Hi all. I know this is long, but I took quite a while to try and explain it - I'd really appreciate your advice/comments

So I was driving back from work today through the big wide open canyon roads and was going a little quicker than what my mother would call sensible. We all have those moments though so this thread isn't about that.

I noticed some things about my car on high speed turns that just seem out of place. I was hoping you could share experiences. I have M7 springs, USS and strut bar. I love the handling during 99% of driving but some stuff scared me tonight. I have been struggling for a way to describe it and I want to say that my car felt "top heavy" during the turns. There just felt like there was way more weight shifting than there should be in a lowered car. I had a friends S2000 in front of me and where his car looked super squat and stuck, I really felt like I was rolling and bouncing too much. It was like the "go-kart" feeling had completely gone. Granted a couple of corners i had to lift A LITTLE (not much) more just a backing off the throttle. I have been well taught in high speed schools both back in the UK and here so yes I know I shouldnt and I WAS not driving erratically, but the weight shift was quite alarming when I did this... does anybody know what I'm talking about or understand what I mean? I love my suspension and the work that M7 does, maybe I just past the limit of stock shocks etc...

Second part was having to break hard at one point. I have just had an alignment and was pointing straight but my cur ducked and bucked violently left then right. I've been lucky enough that the only true sports cars I have driven before were M3's and Audi S4's - both of which when you planted the break just gripped and stopped. This bucking scared the cr*p out of me. Again any comments much appreciated.

 

Sounds like you need an s2k

 

Ouch! Low blow...!

 

See the thread for the Alta PSRS - new front lower bushings solved this exact same problem for me. I'm not saying that the ALTA bushings are the only ones that will work, but I AM pointing the finger at the miserable blobs that the MINI bushings eventually become.

 

Haha ouch that was a low blow. I'd have a mini any day over an S2k (I actually almost bought one!) I just wanted to know why I wasn't sitting with him through the corner!

Thanks a lot man, I'll look it up and give it a go!

 

This could be so many things from tire pressure to bad struts due to lowering, to poor alignment to damaged suspension parts i.e broken drop link. I think that most here will notice that you have no upgraded rear sway bar. Kinda a must when lowering the car as you have altered your 'roll center'

Don't start looking into other mods to remedy this issue until you find out exactly what might be wrong.
Oh, and it could have been you... Maybe your adrenaline was up a bit too much and your were a bit tense being that there was another car involved. We tend to do this, especially when our car is not as fast as we thought it was.

 

yep, I'm going to go the rear sway bar pretty soon..I can't believe there was anything else up. The car was in Clarks house of suspension last week in Lake Forest - a really highly thought of place. He did my alignment and sorted my camber for me whilst having a good general look around underneath...

 

What things did this shop do? Do you have the alignment specs? I've heard this about other shops and the results have been horrid.

 

If I were you, I would look into a set of struts that can take the drop from the M7 springs. Possibly Koni FSD or Yellow? I personally am a fan of the yellows due to the adjustability factor.

 

I agree totally.

 

Low roll centers, bingo! Onasled wrote it!

A car that is lowered using softer than stock springs or progressive rate springs WILL have less roll resistance period. A lowered car REQUIRES stiffer springs to achieve the same roll resistance. The degree of loss of roll resistance is determined by geometry; the relationship between the center of gravity and static/dynamic roll centers.

 

This is because the instant roll center moves down as the angles between the lateral links and the ground increase as the car is lowered. There are other factors of course, but this is the biggest reason. I think this is one reason my car plows a little around medium speed, high-banked turns (around 20 degrees, as can be found at the Streets of Willow, for instance).

 

...and the instantaneous centers are used to locate the roll centers.

 

ONE SOLUTION: Please let this be a warning

Driving today I skidded my car badly breaking on the freeway - after last night AND that, I was really freaked out. As I drove on my tire pressure warning light came on. Again, pretty freaked out. I pull over and check my tire pressures at a gas station. I'll be damned. 63psi, 59psi, 60psi and 60psi. UNBELIEVABLE.

The car was in the dealer to get a rattle fixed last week - I had no idea they would mess with my tire pressures - this combined with the fact that the service manager knows exactly how **** I am about my car and always set to 34 36. It blew my mind. I was probably running on oval shaped tires. I'm guessing that is the majority of my problem!

 

So is there a common solution to this type of problem for those of us that have bought the progressive type springs like M7?? I'm really interested in this - thanks for sharing

 

I'm not sure about how to "compensate" for the progressive rate springs, other than to get shocks that are "matched" or recommended for those springs specs. I've never personally had such an issue as I don't like changing out the spring or shock seperately. I feel that if you change one without the other, then one of the components will be doing more work than the other. I.E. Stiffer springs, stock shock = springs doing more of the work, and vice versa. I have a friend that had a very similar experience to yours after he lowered his subaru. He got cheapo no name springs from ebay and you could totally feel how horrible the ride was after he put them in. The car would bounce rapidly with the contours of the road, especially at high speed. As far as your situation goes, I'd say get a set of shocks that will work in harmony with the M7 springs. Good Luck!

 

That's a safe bet. Yeow! Glad you checked that before it was too late.

 

yep scary stuff....

 

I had a similiar experience last December but this was my mistake. Cornering, I would notice something felt odd and the car pulled when driving straight. I did have a tire, driver front, that didn't like the temp changes during this period of 70's one day and 30's the next. I finally had it checked and a nail was found.

I would walk around the car everyday to glimpse at the tires. I noticed the one tire bulging so I would take care of it by adding 3 to 5 psi. What I didn't notice was the passenger side front. Not until one day I checked all pressures. It was at 42psi. 10 more psi than the opposite side.

I failed to correct the tire pressures after an autocross event at the end of November. I still have no idea how I got 42psi as I never run it higher than 35psi. Mistakes like this can happen and fortunately I caught it before a big mistake happened. One thing I have noticed about the MINI. Tire pressures, even a small change, can effect the handling drastically.

 

This is how my cars felt until I replaced all the bushings. Also, playing with the alignment has allowed me fine tune the weight shift dynamic.

 

Well, I don't know where you live, but in the NE the temps have been below zero for a long time and my tire psi were set accordingly. Yesterday the temps reached the high 40s and tire psi grew by 7-8psi - basically about 40-41psi - not really a good thing on salt and sand infested roads.

 

[quote=n1ftyneil;1381111] ....Granted a couple of corners i had to lift A LITTLE (not much) more just a backing off the throttle. I have been well taught in high speed schools both back in the UK and here so yes I know I shouldnt and I WAS not driving erratically, but the weight shift was quite alarming when I did this...[quote]

i don't know if what you experienced is what i experience, but this type of lifting roll is part of what i experience when i get lift throttle oversteer when cornering hard; it seems like the rear end is lifting and rolling.

i started a recent thread asking how to fix it. (i have about 1" of lowering with eibach springs and the rear camber and toe set back to stock with h-sport upper and lower arms.)

 

Not sure you want to "fix" it. It's real hard to advise being that we don't really know how you are driving the car. But, this is one way to get a Mini around a track fast. Throtle steer. By lifting (slightly) you can get the car to rotate nicely.

 

Hey guys, my MCS is experiencing the same bahavior under hard braking. Its been sitting on m7 springs for a few years now with the stock shocks, the shocks are way past due for sure, getting ready to address that.

I also found that my passenger side control arm bushing has alot of play in it, def. has to be the cause of the pulling I'm experiencing under braking. Control arm bushings seem to be designed to wear out on bimmers, my e28 (83 533i) had the same issue, but that badboy is over 20years old.

So in short... shocks and bushings replacement time.

 

Threshold braking invloves a lot more than just handling balance; slow and high speed damping can play a huge role in how a car 'feels' to a driver during threshold braking, but most of do not have this adjustability. Second, I firmly beleive the Mini has waaaaaaaaaaaay too much rear brake bias. I have 83K miles on my car and I am halfway thru my third set of rear brakes

By comparison, I take my 99Si way deep into turns under braking if need be. The first time I attemtped to trail brake into a turn taken a few hundred times with my Si, the Mini almost swaped ends! Yes, I prefer to get my braking out of the way before a turn, but when on a track it's not always possible. I NEVER trail brake the Mini.

The stock rear trailing arm bush may also contribute to some rear steering. But I've talked with others at length regarding poly back there and things just got worse. Onasled and others preparing track only cars are using a ball joint in place of the bushing. Seems to work well on the track...