LargeOrangeFont

iTrader: (7)

You need to go buy an AIM solo for $400 and start testing and tweaking and see what is faster and what gives you more grip. In a weekend you'll learn about a years worth of measuring, adjusting tweaking and feeling things out.

j9fd3s

iTrader: (3)

something like that, the hard part is that he's NOT on a track. on a race track we have a stopwatch, so its quantifiable. on the street its subjective.

the big take away from racing for more than a decade though, is that the hardest thing is to figure out what the problem actually is. once you figure out what the actual problem is, the solution is usually really simple.

we use datalogging, and all the maths and stuff, but we also pretty much try every adjustment. it takes a while, but you find the sweet spot for everything, plus you learn how the car reacts to changes.

since we're on the track we go by quicker lap times, and then drivers preference is a distant #2 (repeatable lap times is the biggie).

LargeOrangeFont

iTrader: (7)

Agreed. What feels good on the street is probably safer, and probably slower. You are kind of chasing your tail out on the street. I can't get the car to react the same on the street as is does on the track anyway, even when I used to run good street tires. You just can't get enough heat in the them.

ZDan

The example I gave doesn't represent the extents of what my car is exposed to. At some tracks that are not perfectly flat I get close to 150, and at the Texas Mile hit 184.8 before hitting some pretty decent sized undulations at the beginning of the braking zone. Most tracks have their bumpy parts and often the fast way around involves going over curbing (like the chicane at Watkins Glen)

Anyway, if you don't feel the car is stable at the top of 4th gear on some roads, slow down!

[Quote]The softer springs were more forgiving, on the flat portion and newer roads the shocks handle very well, just seems like at a slightly lower grip limit. Perhaps my perception is off and I am really going that fast. it could be. I am going to try the ohlins with the softer spring rates, and if I don't like that or they are too soft I am going back to the 11's and running them with that or stepping up the rear to an 8KG spring.[/ quote]If I weren't tracking the car, I'd probably run 11 fronts with 8 or 9 rears.

Shouldn't need break in. I set mine up almost exactly as prescribed, but with the fronts set about 5km lower.

lOOkatme

iTrader: (19)

I just tried the new springs and shocks.

I did settings 5, 10, 17 both front and rear. the car seemed good around 10ish so I ran it on 12/12.

The car is a BEAST. Like holey **** cow. Its smooth as can be and highely damped to critical damping, so its soft yet firm.

The car laughed at the same section I was having troubles with on the 11/11 springs. I mean made a fool of those things. Figureatively speaking, throw those 11's in the trash. Garbage.

The car ran 140mph and smooth as silk, no micropenis masturbating up and down. The car has tons of grip, so much I was afraid of pushing it harder on some turns, and I still had more to go with a little turn in tighter to see. The 11's were FAR lower grip wise, and less composed, FAR less composed everywhere. I went up the uphill section cruising at 100mph like it was a stroll in the park. bumps absorbed easily, smooth as silk. the damping is great on these things.

On the high speed sweepers 100+mph stuff the car was amazing. predictable, mostly flat, tons of grip, and lots of margin. The 11K's were darty, short of stroke, and pushed hard. same speed and the softer springs were laughing at it. They had SO much more to go. The car also is easy to settle into a turn, its like it turns and the car can just keep going with such high grip. The 11's would slide so much sooner and have WAY less margin at the limit. The car is an animal, a complete animal.

The last section I know best which has an inside uphill line I railed it. I did the same with the 11's. The 11's are FAR slower. I went so far that I could feel the tires starting to talk, probably 80-90 mph on a 30-35mph turn, its a tighter long sweeper where you have visbility upwards, no one was coming and I had an extra lane to go into. Completely rediculous grip. and the tires handled well, suspension handled well, everything was in sink. I also smashed the brakes before some turns and the car is straight as an arrow. The 11's were straight as well.



My suggestion to everyone. Don't knock the softer springs, even with higher damping rates to critical damping. the car glides now, it acts like it should. If I were running the 11's, I would seriously look for some softer spring rates depending on what you drive on. I still don't see how the 11's would outperform a softer set of springs even on the track. something like a 8/6, 8/7 or 9/7 or 9/8 if you want a little higher rate.

BLUE TII

iTrader: (9)

Awesome you found a set up you like!

I still don't see how the 11's would outperform a softer set of springs even on the track

Because Ohlins are Road and Track- that is they have to work for racing too.

If you go softer spring rate on the track or auto-x you are driving around on the bumpstops which have a higher and highly progressive spring rate.

I don't/can't push my car on the street (even on a closed course like the hillclimb) like I can at auto-x or the track so a softer spring set up would no doubt be better on the street.

Really; you think you drive fast, start going to competitive timed events and you learn what fast really is. We all started right where you are and thought we were driving fast on the streets. I am not bashing you in any way.

But for instance at auto-x you push the limit to where you spin and you hammer your transitions because if you F up there are no consequences. Just look at my kart track vid vs my hillclimb vid. So much more conservative where the consequences are higher.

Ohlins engineers aren't dummies, they just made compromises to street performance to make it work better on track.

j9fd3s

iTrader: (3)

glad you found a setup you like!

i quoted that quote, because i think it is kind of my point. at the track you see how the 11's would perform by looking at the lap times. you only need to have an open mind enough to try it.

lOOkatme

iTrader: (19)

I don't really use my car on the track, I mean once in a blue moon for fun. I have a completely open mind. I originally had 12/12 on the car when it came with it. I researched a lot and haven't driven many different set ups and was skeptical about soft rated springs when I had the car. I swapped my set up from 12/12 to 8/6 even though I knew the coilovers were designed and valved around 12/12 springs (I am a manufacturing engineer by trade in NPD). I decided after much thought to try out 8/6 which was much softer rated since softer springs provide more grip through the corners (as a general rule of thumb) and read a lot about how compliant and better they are on bumpier surfaces, It didn't hurt that this spring rate bias copied Mazda's spring rates. I threw those on the ark's and started dialing in the damping. got a setting I liked and the car drove much smoother and had a lot more grip, plus more compliant everywhere. I stepped up to the Ohlins DFV since all the great reviews. I researched shock dyno's etc trying to find why they are so good etc. Kept an open mind and purchased them. I went against my previous data of 8/6 and installed the supplied 11/11 set up as I kept an open mind. I tried dialing in the damping as best I could, just like I did with my old 12/12 set up. The car was less composed and less compliant with less grip than my old set up. the damping is better, but the car was tougher to drive fast and wasn't as smooth. I then was convinced to go back to the old springs, after many hours of fricking installs, ride height adjustments, etc.

I have had a very open mind. I know most systems work best with the supplied parts(I am in new product development and I understand how the design guys design systems and all the R&D behind it). I also understand that they designed it for worst case scenario's, cars with probably more track time in harsher conditions with possibly some aero. still can't ignore physics and the frequencies of the suspension.

I also find it weird that they supplied 11/11, in the face of how much research and development Mazda put into this car and with the stock rates being 263/190 lbs/in. I went to 8/6 as its a lot stiffer than stock 70+%, and maintained the stock to rear spring rate bias as Mazda engineers kept, using the stock bars. If anything, Mazda designed exactly what I found, soft springs and big sway bars to control roll. I am running wider wheels and tires with more grip than stock, hence run a little higher spring rates (70+%). If you can get a little more suspension travel I still think softer would be even better, like a 7/5 set up. I don't think it will work the coilovers for the ride height I want.

LargeOrangeFont

iTrader: (7)

Comparing a street setup to a track setup is not a valid comparison. Mazda developed the car as a street car, and you bought a shock setup that is general track focused coilover offering designed to work ok no matter what other upgrades (or lack of) you have done. They don't claim that setup to be perfect for every road surface.

Every element of car setup is a compromise. A track setup is not going to be the best setup for the street and vice versa.

j9fd3s

iTrader: (3)

i don't know why the JDM tuners prefer a square spring setup, but 11k is soft for a race car. we're running 13/9 in a miata, and its comfortable

BLUE TII

iTrader: (9)

i don't know why the JDM tuners prefer a square spring setup, but 11k is soft for a race car. we're running 13/9 in a miata, and its comfortable

In Japan oversteer defines the sports car as much as horsepower does in America.

If a car understeers in Japan its probably a hairdresser's car- ie its not manly

j9fd3s

iTrader: (3)

we do have great hair... well Alice and i do

ZDan

In the range of spring rates we are talking about, for ultimate performance, 11kg is going to be better than 8. At the limit on the track, 8ish kg/mm is definitely going to be slower. On the street, 8ish spring rates may be a better compromise overall, but not because they have more grip or better ultimate performance.

We all must take it easy on the street, period. You may be able to consistently get to 75-80% cornering potential on a road you know very well, but any more than that and it's just a matter of time...

At the track, you don't have to worry about oncoming traffic and you have a pretty good idea of conditions at every turn because you were just there ~90 seconds ago. At the track, you can repeatedly dance are around corners at and even beyond the limits of adhesion. That's where you'll find that rates stiffer than 8ish are better for ultimate performance.

On the street, there is simply no way you are dancing around on the limits of adhesion. To many variables, too much to lose. At 75%, on the street, I'm the first to agree that softer spring rates are probably better for a lot of reasons, mainly the ride is less "busy", NOT that there is "more grip" (there isn't).

Waitaminute, avaialable shock stroke is the same either way and you'll use *less* stroke on the stiffer springs.

At the track, you're at the limits every single corner. Even 11/11 is soft, too much suspension motion and too much body roll. Fwiw I went nearly a second faster with the Ohlins 11/11 setup vs. my previous 9/7 setup on the same tires. Softer is fine for the street. It is not faster, though. More confidence-inspiring? In the context of driving at 75% on streets where conditions are not 100% known and you aren't able to be on your marks to within inches consistently, OK, 8ish spring rates are probably more forgiving. But not ultimately faster...

For anyone tracking on semi-serious tires (NT01 or R888 or better), I would not go softer.

My .02...

ZDan

This is a bit of a myth. It is true that if you can change the balance of a car by stiffening or softening one end, but it is a *secondary* effect that causes you to lose grip at the stiffened end or gain grip at the softened end. It is to do with how much the outside wheel is supporting during cornering at each end of the car. Softening one end of the car reduces the load the outside tire at that end of the car supports, and increases load on the outside tire at the other end of the car. Since grip is not a linear function of load (20% more load will give less than 20% more grip), this effectively gives more grip at the softened end where the outside tire is less "overloaded", and less grip at the other end of the car where the outside tire is *more* "overloaded".

Softening one end of the car doesn't give that end more grip in a vacuum. It gives that end more grip *at the expense of ultimate grip at the other end*. Overall grip is (sort of) conserved.

It's not like you can gain more overall grip by softening both ends of the car.

lOOkatme

iTrader: (19)

no, the softer the springs and sway bars, the higher the mechanical grip the car has (period). Shiek at Fatcatmotorsports tested this on his Miata, his car was pulling 1.1G on the skidpad, he disconnected his sway bars and he pulled 1.3G's on the skidpad. This was with 195's toyo R1R's.

Under the tech tip by suspension tuners/engineers

http://www.optimumg.com/docs/Springs...Tech_Tip_1.pdf

Lower frequencies produce a softer suspension with more mechanical grip, however the
response will be slower in transient (what drivers report as “lack of support”). Higher
frequencies create less suspension travel for a given track, allowing lower ride heights, and in
turn, lowering the center of gravity.

Suspension tuning by Bimmerhaus
KONI shock tuning guide

10. In general, stiffening one end of the car will reduce the mechanical grip on that end. In other words, when you raise the spring rate, increase sway bar size or stiffness, stiffen the bump or rebound of a shock, install firmer bushings, etc. you will reduce the grip on that end and decrease traction. To increase grip you must lower the spring rate, decrease the sway bar size of stiffness, soften the shocks, use softer bushings, etc. (Tire pressure is another contributing factor, but that's a discussion for another day.)


Race car design Book
https://books.google.com/books?id=FR...0rates&f=false

"However it is true that to maximise mechanical grip the suspension should be as soft as possible."

Read the book linked for explenation why. talks about droop and the force applied to the ground in the opposite direction of the car.



Almost every single thread/book/etc I have seen has said to run the softest springs as possible to run. Now race cars run some stiff springs due to aerodynamic grip, lower CG, etc, etc, etc. But they are still running the softest possible spring rate that they can. Some of those cars are also running slicks with huge downforce, way different ball game then my car with little to no aero, and street tires.

I think a lot of people could have the wrong paradigm around spring rates on most of these forums. softest gives most mechanical grip.

LargeOrangeFont

iTrader: (7)

Empirically you are correct in the isolated examples, but the paradigm for street and track use are very different, and really can't be compared in the same context. You are talking about this in absolutes, and the reality is that there are no real absolutes.

Yes you'll make more grip with a bar disconnected on a skid pad but no one is racing around a skidpad. The strut and damper are secondary devices to the primary traction device - the tires. On a Mac strut car (any car really) it is far more important to keep as much of the tire contact patch on the road as possible. That is why you GAIN grip on a Mac strut car when you stiffen the front end.

BLUE TII

iTrader: (9)

no, the softer the springs and sway bars, the higher the mechanical grip the car has (period).

I agree with this theory, but I maintain it doesn't have to do with the actual mechanical grip available at the tire (which has not changed) but the driver's ability to modulate the weight transfer more effectively so as not to overshoot that available tire grip.

It also precisely why racer's will have to run a higher spring rate. Once you are on the bumpstops you are on a higher and exponential spring rate and it is hard to modulate.

FD auto-x guys don't race on 16k or 14k springs because they like to skid around the parking lot, its to keep them off the even higher and exponential spring rate of the bumpstops.

ZDan

Going around a flat skidpad, stiffness has little to do with maximum maintainable grip. Add some bumps and damping becomes a huge factor, spring rates too, but less so.

Remove sway bars and all bets are off as you've most certainly changed the balance of the car. If the car had a built-in understeer bias that was holding it back on the skidpad, removing front and rear bars would act to correct that if the front bar was significantly stiffer than the rear (pretty much the rule). It doesn't necessarily mean that softer rates = more grip. Not that I'm ready to take 2nd-hand "test" data at face value anyway!

I maintain that *for the spring rate ranges we are talking about for the FD* (8k -12k range), the stiffer end of that range is going to be faster and is not going to have less ultimate grip.

For sure if someone swapped from 11k to 8k and was suddenly WAY faster *on the street*, that says more about driver confidence level at grip levels well below ultimate than actual ultimate grip levels available on those setups.

I think a *large* part of the reason people think that softer => more grip is what i've described a couple of times before already. You soften one end of the car, yes, you get more cornering grip at that end *and lose cornering grip at the other end*. You've changed the roll stiffness distribution which affects both ends of the car, you're easing the load on the outside tire at the softer end and increased it at the other end. And the opposite happens when you stiffen one end. This phenomenon does *NOT* mean that softer rates = more grip. You could achieve the same end result cornering in one direction by weight-jacking the car (purposely changing the corner weights to bias one diagonal over the other) and keeping the same spring rates (of course you'd get the opposite effect cornering in the other direction).

In the end, the optimal spring rate is dependent on what type of surface you're driving on. Obviously, the bumpier the surface, the softer the spring rates. But for the rates we're talking about, the stiffer end of the spectrum is not really going to have any less ultimate grip for most "performance driving" scenarios and will certainly be faster at almost any road course or autocross.

Another thing to consider is how much camber is needed. Stiffer needs less static camber to achieve maximum lateral grip, softer needs more static camber. This affects ultimate braking and grip for accelerating out of corners. A stiffer setup is less compromised in this regard, particularly for braking.

All of that said, I certainly agree that 8ish spring rates are more suitable for the street. But it's not because that setup will have inherently more ultimate grip!

ZDan

Regarding the droop argument in the link (Race car design Book
https://books.google.com/books?id=FR...0rates&f=false), an FD on 13kg/mm front springs with 2mm preload should have 68mm of droop travel available, which is plenty. It's still a heavy and relatively softly-sprung vehicle compared to a lightweight high-downforce formula car.

lOOkatme

iTrader: (19)

Oh but it does. the tires are seeing different loads at different spring rates. every tire contributes to grip, with softer spring rates, the entire contribution is the most. stiffer overloads the outer tires (doesn't matter where that stiffness comes from, sways, springs, etc).

I am not saying that softer springs will undoubtly be faster or better, I am simply stating that softer springs have higher grip, because it's true.


The softest rate that one can run that keeps you off the bumpstops and prevents the car from bottoming out offers the most grip.

AutoX could very well be different as most of those courses are very transition dependent, road courses and canyon roads are much more sweeperish, long straights, etc. Even hill climbs are more sweeperish, none of them contain a slalom type scenario, perhaps some slow speed sharp corners, but nothing back and forth like AutoX. I think the autoX guys run high rates for the transitioning. I am not an AutoX guy though and they can chime in.


I am not trying to convince anyone to change their rates, I am not saying softer is better for everyone, I am just getting this knowledge out there and what I have observed with my car and my tastes. I am also sure my tires probably are stiffer than most on this forum, so I am not getting any sort of damping through the tires like some others running smaller diameter and less stretched tires. The tires when driven hard have insane amounts of grip and VERY direct, progressive breakaway. I like my current set up because it has a high limit, but also forgiving, compliant, and progressive at the limit.

lOOkatme

iTrader: (19)

Softer = more grip. even on a flat as smooth as you can get road going in a circle. the G force will be higher with softer (so long you don't hit a hard stop, bump stop, bottom car, etc).


I took the 11K springs to their max, thank you tires for being so progressive, on a few turns. The stiffer spring rate had less grip. The stiffer springs do have better transitional back and forth movements, and I like that aspect of it, but when it comes to grip, its not even close. That was the first reason I even wanted to swap back to the other springs in the first place. grip and compliance to the road. I am not trying in anyway to diss Ohlins or anyone on this forum. My intentions are far from that and I hope no one takes it that way. I am simply stating that my car picked up a substantial amount of grip (noticeable amounts) and a ton of compliance over all aspects of the car. turns, straights low and high speed, etc. I also don't notice a HUGE difference in transitions. In fact, I like how the rear behaves more now than before on the corners. Furthermore, weight transfered with the lower rate springs increases grip under braking and acceleration.

The goal then becomes, how soft can you go where the car is still composed in almost every situation. high speed cornering, low speed corners, bumpy sections, smooth sections, braking, acceleration, and transitions. I saw a HUGE impact on compliance (positive), big impact on cornering grip (positive), big impact on acceleration over bumpy sections (positive), and small impact on transitions (negative way).

I took one corner hard on the ohlins where the front hopped over a bump and I did a little skid in the front, I went over the same spot with the softer set up and the suspension just soaked it up like the bump was just a little bump.

On the 11's if someone asked me if the canyon road was bad to drive on my reply would be, its really bumpy and the car is loose. Same question asked how bumpy the road is with the 8/6 set up, I would reply, pretty smooth road.

BLUE TII

iTrader: (9)

Your description of how a softer spring rate drives is what we expect and correct. This feel is also what matters to the driver, so we aren't discounting it.

Sadly, the reason for softer suspension allowing us to maintain grip better is because we as drivers have our limits.

We are just telling you most the physics for what you are saying is wrong regarding grip.

Bump scenario-
The softer spring rate will be better over bumps, I agree.
As long as you are keeping it off the bumpstops (obviously, as it become a stiffer spring then).

Weight transfer to tires scenario-
Grip does not increase with vertical tire loading (what happens with weight tranfer onto tires), it decreases.

Body roll has negligible effect on weight transfer as long as the CG and RCs correlate as on the FD chassis.

https://grassrootsmotorsports.com/ar...load-transfer/

j9fd3s

iTrader: (3)

lmao, you spelled his name wrong, he's going to send you snarky emails now! "My name is spelled 'Shaikh.' Not 'Shiek.' "

i would take his claims with a grain of salt, as he's not really targeted toward the racers, his target is the guy who just bought a xx car and wants to take it to the track for the first time.

j9fd3s

iTrader: (3)

these two statements are incorrect. what you want to say is that the CORRECT spring rate is faster, you can be too hard OR too soft.

we're currently running a miata, and its a picky car, its really adamant about being the PTE/TTE winner this year.

we are currently running around 13k/9k springs, on Ohlins, and we changed the springs one day, and it is slower softer AND stiffer.

i would expect the FD to be different, but you still need to be in the happy place of the bell curve.

ZDan

Leftside to rightside weight transfer during cornering is a function of cornering g's, c.g. height, and track width. It is NOT a function of spring rate! Sway bars and different front/rear spring rates dictate how much of the lateral weight transfer is at the front and how much at the rear.

3000 lb. car with 96" wheelbase and 16" high c.g. cornering at 1g steady state is experiencing 3000 lb * 1g * 16"/96" = 500 lb. 500 lb. (total F+R) is added to the outside tires and taken off of the inside tires, whatever the spring and swaybar rates are.

Ah, but it's not true...