My now 10-week-old 2008 MCS JCW has the standard "sport suspension," but I'd like to improve its handling without excessive lowering. I'm in Center City Philly (where the streets are terrible), and don't want to wreck my JCW aero kit or new wheels, or have tire rubbing problems.

Any suggestions for suspension improvement alternatives for spirited city and country road (but not track) driving would be greatly appreciated.

 

a 19mm sway bar should help you some but it might harshen the ride a smidgen

 

JCW suspension is the only choice that slightly lowers .4" versus the various spring and coilover options that are generally over an inch drop. It also improves all handling components rather than just one.

If you want to go cheaper, or not lower at all, or just do one bit at a time here are a few suggestions:

I agree with Corin, for street use a heavier 19mm rear sway is a great cheap mod and will not affect ride quality, just seriously reduce body roll in turns.

Koni sport struts would be a great handling improvement. There isn't much more you can do without lowering the car. I'm not a big fan of lowering springs for several reasons so I am not plugging those.

 

Start with the swaybar, you can't go wrong there.

 

Just added an H-Sport 19mm sway bar to my standard suspension R56 MCS. Had it installed yesterday and only had chance to try it out on a few twisties. I have it set on the middle position. It does make the ride harsher on some surfaces, unnoticeable on others. My first impression is that it improves stability on rough curves. Car doesn't jump around quite so much, and yes it does reduce body roll some. Seems like it has been a worthwhile mod.

 

Isn't the stock sport sway bar 18mm from the factory on the R56? How much difference could going to a 19mm make?

 

Thumper, you are correct!!

Here are the sizes of the R56 rear sway bars, which I read on my Mini dealer's parts dept.'s computer screen: Standard susp. 17mm; Sport susp. 18mm; and
JCW sport susp. only 18.5mm.

While I was looking, I also noted the sizes of the R56 front sway bars:
Std. 22.5mm; Sport 23.5; and JCW Sport only 24mm.

I believe the JCW Sport susp. would improve my MCS JCW's handling a bit, while only lowering it 10mm (.4"); and it would be fully integrated with the rest of the car. But, since the JCW Sport susp. is $2K+ installed, I'm just tyring to find out what else I should consider that doesn't require excessive lowering.

 

If you're going to spend $2000 on suspension, forget about sway bars and buy a set of JIC/Cross Coilovers. I guarantee you that a car with stock sway bars and Cross Coilovers is going to shave off 2-3 seconds on the track over a similar "Springs + Sway Bar" approach.

Even if you don't track your car, it makes the car a LOT more enjoyable to drive.

Cars equipped with a swaybar and springs (Without shocks specifically valved for said springs) tend to skitter across the pavement during hard cornering. Throw your car into a hard corner sometime and try it.

When you stiffen the chasis that much it doesn't allow any flex anymore, so rather than flexing the back end of the car and allowing optimum contact with the ground, you're tying the suspension to a particular angle, and the rear tires struggle to maintain traction in a turn.

The Cross Coils maintain this rear traction, which allows the rear to track with the front, rather than just slinging it around (Along for the ride).

As for the comments about sway bars making the ride stiffer, I see no way that your ride quality could have been affected by installing a sway bar. Keep in mind during most street driving your sway bar isn't even a factor (You could remove it and the car would drive the same). It only comes into play when body flex is encountered during hard cornering.

 

Potholes are going to ruin your wheels regardless of what suspension you have and how low you go.

You would have to go really low to endanger the actual aero kit and not just the plastic flaps underneath the car.

I would give Jan at RMW a call about the Cross coilovers. He'll know what the minimum, if any, drop is with them. I have them and love the ride, looks and handling. Plus, you can lower to the look you want and if you find yourself rubbing, you can raise it to just where you want it versus being locked in at 10mm.
Driveways, dips, and speedbumps are the only things I have to be wary of with my lowered setup. I avoid bumps and holes and egregiously bad pavement sections not because of scraping issues.

 

Nick, thanks for all your advice.

I realize that height adjustable coilovers are another possibility, and have seen that the JIC/Cross's can be lowered as little as 1/2". But, what else, if anything, would I also have to modify or add if I install Cross (or other comparable) coilovers?

 

Wolfgang, thanks for your advice and Cross coilover recommendation, too.

What other suspension components, if any, did you change when you put your Cross coilovers on?

 

I did nothing else. I'm going back in a week or so for a final alignment and height adjustment. At that point we'll decide if I need adjustable lower control arms to remove some of the negative camber from the rear wheels.

 

Nothing, they come with camberplates for the front, they even have new droplinks. Jan can get you a set in any spring rate you want (Softer, stiffer, etc) and right now with mine set at about 45% dampening in the front and 55% in the rear, it feels pretty darn close to stock ride quality.

 

Nick:

Over the past few days, I've also been following the Your MCS coilover reference thread on the 1st Gen Mini suspension board where, in addition to info. and pix on 25 or 30 different coilovers, I noticed a comment you made about linear springs being preferable for performance and progressive springs being preferable for comfort.

As you know, the JIC/Cross coilovers have linear springs, but the Bilstein PSS9's, which I gather is another very high quality, adjustable coilover, has progressive springs.

What are you thoughts about the PSS9's in general? How do you feel they compare to the Cross? And, given that I don't intend to track or autocross my Mini, which do you think would be a better choice for me?

Thanks, in advance, for any further input you can give me.

Bob B.

 

I'm not familiar with the PSS9's. Never driven a car with them installed. Posted in another thread about Progressive vs Linear, so check that out for more info.

I personally think that for the money the Cross setup is the best there is. That's just my opinion though, so others may feel different.

One thing about the PSS9's is that I don't think the spring preload is adjustable independent of ride height, and vice versa. So the more you lower your car, the worse your ride quality is going to be. On the Cross (And I think Megan is the only other company) you can adjust ride height while maintaining spring preload. So you can go low, without messing with ride quality, handling, or shock travel.

 

I don't have the sport suspension. I have regular stock suspension. The H-Sport 19mm rear sway bar has three positions. Over the stock 17mm bar they provide +54%,+88% & +128% stiffness.

 

Body flex?

If you look at the design of a rear sway bar, it is obvious that it comes into play whenever the wheel on one side is at a different height than the other side (one spring is more compressed than the other). A sway bar links the suspension on one side to the suspension on the other, via a leverage system. So, when the car leans -- compressing the spring on one side and extending the other -- the sway bar is twisted. Its resistance to twisting exerts pressure towards equalizing them.

The way it affects ride is that when a bump affects only the wheel on one side, it twists the bar, creating more resistance to suspension travel on that side, and putting force on the other wheel to move in tandem with the wheel going over the bump.

I don't see how body flex would have much to do with it. That is where interior struts come into play.

 

BC is the oem for megan (to megan's specs). And my understanding is the struts are a bit more robust in BC colors. minspeed.net carries them. In any case, you can swap springs to your heart's content as they are the 2.5 ID style. Supposedly, they are releasing a version for the r56. Call minspeed to find out.

But what do I know, I'm running FSDs with stock springs on a r53.

 

I don't think going over a bump when the car's going straight uses the sway bar at all. I think the sway bar only flexes when the car's weight shifts to the outside of a turn. The coilover unit absorbs the straight ahead bump entirely.
Maybe someone can explain to me why a thicker front asb makes the car understeer more, whereas a rear asb makes it understeer less. The SS has thicker bars front and rear (dunno what the JCW kit has, I assume the same). I'd think that a thicker bar in front would mean less body lean, less load on the outside front wheel, less understeer. I'd like to know the physics.

 

I pondered,researched,read,querried,mused...long and hard
IMO,slap some TSW springs over oem shocks, and rear anti sway of your chosing+ light wheels and good non RF's-great improvement!
-next to a high end coilover...its gotta be best bang for buck(TSW's)
ps-ride height change is fractional

 

I'm pretty sure stock suspension is 17mm rear, SS+ is 18, JCW is 18.5. For the R56...

Stiffening up the rear end affects traction in the rear. You get less traction with a sway bar, hence the back end wants to come around more. That's why it's better to run a set of coilovers with the stock sway bar then to run a really stiff swaybar on stock or slightly stiffer springs.

 

Look at the way it works. The long straight section is attached to the body in bushings so it can rotate, but not bend much. The ends are bent forming levers. The end of the lever part attaches to a rod that connects it to the lower part of the suspension near the wheel. When the wheel goes over a bump and moves upward, the rod moves upward pushing on the lever end of the sway bar. This rotates the bar making the lever at the other end want to move upwards. The resistance that wheel has to moving upwards is transferred back to the other wheel through the sway bar. So, it is less free to move independently from the other side wheel.

If the sway bar was completely inflexible, the two wheels would move up and down together. One wheel could not be extended down farther from the body than the other -- no body roll. As it is, the sway bar flexes. The stronger the bar, the less it flexes, the less body roll.

For a smooth ride, you want each wheel to go up and down over bump with as little force transferred to the body as possible. A stiff sway bar inhibits the independent action of each wheel. It ties the right side wheel to the left side wheel.

 

I'd like to hear an explanation of how that works, as it is counter-intuitive. Seems to me that when you have body roll weight is being transferred to the outside wheel. So, you have a significant difference in the down force on the two wheels. I would think the traction would be better with the load more evenly distributed to both wheels.

If it was better to load up the outside wheel and let the inner wheel lift, one would think that race cars would have very soft suspensions. As it is, they have very stiff suspensions.

It seems to me that a stiffer sway bar, like stiffer springs would give you better traction, not worse.

 

I think we're both trying to explain the same thing, I'm just not doing a very good job of getting the point I'm trying to make across (It's been a long day).

Here's a good article on sway bar tech.

http://www.houseofthud.com/cartech/swaybars.htm

A sway bar should only be loaded when one side of the suspension is loaded more than the other (Heavy turning, bump on one side, etc). Like Newt said, hitting a bump straight on isn't going to cause any sway bar activity.

A sway bar *shouldn't* cause any change in ride quality, at least not unless you hit a lot of bumps with one side of your suspension (And even then, the difference shouldn't really be enough to notice).

 

this is kinda OT, so let me first respond to the OP PDQ...

on rough streets, with the suspension you have, i'd be really tempted to leave well enough alone for a year... that's a damned good setup right there! why not enjoy it for a while before upgrading it?

OK, now the OT part...

why does a stiffer front sway bar contribute to understeer, and a stiffer rear one make the car loose? it boils down to the shape of a graph.

the graph i refer to is the one that plots the lateral grip at the contact patch, as the vertical load increases from zero... essentially the slope of that graph illustrates the available coefficient of friction.

all the graphs i've seen of this type share one feature - they rise steeply until a limit is reached, and then they slope downwards again (less steeply)

that means each tire has a happy place, where the combination of mechanical grip, hysterisis, tread and sidewall stiffness is optimized. less vertical load puts you towards the left side of the graph (less lateral grip) and too much vertical load ALSO reduces lateral grip relative to the "happy place"

and all THAT fits in as follows...

whichever end of a stiff chassis which contains the greater relative roll resistance will wind up doing the bulk of the work in controlling chassis roll angle. so if i put a relatively stiffer bar in front, the chassis roll momentum will shift more weight to the outside contact patch on the front end. if i put a relatively stiffer bar in back, then the same effect will maximize weight transfer to the outside rear.

in any case where weight transfer creates a vertical load that exceeds the optimum range for the tire, a loss of traction will occur.

this is exacerbated by the effect of that stiff bar at the inner tire - again, focussing on the axle that is doing the most work in opposing chassis roll.

the inner tire of course sees the opposite effect as the outer tire, and as the total weight transfer rises the inner tire loses vertical load, and again moves out its "happy place" producing a loss of traction

the whole thing made sense to me once i realized that a tire will NOT produce a linear amount of lateral grip relative to vertical load - that curve slopes off!

cheers,

charlie

ps: i went looking for a graph, and found THIS: (http://www.neohio-scca.org/comp_clin...educed%202.pdf) which explains the matter much better than i did.

pps: this is also helpful i reckon: http://home.scarlet.be/~be067749/58/c1/index.htm

ppps: if that all didn't amuse you, try this! http://www.dynamore.de/download/af04/papers/B-I-4.pdf