Hi all

I have just ordered an F55 Cooper. (Current car is Suzuki Swift Sports - beginners Mini I reckon…) A nice corner, done as well as I can, is the highlight of my motoring pleasure, and having just sludged and wallowed around in a borrowed 1996 corolla for a week while my swift was in the shop, I appreciate how far from fun some cars are, and am grateful that we have Minis and Swifts to add meaning to our lives!

My regular roads are fun and windy but a bit rough, I do a bit of gravel too when I go away for work.

In the end I went with 16" wheels and variable dampers. Seems a bit tame now I spell it out. It was a very tough choice to not go to sports suspension, and really not helped by the lack of demo cars with either VDC or SS to drive in my area. Im still not sure Ive made the right choice actually, but I went for twiddle-ability, being able to go soft for my girlfriend (umm, that didn't come out right - I meant soft in the suspension dammit, get your minds out the gutter!) or when my neck is stiff and sore.

I figured that if the VDC feels too wimpy and body-rolly, then I could start with upgrading to 17"wheels or go for some of the wonderful things I have read about on these forums, like swapping the rear sway bar (best bang for buck apparently), or changing to coilovers, or perhaps just new springs and dampers.

Suspension tuning seems like a black art to me. I assume the Mini engineers chose what they think is a balanced setup, though it is obviously not firm and racy enough for all tastes.

So, please, can the more suspension savvy folk here tell me:

How much can you mess with the components before you risk something dangerous, like unbalancing the car or making it unpredictable and spinning, slipping or rolling it or some such?

Are there any negatives of simply upping the rear sway bar diameter?

Is it an option to do, say, sway bar and springs but leave the original dampers?

How much difference do harder bushings and mounts, such as those available at Way's make, if you didn't change anything else?

I gather changing to slightly negative camber helps grip - and tyre wear? - if you do a lot of twisties. I definitely scrubbed out the outside of my tires on the Swift, maybe some of that was alignment, some of it the cornering? Does negative camber adversely affect tyre wear or handling on longer, straighter trips?

Any other instructional comments welcome! There are some folks here who race and fiddle with things, and I appreciate any knowledge shared.

 

Excellent questions! Short answer is: if you don't know what you're doing, yes, you can mess up your suspension. Worse, you could kill yourself.

However, knowledge is available:

http://www.rapid-racer.com/suspension-tuning.php

 

On a slightly brighter note
Venders tend to like repeat customers, it's in their interest to keep you out of ditches etc

Your on the right forum, you just need to appreciate "why" Any particular modification is good, or recommended by that poster, there is no universal best thing in all circumstances

 

I think it'd be pretty hard to ruin your suspension to the point that it's hazardous to drive on the road. If you're buying a "kit" of something (springs, coilovers, etc) from a vendor you shouldn't have anything to worry about.

Moving to a 17" wheel won't affect the body roll just the responsiveness of the steering wheel.

There are very little downsides to a rear swaybar.

Adding more negative camber will help with front-end grip. You have to have a lot of camber before you really start to adversely affect tire wear. If you're somewhere between -1 and -2 degrees you should be fine.

All of your questions are answered repeatedly in various forum threads. You would be well served to spend some time researching and reading.

 

Welcome to NAM

It sounds like you have yet to take delivery of your F55. My first advice would be to simply get accustomed to the car how it will be delivered. If after some time you find a specific aspect of the handling lacking, we'll be more than happy to guide you to an appropriate solution.

Suspension tuning definitely is not a black art, it is however fairly complicated. The combination of chassis rigidity, damper curves/hysteresis/stiction, spring rate, bushing rate, tire rate, and kinematics (control arm movement and the resulting camber/caster/toe/ackerman/sai/anti-dive curves) all interplay to create a specific reaction to a certain input. The OEM's then engineer each aspect to provide a quiet, comfortable, balanced handling car within their design intents and budget available. You always have to keep in mind that most drivers have marginal training (especially here in the USA!), so most suspension tunes are designed to be safe and predictable for the average Joe.

The link lsmith42 posted is a good foundation of knowledge. The classic but always helpful is an excellent book to have on your auto-geek shelf.

Bringing it back to MINI specific, if you find the car to understeer more than you prefer, then the easiest solution is a stiffer rear sway bar. I always recommend to people adding stiffer sway bars to put it on the softest setting, learn the behavior change carefully, and then build up to the balance you desire.

I rarely recommend lowering springs, as they all but eliminate compression travel. On the R53 and R56 generation MINI's, any lowering spring would result in the car being 100% bumpstop active with zero free compression travel. This means the car cannot absorb any large bumps and will also have a very high effective wheel rate in corners, higher than the tires can handle. The result is poor/harsh ride quality and skittish/unpredictable handling on variable mu surfaces. If you wan to change the ride height of the car, doing it the right way means specific-designed dampers that move the total stroke around your desired ride height (e.g. BC coil-overs are a good low-cost example, KW variant coil-over sets are a good mid-price example, and fully custom Anze/Penske solution would be a world-beating high-end example). Prices are somewhere in the $1k, $2.5k, and $5k+ ranges, respectively

 

Things as simple as coils, springs, sways, etc aren't going to mess the car up with proper installs. Lots of engineering went into quality products. Buying cheaper coils or cheaper suspension components will definitely not hold up as adequately. It's the whole, "You get what you pay for," moto. Aftermarket companies provide warranties with their products. This gives the consumer an ease of mind that their product is that of quality. Things such as spacers may wear out your wheel bearings faster, and possibly stiffening the chassis may be harsher on stock bushings a bit more, but it in no way means you are going to ruin the suspension on the vehicle. Just do your research and ask questions. It's not complicated and there are a lot of people/companies out there willing to help and teach you the art of the aftermarket world. Please, do not hesitate to contact us with any questions you may have and happy modding!

-Luccia

 

I've always had a habit of doing brakes and suspension before any performance modifications...

Trivia question: has anyone measured the stock suspension travel of the F55/56? It would be interesting to know what % of travel gets lost when lowering... I've already got the NM sway bar and end links in the garage, and I'm looking at their springs, which provide a 1.2" drop with the B38.

My last car was lowered an inch, and I never found the bump stops with that. I did, however, learn the pain of very low profile tires with California potholes!

 

Thanks to all replies so far.

ISmith42 thanks for the link - I have read through it all and its a good grounding thank you. And yes to doing suspension first - the f55/6 has plenty of torque and speed for anything I want to do on a public road, our police are obsessed by trying to reduce speed, its so boring.

V10Climber good point about vendors not wanting customers getting hurt. I am indeed still researching.

Ryephile - you made me laugh - after claiming this is not a black art, then writing:"The combination of chassis rigidity, damper curves/hysteresis/stiction, spring rate, bushing rate, tire rate, and kinematics (control arm movement and the resulting camber/caster/toe/ackerman/sai/anti-dive curves) all interplay to create a specific reaction to a certain input." ...I remember enough of my engineering degree to recognise that you did actually use english, but I might struggle to convince my mother of that fact
And great info re the lowering thank you. One sees a lot of lowered cars, and I often wonder if they have been made undrivable, in the name of simply looking cool.

And Pelicanparts, thank you for the reassurance.