E9X M3 JRZ RS PRO track guys

[kaiv]

So I went to Buttonwillow this Sunday and I have to say I’m pretty happy; the balance and feel is pretty good so far!

Special thanks to OC3 and Okusa for their help with setup/settings.

Again the specs:

RS PRO (v1) 200psi F / 250psi R
550F/800R (stock rear location)
-3F / 0 toe
-2R / 1/8th toe in
275 NT01

I kept a log of how the car handled at various settings and how fast it was. See below-

Session 1:

Front: 10 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 39 psi hot

PB’d on second lap, 1:58.6. Car felt good but I wanted a touch more corner entry / turn in bite.

Session 2:

Front: 10 comp / 18 reb
Rear: 10 comp / 13 reb
Tires: 35 psi hot

Added 2 clicks of front rebound and 2 clicks of rear compression and lowered tire pressure.

Car felt worse but PB’d again, 1:57.960.

Session 3:

Front: 10 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 33 psi hot

Dialed the dampers back to session 1 settings but lowered the tire pressure some more since it didn’t look I was using the shoulders at all.

Car felt similar as session 1, still would like more razor sharp corner entry bite. Best lap was 1:58.2.

Session 4:

Front: 8 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 33 psi hot

Reduced front compression by 2 clicks thinking it would allow the car to turn better when I brake into a turn.

Couldn’t tell the difference TBH. And by then the track was getting hot and greasy. Ran 2:00 flat throughout that session.

Session 5:

Front: 10 comp / 20 reb
Rear: 10 comp / 18 reb
Tires: 33 psi hot

With those the car felt the best thus far and I PB’d for the third time that day with a 1:57.910!

Interesting observation (for me anyways); if you compare the settings from the early sessions to the last, the big difference is the rear dampers. All this time I had been trying to tweak the fronts to get the car to turn how I want it but I guess it was the rear that needed tweaking (!). There’s definitely a lot more to suspension setup than I know lol

Any thoughts/comments/criticism welcome!

[M3 Number 86]

clicks from full soft or full hard?

awesome times.

[AriuSen]

Kaiv, great time!!!
and keeps us posted with your tweaks!
from my understanding if you want faster corner entry, you need to increase front rebound and thats what you did on session 5.
based on your driving style, I think increasing rebound and compression on the rear would be a good test since it will give you more oversteer? you know im not expert lol

[AriuSen]

Not sure this will help

[kaiv]

Thanks guys. I'll keep posting, maybe others will find all this useful in the future.

Clicks are from full soft.

Alex: see that watermark at the bottom of the second pic you posted? Might apply more to motorcycles than cars lol

When figuring out what to tweak, I started using Carroll Smith's Engineer in your pocket booklet and this (attached)

Full link http://www.rapid-racer.com/suspension-tuning.php

[PrimeBMW]

Originally Posted by kaiv

So I went to Buttonwillow this Sunday and I have to say I’m pretty happy; the balance and feel is pretty good so far!

Special thanks to OC3 and Okusa for their help with setup/settings.

Again the specs:

RS PRO (v1) 200psi F / 250psi R
550F/800R (stock rear location)
-3F / 0 toe
-2R / 1/8th toe in
275 NT01

I kept a log of how the car handled at various settings and how fast it was. See below-

Session 1:

Front: 10 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 39 psi hot

PB’d on second lap, 1:58.6. Car felt good but I wanted a touch more corner entry / turn in bite.

Session 2:

Front: 10 comp / 18 reb
Rear: 10 comp / 13 reb
Tires: 35 psi hot

Added 2 clicks of front rebound and 2 clicks of rear compression and lowered tire pressure.

Car felt worse but PB’d again, 1:57.960.

Session 3:

Front: 10 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 33 psi hot

Dialed the dampers back to session 1 settings but lowered the tire pressure some more since it didn’t look I was using the shoulders at all.

Car felt similar as session 1, still would like more razor sharp corner entry bite. Best lap was 1:58.2.

Session 4:

Front: 8 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 33 psi hot

Reduced front compression by 2 clicks thinking it would allow the car to turn better when I brake into a turn.

Couldn’t tell the difference TBH. And by then the track was getting hot and greasy. Ran 2:00 flat throughout that session.

Session 5:

Front: 10 comp / 20 reb
Rear: 10 comp / 18 reb
Tires: 33 psi hot

With those the car felt the best thus far and I PB’d for the third time that day with a 1:57.910!

Interesting observation (for me anyways); if you compare the settings from the early sessions to the last, the big difference is the rear dampers. All this time I had been trying to tweak the fronts to get the car to turn how I want it but I guess it was the rear that needed tweaking (!). There’s definitely a lot more to suspension setup than I know lol

Any thoughts/comments/criticism welcome!

Glad it's working out. I just expressed what it would do but I am very particular/sensitive to how the car is set up. I also have access to a very good suspension expert and racer so easy decision for me.

[chris82]

Originally Posted by kaiv

So I went to Buttonwillow this Sunday and I have to say I’m pretty happy; the balance and feel is pretty good so far!

Special thanks to OC3 and Okusa for their help with setup/settings.

Again the specs:

RS PRO (v1) 200psi F / 250psi R
550F/800R (stock rear location)
-3F / 0 toe
-2R / 1/8th toe in
275 NT01

I kept a log of how the car handled at various settings and how fast it was. See below-

Session 1:

Front: 10 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 39 psi hot

PB’d on second lap, 1:58.6. Car felt good but I wanted a touch more corner entry / turn in bite.

Session 2:

Front: 10 comp / 18 reb
Rear: 10 comp / 13 reb
Tires: 35 psi hot

Added 2 clicks of front rebound and 2 clicks of rear compression and lowered tire pressure.

Car felt worse but PB’d again, 1:57.960.

Session 3:

Front: 10 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 33 psi hot

Dialed the dampers back to session 1 settings but lowered the tire pressure some more since it didn’t look I was using the shoulders at all.

Car felt similar as session 1, still would like more razor sharp corner entry bite. Best lap was 1:58.2.

Session 4:

Front: 8 comp / 16 reb
Rear: 8 comp / 13 reb
Tires: 33 psi hot

Reduced front compression by 2 clicks thinking it would allow the car to turn better when I brake into a turn.

Couldn’t tell the difference TBH. And by then the track was getting hot and greasy. Ran 2:00 flat throughout that session.

Session 5:

Front: 10 comp / 20 reb
Rear: 10 comp / 18 reb
Tires: 33 psi hot

With those the car felt the best thus far and I PB’d for the third time that day with a 1:57.910!

Interesting observation (for me anyways); if you compare the settings from the early sessions to the last, the big difference is the rear dampers. All this time I had been trying to tweak the fronts to get the car to turn how I want it but I guess it was the rear that needed tweaking (!). There’s definitely a lot more to suspension setup than I know lol

Any thoughts/comments/criticism welcome!

Have you thought about trying to increase the compression in the front to get better turn in? You should read the vehicle dynamics book written by the JRZ founder (Jan), great stuff in there, and it's all based on physics which is why JRZs are so amazing. He will say increase the compression where the grip is lacking. So in your case you want a sharper turn in, I'd say increase the compression up front (granted everything else is remaining the same)

[kaiv]

Originally Posted by PrimeBMW

Glad it's working out. I just expressed what it would do but I am very particular/sensitive to how the car is set up. I also have access to a very good suspension expert and racer so easy decision for me.

I think that's the biggest problem here. We have lots of installers but when it comes to setup ... IDK

Originally Posted by chris82

Have you thought about trying to increase the compression in the front to get better turn in? You should read the vehicle dynamics book written by the JRZ founder (Jan), great stuff in there, and it's all based on physics which is why JRZs are so amazing. He will say increase the compression where the grip is lacking. So in your case you want a sharper turn in, I'd say increase the compression up front (granted everything else is remaining the same)

Actually it looks like I need to do the opposite



My friend explained that you get grip by pressing down on the given tire, increasing compression on that corner or axle causes it to resist the weight from coming down on it. So, increasing front compression will not result in better grip at turn in while braking

Anyways, just ordered Jan Zuijdijk's book.

Thanks fellas!

[M3 Number 86]

Originally Posted by chris82

Have you thought about trying to increase the compression in the front to get better turn in? You should read the vehicle dynamics book written by the JRZ founder (Jan), great stuff in there, and it's all based on physics which is why JRZs are so amazing. He will say increase the compression where the grip is lacking. So in your case you want a sharper turn in, I'd say increase the compression up front (granted everything else is remaining the same)

increasing compression in the front will make the car skip rather than grip no?

[xchosun1x]

awesome information man!!!!

[chris82]

Originally Posted by kaiv

I think that's the biggest problem here. We have lots of installers but when it comes to setup ... IDK




Actually it looks like I need to do the opposite



My friend explained that you get grip by pressing down on the given tire, increasing compression on that corner or axle causes it to resist the weight from coming down on it. So, increasing front compression will not result in better grip at turn in while braking

Anyways, just ordered Jan Zuijdijk's book.

Thanks fellas!

But for sharper turn in (I thought that's what you were talking about) it does say increase front compression. Anyways, I was just going off of something suggested in that book. It's a great read! But it is translated so it isn't perfect english

Originally Posted by M3 Number 86

increasing compression in the front will make the car skip rather than grip no?

Don't have the exact answer for you. Only the driver can tell us that!

[kaiv]

Thanks, I appreciate it. Got the book in the mail already, just haven't had a chance to dive into it just yet!