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....LOLQuote:
Originally Posted by J. Fast
http://imageshack.us/a/img17/5660/ch...ueblo70the.jpg
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.
I thought this was appropriate to stick here:
http://i.imgur.com/XzPsd.gif
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
http://forums.rennlist.com/upload/img_2469.jpg
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
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
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!Quote:
Originally Posted by J. Fast
http://imageshack.us/a/img17/985/jercuttin.jpg
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.Quote:
Originally Posted by J. Fast
Hey, you coming to HPR on Friday? Jake, Hal, and myself will be there. Whoot!
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.
http://imageshack.us/a/img593/4338/n7cd.jpg
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
http://imageshack.us/a/img577/4494/q2ld.jpg
http://imageshack.us/a/img854/207/iiz.jpg
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.
http://imageshack.us/a/img850/9499/bxu.jpg
http://imageshack.us/a/img507/8614/8r8l.jpg
http://imageshack.us/a/img24/7057/ljnq.jpg
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.
http://imageshack.us/a/img515/8357/l0s.jpg
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.
http://imageshack.us/a/img195/4866/lgjr.jpg
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".
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!
I really love that hood.
Awesome pics!
Also like the hood, may I ask where you got it from?
184MPH!? That is fast..
Also, what is the thing sticking out of your hood?
Thats the tow hookQuote:
Originally Posted by HLxDrummer
To be fair, it's a loooong straight. I was just able to carry more speed through T3 which lead to the faster straight time.Quote:
Originally Posted by HLxDrummer
Attachment 5566
Yes, that's the tow hook. The kind that poke out of the front of the car is pretty much a spear should you T-bone someone. There's even talks of someday banning them. I personally didn't want to ever spear someone I went that route instead.
The hood came from Chaser Aerodynamics from about 3 year ago? Something like that...
Thanks for information, I have to get a quote from them.Quote:
Originally Posted by Erron Spalsbury
Have you had to reinforce the hood in any way in order for it to stay in one piece at 184 mph
I've seen a few stories of CF/fiberglass hoods not being stable at high speed.
I haven't. I also don't use the stock latch but dual OMP hood pins.
Yo E, what did you collect for tire data? What were your inside and outside temps on the corners? Dam you pushed that tire like mad. Haha, you totally killed it! I was hoping to see you and Hal go at it on the straightway. Good times man! Looks like you only have a few lil bugs left. You coming back out on Sunday?
16 degrees higher on the outside edge with the point and shoot IR. Not really the correct way to measure temp but I didn't have access to a probe. They didn't really go over temp, I just didn't have enough camber dialed in. No bluing on the tire so that's good. I think these tires were just about done anyway. I just pressed too hard down in Danny's Lesson to feel the load out on the heavy side of the car and lap after lap took it's toll. I'll dial in more camber and have at it again. I thought about running the cam bolts but I think I'll just hoggle out the pillow ball mount and tilt the whole enchilada. I think I'll even drop the car another inch or so as I never even came close to hitting the fender with the tire.
Want to see something crazy familiar?
http://i788.photobucket.com/albums/y...ps38a875d0.jpg
The pic above is from a 14k front and a 10k rear. The alignment is good. I put in a bump steer to correct the shouldering . Look how bad I was pushing the tire. There's a ton of understeer bias. . I changed the rear spring rate to match the front so 14k front and rears. I shifted the bias to neutral and stopped pushing the tire. You can see it in the tire wear. I also even'd out the tire temp across the tire. I changed the tire wear issue in the suspension alone. Here's a pic of the same type of tire on the same corner with a 14k front and rear with a dual 200lb helper 1" from bind.
http://i788.photobucket.com/albums/y...psaf9f0769.jpg
Very cool! Well, not the tire wear, but you know what I mean. LOL
Next time out I'm taking a paint pen, doing one lap with horizontal lines across the tire so I can see more of which portion of the tire I'm using.
What's the ride like as a DD?Quote:
Originally Posted by J. Fast
So, all thoughts/theories/hunch were correct then? We benefit more from a 50/50 biased spring rate?
*side note* you guys are awesome, wish I could race! Love the pics!
184 is fast. So is your over heating issue gone? Did you try that coolant system bleeder that I showed you before?Quote:
Originally Posted by Erron Spalsbury
Not in my case. The majority of the weight is still in the front of the car. Even with the big wing and diffuser there's little chance I'm pulling another 700 lbs of downforce from both which would make the car more of a 50/50 weight split. What I need to do is put zip ties on the shocks and find a long straight road. Take the car up to speed and see how much downforce is put on the rear. From the springrate (1100 in my case) I can extrapolate how much the wing and diffuser generate. Keep in mind that any posted downforce is typically rated with the car it was tested on as very different results come from different cars.Quote:
Originally Posted by Nihil
Oh, and no the overheating is still there unfortunately. I know what it is, I've just been reluctant to actually do it.
So this tire thing, E... check this out man, this really awesome guy Steve Sulatycki put this together for our McStrut behavior. When we lower our suspension we lower the roll center but we actually spread the instant centers which promotes more roll and induces rear wheel lift and exacerbates tire shouldering. You can mask it with more spring which will resolve the tire lift issue (tire lift like illustrated by chumpy) but the roll is still present however, we can implement more spring to offset the moment lever. Really, we want to stay off of the bump stops and use the springs and valving in the dampeners and ensure the the dampeners are valved with the right blow off.
Here is stock:
http://i788.photobucket.com/albums/y...ps4b073736.png
http://i788.photobucket.com/albums/y...pse8790302.png
Figure 3 & 4 is what happened with our DSM, we lowered the suspension by me cutting off a few spring coils to get us to the bumpstops, however, we compromised and took the penalty of accelerated tire wear due to the increased body roll. We were throwing the mass of the car so far out of the roll center it resulted in us lifting a tire.
http://i788.photobucket.com/albums/y...ps5125840a.png
http://i788.photobucket.com/albums/y...ps02b2bfdf.png
Now comes the good stuff, Camber plates. So lets say now we install aftermarket dampeners with some adjustable camber plates and we setup the suspension and add a couple of degrees of camber on a stock ride height. Look where a camber adjustment moves the roll center in Figure 6.
http://i788.photobucket.com/albums/y...psec771525.png
http://i788.photobucket.com/albums/y...ps9d5edb29.png
Now onto the issue you and I were seeing, tire shouldering. Look what happens when you max out the camber adjustment at the plates and lower the suspension 2". Look where the roll center is... Do you see it? Haha, no! You can add a big as spring to counter the length of the roll lever arm, or you can adjust the bump steer and shim the ball joint to restore the designed control arm angle. Once the SAI is corrected you no longer need that big ass spring. It's possible to use a lower spring rate. See Figure 8 for where the RC is. Fast is between the tires :)
http://i788.photobucket.com/albums/y...psbfd43eb7.png
http://i788.photobucket.com/albums/y...ps0951992c.png
I really liked the pictures you linked in from Motiq. That setup was really awesome. The thing I liked most about it was that it was a double wishbone suspension. We don't get into roll situations with camber adjustments on a wishbone suspension like we do with McStrut's. They are superior in every way there just really expensvie to maintain because there's more moving parts.
I got rid of the roll and tire wear and require less spring because I'm not throwing more weight out of the body, I'm keeping it in. When the SAI is geometrically corrected like in Figure #1 and the control arm is positioned correctly you dont have to use a big spring to counter the weight bail out.
And whomever asked about the 200 dual springs? I love it. Rides like stock and gets real naughty when I come into the spring crossover.
I try to do this with a infrared pyrometer....not sure how accurate it is...Quote:
Originally Posted by Erron Spalsbury
A couple of things I see in there that aren't really taken into account..
Full doc is here.. http://zzyzxmotorsports.com/library/...h-20070918.pdf
The first is that isn't taking into account the loss of camber while turning the wheel. This is a depiction of a car that rolls 4 degrees. (that's huge, very low spring rate, 200??) There's also no accounting for the sway bars.
I do really like what Steve has to say here, this makes perfect sense.
"For a strut setup, all the theory and my personal experience boils down to a simple set of recommendations:
1. Never lower the car to the point where the inner pivot point is lower than the outer pivot point - what I call "inverted" front lower control arms. Level (e.g. parallel to the ground) is OK.
2. Always set your camber plates to equal positions L/R, regardless of your target camber. Fine adjustments to equal up camber L/F should be made at the eccentric bolt on the strut (if applicable). If you end up with 2-3 10ths of a degree difference L/R, better to leave it as-is rather than end up with a skewed roll center.
3. Target camber for "performance" applications should not be less than -2.5 or so. IMO, -2.0 is not enough camber to maximize grip and on the track will lead to more wear on the outside of the tire. Most (competitive) strut setups I've worked with over the years are at least -2.7, and are as often times around -3.0. Assuming you run zero toe, you should not expect unusual wear with even -2.5 or so. I run -2.7 with zero toe and my Boss is a daily and there's no uneven wear at this point. Same was true with my last Miata; but we know those little guys are easy on tires... :) Unlike some, I've seen no real benefit to "toe out" setups that is worth the additional tire wear."
For my setup, I know what it is. That's the tire that takes the most abuse on HPR as there are more right handers than lefts. It's also the heaviest corner on the car and takes a ton of abuse on the downhill right handers. The right side of the car didn't experience quite as much abuse as the left, I shouldn't have dialed back the camber. I also had a neat conversation with the SCR guys about spring rates. Turns out they are running multiples, as in 4 different spring rates to account for the corner weight miss-match but that's a whole 'nuter discussion.
Vroom4, as I've learned and it sounds like you and I have the same type of IR pyrometer, these aren't the best for tire temps. Since they only read on the surface the temps can vary greatly with just a few rolls of the tire. It's pretty tough to hook a corner and jump right out to get tire temps. The correct way (which I've only had access to a few times) is with a tire probe. We need to see what the carcass of the tire temp is which is a few millimeters down from the outer tire surface area. I was reading 16 degrees difference on the outer edge of mine and I'd bet it was considerably more to be honest. Something like this is what I had borrowed in the past but haven't coughed up the cash for one of my own yet. https://www.pegasusautoracing.com/pr...asp?RecID=2515
how about caster? more caster should give you the camber you need around corners.
Caster is another adjustment with compromises.Quote:
Originally Posted by mehrshadvr4
I think heavy steering is the only one.
Quick edit from Fridays track session of testing...
http://www.youtube.com/watch?v=Ss4GG...ature=youtu.be
For some reason the HD only shows up if I post it as a link... It's up now in 1080p.
Are those tire pieces flying when you take sharp turn? Also I never notice anyone run big camber like puma GTO did. I'm sure puma had their suspension dialed in the best for 3000gt?
Attachment 5573
ralliart3000gt said the front has negative 6 degree of camber. crazy.
even the rear has tons of camber.
Attachment 5574
They also ran narrower tires than we do, the narrower the tire, the more camber it needs.Quote:
Originally Posted by mehrshadvr4
Yeah, that's tire rubber. Not mine, but just someones on the track. It's what we call marbles. Rolled pieces of rubber coming off of slicks.Quote:
Originally Posted by mehrshadvr4
That's exactly right. The Puma GTO guys knew what was up.
You Sunday driving in that vid, E? Your 5 seconds off your last NASA trial pace. Looks like your slipping a lot on Danny Lesson and turn 11. Were the drivers side tires significantly hotter than the passenger side?Quote:
Originally Posted by Erron Spalsbury
How did you like the Hawk DTC 70 brake pads? You think I can use them with DOT comps or is that not enough tire?
Sunday... $100 for all day. You're coming right?
Im going to do some outside the box stuff this week man. I'm considering ditching the sway bars all together to see what an independent suspension feels like. Apparently its really grippy. I'm going to load up droop and see what happens when I compress a corner and pull the opposing up with the spring. Will be interesting to see if that setup will behave like a sway but keep the grip of an independent suspension and ditch the tire slip penalty of the antiroll at the tire.
Nah, the car wasn't slipping or anything I was just out testing.(yes, driving like a Nana!) Going deep on occasion (off apex) to throw it in, seeing how much lean I could get out of her. See how much of the suspension I'm using now? I't like hardly 2 inches. :) You gotta ride in it now! It's good stuff. I also had a small thought about the perches popping the outter ring off and kept that on my mind. (Listening for the BANG! Like what happened to Chumpy) I'm really happy with the way the car performed. I'm sure I can take it well under the 2 minute mark now, if I can get this cooling thing sorted out. I'm flat-bottoming and sealing off the engine bay on Saturday with an .063 aluminum sheet. I still don't have tires on it but I'd like to come and watch everyone play on Sunday. When are you heading out there? Are you runnin'?
The pads were awesome, but that's my 3rd day on those, I had those on at Nasa last summer. I think the Torque brake fluid is a winner as well but honestly I had changed the fluid, added the brake coolers and the titanium backing plates all at one time so I don't really know what made the biggest difference.
Currently on a hot track. I've. On my third spring setup. First setup was 600lb springs with a 200 lb 1" from bind. Lap average was 2:09. Fastest lap 2:07. Boiled my ATE Blue brake fluid and lost brakes 100% on literally the last lap. Pedal sank all the way to the floor and no brakes! Holy Fuck! When I pit the front rotors were 800 degrees and the rears were 410. Front tire temps were probed at 160 outer and 148'degrees inner. The rears were 150 outer and 135 inner.2nd session... Springs setup at 600lb front and 600 lb rear. Also swapped the brake fluid out for Motul RBF 600. Lap average was 2:05 was experiencing a lot of Oversteer. Rear wars like mash potatoes and really loose. Pit and noticed I was shouldering rears a bit. Rear tire temps were 165 outer and 150 inner. Fronts were 158 outer and 154 inner. Brakes held, lap average 2:04. Fastest lap 2:03. outbreakThird session...dual springs in rear, single 600 in the front. Tire temps were 157 degrees rear outer and 154 inner. Fronts... 168 outer 163 inner (also about 10 degrees warmer). Lap average 2:02.7. Fastest lap 2:01.9.Gearbox is starting to get noisy and grind third too!
Jeremy, what struts are you using?
What was your alignment?Quote:
Originally Posted by J. Fast