Is our suspension setup correctly by aftermarket strut MFR's? Is the bias correct?

**Erron Spalsbury** · 06-12-2013, 05:32 PM

Originally Posted by J. Fast

1 drastically big difference between the two is that a softer spring rate with droop built in allows you to accelerate from the apex of a corner wherin with big spring you have to wait for the car to settle on the tire before you can accelerate. There is a workaround for it... It's called electronic YAW, but we don't have the luxury of electronicly adjusting grip at each corner independently. The setup I'm after is more of a universal set up verses road course only.

What do you mean by "settle on a tire"? (did we switch to a Rally discussion when I wasn't paying attention?) That's one big reason to go with a stiffer spring, weight transition is so much faster. This guy, had too soft of springs....LOL

**J. Fast** · 06-12-2013, 11:05 PM

Hey, I remember that. Kinda yes, but really,no. That right there is a perfect example of driving beyond the limits of our suspension. We were well beyond the valving blow off point and had a terrible knee for the application ( we couldn't afford better ) consequently. we were slamming the bumpstops. Even if we added more spring we were well beyond the valving capability of our dampeners... so far beyond our valving it was impossible to keep the shock off the bump stops. More spring would have helped, but really but we need was a suspension optimized for our setup. Unfortunately, because of the rules, we were quite limited to what we could put on without having to take on penalty laps or get kicked off the track like the Miata team did, lol.

If you believe multiple rate spring setups are solely intended for rally you're mistaken. They are segways to adjustable valving points in dampeners with available adjustments. For example, JRZ triple adjustable dampener can be tuned for low, medium, and high in compression and extension. It's possible to dampen for each spring stack between the isolator so you can valve for 200lb spring , 400lb spring, and a 600-pound spring and the ride frequency associated with each stack. The reason why we don't see them more? Well, they're bloody expensive to build, but most importantly we're often limited by the overall suspension travel and how much room we have to compartmentalize multiple springs.

**anyonebutme** · 06-12-2013, 11:09 PM

I thought this was appropriate to stick here:

**J. Fast** · 06-12-2013, 11:20 PM

If anyone out there is wondering wtf I'm talking about... Take a look at this:

Design your own Dual Spring-Rate Coilovers - Page 2 - Rennlist Discussion Forums

**J. Fast** · 06-12-2013, 11:27 PM

Lol, I like to separate the static from the noise. Gotta go work on my car get ready for the track on these

.

http://www.amsperformance.com/cart/J...nsion-Kit.html

**Nihil** · 06-12-2013, 11:35 PM

In the dirt bike world, your valving is what is progressive, that's what does all your dampening, then you match a spring rate to the weight of the rider and if they surpass that, then it goes beyond their weight and into their aggressiveness as well. Having said this, when you team up a progressive spring with the valving, you get a spring that is initially soft, that progressively gets more stiff, along with the valving that does the same, which in turn, gives you a very mushy wallowing feeling along with a harshness, since the progressive spring sags into/through the softer initial valving, you end up riding on the stiffer stroke of the valving, which creates a harsh feel and over rapid rough terrain you're riding on the soft part, which is too soft because the spring is progressive, which gives you the wallowing feeling because you're just blowing through the initial stroke.

I'd think a straight rate would be best, just go with a lighter spring, rather than helper springs. In comparison, a dirt bike, going over "whoops" or rapid terrain changes, would be similar to a winding road creating body roll.

I know, two different worlds, but I'd assume the valving in car suspension is still a progressive valving, no? So in my mind, still very similar. What are the stock spring rates on our car?

I'm almost thinking, a straight rate spring with a 25-30% increase on the front, and matching the rears to that, would be a nice upgraded start? (this obviously wouldn't be the case for someone like Erron who strictly races his car, the thought is more for the person wanting an aggressive DD'er with some track use)

I dunno, I've often wondered these things and this seems to be a nice discussion thread for it so I'm just throwin my ideas/thoughts out there, let me know if I get carried away

**Erron Spalsbury** · 06-13-2013, 12:00 AM

Originally Posted by J. Fast

That right there is a perfect example of driving beyond the limits of our suspension. We were well beyond the valving blow off point and had a terrible knee for the application ( we couldn't afford better ) consequently. we were slamming the bumpstops. Even if we added more spring we were well beyond the valving capability of our dampeners... so far beyond our valving it was impossible to keep the shock off the bump stops. More spring would have helped, but really but we need was a suspension optimized for our setup. Unfortunately, because of the rules, we were quite limited to what we could put on without having to take on penalty laps or get kicked off the track like the Miata team did, lol.

That Miata sucked! LOL (he kicked our ass) We weren't beyond the dampening, we were beyond the spring rate. (holy hell, WAY beyond, LOL!) The dampeners are still good. The springs were so soft, we (well, you actually) cut them so we be on the bump stops. Effectively creating a car with a billion lbs/in spring rate. All 6 drivers dropped over 5 seconds per lap the 2nd day, remember? Man, that was a fun weekend!

Originally Posted by J. Fast

If you believe multiple rate spring setups are solely intended for rally you're mistaken. .

I never said that buddy, I asked in reference to the "tire settling" comment. I knew exactly what you were talking about, Paul had the dual spring setup on his 2G with the Penske's back at Nats in '05. The lower spring rate spring has to compress before the larger spring does.

Hey, you coming to HPR on Friday? Jake, Hal, and myself will be there. Whoot!

**Erron Spalsbury** · 06-17-2013, 02:08 PM

Ok, the track testing wen't pretty well. For those of you that don't have me on Facebook I'll cross post some of the pics from Friday.
Headed out at about 10am, car loaded, springs installed are the 1300 lb/in front and 1100 lb/in in the back. Front camber dialed back a bit, -2 and the back I left set at -3.5.

Got to the track and it was a nice day, mild breeze and about 90 degrees F. (notice my buddies 850 HP Eclipse behind me) He came out to play as well. LOL

After a nice giant hot dog from the concession stand and a lot more Pepsi than I should have drank we took to the track.

I have some nice side car video from the GoPro but have yet to edit it down from the long weekend, that will be posted here once complete.

First initial thoughts of massive increase in spring rate is HOLY CRAP! The car was so stable at speed. The turn in is quick and snappy and it offers a feeling from the tires that I've never had. Truly, a feedback from the car that I've never experienced. I'd hate to say it made a better driver but certainly a more aware driver. The lifting of the 4th wheel during high G loads is entirely gone now. I was told by my buddy Jake who was there spotting for me said the car looked much more controlled and level through the turns. I'd have to believe him as I felt the same way while driving. The one thing I should not have done was reduce the camber in the front wheels. I had it setup fairly well on the old springs but thought a reduction would be beneficial due to some previous inner tire wear. I should have left it, or possibly even dialed more in. Something I didn't think about was with the old springs the compression of the suspension would dial in more camber. With the additional spring rate and not as much compression I experienced some outer tire wear. I knew these slicks were on their 3rd day and didn't have much left but at about lap 25 the traction just seem to go "off" on hard right handers. Coming into the pits for a quick visual turned out to be the day ender.

I could have swapped it to the back and headed back out but considering I was hitting a new personal best on the front straight (184mph) I figured that would be a really bad idea to push my luck.
All in all a very successful day of testing and I'm extremely happy with these spring rates. For me it really did define the term, "the car feels like it's on rails".

**Erron Spalsbury** · 06-17-2013, 02:56 PM

A little light reading this morning and came across this.
Nerd's Eye View: Rowe Racing SLS AMG
Third pic down they show the front suspension so I thought I'd like to see what some of the big boys run spring rate wise and low and behold, the pi shows the part number of the KW spring!
60110161
Which I found in the KW catalog, page 35.
http://www.kw-suspensions.eu/pdf/kw_racing_catalog.pdf

A quick conversion shows it to be 1541 lb/in on the fronts. I can't quite see the part number on the back one but I did notice they do run the duals on the back only. My guess would be for softer compression for when the wing comes into play or possibly to run a higher rake on the car at slower speeds. Neat stuff!