Choosing the right coilovers
05-25-2016, 11:31 AM
#152
More consistency, more positive locking, no worries about fade, lifetime maintenance-free operation (minus fluid changes). Lots of the 370Z guys have switched as the viscous units fade not only with heat but with time.
And yes, I plan on keeping the wheels on the ground. I gave up jumping my G37 off BMX ramps years ago. I kid.
Good simple explanation of various rear LSD types:
Basic Introduction to Helical, Torsen & Mechanical LSDs
And yes, I plan on keeping the wheels on the ground. I gave up jumping my G37 off BMX ramps years ago. I kid.
Good simple explanation of various rear LSD types:
Basic Introduction to Helical, Torsen & Mechanical LSDs
05-26-2016, 11:17 AM
#154
Did a longer run on some pretty ****ty highways this morning. Definitely too hard in the rear for comfortable highway cruising. Going to back down two notches in the rear. Fronts feel great. Far more planted in high speed sweepers, more neutral and natural feeling. Sway? What sway?
No problem getting into my parking space this morning either. Was waiting to hear that scraping sound.
Update Edit: I've backed off the rears and I believe I'm at 7 from full soft and I ran both 10 and 8 at the front today. I believe, and I'll figure this out tomorrow, if I did 6 in the rear and 8 up front, I'd be about where the IPL shocks are without the additional body movement due to the lighter spring rates. Just to give you an idea of how firm these shocks can get! I think if greater control over stock with everyday real world ride is important, go with the E model over the S. When the road is smoother (read most other states outside Michigan, New Jersey and NYC), even at the higher settings, the ride is extraordinary. The sharp bumps don't upset the car as much as big undulations. We have a lot of clay earth here in San Antonio and roads get big ripples in them. Going over that sort of bump, with the suspension dialed up, I definitely feel the extra spring rate over stock. I can go around fast sweepers with sharp bumps mid corner and the car does not get upset. The rear doesn't skip out.
Update Edit #2: I'm at 6 front, 3 rear, basically as comfortable as the IPL suspension but without the "fuss" of the IPL suspension which can get fidgety and make the car move around. The Aragostas produce less body movement and maybe even a bit more compliance over the IPL Tokicos which is saying something as the Tokico's a twin tube. Just very supple, controlled damping that acts very quickly. No pogoing down, no float, no spring bounce, even at the lower damper settings. If you soften the dampers up, it does affect turn-in and you're able to affect the front/rear balance as well. The more firm things are up front, the more immediate the car is to input. Even at full soft, it's better than stock by a good bit. It's still forgiving and you can toss it around with more accuracy and confidence.
Going to go to 7 front, four rear for daily driving. In all honesty, a remote electronic adjuster, like the EDFC, would be killer with these shocks. We have some very smooth roads where I could take advantage of the increase in stiffness but there are a few sections of my daily commute which are like riding off road in the Paris-Dakar. Big mid-corner bumps, rippled asphalt that resemble whoop-de-do's on a motocross track, etc...a real test for daily, real-world livability.
These things would absolutely rock on a road or autocross course with stickier rubber.
No problem getting into my parking space this morning either. Was waiting to hear that scraping sound.
Update Edit: I've backed off the rears and I believe I'm at 7 from full soft and I ran both 10 and 8 at the front today. I believe, and I'll figure this out tomorrow, if I did 6 in the rear and 8 up front, I'd be about where the IPL shocks are without the additional body movement due to the lighter spring rates. Just to give you an idea of how firm these shocks can get! I think if greater control over stock with everyday real world ride is important, go with the E model over the S. When the road is smoother (read most other states outside Michigan, New Jersey and NYC), even at the higher settings, the ride is extraordinary. The sharp bumps don't upset the car as much as big undulations. We have a lot of clay earth here in San Antonio and roads get big ripples in them. Going over that sort of bump, with the suspension dialed up, I definitely feel the extra spring rate over stock. I can go around fast sweepers with sharp bumps mid corner and the car does not get upset. The rear doesn't skip out.
Update Edit #2: I'm at 6 front, 3 rear, basically as comfortable as the IPL suspension but without the "fuss" of the IPL suspension which can get fidgety and make the car move around. The Aragostas produce less body movement and maybe even a bit more compliance over the IPL Tokicos which is saying something as the Tokico's a twin tube. Just very supple, controlled damping that acts very quickly. No pogoing down, no float, no spring bounce, even at the lower damper settings. If you soften the dampers up, it does affect turn-in and you're able to affect the front/rear balance as well. The more firm things are up front, the more immediate the car is to input. Even at full soft, it's better than stock by a good bit. It's still forgiving and you can toss it around with more accuracy and confidence.
Going to go to 7 front, four rear for daily driving. In all honesty, a remote electronic adjuster, like the EDFC, would be killer with these shocks. We have some very smooth roads where I could take advantage of the increase in stiffness but there are a few sections of my daily commute which are like riding off road in the Paris-Dakar. Big mid-corner bumps, rippled asphalt that resemble whoop-de-do's on a motocross track, etc...a real test for daily, real-world livability.
These things would absolutely rock on a road or autocross course with stickier rubber.
Last edited by Ape Factory; 05-29-2016 at 06:43 PM.
05-30-2016, 12:14 AM
#156
Thanks, appreciated. It's a bit of a process compounded by a lot of OCD but fun none-the-less. I may even mess with spring rates a bit and down the road, convert them to two-way adjustable. It'll be interesting to see what lighter wheels, tires and rotors yield.
05-30-2016, 01:29 AM
#157
I've been emailing Fat Cat. He's recommending 800/600 lb/in springs to get 1.64/1.9 Hz wheel frequencies. The rear is stiffer than I'd expect but that's what he calculates for flat ride. The process caused me to measure the sway bars, which I posted, apparently for the first time on this board.
At the same time, I'm reading Chassis Design - Principles and Analysis. I'm having to ignore the math since I haven't fooled with calculus since 1978. At least there are summaries that explain what the math proves. One thing it shows is the roll center isn't parallel to the ground; the front roll center is at the ground while the rear is at the top of the differential. I will have to reread the beginning because I don't know why the roll center is inclined. I think it has to do with roll rate and the way it loads the tires to impart a basic understeer character.
Flat ride has been mentioned and explained, though. This allows the rear end to keep up with the front when hit with a disturbance. Also improves grip while traveling quickly over rough roads.
At the same time, I'm reading Chassis Design - Principles and Analysis. I'm having to ignore the math since I haven't fooled with calculus since 1978. At least there are summaries that explain what the math proves. One thing it shows is the roll center isn't parallel to the ground; the front roll center is at the ground while the rear is at the top of the differential. I will have to reread the beginning because I don't know why the roll center is inclined. I think it has to do with roll rate and the way it loads the tires to impart a basic understeer character.
Flat ride has been mentioned and explained, though. This allows the rear end to keep up with the front when hit with a disturbance. Also improves grip while traveling quickly over rough roads.
Last edited by slartibartfast; 05-30-2016 at 01:36 AM.
05-30-2016, 02:39 AM
#158
Yeah those numbers are fairly high but as long as the damper is designed to handle the spring, you should be ok. But that's 14kg/mm front, and 10.7 rear. It was explained to me that it's not the spring rate which causes harshness but rebound damping. With that said, the damper's curve and spring rate are directly limited by your wheel/tire package. If you don't have the tires to take advantage of the extra grip, you won't be happy with the car's ride and handling.
Roll center is determined off of the upper and lower suspension arm angle, intersection point and the wheel contact point to intersection point of the upper and lower arms. So...if the mounting points of the front suspension are different from the rear, the arm angle is going to be different and thus the roll center front vs. rear. I'd be surprised if our front roll center was at ground level given the angle of the the top and bottom arms.
I'm a little confused by flat ride...wouldn't it require the front/rear wheel frequencies to be the same?
Here's a Miata thread by Fat Cat on flat ride:
Got Flat Ride? Optimizing YOUR aftermarket suspension! - MX-5 Miata Forum
Interesting the feedback given on ride characteristics by various owners.
I have a theory on my rear suspension performance but I need to check something out first and I'll report my findings.
Roll center is determined off of the upper and lower suspension arm angle, intersection point and the wheel contact point to intersection point of the upper and lower arms. So...if the mounting points of the front suspension are different from the rear, the arm angle is going to be different and thus the roll center front vs. rear. I'd be surprised if our front roll center was at ground level given the angle of the the top and bottom arms.
I'm a little confused by flat ride...wouldn't it require the front/rear wheel frequencies to be the same?
Here's a Miata thread by Fat Cat on flat ride:
Got Flat Ride? Optimizing YOUR aftermarket suspension! - MX-5 Miata Forum
Interesting the feedback given on ride characteristics by various owners.
I have a theory on my rear suspension performance but I need to check something out first and I'll report my findings.
05-30-2016, 12:27 PM
#159
The flat ride concept is that you want both ends of the car to reach equilibrium at the same time after a disturbance. Since the front hits first, the rear has to have a higher frequency (stiffness) so it can process the disturbance more quickly to return to equilibrium at the same time as the front.
Running Potenza S-04 Pole Positions on the stock sedan S wheels. I might buy coupe S sized wheels but not sure. Maybe square 9.5" or 10"? The staggered set-up is noted by Ollie in the book to be better for handling. The big eye-opener here is that the rear is the fulcrum against which the car is turned.
I know how the roll center is calculated, I don't fully understand why it's typically inclined. With the vehicle CG roughly 18" off the ground, the front has a strong moment arm compared to the rear. Ollie consistently shows front roll center to be at ground level, mostly because of steering considerations. Tie rod lengths and angles, whether they lead or trail the front "axle", anti-dive, axle tramp, shimmy reduction, etc, etc.
I experienced flat ride in my Sentra SE-R after a spring upgrade but didn't know the concept at the time. With its light weight and relatively short wheelbase, I didn't care for it on the street. It worked really well at Texas World Speedway, though. Between the stiffer springs and AGX dampers, I didn't have to lift when coming down off the banking into turn 1. The transition to the apron would put a softer car into the weeds. I expect it the rear feel won't be so bad in the G. With the relatively long wheelbase, the rear frequency has to be rather higher than the front.
And these are Bilstein monotube dampers that are custom-valved for the spring rates.
Running Potenza S-04 Pole Positions on the stock sedan S wheels. I might buy coupe S sized wheels but not sure. Maybe square 9.5" or 10"? The staggered set-up is noted by Ollie in the book to be better for handling. The big eye-opener here is that the rear is the fulcrum against which the car is turned.
I know how the roll center is calculated, I don't fully understand why it's typically inclined. With the vehicle CG roughly 18" off the ground, the front has a strong moment arm compared to the rear. Ollie consistently shows front roll center to be at ground level, mostly because of steering considerations. Tie rod lengths and angles, whether they lead or trail the front "axle", anti-dive, axle tramp, shimmy reduction, etc, etc.
I experienced flat ride in my Sentra SE-R after a spring upgrade but didn't know the concept at the time. With its light weight and relatively short wheelbase, I didn't care for it on the street. It worked really well at Texas World Speedway, though. Between the stiffer springs and AGX dampers, I didn't have to lift when coming down off the banking into turn 1. The transition to the apron would put a softer car into the weeds. I expect it the rear feel won't be so bad in the G. With the relatively long wheelbase, the rear frequency has to be rather higher than the front.
And these are Bilstein monotube dampers that are custom-valved for the spring rates.
Last edited by slartibartfast; 05-30-2016 at 12:41 PM.
05-30-2016, 02:35 PM
#160
It's inclined most likely due to the CV axles and different suspension mounting points.
Good concise explanation on the flat ride concept. Edit: Been thinking about this and I would hope, within the distance between the front and rear axle line, that the front suspension would have already reacted to whatever road imperfection presented itself and already has the front wheel back on the ground. At higher speeds, I can't see two chassis inputs (bumps), one for the front, and one for the rear, having that great of an effect or even one we'd be able to detect.
This morning, on a hunch I had, I double checked rear preload and discovered it was 15mm too much. I reset it at 10mm and dialed everything up a bit, 8 front 5 rear. Rides much better shockingly. Enough I may go two more bumps all around. This was on a full tank of gas which does make a difference.
I had set the bump stops up about 30mm from the top of the strut body and they had not moved. So I was not riding the bump stops. Amazing what the right preload can do for your ride.
Good concise explanation on the flat ride concept. Edit: Been thinking about this and I would hope, within the distance between the front and rear axle line, that the front suspension would have already reacted to whatever road imperfection presented itself and already has the front wheel back on the ground. At higher speeds, I can't see two chassis inputs (bumps), one for the front, and one for the rear, having that great of an effect or even one we'd be able to detect.
This morning, on a hunch I had, I double checked rear preload and discovered it was 15mm too much. I reset it at 10mm and dialed everything up a bit, 8 front 5 rear. Rides much better shockingly. Enough I may go two more bumps all around. This was on a full tank of gas which does make a difference.
I had set the bump stops up about 30mm from the top of the strut body and they had not moved. So I was not riding the bump stops. Amazing what the right preload can do for your ride.
Last edited by Ape Factory; 05-30-2016 at 06:57 PM.
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