unfortuately suspension tuning is heavily biased to driver input,
weather, street/track conditions, etc. where there is no one fixed
variable.

that is why you have to trial and error. and we aren't boneheads,
we know the basics of what works and where to start. the rest
is testing it out on the course or street to dial it in. the time
spent typing long text should be better spent trying out your
settings on your car. spec racing is wat non-car enthusiasts
do with magazines.

 

But if you want to win races then driver needs to learn the correct input for a properly tuned suspension. A driver that is used to driving very fast in a Mini with 300/450 spring rates is going to drive rather poorly, and claim the car is too slippery when he drives on 600/1000 spring rates. He needs to learn how to drive the car on such springs and then he will be a lot faster then ever before.
So, set the car up correctly and then learn how to drive it.

Also, just to note, stiffer springs will not 'mushroom' the car as much as softer springs. It's the bump stoping that is the culprit here.

 

Boy are you correct. A real and under appreciated problem for some setups.

John Petrich in Seattle

"Also, just to note, stiffer springs will not 'mushroom' the car as much as softer springs. It's the bump stoping that is the culprit here."

 

Ken and the rest,

I don't know what we actually "know". Yes, there are a lot of strongly held theories and a lot of good ideas based on first principles. But, what are the tried and proven approaches? Yes, there are a load of non-suspension related variables that can significantly influence track performance. But, we would benefit from knowing certain facts, certain key variables, those relevant to MINI to help us in our suspension development process.

Maybe this isn't the right time for the MINI community to try and pull together this knowledge base. Maybe it is too hard of a job.

I haven't identified a book or a website that outlines in any detail a comprehensive understanding of the MINI suspension and that outlines a logical suspension development process. I'd like to know more and be secure that the knowledge that I have is at least 1/2 way accurate, consistent with first principles, and relatively uncontaminated by commercial interests. We can work with resources of a more general nature, like the book, Race Car Vehicle Dynamics, cited by Meb and others. But, that process leaves a lot to the imagination and engineering knowledge. Sure, a vital imagination and engineering know how will seperate the 'winners' for the 'losers', but we're not talking about 'winning' or 'losing'. We're talking about consolidating and disseminating knowledge.

At work today, was thinking that someone would do us all a great service by developing a website devoted to this area. A "sticky" on NAM probably won't work due to the potential for conflict with supporting vendors. Maybe none of us, individually, has the capability of such an undertaking. But, together we might be able to pool our knowledge and abilities to pull together a MINI suspension tuning guide.

Whew! It's getting late. Don't know what other's think about Jeff's question and my plea.

Regards,
John Petrich in Seattle

 

The best coilover setup for a dual purpose car I have found to date is the H&R street package. It uses Bilstein dampers and 469/240# springs that are valved accordingly. Not too harsh on the street and pretty good at the track. (I live in NJ and the streets do leave a lot to be desired.)
Arrive and drive.

 

"...stiffer springs will not 'mushroom' the car as much as softer springs. It's the bump stoping that is the culprit here."

Correct. But that truth is the opposite of what I think most people believe.

 

As all good team do, we change springs and shock valving according to the track. We even carry dozens of combinations in the trailer along with our scales and alignment equipment in case we guessed wrong at the shop.
Yes, tire pressures and rebound/compression are easy to change at the track but toe and camber are not. One affects the other and it also changes the balance. Get out the equipment!

 

Changing springs is not necessary with my Spitfire. Maybe so in your Mini but I don't see how the principles would change. You keep doing what you're doing and so will I, I'm just sharing my experience with my race car.

Happy Friday

 

I think we all need to ask ourselves this question; what are my goals and how much time and money am I willing to invest?

I would like to find a a basic track setup that I can leave alone. That is my goal for today; I'm a father, a husband and I run a huge design dept in Ct, I do not have time for more. Yet, I am very curious and will continue to read, learn, share, learn and eventually get to a point when I can appreciate the different track setups when my kids leave . I agree with Spitfire, and Don - who seem to determine the boundaries at the track. In a comptetative environment where fractions of a second make a difference, it is ill advised to sit still. Experimenting and failing teach us more than sitting still. Yet, I understand spitfire's postion too...the mini is a newer plateform, however, so I would expect much more experimentation to take place for some time to come.

I am still not happy with my setup which was designed as a compromise. I feel I'm onto a better idea now and once there I'll leave it alone...for a while. But I could not have arrived at this point in tuning without lots of experiemtning. And Key to Jeff's openning thread, perhaps experimenting should be more science than guess work...it might actually save us some money.

If I may Don, you are in a different place than most of us; your life is tuning and racing. Trying new 'things' is a must as well as establishing the minute differences at each track that determine either a win or second place. I think you hold the potential to push the Mini plateform way farther than backyard mechanics like me. Seeing and feeling things others do not notice, or care about, is an asset.

 

I've been following this for a while now and this is a very intersting discussion. Its funny, as I was just thinking about the pros/cons of lower CG vs suspension geometry.

There will always be needs for different suspension setups as some of us use our daily drivers for track days, and others have dedicated track cars. I'll argue that non-dampening adjustable setups, when valved correctly can offer a great middle ground ... "arrive and drive" as others have said. I love my KW variant 1s, and ireland fixed camber plates for this reason—No need to worry about switching settings, just a good setup that I'm learning to drive quickly.

Personally I'm very interested in the ride height question. I could lower the car another 1" and still be within KWs recommended settings, but I don't know if the lower CG would make up for the changes in suspension geometry

All in all, a very interesting thread and I'm looking forward to reading the future posts.

 

...make the track wider and some, perhaps all, of the ill roll couple effects go away.

 

look at all this crap that I started.

yes, as Onasled mentioned, i have to agree that the mushroom is
coming from the bumpstop and not just the springs.

ive yet to try those FSD's... should be a nice setup with the
H-Sports. im probably going to soften up the rear 22mm
after getting the dampers.

 

Amen to John's post 25 and 29. I love the idea of an information repository to help direct anyone who wishes to tune their MINI suspension. In the end, I don't know that a sticky wouldn't work since most of what we're talking about, i.e., geometry and the effects of altering suspension settings on MINI handling behavior, is independent of vendor interest. Or at least, it's easy to distinguish something along the lines of: "to combat symptom X, experienced under your described conditions, you can try increasing spring rate or ..." or "the calcs suggest that you may need more negative camber/more + toe (or whatever)" from something like "Those coilovers suck. You should have bought such-and-such other ones," and the like. These forums and a sticky may be the best way to attract and keep a large MINI crowd. But I'm open to other options.

As to Meb's comments about time -- boy do I agree now that I have a newborn on top of work pressure and responsibilities...but I know you, me and others will still tinker, particularly if we have a set of tools that allow us to intelligently determine what we may do next time we get to the track, and those alterations will have solid grounding in first principles. In essence, we'll hopefully have the ability to drastically decrease the number of outright poor setups we end up trying.

Don (and others) As for my future coilovers, the more I think about it, the more I want additional degrees of freedom and the ability to get myself in even more trouble -- I think I want separately adjustable compression and rebound damping (and 2.25 or 2.5" diameter springs). In the end, it'll FORCE me to carry this work forward to prevent me from spiraling down the adjustment toilet, sampling crappy setup after crappy setup. To that end, I'll probably go the route of PD or K-mac plates so I can increase the degrees of freedom even more (caster and camber)... H&R doesn't have any double adjustables that I see. I'm gravitating toward KW v3 or perhaps some custom Konis. Hell, why not Motons (better hide THAT credit card statement from the little lady) ; )

Oh, and I've been straightened out on the whole "minimum drop" thing. Turns out that all those referenced coilovers with uncorrectable drops weren't ride height adjustable versions. My bad.

One last point that probably got lost in my previous posts:
Am I hopelessly naive regarding the expertise of the autobody profession? I am under the impression that the reputable shops simply MUST have reference materials that tell them where all the "important" parts of a car (read: suspension pickup points) need to be. I mean, if one bends the frame rail/front inner fender in 0.5", it's not generally obvious. They need to be able to figure this out; after that, they need to be able to verify everything's square and in its proper place. They, therefore, must (?) have references that list all such vital stats -- if so, our work for the suspension modeling could be essentially done but for the photocopying of those pages! Does anyone know whether this is true?

Jeff

 

Lets keep track of one glaring point; all dampers are not created equal. Well duh you say! Damping force and damping curves are not typically available to us. And as I wrote in the past, we can line up 10 different dampers, all with the same damping force. Each, however, may feel incredibly different due to damping curve characteristics. These characteristics determine how well a damper works with a spring, and, how the car feels to our backside.

This may appear subtle, and is...and is not.