Car is 3 wheeling, Stiffer swaybar or up spring rates?
Mar 23, 2018, 06:23 AM
#31
Evolved Member
put stiffer springs in the back and loosen the rear ARB
Mar 23, 2018, 08:47 AM
#35
EvoM Guru
iTrader: (1)
I've spent the last two years with my Evo autocrossing and searched the forum about this topic and several people here have given out ideas and suggestions on the 3 wheel motion we struggle with. I've seen others with Evos at our local region not 3 wheeling. I asked them about what setup they are running for suspension and found out that the other Evos have a longer rear coil spring setup than I do. My car has 6'' springs on all four corners and they have 6" Front and 7" Rear. I do have a set of 7'' Rear springs at home but they are 10K and I currently have 12k in the rear. This might help you guys out and I would consider doing the same myself.
Mar 23, 2018, 08:58 AM
#36
On my car, I got the rear tire back down on the ground by extending the length of the shock (ride height adjustable independent of the spring perch) and using helper springs to keep the main spring loaded at full droop. It may not make much difference since the load on that back tire is so little, but it has to be better than nothing?
Mar 23, 2018, 09:06 AM
#37
EvoM Guru
iTrader: (1)
On my car, I got the rear tire back down on the ground by extending the length of the shock (ride height adjustable independent of the spring perch) and using helper springs to keep the main spring loaded at full droop. It may not make much difference since the load on that back tire is so little, but it has to be better than nothing?
So, I should rephrase, I didn't think of that...LOL. Going to shorter springs won't stop 3-wheeling.
Last edited by letsgetthisdone; Mar 23, 2018 at 09:12 AM.
Mar 23, 2018, 09:14 AM
#38
Short spring doesnt matter, static deflection and preload matter. With high rates, I run a tender to push through the swaybar a bit once the main spring is starting to reach unloaded. Some dont like this setup but it definitely takes some shock out of the ride when reaching that full droop.
Mar 23, 2018, 09:55 AM
#39
I have not read everything but quick comment:
If the car is Tri-Podding, diving on the outer front, going to stiffer rear than front WILL EXAGGERATE the tripodding, because you are softening the front!
So staggered spring rate or not, the car is diving, pitching over a bit and rear tire is off the ground - lack of droop travel or too much cornering angle, regardless, the car needs to stay flatter so it may need more front spring, or stiffer sway bar, or both, and maybe more rear droop travel.
Regarding stiffer front springs vs rear, - It's typical Japanese setup, and it's been practiced in Europe and obviously in Australia and New Zeland.
All Group N/R4 FIA Rally setups for tarmac feature stiffer front springs, just check Reiger, Ohlins, Sachs, and more.
When approaching a corner, on 65/35 or 70/30 weight bias car like Evo, likely at least 80% of the overall weight will be transferred onto the front wheels, therefore the steady-state spring-rates adjusted to motion-ratios may not be the only answer, depends on driving style and what do you want the car to do.
On street we tend to approach corners braking ahead and going through far more steady state.
On track, we tend to dive in on brakes as deep as we can and get on throttle full as early as possible, in case of Evo with 4WD that can be very early like Porsche 911 due to strong traction both cars have.
So this gets to be a complicated math, figuring out right spring rates, including discounting the validity of front spring-rate bias.
The bias for front spring rates is also practiced by most world TA Evos, such as UK, Australia, NZ, and Japan.
I myself have found to prefer square setup on road, which goes against OEM rear-bias and common-US-forum wizdom. I tend to drive aggressively on road, and feel the car improved a lot its grip by increasing steadily spring rates from OEM, to 7/7.5kg to 8.5/8.5kg, and adding stiffer front bar finally.
Each step resulted in more confidence and more grip, and comfort level is comparable.
This in street car. And consider that the front sway bar is equivalent to some added spring rate- so I am already on fringes of favoring front bias.
My track Evo has the 10/12kg setup on Ohlins, and although I subscribe to Paul Gerrard's know-how/wizdom/modeling-results, I am going to test square setup and front bias: because my front outer tire is always the limiting factor! And if I can limit weight transfer and rolling by increasing roll-resistance, I feel I'll work all 4 tires better and be able to corner faster.
If the car is Tri-Podding, diving on the outer front, going to stiffer rear than front WILL EXAGGERATE the tripodding, because you are softening the front!
So staggered spring rate or not, the car is diving, pitching over a bit and rear tire is off the ground - lack of droop travel or too much cornering angle, regardless, the car needs to stay flatter so it may need more front spring, or stiffer sway bar, or both, and maybe more rear droop travel.
Regarding stiffer front springs vs rear, - It's typical Japanese setup, and it's been practiced in Europe and obviously in Australia and New Zeland.
All Group N/R4 FIA Rally setups for tarmac feature stiffer front springs, just check Reiger, Ohlins, Sachs, and more.
When approaching a corner, on 65/35 or 70/30 weight bias car like Evo, likely at least 80% of the overall weight will be transferred onto the front wheels, therefore the steady-state spring-rates adjusted to motion-ratios may not be the only answer, depends on driving style and what do you want the car to do.
On street we tend to approach corners braking ahead and going through far more steady state.
On track, we tend to dive in on brakes as deep as we can and get on throttle full as early as possible, in case of Evo with 4WD that can be very early like Porsche 911 due to strong traction both cars have.
So this gets to be a complicated math, figuring out right spring rates, including discounting the validity of front spring-rate bias.
The bias for front spring rates is also practiced by most world TA Evos, such as UK, Australia, NZ, and Japan.
I myself have found to prefer square setup on road, which goes against OEM rear-bias and common-US-forum wizdom. I tend to drive aggressively on road, and feel the car improved a lot its grip by increasing steadily spring rates from OEM, to 7/7.5kg to 8.5/8.5kg, and adding stiffer front bar finally.
Each step resulted in more confidence and more grip, and comfort level is comparable.
This in street car. And consider that the front sway bar is equivalent to some added spring rate- so I am already on fringes of favoring front bias.
My track Evo has the 10/12kg setup on Ohlins, and although I subscribe to Paul Gerrard's know-how/wizdom/modeling-results, I am going to test square setup and front bias: because my front outer tire is always the limiting factor! And if I can limit weight transfer and rolling by increasing roll-resistance, I feel I'll work all 4 tires better and be able to corner faster.
Mar 23, 2018, 06:57 PM
#40
I'm only doing street sprints and hill climbs in my car, but after playing around with different setups, I swear by a harder spring in the rear. I've gone against what everyone locally told me, and I love it. I found harder in the front creates too much under steer. I'm on KW Clubsports with 8kg/9kg, and stock roll bars. I'm guessing it will be different on a circuit though.
Mar 25, 2018, 07:36 PM
#41
EvoM Guru
Thread Starter
So ive pulled the springs off the shocks and found the rear shocks and springs are slightly less diameter than front. So simply putting the 14kg on the front and 16kg on the rear.
what im thinking of doing instead is going 12kg front + bigger fsb and leaving the 14kg springs in the rear. How does that sound?
otherwise ill have to track down some larger diameter 14kg springs for the front and just dont really have time before racing this weekend.
what im thinking of doing instead is going 12kg front + bigger fsb and leaving the 14kg springs in the rear. How does that sound?
otherwise ill have to track down some larger diameter 14kg springs for the front and just dont really have time before racing this weekend.
Mar 26, 2018, 10:26 AM
#42
Try it, and and....
In the past we used to rake the cars aggressively.
I certainly did my own, and overtime I decreased the rake to about 3/8".
There is an added benefit by Raking: Aero. It keeps pressure under the car somewhat lower, as air exits toward the back.
But I noticed that nowadays most track-Evos that are expertly prepared by successful teams, are nearly flat: same ride height more or less from ground to "pinch weld".
You may want to try to lower the rear, to try to keep the rear inner wheel on the ground and maybe slightly diminish the dive-under-brakes.
Good luck, hope its a good direction swapping to softer spring and adding sway bar: we're looking forward to hear your comments.
In the past we used to rake the cars aggressively.
I certainly did my own, and overtime I decreased the rake to about 3/8".
There is an added benefit by Raking: Aero. It keeps pressure under the car somewhat lower, as air exits toward the back.
But I noticed that nowadays most track-Evos that are expertly prepared by successful teams, are nearly flat: same ride height more or less from ground to "pinch weld".
You may want to try to lower the rear, to try to keep the rear inner wheel on the ground and maybe slightly diminish the dive-under-brakes.
Good luck, hope its a good direction swapping to softer spring and adding sway bar: we're looking forward to hear your comments.
Mar 26, 2018, 08:18 PM
#43
EvoM Guru
Thread Starter
yea i also removed the 20mm rake i was recommended by the suspension guy to stop diving.
So i havnt measured the car cause we r still doing the sequential install and its up on stands but once its on the ground again i will measure it and it should be level.
One thing i would really like to do is set the ride height up. im wondering if maybe the ride height is too high and the suspension isnt getting much travel. i tried to keep the A arms level but i might drop the whole car down like 20mm and see how that feels also. probably not for this track as pukekohe is stupidly bumpy and the car already bottoms out down the front straight.
But this is why we do it! to experiment n try stuff. and why we have forums so we can all combine our learnings! i will definately report back on how it handles with the softer springs in the front and sway bar. and we will move the sway bar from soft to med to hard and see what happens also
So i havnt measured the car cause we r still doing the sequential install and its up on stands but once its on the ground again i will measure it and it should be level.
One thing i would really like to do is set the ride height up. im wondering if maybe the ride height is too high and the suspension isnt getting much travel. i tried to keep the A arms level but i might drop the whole car down like 20mm and see how that feels also. probably not for this track as pukekohe is stupidly bumpy and the car already bottoms out down the front straight.
But this is why we do it! to experiment n try stuff. and why we have forums so we can all combine our learnings! i will definately report back on how it handles with the softer springs in the front and sway bar. and we will move the sway bar from soft to med to hard and see what happens also
