suspension thoughts?
Feb 17, 2010, 10:05 AM
#1
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suspension thoughts?
I'm starting this thread as too not get off topic in another thread. I'm wondering if my suspension is too tight or over powering my tire setup?
My wheels and tires:
17x8.5" +35 Enkei NT03+M's
Tires. 255/40R/17 (I use various compounds, Direzza Start Specs, HTR ZIII's, ect..)
Suspension:
Tanabe 7 Series Coilovers
Pro 210 Springs (not sure of the spring rates, either 12/10 or 14/12?)
Underbracing
25mm front sway bar
22mm rear sway bar
Energy Complete Bushings set
Perrin PPSR kit
The car is lowered quite a bit, and the coilovers are on full stiff because I do not have a controller for them that work (Their electric
)
The car tends to understeer and be twitchy.
Alignment specs are always changing but for now:
-1.8 camber front, .16 toe out front, +.5 caster front
-1.0 camber rear, 0.0 toe rear, 0.0 caster rear
I'm also curious how you track guys with 255's are aligning your cars?
Thanks
My wheels and tires:
17x8.5" +35 Enkei NT03+M's
Tires. 255/40R/17 (I use various compounds, Direzza Start Specs, HTR ZIII's, ect..)
Suspension:
Tanabe 7 Series Coilovers
Pro 210 Springs (not sure of the spring rates, either 12/10 or 14/12?)
Underbracing
25mm front sway bar
22mm rear sway bar
Energy Complete Bushings set
Perrin PPSR kit
The car is lowered quite a bit, and the coilovers are on full stiff because I do not have a controller for them that work (Their electric
)The car tends to understeer and be twitchy.
Alignment specs are always changing but for now:
-1.8 camber front, .16 toe out front, +.5 caster front
-1.0 camber rear, 0.0 toe rear, 0.0 caster rear
I'm also curious how you track guys with 255's are aligning your cars?
Thanks
Feb 17, 2010, 10:32 AM
#2
That is a little stiff for street tires, and those spring rates (softer in the rear) will lead to understeer especially with that little camber up front.
You've got to find a way to adjust the damping....full stiff must be brutal and it's probably a big reason the car is unsettled and twitchy. That's silly you can't adjust them without the electronic controller. Are you sure there's no way you can adjust?
The toe out up front is also causing the twitchiness.
To be honest, there is a lot to fix on that set-up. New coilovers that you can actually adjust and probably have better damping, better correct spring rates, new alignment, don't lower the car so much, etc.
- Andrew
You've got to find a way to adjust the damping....full stiff must be brutal and it's probably a big reason the car is unsettled and twitchy. That's silly you can't adjust them without the electronic controller. Are you sure there's no way you can adjust?
The toe out up front is also causing the twitchiness.
To be honest, there is a lot to fix on that set-up. New coilovers that you can actually adjust and probably have better damping, better correct spring rates, new alignment, don't lower the car so much, etc.
- Andrew
Last edited by GTWORX.com; Feb 17, 2010 at 10:38 AM.
Feb 17, 2010, 10:50 AM
#3
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haha well i have the $500 said controller, but I can't get a wiring diagram. working on it though.
The car is not as low as it could be. I can post pics and tell me what you think.
Would this setup be acceptable for race tires? It is a track only car that has had some majr weight reduction and is pushing 450whp
As far as an alignment for HPDE and TT what would you recommend?
The car is not as low as it could be. I can post pics and tell me what you think.
Would this setup be acceptable for race tires? It is a track only car that has had some majr weight reduction and is pushing 450whp
As far as an alignment for HPDE and TT what would you recommend?
Feb 17, 2010, 01:13 PM
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I agree with Andrew that that is too much spring for street tires (not to mention the spring rates being swapped front to rear). More negative camber up front would also help. STU autoX guys are limited to 245 street tires and run at least -3 degrees. Dial in a little more negative rear camber as well.
Feb 18, 2010, 12:03 PM
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what do you mean? I thought you needed a stiffer spring up front? The Tanabe 7 series came with 2 options. (12/10 front rear OR 14/12 front rear) I didnt buy the coilovers though, a friend did and I do not know what spring rates he purchased and all the paint is peeled off the springs?
Would it be beneficial for me to go away from the 255-275 street tires and maybe go back to a 245 Hoosier A6 or equivalent?
I believe the NASA ProRacing TTU rules say that:
245 or smaller add 0.8
250-275 add 0.4
244-267 non DOT approved add .4
Any NON-DOT approved tire subtract 0.75
So I'm thinking it would be more beneficial for me to run a 245 R-Compound since I'm already being penalized for having a 255 when I could have a 275 with the same point evaluation and save some points
Would it be beneficial for me to go away from the 255-275 street tires and maybe go back to a 245 Hoosier A6 or equivalent?
I believe the NASA ProRacing TTU rules say that:
245 or smaller add 0.8
250-275 add 0.4
244-267 non DOT approved add .4
Any NON-DOT approved tire subtract 0.75
So I'm thinking it would be more beneficial for me to run a 245 R-Compound since I'm already being penalized for having a 255 when I could have a 275 with the same point evaluation and save some points
Last edited by MitsoKid; Feb 18, 2010 at 12:12 PM.
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Feb 18, 2010, 12:28 PM
#8
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You do not want stiffer springs in the front of the EVO.
https://www.evolutionm.net/forums/ev...-your-evo.html
- Andrew
https://www.evolutionm.net/forums/ev...-your-evo.html
- Andrew
as you can see I am no suspension guru at all, I'm trying to learn this stuff still.
Feb 18, 2010, 12:46 PM
#9
To be honest I would dump those coilovers like a blind date that keeps talking about her ex and has breath worse than my dog! Sorry, i think it would be best if we see other people. Can't adjust, damping probably isn't good, crappy spring rates, etc.
It happens...it's a learning process and it's not easy. But get a coilover from someone that knows how to build suspensions! A lot of companies get it wrong, because in reality they don't know what they're doing....
- Andrew
It happens...it's a learning process and it's not easy. But get a coilover from someone that knows how to build suspensions! A lot of companies get it wrong, because in reality they don't know what they're doing....
- Andrew
Feb 18, 2010, 12:57 PM
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Well I'm trying to learn this stuff myself, I'm trying to build my own TT car and suspension and brakes are where I really want to tune the car.
I got my entire suspension from a friend for $1,000 almost new, so I couldnt turn it down. I'm going to try to get the controller hooked up so I can set the rebound/damping on the things. they will go super soft if I set them soft, or race car stiff.
1 thing I do like about them is how they vary at speed, the slower I go the softer they get, the faster the stiffer.. This is fully programmable too with the controller and legal in Nasa TT.
Idk I will definitely do more research
I got my entire suspension from a friend for $1,000 almost new, so I couldnt turn it down. I'm going to try to get the controller hooked up so I can set the rebound/damping on the things. they will go super soft if I set them soft, or race car stiff.
1 thing I do like about them is how they vary at speed, the slower I go the softer they get, the faster the stiffer.. This is fully programmable too with the controller and legal in Nasa TT.
Idk I will definitely do more research
Feb 18, 2010, 01:08 PM
#11
Ask yourself why you want them to get stiffer when you're moving faster and softer when you're going slower? Does that make sense? Do you have a shock dyno of the different adjustments?
EDIT: to me that TEAS controller always sounded not just gimmicky, but not really even what you want, especially on a track car. A track car that is moving fast wants stability, and firming the damper up is not going to do this. A slow moving track car wants rotation, because if it's going slow it's in a tight corner. Beyond all that, I absolutely would not want my car to be changing damping profiles left and right while i'm on the track. The other thing is you have to be sure that damper settings are consistent between settings for all 4 shocks. Sadly this is not the case for many popular coilovers. It's also common practice to reset the damper to full soft (or full stiff depending on the damper) before changing the settings to rezero the damper. This isn't possible with an electronic controller as far as I know, especially if it's trying to do it while the vehicle is moving.
Without a shock dyno, you have to do things by the seat of your pants, but that's just impossible if your working with a moving target. It's just way too complex for the sake of being different, but it's not actually an improvement especially for the track IMO. You need to focus on getting the car reliable and easy to drive....these sound like they would be good at doing the opposite of that. Find a good baseline set-up with coilovers with good damping curves and good spring rates.
- Andrew
EDIT: to me that TEAS controller always sounded not just gimmicky, but not really even what you want, especially on a track car. A track car that is moving fast wants stability, and firming the damper up is not going to do this. A slow moving track car wants rotation, because if it's going slow it's in a tight corner. Beyond all that, I absolutely would not want my car to be changing damping profiles left and right while i'm on the track. The other thing is you have to be sure that damper settings are consistent between settings for all 4 shocks. Sadly this is not the case for many popular coilovers. It's also common practice to reset the damper to full soft (or full stiff depending on the damper) before changing the settings to rezero the damper. This isn't possible with an electronic controller as far as I know, especially if it's trying to do it while the vehicle is moving.
Without a shock dyno, you have to do things by the seat of your pants, but that's just impossible if your working with a moving target. It's just way too complex for the sake of being different, but it's not actually an improvement especially for the track IMO. You need to focus on getting the car reliable and easy to drive....these sound like they would be good at doing the opposite of that. Find a good baseline set-up with coilovers with good damping curves and good spring rates.
- Andrew
Last edited by GTWORX.com; Feb 18, 2010 at 01:22 PM.
Feb 18, 2010, 10:32 PM
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Depending on if you've done anything to align the front roll center on the EVO (Steering Bushing Kit or the Lower Control Arm Kit) the EVO suffers from a funky camber curve that can cause problems unless you have a very closely dialed in ride height. The exact numbers elude me right now. Sorry
In fact when I put on a new set of slightly larger road tires just before this last winter hit, the extra 3/8" ride height increase caused a situation with a lot of bump steer in my EVO. After pulling out the tape measure and resetting the ride height it dialed right in.
After I'm done messing with a spring combo (only ran a couple so far) the first thing I do is very very carefully set the ride height.
I'm on 475 in-lb fronts and 550 in-lb rears on a Paul Gerrard / Vishnu Valving Kit on some older Ohlins R/T. However many other companies have figured out the valving dynamics for the EVO and you can get a good valve setup without too much searching effort.
My street alignments are:
2.0 deg front camber (still acceptable for street)
0.8 deg rear camber
0 toe all the way around
With no front roll bar change and a set of rear sway bar end links I have an Evo that understeers just a tad at a constant radius, constant throttle mid-speed corner and if I breathe off of the throttle, or left-foot brake for weight transfer the understeer stops and the rear starts to rotate (slowly).
Without me being a suspension expert in general, I've found a ride height setup benefits the EVO greatly and you might have some good success on getting it to or verifying you're already at the proper height. Perhaps somebody could chime in on the ride height settings?
Best of Luck,
~j.
In fact when I put on a new set of slightly larger road tires just before this last winter hit, the extra 3/8" ride height increase caused a situation with a lot of bump steer in my EVO. After pulling out the tape measure and resetting the ride height it dialed right in.
After I'm done messing with a spring combo (only ran a couple so far) the first thing I do is very very carefully set the ride height.
I'm on 475 in-lb fronts and 550 in-lb rears on a Paul Gerrard / Vishnu Valving Kit on some older Ohlins R/T. However many other companies have figured out the valving dynamics for the EVO and you can get a good valve setup without too much searching effort.
My street alignments are:
2.0 deg front camber (still acceptable for street)
0.8 deg rear camber
0 toe all the way around
With no front roll bar change and a set of rear sway bar end links I have an Evo that understeers just a tad at a constant radius, constant throttle mid-speed corner and if I breathe off of the throttle, or left-foot brake for weight transfer the understeer stops and the rear starts to rotate (slowly).
Without me being a suspension expert in general, I've found a ride height setup benefits the EVO greatly and you might have some good success on getting it to or verifying you're already at the proper height. Perhaps somebody could chime in on the ride height settings?
Best of Luck,
~j.
Feb 18, 2010, 10:38 PM
#14
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^ thats interesting. I'm wondering what the perfect ride height is. How do you measure that?
Does the fact that I am completely gutted and caged make a difference? I've taken alot of weight out of the car and added some of it back in different places
Does the fact that I am completely gutted and caged make a difference? I've taken alot of weight out of the car and added some of it back in different places
Feb 19, 2010, 12:36 PM
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To respond to your question, and to prefix my comment -- I'm trying to be accurate, and not pull too many assumptions on my end. I just don't have a lot of true "racing" experience, so take what I say with a grain of salt. 
I don't think being gutted and caged makes a huge difference. When I was talking with Paul and company about his suspension work, ride height relates more to the camber curve profile you're dealing with. If the camber curve doesn't match the body roll characteristic of the EVO then max. contact patch is not captured in a corner, and maintained if there are "bumps" in the corner.
A couple of things I haven't pursued relative to the EVO is changing out a steering bushing in the steering rack. Some say that when you change that out, bump steer is reduced over the whole travel range, making ride height a little more forgiving. Also there is a lower control arm kit that effectively lowers (I think) your lower control arm to place the camber curve in a more ideal spot over a large range of the ride height.
With that said ... on my setup ... I'm going to pull some numbers from out of the memory ether in my brain. I think the fronts are suppost to be setup at 13.5" front from the center hub to stock fender lip ... the rears I think are 13.625" from hub center to stock fender lip. Both should be maintained to plus minus 1/8" but the rear is much more forgiving than the front. If you can be patient, I'll go measure the EVO later today and try and make it back to respond.
The measurement seems weird ... but with even my little pocket 3' tape measure, if I carefully put the tab in the middle of my hub without too much deflection, and draw it verticle to my stock fender, I can get within 1/8" very easily. After the bump steer seems gone I know I'm pretty close, and start to mess with my compression and rebound settings.
I hope that helps ... standby for numbers.
~j.
I don't think being gutted and caged makes a huge difference. When I was talking with Paul and company about his suspension work, ride height relates more to the camber curve profile you're dealing with. If the camber curve doesn't match the body roll characteristic of the EVO then max. contact patch is not captured in a corner, and maintained if there are "bumps" in the corner.
A couple of things I haven't pursued relative to the EVO is changing out a steering bushing in the steering rack. Some say that when you change that out, bump steer is reduced over the whole travel range, making ride height a little more forgiving. Also there is a lower control arm kit that effectively lowers (I think) your lower control arm to place the camber curve in a more ideal spot over a large range of the ride height.
With that said ... on my setup ... I'm going to pull some numbers from out of the memory ether in my brain. I think the fronts are suppost to be setup at 13.5" front from the center hub to stock fender lip ... the rears I think are 13.625" from hub center to stock fender lip. Both should be maintained to plus minus 1/8" but the rear is much more forgiving than the front. If you can be patient, I'll go measure the EVO later today and try and make it back to respond.
The measurement seems weird ... but with even my little pocket 3' tape measure, if I carefully put the tab in the middle of my hub without too much deflection, and draw it verticle to my stock fender, I can get within 1/8" very easily. After the bump steer seems gone I know I'm pretty close, and start to mess with my compression and rebound settings.
I hope that helps ... standby for numbers.
~j.