E9x M3 Coilover track guys: what's your spring rate

[kaiv]

Trying to get a general idea of what kind of spring rates people are running.
Is a 300# stagger from front to rear popular ? I like a loose car with a ton of front end bite. Understeer is my biggest enemy, currently have none and would hate to introduce some when making the switch to coilovers.

Track guys please chime in!
Please also note which dampers you're using and for those of you that drive on the street a short comment on compliance/comfort would be appreciated.

Note: I prefer input from the quicker/ more experience guys -no offense to the noobs but a lot of inexperienced/slow people love to comment on go fast parts it seems :X

[///Mobbin]

I'm curious as well, good thread.

[surlynkid]

700/1000 with MCS 2-way non reservoir. It is stiff and maybe too stiff for some folks but it'll move around the track.

[evilspiritM3]

Originally Posted by surlynkid

700/1000 with MCS 2-way non reservoir. It is stiff and maybe too stiff for some folks but it'll move around the track.

+1

[FogCityM3]

TC Kline D/A Front: 350, Rear 600. I feel the front is perfect, I think rear can use 700 as I get some bottoming out in the rear at turn 6 at Laguna seca. I run stiffer compression and rebound as a solution in rear vs front and understeer is nearly nonexistent.

On the street, in soft setting this kit rides better than stock.

[1MOREMOD]

E46 has 700/800 on mcs singles seems about right

[VictorH]

Is this for track only, dual purpose or street & track?

My car is daily driver, 3-6 track events per year since new.
425 front, 700 rear, JRZ RS

No understeer, really more limited by rear traction.

[kaiv]

Some great input already, thanks guys. My car is a street car that spends a lot of time on the track.

Seems like a ~300 stagger is a favorite. A good race shop told me "for the style you want, having the softer rate up front and the large difference will encourage front and bite, allow you to rotate easily and work well if the need to burn tires comes around" which some of you guys' feedback confirms.

VictorH- above source suggests a little more squat in the rear and a tad of understeer to get the power down sooner.

[kaiv]

Forgot to ask, do you guys run tender springs? Just about every pic I see of a JRZ on this forum has a 150# tender on it, front and rear. Not the case for MCS. I'm curious if those are used to keep the main spring set like a helper + add some compliance on initial bump?

Either way keep the replies coming

[dbyrd]

I went through this same issue when I was looking at after-market dampers - search a few of my previous threads for more details. I DD my car >50 miles per day. I have MCS singles and initially went with 450/800 spring rates. The ride was as soft as stock with the dampers adjusted to lower settings for street so I bumped it up to 600/900. I still find it quite compliant on the street with the rebound dialed down.

I'm still running on stock subframe bushings so I'm not sure how much stiffer it will feel when I go to solid aluminum bushings soon. A buddy with an e92 with KWs rode to lunch with me at my last track event and he commented on how much more compliant my car was relative to his - this was with the rebound three clicks from fully stiff. Love my MCS dampers but should have gone with the doubles. I'll upgrade to doubles at the first rebuild.

[dogbone]

Hey Kaiv.

I've got JRZ RS Pro 600/800, but I have a 100lb of blower in the front. If you want more rotation, I would agree with what the race shop told you---at least 300 lbs spread. If you want it to always be on the edge in the rear, you might even consider 550/900 or even 500/900. Owen's RS Pro setup has 550 in the front (750 rear). I always thought that felt really nice before the blower was put in. 500/900 could be a lot of fun for you! ----although it might be a bit stiff on the street…. My RS Pro setup started with 450/650. It was ok---very comfy on the street, but I felt the weight of the car was a bit lumbering on the track. I wanted the springs to help resist the car from leaning so much. If I recall correctly, Randall used to run something like 500/800 on his RS Pro.

I hope the coilover you're considering is dual adjustable. A guy like you will want that discreet control. If you don't go too aggressive with spring in the rear, you'll want to put the rebound high in the rear and mellower in the front. This will make the rear of the car even more edgy. On a dual adjustable JRZ, the rebound adjustment can change the feel a LOT.

As far as tender springs----the way I ran my car pre-roll cage was without tender springs in rear, and with 150 lb tender springs in front. After the gutting and caging, the car was so much lighter that it sat higher and needed to be lowered back to correct ride height. We ended up removing the tender springs in the front so that we could raise the spring perch out of the way of the tire but still lower the car, so now I have no tender springs at all. I've had two days at Laguna, four days at Buttonwillow, one day at Thunderhill and one at Sonoma, and I haven't heard a peep from any springs when the car unweights. It's been totally fine. No noise or clunks or weirdness at all----not even with a full unweighting-while-turning like at Corkscrew at Laguna. Honestly, when you see how easily that 150 lb spring compresses as you lower the car back onto the floor after jacking it up, you realize it's not doing anything as far as changing ride quality on bumps. It's only job is to keep the spring happily seated when the car fully unweights. I can assure you that the spring sits 100% compressed at all times when there's any weight whatsoever on the front.

Now that i have the wing on the back (and no front splitter), I've been paranoid about understeer, although I don't seem to be getting much. The wing is basically compensating for losing so much weight from the rear. The angle of attack is not very aggressive. The rear of the car was very dancy after the gutting. You could just tell it wanted to go----especially with the power of the blower. Jean-Sebastien drove it at Laguna and his first comment was that the car needed a wing because the rear was so active. Anyway, before the wing went on there, I was worried that the lightened car was over-sprung. And it probably was. But now with the wing on there, it feels correct back there at speed. And at low speeds, I can throw the back around quite easily. I've also lessened the stiffness of the front sway bar by one hole to see if that gives the front a bit more grip too. I'll drive that for the first time this weekend at Big Willow. Ultimately, given the weight of the car now, the best solution for me might be to drop to 550 in the front---even if I put aero on the front. We'll see!

[Casey@RWE]

Originally Posted by dogbone

Hey Kaiv.

I've got JRZ RS Pro 600/800, but I have a 100lb of blower in the front. If you want more rotation, I would agree with what the race shop told you---at least 300 lbs spread. If you want it to always be on the edge in the rear, you might even consider 550/900 or even 500/900. Owen's RS Pro setup has 550 in the front (750 rear). I always thought that felt really nice before the blower was put in. 500/900 could be a lot of fun for you! ----although it might be a bit stiff on the street…. My RS Pro setup started with 450/650. It was ok---very comfy on the street, but I felt the weight of the car was a bit lumbering on the track. I wanted the springs to help resist the car from leaning so much. If I recall correctly, Randall used to run something like 500/800 on his RS Pro.

I hope the coilover you're considering is dual adjustable. A guy like you will want that discreet control. If you don't go too aggressive with spring in the rear, you'll want to put the rebound high in the rear and mellower in the front. This will make the rear of the car even more edgy. On a dual adjustable JRZ, the rebound adjustment can change the feel a LOT.

As far as tender springs----the way I ran my car pre-roll cage was without tender springs in rear, and with 150 lb tender springs in front. After the gutting and caging, the car was so much lighter that it sat higher and needed to be lowered back to correct ride height. We ended up removing the tender springs in the front so that we could raise the spring perch out of the way of the tire but still lower the car, so now I have no tender springs at all. I've had two days at Laguna, four days at Buttonwillow, one day at Thunderhill and one at Sonoma, and I haven't heard a peep from any springs when the car unweights. It's been totally fine. No noise or clunks or weirdness at all----not even with a full unweighting-while-turning like at Corkscrew at Laguna. Honestly, when you see how easily that 150 lb spring compresses as you lower the car back onto the floor after jacking it up, you realize it's not doing anything as far as changing ride quality on bumps. It's only job is to keep the spring happily seated when the car fully unweights. I can assure you that the spring sits 100% compressed at all times when there's any weight whatsoever on the front.

Now that i have the wing on the back (and no front splitter), I've been paranoid about understeer, although I don't seem to be getting much. The wing is basically compensating for losing so much weight from the rear. The angle of attack is not very aggressive. The rear of the car was very dancy after the gutting. You could just tell it wanted to go----especially with the power of the blower. Jean-Sebastien drove it at Laguna and his first comment was that the car needed a wing because the rear was so active. Anyway, before the wing went on there, I was worried that the lightened car was over-sprung. And it probably was. But now with the wing on there, it feels correct back there at speed. And at low speeds, I can throw the back around quite easily. I've also lessened the stiffness of the front sway bar by one hole to see if that gives the front a bit more grip too. I'll drive that for the first time this weekend at Big Willow. Ultimately, given the weight of the car now, the best solution for me might be to drop to 550 in the front---even if I put aero on the front. We'll see!

Lol, I'm the track shop Gabe. Kaiv just doesn't trust me enough!

[dogbone]

Originally Posted by Casey@RWE

Lol, I'm the track shop Gabe. Kaiv just doesn't trust me enough!

hehe awwww Casey, you'll be ok. Don't cry! Just cross-check him the next time you see him! A couple minutes in the penalty box will totally be worth it.

For those that didn't see my track build thread, RWE was the shop that did the gutting, cage, wing and suspension alterations. Worked out great! (You can check it out here: http://www.m3post.com/forums/showthread.php?t=1158445 )

kaiv knows this, but it's also worth noting for anyone else reading this that alignment can affect things quite a LOTTTT----turn-in, braking, etc. In the end, I tried a couple different alignments before I settled on what I'm on now. But alignments really are a personal thing. Everybody likes something different there.

[imolam3]

Kaiv, when I talked to James at BW, he suggested to corner balance the car then use the wt at each corner to get the spring rates. Mine is at 700F/800R. Car is 3200 lb with driver/1/2 tank of gas. Coming back to COTA soon?

[kaiv]

Originally Posted by Casey@RWE

Lol, I'm the track shop Gabe. Kaiv just doesn't trust me enough!

Oh I do, and I'll most likely go with the rates you recommended, but some more opinions is nice!

Thanks everyone for the replies!!

Originally Posted by imolam3

Kaiv, when I talked to James at BW, he suggested to corner balance the car then use the wt at each corner to get the spring rates. Mine is at 700F/800R. Car is 3200 lb with driver/1/2 tank of gas. Coming back to COTA soon?

E46 is different. Maybe I'll do the trek again next year once I get everything dialed in (and before warranty expires LOL )

[M3 Number 86]

Originally Posted by kaiv

Note: I prefer input from the quicker/ more experience guys -no offense to the noobs but a lot of inexperienced/slow people love to comment on go fast parts it seems :X

Why don't you try driving m3SennA 's car first?

He increased his springs rates on his coils.

[kaiv]

I drove m3senna's when he had kw cs. I was right away ~3 sec faster than in my own car on stock dampers but it had a bit of understeer and the rear was completely locked down. Did he change his setup since?

[M3 Number 86]

Originally Posted by kaiv

I drove m3senna's when he had kw cs. I was right away ~3 sec faster than in my own car on stock dampers but it had a bit of understeer and the rear was completely locked down. Did he change his setup since?

was this within last couple weeks? I know he changed his front springs but got the rears done recently.

when i drove his car 80% it still cornered faster than mine LOL.

[Casey@RWE]

Originally Posted by dogbone

hehe awwww Casey, you'll be ok. Don't cry! Just cross-check him the next time you see him! A couple minutes in the penalty box will totally be worth it.

For those that didn't see my track build thread, RWE was the shop that did the gutting, cage, wing and suspension alterations. Worked out great! (You can check it out here: http://www.m3post.com/forums/showthread.php?t=1158445 )

kaiv knows this, but it's also worth noting for anyone else reading this that alignment can affect things quite a LOTTTT----turn-in, braking, etc. In the end, I tried a couple different alignments before I settled on what I'm on now. But alignments really are a personal thing. Everybody likes something different there.

The damage will never be undone...

[Casey@RWE]

Originally Posted by imolam3

Kaiv, when I talked to James at BW, he suggested to corner balance the car then use the wt at each corner to get the spring rates. Mine is at 700F/800R. Car is 3200 lb with driver/1/2 tank of gas. Coming back to COTA soon?

Did he say weigh the car first? Or did he specifically say corner balance? Corner balancing a car with random springs isnt going to help. What you want is an even height front to rear (Unless you plan on running a rake in the car) to determine where the weight is so you can get a good even starting point and adjust from there. This works great if you're on a new car and you don't know what you want the end setup to be yet (ie. more squat on exit, oversteer, understeer etc.). Of course, if you don't know the wheel motion ratio for the given application then you're completely wasting your time.

[Greg S]

I'm on MCS double remote reservoir dampers on 850F 750R with the rear is a true coilover configuration.

[PrimeBMW]

I've had MCS singles on my car for about 2 weeks now. 550F and 675R to keep it comfortable on the street as the E92 M3 is my back up track car. The good news is that it is arguably just as comfortable as stock and 2.5-3 sec faster on the local tracks. It pushes a little with -2.5 front camber but that is the compromise I need to make. I should be able to dial out the understeer with tire pressures and or a stiffer front bar.