Aaron, did you guys see much spring rate difference going RA1 to RR?Originally Posted by Suck fumes
I don't think I get the hard transitions from "good" to "bad" like hitting the bumpstops or bottoming shocks. Of course that could literally be my inability to recognize it.
+1
Last edited by Fbody383; 08-22-2014 at 11:12 AM.
#39 CMC Camaro
Orange is Fast!
CMC-NT01 FTW!
We don't change springs during the season. I find one combo I like and setup the car around it. We didn't change anything going from ra1 to RR. Shocks are huge! You can tell when they bottom out when you enter the turn and the car gets fully loaded on one side. If it starts to push right as you start to turn and steadily gets worse as you accelerate then your on the bumps. If it starts to step out on the rear under the same scenario then the rear is bottoming out. Now for me it's a feel thing. I can drive a car and know exactly what it needs by how it behaves but that's just seat time that you need to get to understand that. You need to go to a test day and purposefully change things to see what they feel like to really know what works.
I don't mean when a shock bottoms out, I mean when it's too stiff or too soft. I know they're most active during corner entry/exit, but am not yet smart enough to know when to blame a shock for an undesirable behavior vs springs/sways. I am still curious about stiff spring/soft bar vs soft spring/hard bar. I've googled the matter and there seems to be no definitive answer. So if a bar is rated 100# less than another, do I subtract 100# from the spring rate or 50#? Or is it way more complicated than that? Since the sway and shock mount so close, I figure it's fair to consider their effects about equal with respect to wheel rate. My mindset is that softer = more grip too, but I really do want to see what the 950 setup drives like properly balanced before going softer yet in case it does end up working with the 30mm bar. At what point should I worry about my shocks being out of their usable range? Another part of my reluctance to go softer. Then again, if the combined wheel rates of the springs plus sways comes out similar then maybe it's not that big of a deal? I also want to measure my pickup points and calculate wheel rates with different spacers. I that'll help me wrap my head around that matter too.
Dave what bars do you run? Didn't see that in your first reply.
Last edited by Supercharged111; 08-22-2014 at 10:23 PM.
Listen to your butt. Record what it says. Think about what it said. Think some more. Make a single change. Repeat.
You put a 950 spring in any car and you might as well remove the shock cause it will do nothing haha. Might as well be racing a train that doesn't flex at all and will be so unstable and twitchy you will get eaten alive in the turns. Like I said a thousand times before but only one person has listened.....softer is faster! You just have to be smooth! You'll be surprised how much longer tires last and how consistent your tires will be too cause the suspension actually moves and works instead of putting all the pressure on the tires and Sliding them.
Last edited by Suck fumes; 08-23-2014 at 12:09 AM.
Depends on the motion ratio, on a mustang 950 isn't bad, wheel rate is ~1/4 of that
Like I said only one person has listened to me and he is a lot faster now. Y'all can choose what you want.
Aaron don't forget 950 is noticeably soft compared to what I had. I went from a 1200 down to a 950, a 250# drop is significant. I don't think it's the end all, IMO I need to go too soft before finding what I really like. I think the biggest shocker is that it doesn't oversteer like crazy with 325 out back.
Remember where I said above that the 4th gens like a 3 to 3.5:1 front/rear spring ratio? Well w/ the 950/325's you are at a 2.9:1 ratio. Right on track. Combined w/ soft bars, you may be close. I ran 850's and 275 for a year or so. Car was OK, but not consistent from track to track. Biggest issue was standing starts. I would just get killed due to rear tire spin. No weight transfer. Softer springs allow the weight to shift. You need this to happen.
The F/R rate ratio is a guide as some guys like a lose car and some can't drive one that way. Lose is fast, but is hell on rear tires. makes the front work very well though as they can do more stopping and less of the turning. Remember, brakes and throttle are for turning too.
I agree w/ Aaron to a point. You can go too soft. Since roll rate stiffness is limited by the sway bars, you must add some spring rate to compensate for that. If softer was better no matter what, we all would be running OEM spring rates. Trust me, I've run 5 years on a 550/175 rate set-up w/ 315's on all 4 corners w/ a previous 4th gen. My CMC car is way faster w/ 200 less HP.
Set-up is a puzzle. The pieces of the puzzle are springs, sway bars, camber, caster. Mess w/ one and all need adjusting.
One way to tell is all the puzzle pieces are fitting well is to look at tire temps across the face as well as air pressures of the tires front to rear. If your F/R pressures are different by more than 5lbs, you need a set-up change. If your tire temps across the face of the tire are off by more and 10 degree steps (ex: outside220, middle205, inside220 = too low air pressure) you need a set-up change.
You should be using the tires equally across the face. This gives you even tire temps (10 degree total spread should be the goal). My tire pressures are normally 2 or so different at most from front to rear. I may even have a difference of 1 or 2 from left to right.
#1 -Know why your making a change, #2 - predict what that change will give you. #3- If you get something different, question #1. #4 - If you get what you expected, was it more or less than what you need. #5 - Go back to #1.
So you have the rate ratio range (3 to 3.5:1) as a guide. Are you in that zone?
How are your tire temps across the face?
How are your air pressures from tire to tire?
Is the car faster now than before?
Also, never use tire wear as a guide to set-up. I need to flip my tire between each event to get full life out of them.
After I sell my CMC car this yr I'll reveal some numbers on my car but until then I have to remain quiet haha.
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