Looking for input from Evo members with significant setup experience
Jul 9, 2010, 08:40 AM
#91
The car still plowed like a pig through it's own **** on "ON THROTTLE" corner exit. It was more manageable than before, but still bad. Maybe the correct ride height will help this, however I feel that it will not make as a significant enough difference to provide the results I'm looking for. We're giving up a lot of time having to wait to get on throttle...especially with the turbo setup... the delay is compounded! To fix this I ordered the Gruppe-S ACD "Race" flash... I can get it in a few days and we'll see if its significant enough. If that doesn't allow me to rotate the car with the loud pedal...its time for a TRE diff! I'm skeptical that the flash will do what I want, but it might make it better. Only time will tell.
Jul 9, 2010, 11:35 AM
#92
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^ Certainly advantages (cheap and easy) and disadvantages to that....really good dampers would be a must have at that point IMO so maybe it's not so cheap. And you'll probably still end up wanting some roll center correction. But it's not a terrible idea....it could help but the "problem" is still there.
- Andrew
- Andrew
you need to keep roll centers in check. Also dont run the dampers at full stiff...
Jul 9, 2010, 02:09 PM
#94
I had my previous event on 6/11...I think you stated I needed a rear diff somewhere around 6/23 and I figured that it would take at LEAST 2 weeks to get there and back making the diff arrive at my house on 7/6 (1 day before the practice lapping day) I figured that the practice would be absolutely necessary...and I feel I made the right decision. My next track event is this coming Friday 7/16. I will have enough time after the next event to send the differential out and put the car on jackstands (it pretty much sits in the garage most of the time anyway
) I would've much rather done the TRE rear diff, but the time spacing simply didn't allow it before this event. If the reflash doesn't do anything... I can send it back to Gruppe-S...and then send my diff to TRE.
I'm not doubting that you're wright, I'm hoping that you're wrong about the reflash.
Bchappy...any suggestions as to what damper settings I should be using or a good way to determine how they should be set?
Drew... Maybe next season unless I start making big money doing side work lol.
Jul 10, 2010, 04:43 AM
#95
Ok... raised the car tonight and reset for some MASSIVE toe out for an autocross this Saturday (this morning actually)
Ride height as measured from the center of the wheel to the fender (i know...still not right, but closer!)
LF - 13 10/16"
RF - 14"
LR - 13 1/16"
RR - 13 9/16"
Interesting bit...the rear shocks have used up all the available space. If I raise the perch any higher I'm going to be limiting my shock travel. the 1/2" inch difference is setup by the difference of the threaded sleeve in the lower mount. I WONDER if my damping is different because of this left to right.
The FLCA is ALMOST flat to the horizon, but not quite. I can fit two fingers between the slick and the tire on the passenger side..and slightly less than that on the driver side. I think we're getting inside the ball park. This week we should be on the diamond...and hopefully on the mound by Friday.
Filled up the cans with Trick 114... ready to go to the local Bellingham auto-x
Ride height as measured from the center of the wheel to the fender (i know...still not right, but closer!)
LF - 13 10/16"
RF - 14"
LR - 13 1/16"
RR - 13 9/16"
Interesting bit...the rear shocks have used up all the available space. If I raise the perch any higher I'm going to be limiting my shock travel. the 1/2" inch difference is setup by the difference of the threaded sleeve in the lower mount. I WONDER if my damping is different because of this left to right.
The FLCA is ALMOST flat to the horizon, but not quite. I can fit two fingers between the slick and the tire on the passenger side..and slightly less than that on the driver side. I think we're getting inside the ball park. This week we should be on the diamond...and hopefully on the mound by Friday.
Filled up the cans with Trick 114... ready to go to the local Bellingham auto-x
Jul 11, 2010, 12:48 PM
#96
Took 1st and 2nd place at the Chuckanut Sports Car Club auto-x in the C2 class (BSP I guess) We had the fastest car at the event...only beaten by the WWU FSAE team (v48)
WWU FSAE 50.8x
Scott driving 54.9
Me driving 55.7
Dan (92 turbo civic eg) 56.7
It was my 2nd ever autocross...and I had FTD on the FSAE car until the afternoon when they started to figure out the course. We had nearly 2 seconds on everyone else...
So that was fun. The car picked up the inside rear tire still... that causes the bucking issue. The power felt great. Brakes were amazing! Grip was right on.
We'll have to see how the ACD reflash will work... Still haven't corner balanced the car...it needs to go back and get aligned again. I'm doing my own alignments in the garage and then checking them against the hunter rack so hopefully I can start doing my own alignments with some confidence. I made some ghetto toe plates last night that worked well.
We're going to get the car prepped by Wednesday night...so we can get a good nights sleep. We haven't done that yet, so we want to see if its all its cracked up to be!
we played with the damper settings a bit at the auto-x, but other than that...we just drove the car.
WWU FSAE 50.8x
Scott driving 54.9
Me driving 55.7
Dan (92 turbo civic eg) 56.7
It was my 2nd ever autocross...and I had FTD on the FSAE car until the afternoon when they started to figure out the course. We had nearly 2 seconds on everyone else...
So that was fun. The car picked up the inside rear tire still... that causes the bucking issue. The power felt great. Brakes were amazing! Grip was right on.
We'll have to see how the ACD reflash will work... Still haven't corner balanced the car...it needs to go back and get aligned again. I'm doing my own alignments in the garage and then checking them against the hunter rack so hopefully I can start doing my own alignments with some confidence. I made some ghetto toe plates last night that worked well.
We're going to get the car prepped by Wednesday night...so we can get a good nights sleep. We haven't done that yet, so we want to see if its all its cracked up to be!
we played with the damper settings a bit at the auto-x, but other than that...we just drove the car.
Jul 13, 2010, 09:19 PM
#98
In related news,
I'm working on the car tonight. Should finish the front right caliper and drop the car on the other NT03's and RE-11's for a corner balance tomorrow after work. A senior engineer that I work with races DSR cars @ PIR, SIR, etc... has some nice scales he's bringing to the Technical Center so we can corner balance the car. Don's a champ!
Matt Nucci and I have been talking for hours about ways to combat lifting the inside rear tire as well increasing front grip.
Two things I'm starting to understand. Given the trackwidth and cg of the Evo... it's going to be a 3 wheel monster on the tight ones. Putting the same size slicks all around on a 60/40 weighted car...will always understeer in steady state cornering w/out aero.
I've been going through my calculations with matt...
IIRC
Front
10k spring = 560#
980 lb corner weight
120 lb unsprung weight
860 lb sprung corner weight
560*0.94*0.94 = 495
860/495 = 1.74" per g of cornering
Track width in the front ~ 62"
tan-1(1.74/(62/2))) = 3.3 degrees of body roll per G
If you translate that to 1.2 or 1.3g's assume its a linear extrapolation... 4.3 degrees @ 1.3g's !!!!
Go figure why I have understeer issues at the limit...I'm losing my static camber. I need to raise the front rates...or add more caster/camber. I'm all out of camber adjustment and the caster isn't adjustable without some crazy camber plates.
if I jump to a 12k spring up front drop that roll to 2.7 degrees @ 1g and IIRC 3.3 degrees @ 1.3g's.
GRANTED...this doesn't take into account the spring rate addition by the ARB, which does add spring rate.
I'm planning on buying two 14k or 15k springs to swap to the rear and then swap the 12k's to the front. I need to wait until we have a practice day to see how it affects the lap times (skidpad!)
I would really like to decrease the rear ARB, but making big changes prior to raceday without validation is a big no-no!
My idea is...
12k Front
15k Rear
Reduce the Rear ARB setting from MAX to MED (3 settings; MAX, MED, and MIN)
Run slightly less rear camber (-2degrees to -1.5degrees)
this *SHOULD* according to my limited understanding of suspension dynamics...
Reduce my roll rate in the front keeping my camber gain to a healthy amount.
Reduce the amount the rear rolls (help keep 4 wheels on the ground)
Decrease my rear droop due to the spring rate, yet increase the droop with a softer rear ARB.
Decrease rear grip to achieve this so called "balance" (that i don't think exists with this car given its 60/40 distribution...and same size slicks on every corner) by running less camber in the rear. With the increased spring rate, my roll rate is also decreased (bar counter acting this..since it got softer) which *should* decrease my overall camber gain...which means I'd need to compensate the camber setting for this change as well. I'll have to ball park it and do some calc's, but it may very well end up closer to -1 degrees than -2 degrees camber in the rear.
I want to try this, but I feel that this Friday is not the day to try this. The next lapping day is on the 27th and I plan on doing a well prepared test plan and go through some different combinations. I'll bring the springs so I can swap them at the track! I'll be getting some Hyperco 750's (5.5" baby!) for the rear.
I'll buy them from Andrew @ GTWORKS... From the small conversations we've had and his willingness to openly discuss suspension dynamics I really think he'll be a pleasure to work/communicate with. When the time comes I'll be buying my Ohlins/JRZ's from them.
I'll be pleased to find a person ((like Aaron (JohnBradley@EnglishRacing) does with engines)) to bounce suspension ideas/setups off of.
I'm working on the car tonight. Should finish the front right caliper and drop the car on the other NT03's and RE-11's for a corner balance tomorrow after work. A senior engineer that I work with races DSR cars @ PIR, SIR, etc... has some nice scales he's bringing to the Technical Center so we can corner balance the car. Don's a champ!
Matt Nucci and I have been talking for hours about ways to combat lifting the inside rear tire as well increasing front grip.
Two things I'm starting to understand. Given the trackwidth and cg of the Evo... it's going to be a 3 wheel monster on the tight ones. Putting the same size slicks all around on a 60/40 weighted car...will always understeer in steady state cornering w/out aero.
I've been going through my calculations with matt...
IIRC
Front
10k spring = 560#
980 lb corner weight
120 lb unsprung weight
860 lb sprung corner weight
560*0.94*0.94 = 495
860/495 = 1.74" per g of cornering
Track width in the front ~ 62"
tan-1(1.74/(62/2))) = 3.3 degrees of body roll per G
If you translate that to 1.2 or 1.3g's assume its a linear extrapolation... 4.3 degrees @ 1.3g's !!!!
Go figure why I have understeer issues at the limit...I'm losing my static camber. I need to raise the front rates...or add more caster/camber. I'm all out of camber adjustment and the caster isn't adjustable without some crazy camber plates.
if I jump to a 12k spring up front drop that roll to 2.7 degrees @ 1g and IIRC 3.3 degrees @ 1.3g's.
GRANTED...this doesn't take into account the spring rate addition by the ARB, which does add spring rate.
I'm planning on buying two 14k or 15k springs to swap to the rear and then swap the 12k's to the front. I need to wait until we have a practice day to see how it affects the lap times (skidpad!)
I would really like to decrease the rear ARB, but making big changes prior to raceday without validation is a big no-no!
My idea is...
12k Front
15k Rear
Reduce the Rear ARB setting from MAX to MED (3 settings; MAX, MED, and MIN)
Run slightly less rear camber (-2degrees to -1.5degrees)
this *SHOULD* according to my limited understanding of suspension dynamics...
Reduce my roll rate in the front keeping my camber gain to a healthy amount.
Reduce the amount the rear rolls (help keep 4 wheels on the ground)
Decrease my rear droop due to the spring rate, yet increase the droop with a softer rear ARB.
Decrease rear grip to achieve this so called "balance" (that i don't think exists with this car given its 60/40 distribution...and same size slicks on every corner) by running less camber in the rear. With the increased spring rate, my roll rate is also decreased (bar counter acting this..since it got softer) which *should* decrease my overall camber gain...which means I'd need to compensate the camber setting for this change as well. I'll have to ball park it and do some calc's, but it may very well end up closer to -1 degrees than -2 degrees camber in the rear.
I want to try this, but I feel that this Friday is not the day to try this. The next lapping day is on the 27th and I plan on doing a well prepared test plan and go through some different combinations. I'll bring the springs so I can swap them at the track! I'll be getting some Hyperco 750's (5.5" baby!) for the rear.
I'll buy them from Andrew @ GTWORKS... From the small conversations we've had and his willingness to openly discuss suspension dynamics I really think he'll be a pleasure to work/communicate with. When the time comes I'll be buying my Ohlins/JRZ's from them.
I'll be pleased to find a person ((like Aaron (JohnBradley@EnglishRacing) does with engines)) to bounce suspension ideas/setups off of.
Last edited by R/TErnie; Jul 13, 2010 at 09:56 PM.
Jul 14, 2010, 07:13 AM
#100
In related news,...
Matt Nucci and I have been talking for hours about ways to combat lifting the inside rear tire as well increasing front grip.
Two things I'm starting to understand. Given the trackwidth and cg of the Evo... it's going to be a 3 wheel monster on the tight ones. Putting the same size slicks all around on a 60/40 weighted car...will always understeer in steady state cornering w/out aero.
Matt Nucci and I have been talking for hours about ways to combat lifting the inside rear tire as well increasing front grip.
Two things I'm starting to understand. Given the trackwidth and cg of the Evo... it's going to be a 3 wheel monster on the tight ones. Putting the same size slicks all around on a 60/40 weighted car...will always understeer in steady state cornering w/out aero.
I disagree with saying that the cars will always push in steady state cornering. If you make the rear stiff enough it will rotate, you just better have a rear diff in there or it's going to suck on corner exit.
I've been going through my calculations with matt...
...
tan-1(1.74/(62/2))) = 3.3 degrees of body roll per G
...
GRANTED...this doesn't take into account the spring rate addition by the ARB, which does add spring rate.
...
I would really like to decrease the rear ARB, but making big changes prior to raceday without validation is a big no-no!
...
tan-1(1.74/(62/2))) = 3.3 degrees of body roll per G
...
GRANTED...this doesn't take into account the spring rate addition by the ARB, which does add spring rate.
...
I would really like to decrease the rear ARB, but making big changes prior to raceday without validation is a big no-no!
, i'd recommend a total roll gradient target somewhere in the 1.5deg/g range.this *SHOULD* according to my limited understanding of suspension dynamics...
...
Decrease rear grip to achieve this so called "balance" (that i don't think exists with this car given its 60/40 distribution...and same size slicks on every corner) by running less camber in the rear. With the increased spring rate, my roll rate is also decreased (bar counter acting this..since it got softer) which *should* decrease my overall camber gain...which means I'd need to compensate the camber setting for this change as well. I'll have to ball park it and do some calc's, but it may very well end up closer to -1 degrees than -2 degrees camber in the rear.
...
Decrease rear grip to achieve this so called "balance" (that i don't think exists with this car given its 60/40 distribution...and same size slicks on every corner) by running less camber in the rear. With the increased spring rate, my roll rate is also decreased (bar counter acting this..since it got softer) which *should* decrease my overall camber gain...which means I'd need to compensate the camber setting for this change as well. I'll have to ball park it and do some calc's, but it may very well end up closer to -1 degrees than -2 degrees camber in the rear.
Jul 15, 2010, 01:24 AM
#101
Hrmmm interesting points.
Griceiv,
I'm trying to gauge what the best combination of drivetrain compensation to fix the "on throttle" understeer. Not only the best combination..the best route to that. financially its pretty easy to pick which happens when. ACD->TRE Rear diff -> GSC 40/60. I guess my concern is will the combination of all three of these modifications be too drastic?
GSC 40/60 Center Diff
TRE Rear Diff
Gruppe-S ACD reflash.
Griceiv,
I'm trying to gauge what the best combination of drivetrain compensation to fix the "on throttle" understeer. Not only the best combination..the best route to that. financially its pretty easy to pick which happens when. ACD->TRE Rear diff -> GSC 40/60. I guess my concern is will the combination of all three of these modifications be too drastic?
GSC 40/60 Center Diff
TRE Rear Diff
Gruppe-S ACD reflash.
Jul 15, 2010, 07:46 AM
#103
Hrmmm interesting points.
Griceiv,
I'm trying to gauge what the best combination of drivetrain compensation to fix the "on throttle" understeer. Not only the best combination..the best route to that. financially its pretty easy to pick which happens when. ACD->TRE Rear diff -> GSC 40/60. I guess my concern is will the combination of all three of these modifications be too drastic?
GSC 40/60 Center Diff
TRE Rear Diff
Gruppe-S ACD reflash.
Griceiv,
I'm trying to gauge what the best combination of drivetrain compensation to fix the "on throttle" understeer. Not only the best combination..the best route to that. financially its pretty easy to pick which happens when. ACD->TRE Rear diff -> GSC 40/60. I guess my concern is will the combination of all three of these modifications be too drastic?
GSC 40/60 Center Diff
TRE Rear Diff
Gruppe-S ACD reflash.
turns out putting 50% of the torque through an axle that has 40% of the weight on it is tail happy enough...at least in my opinion.
Jul 15, 2010, 02:12 PM
#104
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Just FYI Nils had made mention that the TRE rear diff made much more of a difference then the 40/60 center...
I have been playing with rear camber numbers and working the rear bar as well.. Personally I like a softer bar and less camber to obtain some slip angle. More camber in the rear with the bar full stiff makes my car a little confused to say the least.
It has trail brake "pointiness" on turn in then loads up the outsides, lifts the rear inside, the diffs go into confusion it feels and then you work the throttle in and the rear finally steps out a bit.
With less camber and a softer bar it feels more natural to me... But once again thats just me.
My car is significantly under-sprung for AX duty especially on 710s..
So its compromises for me however I still set FTDs and currently lead SM points in my region.
And as far as the dampers go, I just was always told you dont set them to full stiff, but once again I could be wrong. You let the spring control roll, dont use the damper as a spring because it wont work that way.
I set them in the 60-80% range of full "stiff" for the dampers adjustment and make changes to help the transition of the car.
I have been playing with rear camber numbers and working the rear bar as well.. Personally I like a softer bar and less camber to obtain some slip angle. More camber in the rear with the bar full stiff makes my car a little confused to say the least.
It has trail brake "pointiness" on turn in then loads up the outsides, lifts the rear inside, the diffs go into confusion it feels and then you work the throttle in and the rear finally steps out a bit.
With less camber and a softer bar it feels more natural to me... But once again thats just me.
My car is significantly under-sprung for AX duty especially on 710s..
So its compromises for me however I still set FTDs and currently lead SM points in my region.
And as far as the dampers go, I just was always told you dont set them to full stiff, but once again I could be wrong. You let the spring control roll, dont use the damper as a spring because it wont work that way.
I set them in the 60-80% range of full "stiff" for the dampers adjustment and make changes to help the transition of the car.
Last edited by bchappy; Jul 15, 2010 at 02:14 PM.
Jul 15, 2010, 02:53 PM
#105
AMS corner weighted a stock gtr…
LF 1080
RF 1060
LR 980
RR 960
Total weight 3920!!!!
My total weight with balance was 3217
LF 1010
RF 983
LR 613
RR 611
Balance was 49.6% to 50.4%
3.5409 pound per mm of tire – GTR LF
3.5438 pound per mm of tire – Evo LF
That front left weight is SCARY. The GTR carries its weight more gracefully than the Evo. Ti braces and a lightweight subframe would help… lightweight manifold and o2 housing. Maybe some CNC’d aluminum engine mounts instead of steel ones! Remove the AC…should drop a good 40 pounds off the front of the car. Move the ACD pump to the rear of the car...idk...
I’ll really need to attack the weight on the front end. If I could drop 50 pounds off the front… 975/968 taking 50 pounds out of the front of the car would make my pound per mm of tire drop to 3.4210
Great thing about all of this…is I can fabricate it all
LF 1080
RF 1060
LR 980
RR 960
Total weight 3920!!!!
My total weight with balance was 3217
LF 1010
RF 983
LR 613
RR 611
Balance was 49.6% to 50.4%
3.5409 pound per mm of tire – GTR LF
3.5438 pound per mm of tire – Evo LF
That front left weight is SCARY. The GTR carries its weight more gracefully than the Evo. Ti braces and a lightweight subframe would help… lightweight manifold and o2 housing. Maybe some CNC’d aluminum engine mounts instead of steel ones! Remove the AC…should drop a good 40 pounds off the front of the car. Move the ACD pump to the rear of the car...idk...
I’ll really need to attack the weight on the front end. If I could drop 50 pounds off the front… 975/968 taking 50 pounds out of the front of the car would make my pound per mm of tire drop to 3.4210
Great thing about all of this…is I can fabricate it all