So lately I have been running in sport mode every trip. Sometime I forget so I don't remember if the handling issues was in sport or not. I have noticed that it does happens in sports mode, since the one time I almost lost the car, I was in sports mode. I am going to do the mod to allow the car to start in sports mode. I am looking at sway bars so that will be the next install.

 

Warren,

I tried the ABS a few times during threshold and it seemed a little too jumpy for me to try it in trail. Years ago I had a 911 that always seemed to be trying to swap ends. With the JCW it didn't feel like that. The rear felt more like it just broke loose very quickly. My 56S felt more like it tucked itself under in the rear. I was running the JCW in sport, sport, and exhaust open-my three go-fast buttons.

Don't use me for analysis. You guys are far more advanced. I'm just trying to find something that will work for me.

Thanks for the help.

 

What do you mean. This was a cool line. I liked it.
As a side note to all the posters, some people in this thread were hoping that talking about this handling frustration might catch the eye of MINI and maybe they'd take the enthusiast perspective more seriously. There are so many times I log into this NAM website and the JCW section is headlined (bumped to the top again) with "Why does my JCW handle worse than my justa". If anyone in their performance division does read this website, they might be a little embarrassed by now. (Just a reminder, I'm super happy with mine as a whole)

 

LIke warren said this thread is not to say that none of us don't love our JCW's. I think we all agree that we love the car. I am hoping that what we are experiencing is fixable, as I believe it is. If someone at Mini does read this, please take a look at what we described. It is not on every car so might be a small production issue.

Mini has nothing to be embarrassed about, still make an iconic car with a very loyal fan base.

 

I am going to apologize right up front for the length of the following, but I have included this to explain why I believe MINI has actually done what people have asked for with JCW. That is, reduce the understeer that is inherent in a FWD car...

From my experience and what I have read (for example, Randy Pobst, who writes race car driving articles for the SCCA magazine “Sports Car”) what you are describing is consistent with what I would expect to hear concerning a car’s transition from understeer mode to oversteer mode. This can be made to happen in most any car, and the speed in a corner at which this happens and how easily it happens is a function of how the car is setup. It is also a function of how the car is being driven.

A car with the roll stiffness (springs, shocks swaybars, bushings, etc) biased to the rear will make this transition at a much lower speed and much more readily than a car with a more forward bias to the roll stiffness. In a car with the roll stiffness biased to the rear, the transition to oversteer will be at lower speed and will occur much more readily with the application of trail braking. More aggressive the trail braking can transition the car to oversteer almost immediately, This setup benefits the person who typically does heavy straight-line braking and is on the gas before the apex of a turn. The application of power in a corner creates understeer, which compensates for the oversteer caused by the suspension. However, trail braking causes oversteer (or removes understeeer, depending on how you look at it). For a person who typically does trailbraking into a turn, this is not a good setup given the propensity for the car to want to swap ends in this situation. This all happens because, under trail braking, the front wheels gain camber and there is load transfer to the front wheels, which improves their grip. At the same time the rear wheels loose camber and the load is lessened resulting in a reduction in grip. With a suspension that is prone to oversteer, at some point there is insufficient grip in the rear as compared to the front and the car will want to swap ends. It you want to talk about a car’s stability, moving the roll stiffness to the rear is moving the car’s handling to be more unstable. This works really well on an autocross course, but can be a disaster on a road course or a highway on ramp. Randy Pobst has written a lot about this kind of car setup and is not in favor of it.

Also note that all cars will understeer in a corner at a low enough corner speed. Some cars will never leave that understeer mode with increased corner speed. Other cars (think of early 911s, Corvairs, VW beatles) will have a speed in a corner at which they will transition to oversteer and whether that transition occurs is dependent on how the car is driven. The same it true for MINI Coopers, depending on their suspension setup

Most people with a MINI and drive it aggressively feel frustrated with the understeer the car has, hence the typical addition of a big fat rear sway bar to “correct the understeer problem”. MINI, however, takes a more global approach to removing understeeer in the MINI with each of their suspension setups (for the R56 this would be the base Cooper, Cooper S, optional sports suspension, optional JCW sports suspension and GP). They increasing spring rates, shock stiffness and sway bar stiffnesses. With each successive setup MINI has moved the roll stiffness bias more towards the rear. This is going to reduce the feeling of understeer and increase the propensity for a transition to oversteer. This is why a GP 2 will feel more unstable than a Gen II S.

From following this tread and comments made, I believe MINI, with the F56 JCW, has done exactly what people have asked for with the F56 JCW. That is, remove understeer, which is exactly what people are doing for years with MINI Coopers by the addition of big RSB. However, the down side to what MINI has done, as with the RSB mod, the car will more readily transition to oversteer and the stability of of the car is now much more dependent upon on how it is driven. In the right hands (think MINI Challenge cars in the UK) the car can be driven really fast.

As for suspension mods, I like the idea of the Eibach front/rear sway bar kit. However, my guess it that, while it improved the handling issue, it actually moves the roll stiffness bias further to the rear than what the JCW suspension has. The reason for the improvement is that the overall increase in roll stiffness improves the grip on all 4 tires. But, if it has moved the roll stiffness further to the rear, that may be why it didn’t eliminate the issue. However, I think in this case I would to look to improve upon the handling issue some people have described here by going to adjustable coilovers that have a stiffer front spring than rear spring (like the Ohlins for the R56) and would start with the rear shocks on the softest setting and the front shocks on the stiffest setting. Then I would progressively soften the front until I got the car feeling the way I most like it, with the stability I want.

The unfortunate part of all of this is that it is all a compromise. In a MINI, with its front end weight bias, it will will understeer, which is frustrating. This can be improved upon by increasing the roll stiffness of the rear of the car, but this comes with a price. That is, an increased propensity for the car to want to transition to oversteeer. That propensity to want to oversteer can be reduced by increasing the roll stiffness of the front of the car... Like a dog chasing its tail... And then, that all plays into how the car is being driven...

 

Great explanation, Eddie. Thank-you for your time writing it. I've got my first track time with an instructor in three weeks. I'll print this out and take it with me.

 

I liked reading your entire response and you've mentioned before (I think) about stiffer front springs versus rear. This is where my thought process is headed too. Like you said though, so much of this is compromise and they are dealing with a heavy ratio front engine/front drive car. I liked your video you posted in another comment above with the link to the LimeRock track with you in the video ahead.

 

Thanks...

I actually have myself thinking about what I would like to do with the car. I had thought about trying the JCW Pro Coilovers. But when I was writing the above I got to wondering about what direction MINI went with those. I wonder if they biased the springs for even more rear roll stiffness. I would like to find out the spring rates they use as compared to the JCW sports suspension springs I now have. It is hard to find info on these cars. Even realoem.com isn’t listing stuff about this car like they do for previous generation MINIs.

Here are links to 2 post I wrote about the suspension setup on my R56 and why I went the way I did. This may be of interest as background to what I have written here...
https://www.northamericanmotoring.co...ml#post4471232

And a couple of posts later in that same thread:

https://www.northamericanmotoring.co...ml#post4471493

 

I think when I do the springs I will do the progressive in the back. Hoping this might help, still cannot decide on the sway bar. I would like to see what kind of sway bar they have on the challenge car, article does not say.

 

@Eddie07S
Agree, pretty difficult to get hard numbers on this car. I wondered the same about the JCW Pro coil overs, and I think they are basically the same as KW Street Comfort, but without the hardness ****.

MikeMJCW measured his JCW springs here:

https://www.northamericanmotoring.co...ml#post4415376

Same thickness as KW SC, according to their TUV Certificate:

http://docs.kwsuspension.de/ga-KWSC-...AU_1094-18.pdf

If you look at pics of both systems, the springs have the same # of coils, and diameter looks the same. I'm gonna say they are the same =)

So also in that certificate is the info on spring diameter, etc., which maybe you could plug into a spring calculator and get rates. Although they are progressive springs, have different diameters top and bottom... so I don't think it's that simple unfortunately. Maybe someone that knows more can advise.

 

Not sure you want to model a suspension after a race car. They tend to dial in a certain amount of oversteer and the then drive around the consequences. Here is a post you might find interesting:
https://www.northamericanmotoring.co...ml#post4476510

 

I was more referring to this. . They changed nothing in the powerhouse, but oh so much on the handling.

 

Oh...
But the only thing I heard that they did handling-wise was a set of adjustable coilovers and sticky Michelin tires. The rest sounded like the JCW Pro stuff, like the exhaust. And I am surprised about the amount of body roll the car has. That is a lot more than my R56 (with the front and rear swaybars)

The thing that adjustable coilovers (at least the Ohlins for the R56; they don’t make them for the F56. ) is they can be used to make pretty significant changes in the handling characteristics of the car. This is why I think they would make for a good option for dialing out handling issues.

Other than the Ohlins, I am not sure what I would put in. I do know that cheap is not the way to go. AST shocks are a bit pricy but really good. KW makes a good shock but the adjusters are on the top and in the rear you have to take the shock out to adjust it. This leaves me thinking that the Bilstien B16 as the way to go. I like their B8s and their B16 coilovers have the adjuster on the bottom. However, in reading through the B16 info, it says that the stock MINI wheels will need a 11mm spacer to fit. I have not heard that a spacer was needed with the JCW Pro coilovers. So if those are the same as the KWs, maybe they too will fit the wheels without spacers?

 

good info thank you Eddie. I think the Challenge runs Nitron

 

Here's a link to the Nitrons: http://www.nitronracingshocks.com/Mi...t-_p_2122.html
A bit pricey .

 

yup a little pricey

 

Oh, that is just a modest price:
https://www.ecstuning.com/b-ast-susp...ac-b1402s~abv/

 

Maybe a bit of what you are paying for is the MINI name on them and the fact that they ARE SHARP LOOKING!! Love ‘em.

I did note that they are adjustable from the top, which is difficult for the rears...

 

Besides the spring info, there is a lot of good discussion in that whole thread about people’s experiences with various setups, including the JCW Pro coilovers and a couple of front/rear swaybar options. It is a good read for people on this thread.

I like the sounds of the JCW Pro coilovers, with the slightly softer spring in the rear. Just wish they were adjustable.

 

Or, you could go with camber/caster plates:
https://www.northamericanmotoring.co...&postcount=245

 

Anyone ever use the chassis brace? Don't know if this would actually have any affect

 

Stiffening the car is always good. I have known people who have installed them (underbody brace on a friend’s R56 in particular) and it clearly made the stiffer. This was clear when changing tires on the car and when jacking the car up using the foreword jack point both the front and rear tires came off the ground at almost the same time. That was not the case with my ‘07 R56 without the brace.

However, that said, the MINI is a pretty stiff car out of the box and I never did hear from my friend that it made any particular difference out on the track. Mostly, what I would expect from it is a bit more “sharpness” in steering inputs and in transitions. It will probably be more subtle than the “OMG - the front and rear sway bars really flattened the car out” kind of experience people have. And I would expect that it would be noticeable at the track vs the road.

I installed a bolt-in roll bar in my R56, and it clearly stiffened the rear of the car. Did I notice a change in the car’s handling. Maybe, maybe a little. Maybe a tiny bit less understeer. Maybe a little more response to off-throttle rotation of the car in a corner. But not so much of a change in the car’s handling that I changed how I drive or any settings on the car.

 

Hey, for those with DDC and want to switch to a set of coilovers, like the JCW Pro or otherwise, this looks like what you need:
https://www.ecstuning.com/b-kw-suspe...e/68510477~kw/

 

I will probably just stick with springs so I can still use the DDC. Nice to have on long trips.

 

Is there anyone out there that knows the spring rates for the Base, S and JCW versions of the F56?

I wish it was easier to find out things about these cars than it is.