I just did a track day recently at Streets of Willow Springs (CCW) in my R53. Compared to my recent experience driving an F56 MCS (stock) on the same track/config, I was having difficulty getting it to rotate in a gradual fashion. In fact, one time coming of the straight and going into the skidpad / left turn, I over-corrected when the rear end stepped out and ended up spinning out the other way. It was an interesting experience, but also made me appreciate how much easier a time I had controlling the F56 vs. my own R53! The F56 was much more gradual in getting the car to rotate, whereas my R53 would stick... stick... stick.. and then step out all of a sudden.

Currently my setup is:
- ST Coilovers -- dropped to about 0.25" wheel gap
- SPC front camber plates (-1.9 deg front)
- SPC rear LCA (-1.3 deg back)
- BFG Rival 215/45R17 on TD Pro Race 1.2 wheels (17 x 7.5)
- 5 mm spacers front, no spacers rear
- H&R 19 mm rear sway set to soft

Some other things that might have contributed to this:
- My last alignment was 1.5 years ago... time for a new one, but I don't bump curbs/etc. so I suspect it's not too far off (as that's been my experience in previous alignments). Not sure on what the toe was set to currently -- will probably go zero front / slight toe in rear next time based on what I've read here on NAM... currently the car wanders a bit on road imperfections, so I suspect it's pretty close to zero right now.
- My tire pressure for the first session (where I spun) was lower than I probably should have had it - ~30 psi cold F/R. I adjusted to about 35 psi cold F/R later in the day, which seemed help make the car feel more controllable. It was a pretty cold day at the track (50 F high / 30 F low), so that might have compounded things a bit as well.

Any suggestions on steps I might take to make car rotate in a more consistent/gradual fashion? Do I have too much rear camber?

I ended up running pretty slow (fasted lap ~1:42, which is not very fast if you look at other folks times on this track... I ended up getting passed quite a bit). I think part of this might have been my confidence was a bit low due to spinning out earlier, so I wasn't pushing it as hard as I should in many/most turns. Finally, I have to admit that I had more fun in the F56, as even though the limits were lower due to tires/suspension, it was gradual and easy/fun to control...

 

That sounds like a nice setup. Sounds like fun too!

Are you happy with your trail braking? Just from what you said I imagine that turning in at the end of the straight you probably had most of the weight on the nose.

In penance for your tendency to seek the fix in your equipment rather than in your driving technique I would sentence you to at least another 20 laps.

And I'm jealous!

Cheers,

Charlie

Ps: Never any harm in checking the alignment though...

 

Check the rear toe. That setup doesn't look particularly aggressive though so it seems odd that you're having issues with snap oversteer. Is the swaybar binding?

Do you have any idea what the spring rates are on those coilovers?

Sounds like you could use more time at the track. Slow hands are key ;-)

 

Driving style? Are you lifting in the corners? Trailing throttle will make a car snap like that. Check the alignment for sure. You may find something not quite right.

 

Thanks for the thoughts. I probably should have mentioned it above, but I'm sure the biggest problem is the nut behind the wheel. This was my third track day, so I realize I have a lot to learn.

The main reason I'm asking about setup, though, is due to the comparison with my previous track day in an F56. I was able to get that car to rotate smoothly with trail braking and/or throttle lift as necessary. Compared to my R53, it would gradually rotate and was very easy to control. In my R53, though -- let's just say I spun when I tried a little trail braking coming out of the straight (you're right Charlie). So it may not really be a snap oversteer problem, but just adapting to different limits in my R53 vs. the F56 I drove. I'm sure another 20 laps would help. But if there's a way to get my car to rotate a little more smoothly/gradually (like the F56 I drove), I'd like to try for that...

And I think I'll definitely be getting an alignment before my next track day.

 

you didn't mention spring rates - i'd be looking at the alignment first though, year and half is a long time to go without alignment if you're racing it

 

I don't know what the ST coilover spring rates are -- I had these installed a few weeks before my last alignment (i.e. 1.5 years ago). From what I've read, they are progressive springs front / linear rear. The ride is definitely firmer than my last setup was (JCW springs / Koni FSDs), but I suspect some of that is due to the adjustable camber plates up front (vs the IE fixed plates I used to have).

Another thing that came to mind is maybe the stickier tires and increased negative camber basically mean a higher limit before things start slipping (vs. the stock F56 I drove). The F56 would start pushing the front pretty readily on turns (it had stock grand-touring summer rubber), so maybe I was going slower when I was rotating the car and it was more gradual...? With a stickier/firmer setup, I suspect I need to slow my throttle/braking transition more than I did with the F56?

I'll check for binding on the RSB, but I had a 22 mm H-sport in briefly when I first got the car back in 2006...

 

In my experience, whenever it feels like you have uncontrollable oversteer, it's actually because you have too much understeer so that when you lean on it hard enough the rear breaks loose in a big way. Considering all of your mods, the rear bar doesn't look very aggressive - I'd try setting it harder so that the rear lets go a little sooner/easier. It's not nearly as scary as it sounds.

 

I run basically the same setup--different coilovers.
1-check rear toe
2-the car is probably too low--especially the rear (typically the rear is 1/2" higher than the front)
--check how much shock travel to the bump stops--it is likely that you are on the front or rear (or both) bump stop on compression and this causes crazy handling.
R53's don't work very well when lowered too much
3-tire pressures--run about 32F and 35R--the fronts will increase in pressure more rapidly than the rears. For Rivals about 40psi HOT is ideal (up to about 42 on the front)

More time behind the wheel will definitely help. In a well setup FWD you want a little oversteer and balance the car with the throttle early (before the apex), then point the car where you want it to go and add more throttle ( the rear will follow)

 

I'll bet that one of the issues are that the BFG Rivals are overpowering the springrate/damping of the ST coilovers and bottoming out on the bumpstops.

It is important to match the spring/damper rates to the tires you'll be running to have a decent handling car (and especially so if running it on the track).

 

Thanks again everyone for their thoughts on this.

I'm not sure if I was hitting the bump stops or not. Looking at some of the pictures that the track folks took, it doesn't look like I'm compressing that much on the turns -- i.e. maybe turning the 0.25" wheel gap to ~0", and it looks like I'm leaning less than most cars. Would I feel a clunk or something if I bottomed out on the bump stops? There was nothing like that as far as I could tell. Finally, with the 215/45 series tires, I'm probably lowered less than a lot of others -- I have to DD over pretty bad streets here in LA, so I didn't want to go too low. The rear is also slightly higher than the front in my setup, unlike some of the lowered MINIs I see where they really drop the back end.

As Sp4rtan suggested, I was also wondering if maybe I need to make it a little easier to oversteer so that the rear starts to come out sooner (and hopefully more gradually) - hence the question about reducing rear camber a little. Maybe I'll try setting the RSB to the firmer setting as suggested and see how that goes...

As for spring rates/etc. -- I realize the ST coilovers are not necessarily the best for the track. But as I'm only getting started, I'll be happy if I can get the setup to the point where I'm having fun rotating it like I was the F56 earlier.

BTW, what do folks recommend for toe on the rear? I assume I should set the front toe to zero as I indicated earlier?

 

Provided there isn't an issue with spring rates or something snap oversteer typically points to bind or hitting the bumpstops. Could be binding control arms at the limit of travel or the swaybar sticking in the mounts. You won't hear anything hitting the bumpstops but you will certainly feel it. You need to get under the car and verify that you are not hitting the bump stops. If you are hitting the bump stops there are different bumpstops you can get to "tune" how your car reacts when you do hit the bumpstops.

I'd run a touch of toe-in in the rear. Maybe 1/16" total in? We run close to zero but in an auto-x environment you want the car to rotate fairly aggressively.

 

I've driven both the R53 (stock, modified, and fairly-highly-modified) and F56S (stock and stock-on-rack-tires) extensively on track. You're spot-on with the F56 being FAR more gradual in all aspects, but recognize it's also a bigger, heavier, MUCH softer car, and will behave as such. In general, it's easier to drive, sticks better, goes faster, but isn't as much fun and doesn't involve the driver as much. The reactions of that chassis are FAR softer than even a stock R53.

Curious: Did you leave the electro-nannies "on" in the F56? I found they're not really all that intrusive, but definitely make the car more planted up to 85%, but leave something to be desired under hard braking/turning at 85%+.

You've also done a TON to create a lot of front grip (spacers, lower, camber) as well as creating more grip overall - so when your car "lets go" it's doing so at a much higher grip level, and will be far less gradual.

I'd suspect two things, and both have been touched on:
- Check your driving style. Slow hands save lives, and being smooth and gradual in your inputs will allow you to explore your car's more-considerable limits better.
- Check that alignment. A good overall alignment would be parallel to 1/16" toe-in at the rear, and 1/16" toe-in up front. On-rack, parallel to a little toe-out makes 'er seek the apexes better, but can be a handful on the straights and on the street. If you're experiencing minor wandering, a lil' toe-out in back may be the cause.

Also, check your suspension bushings/etc for wear and torque, good practice anyway.

Let us know!

 

On the F56, I disabled the DSC (but not the DTC), and had it in Sport mode as well. I didn't realize until my third session in the car that I could also turn off the DTC by holding the button for >10 sec, but at that point decided to not play with it as I had become pretty comfortable getting it to slide around the track by then.

Also, I agree the F56 was a lot softer... I enjoyed the low end torque and ability to get it to slide where I wanted, but I was also frustrated by how much the front pushed (heavier + poor tires / minimal neg. camber) and the squirming I got under heavy braking. My R53 definitely feels more planted -- the main issue I'm struggling with is getting better feel and control when it starts to lose grip.

Lots of great suggestions in this thread -- here's my list:
1. Check suspension (bump stops, binding RSB, etc.) to make sure everything looks OK. DixonL2 -- I had my front LCA and swaybar bushings replaced with polyurethane ones last year when I got a new clutch installed. I also had the inner/outer ball joints replaced as I figured after 8 years (2.5 in DC) it was a good time to get those taken care of too...
2. New alignment with same camber settings. Set front toe to ~1/16" and rear toe same.
3. Set RSB setting to firm (rather than current soft).
4. More practice! And working on slowing down my steering/braking/throttle transitions. I think this is probably the most important out of everything...

It may be a while before my next trip to the track (probably early spring, but we'll see...). But I'll be sure to come back and provide updates as I have 'em.

 

If you're getting snap oversteer, you may not want that rear bar on "firm", as that will make the car more tail-happy.

Oh - forgot - check and re-check tire pressures on track. 1-2psi can make a big difference, and some tires are far more sensitive to this than others. I know the RE-11's and RE-11a's I've run do much better at relatively lower pressures (32-34) than the other performance tires I've played with at 36-38.

 

The only thing that I could possibly think would cause the snap is the tire pressure being low caused it to roll slightly. In my head I can see the rear rotating while the front tires roll and cause some under-steer that might seem like a snap.

I'm probably the only person seeing it this way. :(

 

Perfect Scandinavian flick is what you did, except for the end swapping =)

Mine's similar set up and I find it "exciting" if I prepare to induce some opposite lock once committed...then it will drift nicely. If caught unprepared, it will bite me so this is where I'm very careful on the streets because there isn't a rhythm. I think I will install heavier bars up front as the current setup is fun but not forgiving...=)

 

I have to step in with all of these opinions.

No one has even mentioned damper rebound.
That will cause mishandling more than anything.

First rule, springs to control roll, not a bar. Then damper compression, and rebound adjustments to control the springs.

Slapping on a set of coilovers like the STs which are at the bottom of the food chain, with no damping control, and expecting to run a track is not the way to go.

 

While there are a lot opinions expressed here and not all bad, I would disagree with your statement "First rule, springs to control roll, not a bar." If you are talking about body roll of the car, it is the sway bar that mainly controls the roll and to a much lesser extent the springs. That is their main function and why cars starting putting in sway bars in the first place.

Sway bars do two things: 1) they are a major factor in establishing the overall roll stiffness of the car and 2) they are a major factor in establishing the front to rear balance in roll stiffness. In a turn a stiffer rear bar will to move weight to the rear by lifting the inside rear tire. This increases the grip in the front but at the same time it decreases grip in the rear. Hence the tendency for oversteer with a larger rear bar.

But, springs and shock also play into the dance a car goes through on a track and all three (sway bars, spring and shocks) go into how a car handles. Because of that, it is not easy to say, when they are all changed, as to what caused what.

As for the OP's question: In this case there are a couple of things I would not do:
- I would not increase the roll stiffness of the rear. That will just adds to the problem. It will increase the tendency for oversteer which is not what is needed, especially with an inexperienced driver (3rd track day, right?).
- I would not turn the DSC/DTC fully off on the track. Being an inexperience driver, that is the only thing between you and the guardrail. You are not in a race. So if it interferes a bit, take that as a learning point. Try to drive so it doesn't come on. You want to drive the car home so why disable the one thing that is designed to make that happen?

One thing I would change is to add a spacer to the rear. The OP has created a lot of front grip. Less offset in the front equates to greater grip. That grip is needs to be added in the rear. I would also look at adding a bit more rear camber. The rear tires may be rolling over at the limits of adhesion causing them loose grip quickly and the snap oversteer. More rear camber will help with that.

There are a number of comments about seat time. Any good instructor will tell you that is the best solution. I would guess that you are lifting a bit once you are get into the corner and likely, once the car starts to rotate, you are not getting back on the throttle. That will cause a snap oversteer. In fact you might be lifting even more as you try to steer into the oversteer which will make matters worse. You need experience and good instruction to learn to control that.

 

Sure- spring rates, damper compression, and rebound are important, but you're dismissing the fact that further tuning done with an adjustable front stabilizer bar would work wonders for this issue.

 

Usually, problems such as this occur when too much is done to a car all at once. Any modifictions, changes in suspension/tire pressures, etc. should be done methodically and one at a time to evaluate whether it helped or hurt. One question: Do you have adjustable drop links on your sway bars? If not, get them. If/when you do, check/adjust with the car level so there's no preload from side-to-side.

 

There are generally two setup philosophies. The first being more spring and less bar and the other being more bar and less spring. Obviously the two setups handle differently but it's sufficient to say that both are popular depending on the car and what the car is used for. For example, lots of circle track guys run big bar setups while road racers generally use more spring and smaller bars.

Generally the idea is to add as much spring as you can to get the natural frequencies high enough to control roll but not too high that you lose bump compliance. The numbers I've always heard and played with on a production car without aero is around 2.5Hz. From there if you still are getting too much roll you're stuck with adding bars to increase overall roll resistance. Obviously there is also a limit as to how much bar you can add before your suspension is no longer "independent" but instead the suspension is "coupled" by the big swaybar.

Swaybars don't generally provide the major roll resistance unless you're running really silly huge bars. Depending on the swaybar motion ratio they can generate pretty small forces and in the case of some RWD cars people just leave the swaybars off completely. They do affect front and rear roll resistances so people do use them to tweak the balance of the car. They're certainly much easier to change at the track than springs.

A swaybar does not affect weight transition between the front and rear wheels. I'm also pretty confident that a larger rear bar does not directly increase grip at the front of the car. There might be some additional grip found by increasing the overall roll resistance of the car but I think there are larger forces at play that would make that additional grip essentially zero.


This is pretty much all good advice for the OP. I'd add more rear camber before messing around with spacers but spacers are super cheap to play around with and see how they affect the vehicle weight transfer and how that affects the handling.

 

The reason I brought up the wheel spacers for the rear is because the OP said that he had wheel spacers on the front; not the rear. I have found that the tire grip on a MINI responds really well to increasing track width, having changed from 38mm ET to 45mm ET wheels with a noticeable change in the tire contact for the worse (change was planned to resolve clearance issues - another story). Hence, my thought was that if he has increased the track width in the front, he is getting more grip in the front because of that. Having not done the same in the back means he has created an imbalance between the front and rear, with the rear on the side of loosing out.

I have to agree that I may of overstated the potential for more grip in the front from a larger rear bar. I was mostly thinking that it would improve the tire contact on the front outside by unloading it a bit. I can't say that my experience would support that conclusion...So, chalk that up to over thinking things.

As for sway bars not be be effective at increasing roll stiffness and removing the sway bars from RWD cars. I expect it is not as simple as that. With cars being a balancing act of compromises it would seem that you would want to take advantage of every "tool in the tool box", sway bars included. If it was as simple as removing the sway bar and putting in stiff springs, why would the car manufactures waste money developing suspension variations around different spring and sway bar rates and put them into cars like the Z28, Boss Mustangs and Challenger and why would race car designers from F1 to showroom stock use them? I believe the reality is that there is no one answer to this. It just takes a Google search of "springs or sway bars" to see that this very same discussion is occurring in virtually every car forum on the internet and no one seems to have "thee answer".

I do appreciate the discussion - it provides food for thought.

 

OK, I finally got an alignment last week, and let's just say it was way off what I listed in my original post. Pretty significant camber differences between L/R sides, and quite a bit of toe out both F/R. I had them align it to my specs above, but reduced the front camber to -1.8 deg. (My thought process being that I'd like to get a little more experience with getting it to rotate more smoothly, and having the front push a little earlier might help do this at slower/safer speeds.) Lesson learned that I need to get an alignment more often.

Following folks' advice above, I had the toe set in 1/16 both F/R. I'm amazed at how much more stable it is on the freeway now! It must have been pretty far out, as before it was a handful to drive on our great L.A. freeways here.

Finally, I left the rear swaybar on soft, as I agree it would be good to try things a bit more methodically -- i.e. see how the accurate alignment changes things first.

Regarding my original issue with the "snap" oversteer -- I suspect what happened is that the poor alignment / toe out caused the rear to come out pretty suddenly. I corrected and got back on the gas, which caused it to quickly start turning the opposite direction, such that I spun out the opposite direction of my original drift. Hopefully the new alignment will help things be a bit more gradual.

Responding to some other comments:
-- ST coilovers -- I realize these are not exactly the best out there, but as they're made by KW I figured they would be better than Megans or some other cheap options. One day it would be nice to get some Ohlins or Cross or similar. But since I'm only getting started at tracking my car, these should hopefully be good enough to start with.
-- Adding spacers to the rear -- Might be tough to do, as the 215 series tires barely fit as-is. I get very minor rubbing on large dips at high speed, so not much space to push the rear tires out any further. I'm only running 5 mm spacers in the front to clear the struts, so that's less than an extra half-inch of track in the front.

Anyway, I appreciate everyone's suggestions. I'm targeting an Auto-X in Feb., so hopefully I'll get a chance to try things out soon.

 

Sounds like you found the culprit. Toe-out is a no-no on the street (as are tail-happy track cars). On the track it's all rhythm, predictable, smooth pavement (or at least pavement that you've driven over more than a few times).

On the street it's all unpredictable, distracting, and you wouldn't want to do the accidental "Scandinavian Flick" while driving home half-distracted by your work for the day, or looking forward to your evening, when you can't pay 100% attention to that massive rear bar set on full-stiffy, when the idiot texting on the Phablet drifts into your lane r-i-g-h-t when you were staring at that attractive person walking their funny dog.

No.

Predictable and stable on the street is everything at that point.

Glad you got 'er under control - and thanks for letting us know!