For the MCS, do you set the ride height

a. slighly higher at the front and lower at the back for improved weight distribution?
b. slighly lower at the front and higher at the back for a bit of rake and improved traction?
c. equal ride height front and back.

All opinions welcomed!

 

a, really doesn't work, so b or c. b, has the advantage of providing a little more rear tire clearance and the car will rotate a little better if the rear is highr than the front.

 

is by analyzing the suspension geometery. If you lower too much, you'll get some problems... I'm running 1/2-3/4 inch lower than stock front and back.

Matt

 

meb- your moment of truth!

 

hehehehehe. No offense Matt. If I actually had time to run AutoX or track time regularly I would run higher, but.....

 

Well said, gowest.

 

My experience thus far as well, and I also (perhaps mistakenly) hold the belief that lowering the CG in the heavy end of the car will reduce roll and weight transfer, which should help the front axle stick better when cornering....I am running lower in the front.

It is a daily driver however, and from experience I make darned sure I can clear a 2x4 on it's side (dodging road kill can also be hazardous around here...).

 

Here we go again

The only way to REALLY know is to study the Mini's suspension movements with a kinematics program. All else is based on theory and sound experience - what we do here for the most part.

Lowering the center of gravity is the single best thing one can do to improve handling. But this can come at the expense of other important relationships. Roll Couple is one big one and camber and toe curves are two additional considerations.

Last two first - I'm keeping this short, I don't have time to be my usual vomitous self. If you've lowered a car to a point that the suspension is in the meat of its aggressive camber and toe curves, every up and down suspension movement will be affected by larger toe and camber changes.

Roll Couple...every syuspension movement occurs first at the roll centers then migrates to every other part of the car. The realationship between roll center and the center of gravity is important because these two are conncected by an invisible lever arm. All else equal, make the lever arm longer and the car rolls faster and with more force - despite a lower center of gravity!

When lowering a car, it is likely that the roll center(s) will lower more than the center(s) of gravity - increasing roll couple. This is almost always true with a Mac Strut...I really think that this is always the case. The only way to over come this is to increase spring and damping rates - which most of us do. But there is a sweet spot in every car whos camber and toe curves along with roll couple relationships have been optimized.

I beleive in not lowering a car more than one inch as a guide. I also keep a little rake in my setup - a hair higher in the back. If you keep the ride height to within an inch of stock, I don't think you can get too far off.

Just make sure all your other adjustable 'stuff' hasn't been messed with...otherwise all the carefull planning and measuring won't mean diddly squat. It still aint' perfect Kenchan, but is driveable.

 

I will not dispute meb's knowledge on this subject but will add some imformation. For anyone who has lowered a MINI and knows how much the alignment has changed, this tells you something. While I don't remember the toe numbers, camber changes a lot in the rear and extremely little in the front, part of the built in understeer. Both ends toe in as well. This indicates an extremely gentle camber curve in front and an agressive curve in rear. Being a front wheel drive car, the front is the more important to us leading me to believe we can lower our car more with less negative effects than most other cars.

I am now on my second set of KW coilovers. The 1st set was the V1, in late 02 to early 03 when they came with straight springs. These came with a stated lowering range of 30-50mm if I remember right. These were replaced with KW's Competition 2 Ways, when I wanted to upgrade to double adjustable shocks. These have a slightly shorter tube, so they can be run even lower. I think KW even told me a minimum of two inches was recommended and that's about where I'm at.

 

Thanks for all your suggestions guys, specially to Meb for a detailed explanation on this topic. My car is stock MCS and fitted with H&R coilovers, it's now lowered about an inch all round which I feel is about right. Any lower and all sorts of problems would show up (scraping front lower lip, excessive rear negative camber, harsh ride, tire rubbing...).
I tried running A and B but didn't feel too comfortable with the handling, so I ended up with about the same ride height front and rear. I've attached a small pic of my car, it's pretty stock looking but hope you like it.

 

The painted trim is a nice touch!

 

hm... i dont know.... ive ran eibach pro-kit springs for awhile now (1.0f, 1.2b) and i feel that handling is more sublime... i can kick the rear out easier if i lift mid corner... i guess its got more to do with the rear sway bar.... but it just seems easier after i lowered the car

 

Ride height, swaybars, spring rates, damping rates, bushings, suspension settings...it's all soup, but the flavor really depends upon the actual mix of any of these.

 

Jackychan and the others,

I couldn't agree more with meb's post #8. He said it all in one short post.

If track success is your goal, lowering your MINI more than 1/2" without significant other changes in your suspension geometry will only set you back. I'm serious.

For a street car, where appearance is likely the prime driver, anything goes consistent with the smoothness of your local roads.

I lowered my dual purpose MINI about 1" and if I had it to do overagain, I wouldn't. Right now for example, I am experimenting with cuting down my bump stops about 1 1/4", front and rear, to regain strut travel. In retrospect, some of my rear end instability under heavy braking on rough surfacess may be related to my stock front struts hitting the bump stops causing the front spring rates hit the stratosphere. The ABS and EBC kick in and the result is a wild ride. Will post more on this in 2 weeks after the next track day. But, performance problems like this and too many others to list are what can happen with much in the way of lowering your MINI.

Hope that this helps,
John Petrich in Seattle

 

error

 

Jackychan and the rest,

Have a little more time to post and to indicate further agreement with Matt (Dr. Obnox) and Michael (meb), but not beat this topic into the ground. Sounds like you, Jackychan, are cautious and not imprudent. You never indicated if you are interested in track driving. My reason for posting further, however, is to get some track oriented suspension geometry data out there for others to comment on.

On the topic of camber gain: The stock MINI seems to be built with about 0.5 degree of negative front camber gain with every inch of spring compression, (a good thing). A MINI lowered about 1" loses that camber gain and starts picking up a small amount of positive camber gain, (a bad thing). On my MINI, my static camber setting is about 2.2 degrees negative. My outside front tire at the track, in a heavy corning situation, runs a dynamic camber of about 2.7 to 3.0 degrees negative, (a very good thing). A MINI lowered 1", with the standard geometry, and a static front camber of 2.2 degrees negative in the same corner would run a dynamic front camber of about 1.8 degrees, (not so bad, but not so good). The solutions are: A) tolerate the less than ideal camber curve, B) don't lower the car, or C) change the pickup points for the lower control arm often referred to as the lower "A" arm.

On the topic of roll center: Michael (meb) made his point quite succinctly. Read and understand every word. I experimented with my MINI and plotted my measurements on a big *** piece of butcher paper to visualize my front end geometry. Lowering my MINI 1" lowered my roll center from about 9" above the ground to slightly below ground level. This change in roll center height is neither good, nor bad, but did have a profound change on my front roll rate. My car behaved in a track environment, just as meb described and I didn't like it. What happened is that the roll couple location went from about 2" below the center of gravity in the stock setting to close to 12" in the lowered setting. The roll couple increases directly with the length of the distance from the center of gravity to the roll center. So, my roll couple increased about 6X when I lowered my MINI 1". The solutions are: A) increase the spring rates, a good idea for a lot of reasons, B) install a stiffer front roll bar - that is, convert the front suspension from an independent suspension to a solid axle suspenson (I'm exaggerating a little, but not much, read the posts of people transitioning from the street to a driveway on 3 wheels), C) reposition the front control arm pickup points to restore the roll center location - approximately the same settings that correct the camber gain situation referred to above, D) tolerate the roll couple changes, or E) don't lower your MINI very much.

I don't want to sound tiresome, but a lot of things happen to the suspension geometry when you lower a MINI. Some called "experts" say that the car handles "fine" and ignore these changes. What these people are really experiencing is that MINI has such fine handling car that you can compromise a fair amount of the ideal suspension design and still have a fine handling car.

Anyway, we should never need track level of handling on the public roads. This discussion is oriented to lowering MINI with optimal track performance in mind.

Looking forward to more discussion,

John Petrich in Seattle

 

Great follow-up John...I made my corrections above Thanks

Michael

 

So back to the original question: to rake or not to rake. I've read in many places that a bit (1/4-1/2") of rake (front lower than rear) is a good thing because it helps turn-in. I heard from a reliable source today that for a FWD car, it's actually better for handling to run reverse rake (rear lower than front). meb says, it's all about the suspension geometry, so does anyone know what works best for the MINI?

 

pure&simple,

There really is no actual data as to what is best for MINI, the loweing and rake question. Am assuming you are interested in track performance.

First principles and accumulated track lore guidance would have you lower the car no more than 1" with a rake toward the front. Even with that level of lowering you are compromising important suspension geometry refinements but make gains from lowering of the CG. The forward rake is to encourage down force on the driven / steering wheels, or at least not reduce the down force with a reverse rake.

This is what I would say. To ask the questions and dare reconsider conventional wisdom is a virtue. Keep it up.

Regards,
John Petrich in Seattle

 

When roll couple is increased as John illustrated, there are two other theoretical cheats;

1) Increase track and the center of gravity drops. This will wear bearings
faster and cause a few other problems. But hey, if yer racing, winning is
winning.

2) Install tires that are one inch smaller in circumference.

These two cheats do not affect suspension travel. Again, in theory, if the car is NOT lowered, roll couple will be decreased by droping the center of gravity - the roll center will be closer to CG.

Unfortunately for me, my race wheels are a 45mm offset, but are one inch smaller. My road wheels are 38mm offset and are the correct 205/45/17s. I may switch these at some point very soon.

 

I decided that I didn't have the cash to get RA1s, so it's another set of Azenis for me. But, the 215/45R16 size seems to be sold out everywhere. There is 205/40R16 in stock, though. The load rating looks sufficient. I wonder if the chin spoiler will scrape on the little chunks of rubber that build up on the track.

 

I've never had a problem Jasen and my drop is a hair lower than your JCW suspension...but the 205/40s are track dedicated tires...I would still run these on the street.

 

Michael, thanks for the confirmation with regards to #2. My rolling diameter is 23.3" (16-205/45) compared to stock 16's at 24.4". The main reason I did this was for "gearing" purposes, but I was wondering if this would help with the roll couple concerns you have shared with us for some time now...

Going with tires that are 1" smaller (diameter), for clarification, doesn't drop the car 1" - but half that as .5" would be above and below the axle.

My MINI is lowered, but I'm not sure how much is due to the perch settings, or the tire change. I guess that is why I started that thread inquiring about what ride height others are running at, and how best to determine that.

 

Actually, that's not true. There is a veritable plethora of information available from the race series in Brittan. You just have to get to know some of the race teams.

 

[quote=TonyB
...for clarification, doesn't drop the car 1" - but half that as .5" would be above and below the axle.[/quote]

I should have written that