires. Remember that you will have ZERO weight advantage in GTS. They will be the same weight as you with stock fenders that fit 10" wheels.

If you say "I want an S50B32 powered E30 because that is fun," that's great. But if you say "I want an S50B32 powered E30 race car," that's a great way to sink a ton of money into a bad project. There is nothing worse than building the wrong car. It costs just as much and the end point sucks ass.

[rfields]

If you say "I want an S50B32 powered E30 because that is fun," that's great. But if you say "I want an S50B32 powered E30 race car," that's a great way to sink a ton of money into a bad project. There is nothing worse than building the wrong car. It costs just as much and the end point sucks ass.

I very much appreciate your concern and advice. (Honestly, I do.)

We still aren't sure that this car will ever see the track in a more competitive situation than time trial, so I am not overly concerned at the moment. I was simply trying to make the point that we aren't terribly worried about creating a bleeding edge gts car from the start. I honestly can't even tell you what engine will be in the car by the time we get it to the point where we start racing more than the clock. Knowing myself, the suspension may very well be some mad-science experiment in dynamic mechanics anyway. Just looking for advice on what's out there now.

[nrubenstein]

I very much appreciate your concern and advice. (Honestly, I do.)

We still aren't sure that this car will ever see the track in a more competitive situation than time trial, so I am not overly concerned at the moment. I was simply trying to make the point that we aren't terribly worried about creating a bleeding edge gts car from the start. I honestly can't even tell you what engine will be in the car by the time we get it to the point where we start racing more than the clock. Knowing myself, the suspension may very well be some mad-science experiment in dynamic mechanics anyway. Just looking for advice on what's out there now.

If you don't know what the end point is going to be, I strongly, strongly recommend that you build towards SpecE30. You'll get a great handling car with an easy and cheap transition to racing - just rip out the interior and add a cage.

If you end up feeling like SE30 is too slow for you, SE30s are reasonably saleable and you can go nuts in GTS from a better starting platform.

The truth is that there isn't *that* much difference in suspensions past a certain point. I've done SE30, TCK, multiple GC/Koni, GC/Bilstein, GC Advance Design, multiple AST, and multiple Moton setups on E30s, E36es and E46es. Yes, there is a difference at the high end, but the difference is generally less than the benefit of starting from the right chassis. And all of them come with different sets of trade offs.

Ad if you are wondering why I am so strongly advocating building the right car, well, just look at my sig. I've sunk a ton of money into the wrong car and there just isn't really any way to fix that other than starting over.

[10Toes]

If you don't know what the end point is going to be, I strongly, strongly recommend that you build towards SpecE30. You'll get a great handling car with an easy and cheap transition to racing - just rip out the interior and add a cage.

If you end up feeling like SE30 is too slow for you, SE30s are reasonably saleable and you can go nuts in GTS from a better starting platform.

The truth is that there isn't *that* much difference in suspensions past a certain point. I've done SE30, TCK, multiple GC/Koni, GC/Bilstein, GC Advance Design, multiple AST, and multiple Moton setups on E30s, E36es and E46es. Yes, there is a difference at the high end, but the difference is generally less than the benefit of starting from the right chassis. And all of them come with different sets of trade offs.

Ad if you are wondering why I am so strongly advocating building the right car, well, just look at my sig. I've sunk a ton of money into the wrong car and there just isn't really any way to fix that other than starting over.

Your spring rates are probably too soft on all your cars....

[nrubenstein]

Your spring rates are probably too soft on all your cars....

I've been as high as 1050/1300 and I have a gigantic box full of springs. The E30 is sprung 375/500 as a daily driver. Of course more spring and some geometry would help. Hell, just camber would help. That isn't the point. All of those are things that I could do the the M3, and the M3 would benefit just as much (and I have a set of ASTs in the attic that I could easily toss onto the M3). The problem is that the starting point on the E30 is so much worse. For autox, the width of the M3 is a huge penalty. On a road course, it's irrelevant, and actually a large part of why it is faster.

I love driving my E30s. On the street. But when performance is measured objectively, they are worse. Subjectively, the E46 is kind of numb. My wife thinks that it's like a really fast Camry. Objectively, it's just flat out naturally faster. And for reasons that swapping an S54 into an E30 will not solve.

[ForcedFirebird]

If you don't know what the end point is going to be, I strongly, strongly recommend that you build towards SpecE30. You'll get a great handling car with an easy and cheap transition to racing - just rip out the interior and add a cage.

If you end up feeling like SE30 is too slow for you, SE30s are reasonably saleable and you can go nuts in GTS from a better starting platform.

The truth is that there isn't *that* much difference in suspensions past a certain point. I've done SE30, TCK, multiple GC/Koni, GC/Bilstein, GC Advance Design, multiple AST, and multiple Moton setups on E30s, E36es and E46es. Yes, there is a difference at the high end, but the difference is generally less than the benefit of starting from the right chassis. And all of them come with different sets of trade offs.

Ad if you are wondering why I am so strongly advocating building the right car, well, just look at my sig. I've sunk a ton of money into the wrong car and there just isn't really any way to fix that other than starting over.

This is great advice. Se30 first, sell to use as a stepping stone to go faster. I watched an e46m3 pull a 2:15.77 this weekend at Sebring, the TT e30's were no where near that.

Se30 is the way I am going, then will use the sale of the car to upgrade when the time comes. Only problem with that is there are more cars than racers in Se30 ATM, so race-ready car values are on a decline.

[Bimmerman325i]

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.

for what it's worth, none of the options I listed require alternate geometry, that is the cost to run proper suspension on STOCK geometry and mounting points.

If you want to really burn money, time, effort, and still be slow, modify the geometry for something custom.

[rfields]

for what it's worth, none of the options I listed require alternate geometry, that is the cost to run proper suspension on STOCK geometry and mounting points.

If you want to really burn money, time, effort, and still be slow, modify the geometry for something custom.

+1
My "just as soon fab my own" comment was meant to illustrate my reluctance to heavily modify stock mounting points, not my propensity to start fabricating crazy shit.

[djjerme]

I will echo nrubenstein, but add this.

Ask yourself why you want to go racing.

Is it to go fast or is for the competition?

If you just want to go fast, then don't get so hung up on one manufacture, and get in to the fastest class you can afford (open or closed wheel.)

If your more interested in competition, then look for a class with decent field size, and build a car for that class.

You never mentioned this before, but have ever done any actual wheel-to-wheel racing before? Club racing is a different beast from HPDE days, or even Time Trials. Watch some of the Spec Miata/SE30/PRO3/IT races from around the country.

When you move to sprint racing, going fast is only part of the skill required, you need to also sometimes play defensive. Other drivers will try to block you out, keep you off your line, or even give you a gentle nudge so you know they are still there. To run at the front, you have to have no problem following another car 8 inches off their bumper at a 100+ mph into a braking zone.

How you win at club racing is not always the equipment you have, its somewhat on your willingness to brake deeper (or not at all), track positioning..etc. I have seen very fast cars lose because of the drivers inability to drive at 10/10ths. I have also seen very fast cars lose through no fault of their own.

Here is something to keep in mind: Only race what you can afford to lose. Accidents happen, and cars get messed up. If you can't afford to fix major issues don't race it; as well if you have so much money wrapped up in it that if something minor happens on the track you rampage through the pits after a race looking for blood, don't do it. Club racing is as much about sportsmanship on and off the track as it is about winning. Most club's won't put up with someone flying off the handle because their life investment just got balled up on the front straight.

Not trying to discourage, just trying to help you get what you want out of racing.

[rfields]

I will echo nrubenstein, but add this.

Ask yourself why you want to go racing.

Is it to go fast or is for the competition?

If you just want to go fast, then don't get so hung up on one manufacture, and get in to the fastest class you can afford (open or closed wheel.)

If your more interested in competition, then look for a class with decent field size, and build a car for that class.

You never mentioned this before, but have ever done any actual wheel-to-wheel racing before? Club racing is a different beast from HPDE days, or even Time Trials. Watch some of the Spec Miata/SE30/PRO3/IT races from around the country.

When you move to sprint racing, going fast is only part of the skill required, you need to also sometimes play defensive. Other drivers will try to block you out, keep you off your line, or even give you a gentle nudge so you know they are still there. To run at the front, you have to have no problem following another car 8 inches off their bumper at a 100+ mph into a braking zone.

How you win at club racing is not always the equipment you have, its somewhat on your willingness to brake deeper (or not at all), track positioning..etc. I have seen very fast cars lose because of the drivers inability to drive at 10/10ths. I have also seen very fast cars lose through no fault of their own.

Here is something to keep in mind: Only race what you can afford to lose. Accidents happen, and cars get messed up. If you can't afford to fix major issues don't race it; as well if you have so much money wrapped up in it that if something minor happens on the track you rampage through the pits after a race looking for blood, don't do it. Club racing is as much about sportsmanship on and off the track as it is about winning. Most club's won't put up with someone flying off the handle because their life investment just got balled up on the front straight.

Not trying to discourage, just trying to help you get what you want out of racing.

Very sage comments sir. I am sure that it is difficult to discern my exact goals from my previous comments. To be honest, I'm still figuring it all out. I am very familiar with real racing: I raced karts, I helped my father who was active in formula and sports racer classes for decades, and I consult on racing aerodynamics for a few teams. I have witnessed both the best and worst: just this past season a team I work for won their region but had an engine explosion/total rebuild of the whole car.

The steps I know for sure I want to take with this car (in order) are:
-overhaul what I've already got
-best brakes and suspension setup I can manage (hence this thread)
-swap in the engine I already have most of (s50b32)
-have fun with it on the track
-make a decision about going racing with it

By the time I get to the final step, I may end up going in a totally different direction. I just don't know yet.

[djjerme]

Good. Those are reasonable goals.

Just always keep this one in your mind:

-have fun with it

otherwise, what's the point.

[Massimo]

E30 JRZ Coilovers

/Thread