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      03-07-2016, 01:26 AM   #1
AriuSen
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My track day journal. new update 11/20/2017

So, today was my first day.....I had a blast!
I love driving the z4m more than any other car I have driven so far, and I cant wait to go back again. Unfortunately, I got a terrible spring rates so I was dancing all over the track... I had to put the dampers very soft to try to balance the spring rates 700lbs/850lbs. I noticed that those are terrible for my car.....not enough weight on the rear to support that rate.

Still had lot of fun! ran with 275/35/18 with 9.5x18 et22...unfortunately the rear rubs a little...I will have to pull a little more....funny is that the front doesnt rub!
The PFC bbk....omg...the best bbk out of brembos and stoptech....braking power is instant!

Well I wont even share my damper settings, because this was a disaster....so I ordered 650lbs/750lbs....hope I am making the right decision.




Last edited by AriuSen; 11-20-2017 at 02:39 PM..
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      03-07-2016, 05:43 AM   #2
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Even 650/750 sounds high. What dampers and tires do you have?
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      03-07-2016, 09:28 AM   #3
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Thanks for posting the video. I liked the Street Fighter reference!
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      03-07-2016, 09:30 AM   #4
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Quote:
Originally Posted by 3002 tii
Even 650/750 sounds high. What dampers and tires do you have?
I have jrz rs2 with Bridgestone re71r
.. Yea maybe 600/700?
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      03-07-2016, 09:39 AM   #5
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I'm running 550/650 hyperco with MCS and love the setup, but mine is a street/track setup.
For a dedicated track beast I would think you can add another 50 with no problem.

How much weight have you trimmed & where?
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      03-07-2016, 09:50 AM   #6
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Quote:
Originally Posted by inTgr8r
I'm running 550/650 hyperco with MCS and love the setup, but mine is a street/track setup.
For a dedicated track beast I would think you can add another 50 with no problem.

How much weight have you trimmed & where?
My car weights about 3930 without driver and almost full tank of gas...if you see my small journal you can see what I stripped...i have time to change the springs.... I think I will do 600/700....sounds more rational.
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      03-07-2016, 09:55 AM   #7
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Quote:
Originally Posted by AriuSen View Post
My car weights about 3930 without driver and almost full tank of gas...if you see my small journal you can see what I stripped...i have time to change the springs.... I think I will do 600/700....sounds more rational.
I think, or at least I hope you mean 2930 lbs? Mine, with full interior and loaded with luggage don't even come close to approaching 3930 lbs

BTW...looks like lots of fun out at the track
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      03-07-2016, 09:56 AM   #8
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Quote:
Originally Posted by XMetal
Quote:
Originally Posted by AriuSen View Post
My car weights about 3930 without driver and almost full tank of gas...if you see my small journal you can see what I stripped...i have time to change the springs.... I think I will do 600/700....sounds more rational.
I think, or at least I hope you mean 2930 lbs? Mine, with full interior and loaded with luggage don't even come close to approaching 3930 lbs
Haha. Yes. Thanks!
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      03-07-2016, 12:17 PM   #9
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Quote:
Originally Posted by inTgr8r View Post
I'm running 550/650 hyperco with MCS and love the setup, but mine is a street/track setup.
For a dedicated track beast I would think you can add another 50 with no problem.

How much weight have you trimmed & where?
why do people usually go with 100lbs difference front and back?

What if I did 600/750?
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      03-07-2016, 02:25 PM   #10
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Quote:
Originally Posted by AriuSen
Quote:
Originally Posted by inTgr8r View Post
I'm running 550/650 hyperco with MCS and love the setup, but mine is a street/track setup.
For a dedicated track beast I would think you can add another 50 with no problem.

How much weight have you trimmed & where?
why do people usually go with 100lbs difference front and back?

What if I did 600/750?
Rear isn't a true coilover and the spring location requires a higher spring rate to make up for the difference in leverage/location. Going with a 100 or so lb higher spring rate in the rear actually means it ends up being more or less equivalent with the front IIRC.
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      03-07-2016, 02:28 PM   #11
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Quote:
Originally Posted by Finnegan
Quote:
Originally Posted by AriuSen
Quote:
Originally Posted by inTgr8r View Post
I'm running 550/650 hyperco with MCS and love the setup, but mine is a street/track setup.
For a dedicated track beast I would think you can add another 50 with no problem.

How much weight have you trimmed & where?
why do people usually go with 100lbs difference front and back?

What if I did 600/750?
Rear isn't a true coilover and the spring location requires a higher spring rate to make up for the difference in leverage/location. Going with a 100 or so lb higher spring rate in the rear actually means it ends up being more or less equivalent with the front IIRC.
Good info.... So what would be the best choice without wing and rcomp?
Would 600/750 be a good idea?
Or 550/700?
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      03-07-2016, 02:40 PM   #12
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Lots of arm crossing! Looks like fun for sure.
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      03-07-2016, 02:45 PM   #13
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Quote:
Originally Posted by AriuSen View Post
Good info.... So what would be the best choice without wing and rcomp?
Would 600/750 be a good idea?
Or 550/700?
Reason for F/R differential is as Finnegan's post.

FWIW, here is info from Vorschlag on their MCS kits for the Z4M

.....
"SPRING RATES : ......These options will include new Hyperco or Swift springs from our recommended packages. The spring options listed include our GT package for daily driven cars, the GTS package for street cars that are also used in autocross and/or track events and the GTR package for race cars that predominantly see track use.

Vorshlag's GT Package is 6" x 500 #/in Front / 5.5" x 550 #/in Rear
Vorshlag's GTS Package is 6" x 550 #/in Front / 5.5" x 650 #/in Rear
Vorshlag's GTR package is 6" x 600 #/in Front, 5.5" x 750 #/in Rear"
.........
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      03-07-2016, 03:01 PM   #14
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Quote:
Originally Posted by wdb
Lots of arm crossing! Looks like fun for sure.
Wasn't that much fun at the time lol... It was more tense than fun
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      03-07-2016, 03:03 PM   #15
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Quote:
Originally Posted by inTgr8r
Quote:
Originally Posted by AriuSen View Post
Good info.... So what would be the best choice without wing and rcomp?
Would 600/750 be a good idea?
Or 550/700?
Reason for F/R differential is as Finnegan's post.

FWIW, here is info from Vorschlag on their MCS kits for the Z4M

.....
"SPRING RATES : ......These options will include new Hyperco or Swift springs from our recommended packages. The spring options listed include our GT package for daily driven cars, the GTS package for street cars that are also used in autocross and/or track events and the GTR package for race cars that predominantly see track use.

Vorshlag's GT Package is 6" x 500 #/in Front / 5.5" x 550 #/in Rear
Vorshlag's GTS Package is 6" x 550 #/in Front / 5.5" x 650 #/in Rear
Vorshlag's GTR package is 6" x 600 #/in Front, 5.5" x 750 #/in Rear"
.........
Thanks a lot!! I guess I will go with 600/750!
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      03-07-2016, 03:09 PM   #16
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I'm just worried that 750 on rear won't be much difference from 850
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      03-07-2016, 03:23 PM   #17
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the z4ms short stiff platform just doesnt need these crazy spring rates, talk to TCK and they run really low spring rates and let the valving do the work..... those guys win races.
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      03-07-2016, 03:38 PM   #18
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Quote:
Originally Posted by Beedub
the z4ms short stiff platform just doesnt need these crazy spring rates, talk to TCK and they run really low spring rates and let the valving do the work..... those guys win races.
I'm so undecided if I go 600/700 or 600/750...i much rather have little bit of oversteer than any understeer
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      03-07-2016, 05:15 PM   #19
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AriuSen,

Looks like you had a fun and exciting time!

Your car was obviously a handful, and I think much of that was attributable to rear springs that were too stiff compared to the fronts. You were getting a lot of oversteer, even with throttle-neutral cornering--that is, not induced by strong acceleration.

I don't know what spring rates are best for a Z4M, but I'd guess that the 150 lb differential between front and rear was considerably too much. The back end was having to do more than its fair share of total roll resistance, which was loading up the outside rear tire a lot more than the outside front.

I also noticed, especially in your earlier laps, that you were getting a lot of oversteer when you let the clutch out after downshifting as you entered the turns. Absent a heel-and-toe downshift, to match the engine rev's with the axle speed, the driveline has to pull the engine speed up to match, and that creates quite a braking effect. Enough that it was throwing the weight forward, lightening the rear end, and forcing the tail of your car out. You did well to catch it!

In friction circle terms, the deceleration force on the rear tires caused by the engine, plus the cornering force from entry into the turn, added up to quite a bit more than the tires could handle. Thus the rear tire breakaway.

Anyway, it all looked like a lot of fun. Compared to your fastest lap, however, when you completed your downshifts before turning in, your earlier laps with all the tail-wagging really killed your lap times. Heel-and-toe downshifting requires some contortion, and sensitive application of both the brake and the accelerator with just your right foot, but I think you'd find it enormously helpful in smoothing out your laps and increasing speed. It might not be quite as much fun, however!

I suspect you already know all of this, but I thought I'd provide my 2 cents, just in case. Good luck with the new springs, and have a great time.

Rick F.
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      03-07-2016, 05:22 PM   #20
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Quote:
Originally Posted by Rick F.
AriuSen,

Looks like you had a fun and exciting time!

Your car was obviously a handful, and I think much of that was attributable to rear springs that were too stiff compared to the fronts. You were getting a lot of oversteer, even with throttle-neutral cornering--that is, not induced by strong acceleration.

I don't know what spring rates are best for a Z4M, but I'd guess that the 150 lb differential between front and rear was considerably too much. The back end was having to do more than its fair share of total roll resistance, which was loading up the outside rear tire a lot more than the outside front.

I also noticed, especially in your earlier laps, that you were getting a lot of oversteer when you let the clutch out after downshifting as you entered the turns. Absent a heel-and-toe downshift, to match the engine rev's with the axle speed, the driveline has to pull the engine speed up to match, and that creates quite a braking effect. Enough that it was throwing the weight forward, lightening the rear end, and forcing the tail of your car out. You did well to catch it!

In friction circle terms, the deceleration force on the rear tires caused by the engine, plus the cornering force from entry into the turn, added up to quite a bit more than the tires could handle. Thus the rear tire breakaway.

Anyway, it all looked like a lot of fun. Compared to your fastest lap, however, when you completed your downshifts before turning in, your earlier laps with all the tail-wagging really killed your lap times. Heel-and-toe downshifting requires some contortion, and sensitive application of both the brake and the accelerator with just your right foot, but I think you'd find it enormously helpful in smoothing out your laps and increasing speed. It might not be quite as much fun, however!

I suspect you already know all of this, but I thought I'd provide my 2 cents, just in case. Good luck with the new springs, and have a great time.

Rick F.
Yea thanks a lot for your feedback! Tips and criticism are always welcome!
I actually do heel n toe. However, I feel like my heel n toe wasn't enough in normal throttle mode....its way too lazy the gas pedal so I don't think it was revving high enough.... I tried to drive on sport, but it's absolutely impossible to drive..... I wish there was a medium option like the e92. I guess I have to get used the normal mode and maybe go on gas more than usual to match Rev.

But yea... Some of the turns I messed up heel n toe and caused the weight to move to the front.... But overall, this track day was one of days that I had the most fun and also it was an awesome school for me... I used to spin a lot before even with e92. And now I know why..... The e92 chassi is so good and so easy to control that you kinda get lazy at times.... The z4 makes me concentrate so much and be very alarmed to oversteer, that my reactions became faster.... I love z4m! Lol. It really teaches me to be a better driver
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      03-07-2016, 06:17 PM   #21
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Fast hands there buddy! Wow.

Two things:

First: Even 700 pounds in the rear might be a bit much. You might be better off going with lower rates maybe 500/550. Intgr8rs MCS rate differential only shows 50 pounds between the front and the rear.

Second: What sways are you running and what are the settings? Need to know what those are before we start looking at spring rates only.

Great stuff by Rick F.

My experience is that heel toeing on the track is completely different than on the street. That's due to how deep you are in to the brakes, and the generally higher rev you're trying to hit with the match compared to street driving, which means trying to give more throttle then you're probably used to as well. If you drive the Z a lot on the street, you build habits that work real well for heel toeing on public roads. But that doesn't help you much on the track, in fact it actually hurts you, since your habits of been ingrained for the street. All that adds up to simply a need for more track time!
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      03-07-2016, 06:42 PM   #22
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Quote:
Originally Posted by Finnegan View Post
Fast hands there buddy! Wow.

Two things:

First: Even 700 pounds in the rear might be a bit much. You might be better off going with lower rates maybe 500/550. Intgr8rs MCS rate differential only shows 50 pounds between the front and the rear.

Second: What sways are you running and what are the settings? Need to know what those are before we start looking at spring rates only.

Great stuff by Rick F.

My experience is that heel toeing on the track is completely different than on the street. That's due to how deep you are in to the brakes, and the generally higher rev you're trying to hit with the match compared to street driving, which means trying to give more throttle then you're probably used to as well. If you drive the Z a lot on the street, you build habits that work real well for heel toeing on public roads. But that doesn't help you much on the track, in fact it actually hurts you, since your habits of been ingrained for the street. All that adds up to simply a need for more track time!

Thanks haha...its from a lot of gokart when I was younger.
Anyway, so I have stock sway bars. I dont plan to get aftermarket sway bar ever....I dont really like them....it makes the car feel more nimble, but I think it always compromise grip.

I only drove the z4 maybe 4 times since I bought it....I dont drive it much...and when I drive on streets, I dont do heel n toe.
With the e92 my heel n toe was much better.....not perfect, but much better....I will have to practice more....I am still learning the potential of the car and limits
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