I'm competing in SCCA auto-xing (Cal Club/Region #19) in STU next year. What spring rates are people running (front/rear) in their M3s? I have a 97 M3 currently in BSP (though barely due to the X-brace, else I'd be in BS).

Thanks,
Gio

i run 525 front 600 rear.

I'm competing in SCCA auto-xing (Cal Club/Region #19) in STU next year. What spring rates are people running (front/rear) in their M3s? I have a 97 M3 currently in BSP (though barely due to the X-brace, else I'd be in BS).

Thanks,
Gio

BJOs rates are probably a great starting point.

You might be able to go a bit softer if you are sticking to street tires.

I guess you are going to a TCK or GC suspension? You can buy several different rates and play with them. I run anything from 450-550# in the front and 500-650# in the rear.

I guess you are going to a TCK or GC suspension? You can buy several different rates and play with them. I run anything from 450-500# in the front and 600-625# in the rear.

Yes VJLAX18, you're right. I'm in the process of choosing either tc kline's racing suspension (Double/Adjustable Coilover) or Ground Control's. I was recommended to either go 450-500 front, and 550-600 rear.

But from people I know and I have heard is that GC's have to be customized for the M3 and that they have to be rebuilt every year. Something I don't want to have to deal with.

Gio

If you are talking about the GC koni's then no, they do not need to be rebuilt every year. If you are talking about AD's... some say that, but IIRC they are only $25 each to be rebuilt.

But from people I know and I have heard is that GC's have to be customized for the M3 and that they have to be rebuilt every year. Something I don't want to have to deal with.
Gio

If you don't want to deal with shocks you should get Bilsteins. I may sell my car completely setup but if I don't my PSS-9's, bars, springs, and camber plates could make your car really handle!

Eric

If you are talking about the GC koni's then no, they do not need to be rebuilt every year. If you are talking about AD's... some say that, but IIRC they are only $25 each to be rebuilt.

I'm talking about Advance-Designs and though cost is not an issue for the rebuilt, it's the labor and the time that my car would be out of commission. I'm going instead with TC Kline's Smart Design Double-Adjustable Koni Coilovers instead.

I'm going instead with TC Kline's Smart Design Double-Adjustable Koni Coilovers instead.
They rock!! :buttrock

hey guys, what is the highest spring rate recommended for Koni SA's?

Matt, I ran 650's in the rear at the last WDCR event and the koni's couldn't handle them.

Matt, I ran 650's in the rear at the last WDCR event and the koni's couldn't handle them.

gotcha - if I go with the GC setup, I was thinking 500f - 575r. Any thoughts?

Also, were your sways at full soft?

Yeah, full soft. Lee is running ~550F/500R now, FYI.

I'm going to be trying some different things next year, so we'll see how they work.

But Lee runs Motons, right? Do you know how he's set compression on them?

Also, IIRC the last time I talked to GC they said that standard Konis should be able to handle very high spring rates. I don't remember exactly what the numbers were, but they were surprisingly high due to the rear suspension geometry. John, have you ever had your Konis rebuilt?

I personally run 450F/600R (that I picked up right after NEDIV ;) ) with Eibach sways at soft F/stiff R. I have a set of 650s I'm waiting to try next season for the rear, but I'm not sure if my somewhat tired Konis will be able to handle them. Maybe it's time to go with DAs; no ADs for me, my car gets driven through snow. :)

Dave

Nope, going to skip rebuilding the Koni's because I'm getting AD's and keeping the Koni's for winter driving. :)

And I know Matt's koni's have just as many events on them as mine, so unless he want's to have them rebuilt, he's just in the same boat as me... but coming from the H&R springs that he has now, the 550+ are going to feel great for him.

Yes, Lee is running Moton's but other's have run rates less then those with the TCK DA's.

Back that rear sway off to full soft and you'll be able to put more power down.

If money isnt much of an object, you arent going to beat a remote resevoir shock. The Moton Clubsports are SOO fast. The ADs were maybe as fast, but they didnt have quite the range of the Moton and they handle the bumps (ala Nationals) like a cadillac. Even with ridiculous spring rates. If you are going to be putting down decent power, you may want to consider losing the rear bar and running higher rates in back. That coupled with a bitchin custom LSD will rock your face off. We can provide any of the aforementioned bits, as well as GC components. Feel free to email me at erik@edgemotorworks.com if you need more info!

Nice plug :stickoutt

Money is a problem right now, so Club Sports are out of the question for me. And my LSD is pretty shot too. :(

If Clubsports are out, then either the GC track plus or TC Klines are great. For rates, 550/650 works. You can bump the rear rate up to 850ish and run a stock rear bar to save some weight or even go to 900ish and ditch the bar altogether. Amazingly, with no rear bar and those rates, the car won't ride too badly. (keeping in mind that the shock in rear is only controlling about 400lbs of wheel rate, not the whole spring rate)

Be sure to do RTABS with GC Shims or sphericals.

The diff I did made a HUGE difference in the way the car rotated and hooked up everywhere, so I can't recommend that mod enough. Upgrading the diff bushings is also a good idea, we manufacture a cool set of all three in Delrin that we are releasing after a season of hardcore abuse. They work great!

We have a new koni that might help Vijax. Externally adjustable, and has better valving than the standard compress to adjust. Give me a call and I will tell you about them.
Dale @GC and Mpact Motorsports

525f, 450r for me with bimmerhaus koni da's and h&r bars - 28mm f / 21mm r

I didn't even notice the bumps on the north course with your old ADs =)



If money isnt much of an object, you arent going to beat a remote resevoir shock. The Moton Clubsports are SOO fast. The ADs were maybe as fast, but they didnt have quite the range of the Moton and they handle the bumps (ala Nationals) like a cadillac. Even with ridiculous spring rates. If you are going to be putting down decent power, you may want to consider losing the rear bar and running higher rates in back. That coupled with a bitchin custom LSD will rock your face off. We can provide any of the aforementioned bits, as well as GC components. Feel free to email me at erik@edgemotorworks.com if you need more info!

so what is the new reasoning for running stiffer springs in front than the rear?

so what is the new reasoning for running stiffer springs in front than the rear?


I think the reasoning goes like this:

"Bob T. likes it that way and he is fast"

It should be noted that other people who are similarly fast do not like his setup at all.

Also keep in mind, even those of us running higher rate springs in the rear, the effective wheel rate is still actually lower than in the front.

how do the TCKR Koni DA's handle spring rates of 800 F, 950 R for example? what would the bump/rebound settings be at this spring rate assuming the car had little (15 mm 325is) to no rear bar?

how do the TCKR Koni DA's handle spring rates of 800 F, 950 R for example? what would the bump/rebound settings be at this spring rate assuming the car had little (15 mm 325is) to no rear bar?

I imagine they can have the Konis valved for whatever spring rates you want.

It also isn't an exact science, and depends on way more variables than just spring and swaybar rate (vehicle weight in particular), so theres no way anyone can tell you to put the "bound at 3, rebound at 4" or something =)

you just gotta play with it, take notes, figure out what feels good.

We have a new koni that might help Vijax. Externally adjustable, and has better valving than the standard compress to adjust. Give me a call and I will tell you about them.
Dale @GC and Mpact Motorsports

Will do Dale, thx.

I imagine they can have the Konis valved for whatever spring rates you want.

It also isn't an exact science, and depends on way more variables than just spring and swaybar rate (vehicle weight in particular), so theres no way anyone can tell you to put the "bound at 3, rebound at 4" or something =)

you just gotta play with it, take notes, figure out what feels good.

I realize this dude :confused ...I have like 8 or 9 sets of springs sitting on shelf along with preliminary setup from half dozen tracks we raced on this season. I was testing at different tracks through the year...toward the end of this season, I was thinking of making some changes to run a light to no rear bar...looking for some baseline inputs from guys running a like spring rate/bar setup...

I would think that autox setups and track setup differ greatly. :)

I think the reasoning goes like this:

"Bob T. likes it that way and he is fast"

well there is some sound rationale to it. camber curves is one.

i went from 525/525 all around to 525f/450r and was instantly faster. in particular, i found i could attack the slaloms n-times harder.

But without shocks to make up for the lack of rate, you're going to coil bind or bottom the shocks out. I tried 450/6's at Nationals with the AD's on full stiff and they were running out of travel.

well there is some sound rationale to it. camber curves is one.

i went from 525/525 all around to 525f/450r and was instantly faster. in particular, i found i could attack the slaloms n-times harder.


even with 600 front 750 rear, the rear wheel rate is still a lot softer. Certainly a twitchier ride like this. Watching Bob T drive it looks like he never goes beyond the limit at all, so understeer is a non issue for him.

In theory he should have to slow down more for the sweepers, but be able to go through slaloms quicker.

how did you judge your getting instantly quicker? swap springs at the track on the same course? or did you start placing higher in pax at your events and such?

Yeah, 450s up front with konis bottomed out on race tires as well, however I had a stock front swaybar at the time.

how did you judge your getting instantly quicker? swap springs at the track on the same course? or did you start placing higher in pax at your events and such?

yep, test sessions locally. last year we ran several local pca events and practice days and would mess with the setup between sessions or try something wacky for fun runs. sometimes the settings would work per theory sometimes they were junk. but it was local events so it's all good.

basic old school stopwatch/video splits and total times.

we brought a max q data (http://www.maxqdata.com) data aq system with us once, but arrived late that day and didn't get a chance to get it set up so no pretty charts.

even with 600 front 750 rear, the rear wheel rate is still a lot softer. Certainly a twitchier ride like this. Watching Bob T drive it looks like he never goes beyond the limit at all, so understeer is a non issue for him.

In theory he should have to slow down more for the sweepers, but be able to go through slaloms quicker.

watching bob's videos, he is most certainly over the limit often. the difference is he is so smooth oscillating +/- 2% around that limit that you don't notice watching from outside. someone like me will have huge oscillations like +/- 20% or more around the limit, so you can see it. also, he is an absolute master of weight management. it's mind boggling. the atwater video on bimmerhaus.com is particularly nice at illustrating this. watch the 2nd offset going out and the slight arc right before the turn-around. actually, better yet watch the topeka pro video... same thing... for the entire freakin run!!! :eek:

as for the the wheel rate thing, i dunno... in all seriousness, i just apply what i read in carroll smith books during highschool & college (when i knew how to read) and learned in formula sae so my understanding of this stuff is really basic. please bear with me.

a 50/50 rwd car with equal wheel rates f & r, identical camber curves f & r will be unmanagable in auto-x. even on a road course. the rear is being asked to provided forward bite and thus must have more traction. even in a pure sweeper, the rear tires have to put down maintainence throttle, meaning they need more load capacity than the fronts to apply the same centripetal force as the fronts. in hack-pyshics-speak, the mangitude of force vector applied by the rear tires in a balanced sweeper is larger than that applied by the front tires. meaning they need more weight on them in steady state. meaning they need less wheel rate.

the more this forward force is, the more weight you need put on the back tires. in other words, the more torque you're putting down, the more weight you need distributed on the rear on steady state to keep the car balanced when you tip in from maintenance throttle. in auto-x we take most turns in 2nd gear whereas on a road course turns are taken in 3rd, 4th, 5th. on an auto-x car in a typical auto-x turn, that's up to twice or more the torque available to the ground compared to a comparable road course car in a typical road course turn.

auto-x consists of two primary components: slaloms and turns. the turns are almost never in steady state. ever. so you can trailbrake, leftfoot, whatever you need to do on the entry to get the front end to bite, but it's all about exit speed and for exit speed you need to put down torque and early, ie: mid turn. slaloms require the rear to be planted. m3s aren't exactly pure sports cars. they are tall, long and skinny compared to a purebred sports car. however, they shine in slaloms where the long wheelbase and
narrow body gets them through much faster. so this setup favors that in exchange for having to be hardcore about trailing the brake on entry, which is more easily done leftfooting.

applying this to an auto-x m3 where the rear tires are particularly narrow in relation to the front (compared to say, a vette), there is plenty of available torque (esp in street mod trim), the front camber curve is total backwards garbage (ie: don't let that f0xker move), the rear camber curve is very good (ie: let it articulate), the car will almost never see a long steady state corner (this is freakin autox), and where its strength lies in slaloms...

but of course, everyone has their preference. i absolutely suck compared to bob and vic and jeff and those guys, so take that into account... just sharing setup.

jmott, what suspension setup was the top E36 in DSP (2nd overall?) running at Natls? His times were about 1? sec. per day faster than yours. Was it his driving, setup or you had a bad day?

Here's a good question for all ya'll. So a certain someone is going to be running wider wheels, and that translates to a wider track. Now wouldn't that add more leverage acting against the springs? :confused

jmott, what suspension setup was the top E36 in DSP (2nd overall?) running at Natls? His times were about 1? sec. per day faster than yours. Was it his driving, setup or you had a bad day?

Fauth I assume runs Bob T style rates since his is a bimmerhaus car.

I was a complete noob and he was a previous national champ? I have a 150k mile 2.5L engine and he has a 2.8? My car weighed 200lbs more? hehe Honestly my bimmer was still very new to me then, had just put the shocks on, set to full soft because I had no clue. First time on hoosiers, first time at nationals. My PAX at local events since nationals has gone from around 10ish to 1st or 2nd lately so I think I've gotten quicker. I


A better comparison is him vs brian matteucci in DSP, who has spring rates similar to mine. He was right there with Fauth on day 1. But driver skill has so much to do with things its really hard to say which setup is fastest. I certainly don't *know* either way. I do know that you can go very very fast with higher rate rears than fronts.

just just thinking about the theory here

rear tires are asked to do forward thrust thus need more downard force on them mid turn. - agreed, but the camber curves in the rear are also better so the rear should have more grip all else beign equal anyway. Also, the fronts have to do the job of changing the direction of the car, this adds some load as well yes?



yep, test sessions locally. last year we ran several local pca events and practice days and would mess with the setup between sessions or try something wacky for fun runs. sometimes the settings would work per theory sometimes they were junk. but it was local events so it's all good.

basic old school stopwatch/video splits and total times.

we brought a max q data (http://www.maxqdata.com) data aq system with us once, but arrived late that day and didn't get a chance to get it set up so no pretty charts.



watching bob's videos, he is most certainly over the limit often. the difference is he is so smooth oscillating +/- 2% around that limit that you don't notice watching from outside. someone like me will have huge oscillations like +/- 20% or more around the limit, so you can see it. also, he is an absolute master of weight management. it's mind boggling. the atwater video on bimmerhaus.com is particularly nice at illustrating this. watch the 2nd offset going out and the slight arc right before the turn-around. actually, better yet watch the topeka pro video... same thing... for the entire freakin run!!! :eek:

as for the the wheel rate thing, i dunno... in all seriousness, i just apply what i read in carroll smith books during highschool & college (when i knew how to read) and learned in formula sae so my understanding of this stuff is really basic. please bear with me.

a 50/50 rwd car with equal wheel rates f & r, identical camber curves f & r will be unmanagable in auto-x. even on a road course. the rear is being asked to provided forward bite and thus must have more traction. even in a pure sweeper, the rear tires have to put down maintainence throttle, meaning they need more load capacity than the fronts to apply the same centripetal force as the fronts. in hack-pyshics-speak, the mangitude of force vector applied by the rear tires in a balanced sweeper is larger than that applied by the front tires. meaning they need more weight on them in steady state. meaning they need less wheel rate.

the more this forward force is, the more weight you need put on the back tires. in other words, the more torque you're putting down, the more weight you need distributed on the rear on steady state to keep the car balanced when you tip in from maintenance throttle. in auto-x we take most turns in 2nd gear whereas on a road course turns are taken in 3rd, 4th, 5th. on an auto-x car in a typical auto-x turn, that's up to twice or more the torque available to the ground compared to a comparable road course car in a typical road course turn.

auto-x consists of two primary components: slaloms and turns. the turns are almost never in steady state. ever. so you can trailbrake, leftfoot, whatever you need to do on the entry to get the front end to bite, but it's all about exit speed and for exit speed you need to put down torque and early, ie: mid turn. slaloms require the rear to be planted. m3s aren't exactly pure sports cars. they are tall, long and skinny compared to a purebred sports car. however, they shine in slaloms where the long wheelbase and
narrow body gets them through much faster. so this setup favors that in exchange for having to be hardcore about trailing the brake on entry, which is more easily done leftfooting.

applying this to an auto-x m3 where the rear tires are particularly narrow in relation to the front (compared to say, a vette), there is plenty of available torque (esp in street mod trim), the front camber curve is total backwards garbage (ie: don't let that f0xker move), the rear camber curve is very good (ie: let it articulate), the car will almost never see a long steady state corner (this is freakin autox), and where its strength lies in slaloms...

but of course, everyone has their preference. i absolutely suck compared to bob and vic and jeff and those guys, so take that into account... just sharing setup.

cleaning out my mailbox and saw this....

agreed, but the camber curves in the rear are also better so the rear should have more grip all else beign equal anyway.

not if you put a lot of static camber on the front then keep it from moving as much as possible while still absorbing the bumps you're facing.

Also, the fronts have to do the job of changing the direction of the car, this adds some load as well yes?

more load to where? in a sweeper, the fronts have to only turn the car while the rears have to turn and apply maintenace throttle. then there's throttle tip-in, which is where we experience the "hard to put power down" issue.

wider wheels, and that translates to a wider track. Now wouldn't that add more leverage acting against the springs?

mostly from the traction not from leverage. those wheels are still attached to the same hub applying force through the same upright, control arms, etc. as before.

i'll be running the same spring rate setup as Megatron (since it came off his car). it will be interesting to see how it does at the DC region autox. im used to the stiffer rear setup, but im open to something new. of course, it may be comparing apples and oranges since my car and i may not be on the same level as the top guys out here, but my goal is to learn what feels best to me with this car.

But without shocks to make up for the lack of rate, you're going to coil bind or bottom the shocks out. I tried 450/6's at Nationals with the AD's on full stiff and they were running out of travel.

john, were you running straight 450/6s or beehives? the beehives can help get you the extra travel you'll need even with off-shelf koni sa's.

keep in mind that the stock springs don't have this issue, even being almost half that spring rate, even paired with the stock shocks. it's an issue of the spring geometry interfering with itself rather than of the spring rate, so going to a different geometry (eg: beehive vs straight) helps in this regard.

TC always recommends autoxers use 450/500 or 500/500...just some info for the cone lovin' crowd ;) :)

Megatron, who makes beehive coils with spring perch end diameters of 2.5" or 60mm? What is max diameter at it's widest point on beehive springs? Anyone else here use or know of others using beehive springs in an adjustable coilover setup?

i just sold a set to joenationwide with my 03-04 suspension setup. they were from ground control and were red eibachs. i believe they were metric, so they would be in metric measurements. here's a pic including the springs. the one closest and furthest from the camera. the springs in the middle are straight 6" springs.

http://megatron.jonuts.com/images/for_sale/swaybars_springs.JPG

So if I were to be buying springs for my Koni SA's on the E46 M3 and I autoX it regularly, what would be the best spring ratio? 525 front 550 rear?

One more question, if the spring ratio is tighter in the front (550 - 500) what does it do in comparison if it was tighter in the back(500 - 550)?

So if I were to be buying springs for my Koni SA's on the E46 M3 and I autoX it regularly, what would be the best spring ratio? 525 front 550 rear?

One more question, if the spring ratio is tighter in the front (550 - 500) what does it do in comparison if it was tighter in the back(500 - 550)?


higher rates in the back - more oversteer/less understeer

higher rates in the front - more understeer/less oversteer

what are the best springs - this is possibly a more difficult question to answer correctly than "how do we put men on the moon"


525front 550rear is a reasonable starting point though. Get those rates and try them. Adjust as necessary

higher rates in the back - more oversteer/less understeer

higher rates in the front - more understeer/less oversteer

what are the best springs - this is possibly a more difficult question to answer correctly than "how do we put men on the moon"


525front 550rear is a reasonable starting point though. Get those rates and try them. Adjust as necessary
Awesome! Thanks for the info :)

One more quick question...Do most aftermarket company springs come with a tighter rate in the back? Or front? Per say my H&R's are more stiff in the front or back?

Awesome! Thanks for the info :)

One more quick question...Do most aftermarket company springs come with a tighter rate in the back? Or front? Per say my H&R's are more stiff in the front or back?


eibachs race springs come in every rate under the sun, you can get whatever you want, and swap them around any which way you want.

There are two school of thought amount the autocross crowd. There are some very fast guys running stiffer front springs, and some very fast guys running stiffer rear springs.

all this info is in this thread already. dont know why im repeating it, lol

I'm not sure why everyone is stressing whether the front is less than the rear or vice versa. It's wheel rate that matters, so to put this in perspective:

Front / Rear Wheel Rates
525F/450R: Front is roughly 243% of Rear
525F/525R: Front is roughly 210% of Rear
450F/525R: Front is roughly 179% of Rear

I would guess anywhere from 150% to 300% front bias would work for people. With our motion ratios, the spring rates that work just happen to be about the same F/R. So there's this pointless debate like having slightly more front to rear or vice versa actually has totally opposite effects, which they do not as seen from the table above.

That table is not taking into account the swaybars, of which people use a huge variety, and tire stagger, so like JMott says, just try out values around a working reference and see what works for you. Having a reference that's worked for others is a good start, and that's where people disagree as to what reference to start from.

This is tuning right? Not bolt on and it should just work. ;)

This is tuning right? Not bolt on and it should just work. ;)


Ahh you beat me to it!