2017 STU Discussion!
Feb 14, 2017, 08:07 AM
#17
I love my quickjack. It's the 5000lb one. I just put the blocks on the frame rail, haven't had any issues. the only pain really is sliding them under the car and lining it up. better than jacking up one side and then the other though. will get the car up super high, enough to freely roll around under the car
Feb 14, 2017, 08:10 AM
#18
With the heavy spring rate we typically run due to poo poo roll centers, static wheel travel is very small and reducing it with preload would be the wrong direction. We actually want more shock travel to handle bump rebound so the shocks don't fully extend and slam into the internal stops.
For this you would need a helper spring to let the main spring fully unseat (captured buy the helper so it doesn't bounce around). Most single height adjustable coilovers are made quite long and definitely need a helper spring.
I don't use a helper up front on Ohlins because I can set preload to zero (collar just touching the spring, not loading) and the front doesn't seem to have the same amount of bounce that the rear has.
Feb 15, 2017, 05:57 AM
#19
Preload isn't necessarily important on our cars with our heavy spring rates. Only reason it would be is for soft springs that need to reduce static deflection to optimize shock static position, and only in one direction (too much compression)
With the heavy spring rate we typically run due to poo poo roll centers, static wheel travel is very small and reducing it with preload would be the wrong direction. We actually want more shock travel to handle bump rebound so the shocks don't fully extend and slam into the internal stops.
For this you would need a helper spring to let the main spring fully unseat (captured buy the helper so it doesn't bounce around). Most single height adjustable coilovers are made quite long and definitely need a helper spring.
I don't use a helper up front on Ohlins because I can set preload to zero (collar just touching the spring, not loading) and the front doesn't seem to have the same amount of bounce that the rear has.
With the heavy spring rate we typically run due to poo poo roll centers, static wheel travel is very small and reducing it with preload would be the wrong direction. We actually want more shock travel to handle bump rebound so the shocks don't fully extend and slam into the internal stops.
For this you would need a helper spring to let the main spring fully unseat (captured buy the helper so it doesn't bounce around). Most single height adjustable coilovers are made quite long and definitely need a helper spring.
I don't use a helper up front on Ohlins because I can set preload to zero (collar just touching the spring, not loading) and the front doesn't seem to have the same amount of bounce that the rear has.
I played with this on my coilover setup and initially loaded up 1/2 inch of preload. Car was was too bouncy. I now run 5mm of preload (set after perch was hand tightened to eliminate any spring wiggle). It def removed the bounce/rough ride. Now im thinking of removing the 5mm and just hand tightening it so the spring doesn't wiggle.
Feb 15, 2017, 07:46 AM
#20
That's definitely where you want to be. And the bounce youre feeling is actually right after the bump in rebound when the shock has a dramatic stop on its internal limiter. Technically its jerk you feel (derivative of acceleration) as it all the sudden stops. The heavier your spring rates, the more likely youll see it just because of the reduced static travel.
Feb 15, 2017, 08:27 AM
#21
That's definitely where you want to be. And the bounce youre feeling is actually right after the bump in rebound when the shock has a dramatic stop on its internal limiter. Technically its jerk you feel (derivative of acceleration) as it all the sudden stops. The heavier your spring rates, the more likely youll see it just because of the reduced static travel.
Feb 15, 2017, 08:39 AM
#22
Evolved Member
I am not sure if I am following this correctly, but setting the position of the bottom perch on the desk is one thing. Adjusting the corner heights is another one altogether. Same spring lengths, but different stiffness, would yield completely different results. So, once you adjust your ride height, than you can see what kind of preload or lack of it you would have at full extension of the shock/strut.
Feb 15, 2017, 09:34 AM
#23
Preload isn't necessarily important on our cars with our heavy spring rates. Only reason it would be is for soft springs that need to reduce static deflection to optimize shock static position, and only in one direction (too much compression)
With the heavy spring rate we typically run due to poo poo roll centers, static wheel travel is very small and reducing it with preload would be the wrong direction. We actually want more shock travel to handle bump rebound so the shocks don't fully extend and slam into the internal stops.
With the heavy spring rate we typically run due to poo poo roll centers, static wheel travel is very small and reducing it with preload would be the wrong direction. We actually want more shock travel to handle bump rebound so the shocks don't fully extend and slam into the internal stops.
Looking on Swift's site, this is exactly what they offer up to 6kg/mm. I don't know how the rebound rates of a coilover will react to the dual spring rate but that might be overthinking it. As AWDBoosted (I believe) pointed out, you can get clearance by running Evo X strut to knuckle brackets on the CT9A.
Feb 15, 2017, 10:51 AM
#24
I am not sure if I am following this correctly, but setting the position of the bottom perch on the desk is one thing. Adjusting the corner heights is another one altogether. Same spring lengths, but different stiffness, would yield completely different results. So, once you adjust your ride height, than you can see what kind of preload or lack of it you would have at full extension of the shock/strut.
This is what I think you are talking about:
https://c1552172.ssl.cf0.rackcdn.com/771210_x800.jpg
This is what I am talking about:
http://xyz-racing.co.uk/product_imag...41784_zoom.png
The following users liked this post:
Murph (Feb 16, 2017)
Feb 15, 2017, 12:56 PM
#26
This is actually something I was pondering the last time I took my coilovers off. I know a few people are using a higher rate 12kg/mm+ spring that are only 6" to get it above a wide tire. However, the high rate spring severely limits the droop travel during rebound and the ability for the tire to keep traction over curbing. It would almost be best to get an assist spring with a 5kg/mm or so rate but then you would lose that clearance.
Looking on Swift's site, this is exactly what they offer up to 6kg/mm. I don't know how the rebound rates of a coilover will react to the dual spring rate but that might be overthinking it. As AWDBoosted (I believe) pointed out, you can get clearance by running Evo X strut to knuckle brackets on the CT9A.
Looking on Swift's site, this is exactly what they offer up to 6kg/mm. I don't know how the rebound rates of a coilover will react to the dual spring rate but that might be overthinking it. As AWDBoosted (I believe) pointed out, you can get clearance by running Evo X strut to knuckle brackets on the CT9A.
I still run similar clearance but now I'm playing with spacers to get the wheel as close to the strut after I figure out how much camber I'll need with 8deg caster on the new control arms.
Feb 18, 2017, 08:32 AM
#27
Quick question for the STU X guys. What rev limit are you running? Obviously we don't make power up there but it is more for gearing. Stock cut is 7600, 8k OK or is it playing with fire?
Feb 20, 2017, 11:56 AM
#28
EvoM Guru
iTrader: (1)
8k is fine.
Mar 19, 2017, 07:35 PM
#29
just wrapped up my first event on 17x9.5s - wow. huge, huge difference in grip, it's unbelievable. it feels like this missing piece of the puzzle that wraps everything together in the car. the car used to have moments of looseness and "bite-iness" in slaloms and transitions that is now completely gone. i'll have to spend some time figuring out the car again, but no big deal there! FTD'd at my event for the first time at an event with "legit" contenders (nats drivers) so pretty happy about that.
The following users liked this post:
Meathooker (Mar 19, 2017)
Mar 20, 2017, 07:51 AM
#30
I installed stiffer rear springs on Saturday. Previously 650/700, now 650/850. Hotchkiss RSB on full stiff. The car is feels substantially better with the stiffer springs in the rear. Now I wish I had made the change earlier.
Changing springs is easy enough that I'll probably try a 700/900 setup next. A local nationals-level autocrosser who previously owned an Evo suggested I try 700/1000, which seems a bit too high. I'm curious enough that I may give it a shot. 1000 lb/in in the rear would require a revalve, but I may just have them revalved with 900 lb/in springs in mind. I certainly can't imagine going higher than 1000 lb/in rears on street tires.
Nice!
Now get some 18x10s, 265s, and stiffer springs.
Changing springs is easy enough that I'll probably try a 700/900 setup next. A local nationals-level autocrosser who previously owned an Evo suggested I try 700/1000, which seems a bit too high. I'm curious enough that I may give it a shot. 1000 lb/in in the rear would require a revalve, but I may just have them revalved with 900 lb/in springs in mind. I certainly can't imagine going higher than 1000 lb/in rears on street tires.
just wrapped up my first event on 17x9.5s - wow. huge, huge difference in grip, it's unbelievable. it feels like this missing piece of the puzzle that wraps everything together in the car. the car used to have moments of looseness and "bite-iness" in slaloms and transitions that is now completely gone. i'll have to spend some time figuring out the car again, but no big deal there! FTD'd at my event for the first time at an event with "legit" contenders (nats drivers) so pretty happy about that.
Now get some 18x10s, 265s, and stiffer springs.