Who has autoX'd on progressive springs?
 

I've been through the archives many a time, and I can't seem to find what I'm looking for concerning progressive rate springs... So let me ask for opinions of those of you who have AUTOCROSSED, or otherwise driven at and beyond traction limits on progressive springs like m7 and H-sport: How is the predictability and stability of the chassis on the limit, and what is the balance like? I see that the H-sport spring's high-end compression strength of the rear spring is more than 50% greater than the front, while the low-end compression strengths are within 10% of eachother. Does this lead to snap oversteer in any situation (snow / rain included)? I'm not sure what the weight distribution of an MCS is, but assuming it's close to 50/50 I'd think the back end might get rather loose as the springs load up. I actually prefer my cars to be setup in such a way that they can be rotated at will, but for obvious safety reasons it needs to be well within predictable limits.

I'm still quite young, and I've spent a lot of my time driving a car setup primarily for autoX with VERY stiff (linear) springs - so ride quality is not a big issue to me (I personally think the ride on my '05 with 16" wheels and non-runflats is quite plush). I do intend to autocross my MCS on a few occasions, but it is also a daily driver. Even so, I like my daily's suspension tuning to be very precise, just so I know it will do exactly what I want it to if I need to manuver quickly. I need some ability to rotate the back end of the car, especially since this is a FWD car and it can't be done with the throttle... But it should be predictable and controlable.

So, would progressive springs cut it?

Try posting this in the Solo section, you might get more replies. I run in stock class which doesn't allow this modification so I can't help you.

I do have a feeling the MINI is more 2/3 front and 1/3 back. You can lift the front and rear end of the car just on the front jacking location, but cannot do the reverse on the rear

It's closer to 60/40 real darn close. Found that when corner weighting the car.

Progressive rate springs are very unpredictable at the limit. Think about it, as they compress, their rate changes, and unless you've memorized the rate at various levels of compression and related that to a particular handling characteristic, it will stay unpredictable.

There is a reason the car came with linear rate springs, which as it turns out are the perfect rate for the chassis, they are predictable.

For good auto-x turn in, steering responce, and snap-throttle turns, a 22mm rear sway bar will do nicely.

As long as you never apply more than 10% braking power in a corner, if that, you'll be ok.

Progressive springs are unstable at the limit, as has been previously said... When loaded up, anything that unloads or loads them will cause significant (and what can be sudden) weight transfer. When I first bought my car, it rode around on H&R springs (progressive) and I hated that setup for autocross and track work...

If you look on race cars, you won't find anyone using progressive springs. That's because they're awful. :) Cold wound, linear rate springs are the ticket whether you're running OEM struts/shocks, aftermarket OR coilovers.

I kinda figured that. Ok, thank-you all for the informative answers. I think my decision is clear now.

On a seperate note, 60/40 weight distribution is god awful... Like, epically bad. I was kinda hoping, this being a car of BMW lineage and all, that it would be a bit closer to 50/50... I mean, I wasn't expecting anything spectacular since it is FWD, but really. I hope this chassis is as brilliant as everyone has made it out to be over the years, because I absolutely HATE understeer.

Based on where I have to put the jack to get the car up on one side evenly, I'd say the weight distribution is worse than that, perhaps 70/30. Though I guess it could depend on how much fuel you have, whether or not your rear seats are in place, lighter suspension parts, etc.

There's no way it's that bad... There are pick-up trucks with better than 70/30.

Maybe my logic is bad.

Ignore everything I said.:o

Any sort of racing, and autox in particular, require totally linear and predictable handling. Progressive springs don't provide that.

...for a rear drive car it's bad. What makes you think that sort of distribution is bad for a front drive car?

Get TSW springs.

Progressive FTL.

Otherwise get coilovers.

If you don't like understeer and want off throttle rotation then get a 22mm rear swaybar.

....and, or more front camber.

We normally see a 60/40ish type bias when putting cars on the scales... Much of it depends on options. A lightweight battery in the front of a Cooper changed the weight distro by 1%, believe it or not...

My Cooper on the coilovers, no options, sits at 57%/43%. We've seen a few others right at 58/42%, too.

IMHO, it's not bad at ALL for a front driver - there are others out there that are worse.

I have the H-sport springs and I curently compete in STS with my MC. I have corner weighted my Mini and they are as follows. 772/774 front 480/485 rear thats pretty close to 60/40. I also have a 22mm adj RASB on the softest setting and I get good rear rotation with about 38 psi in the rear tires. As for the springs, well I've gotten used to them and I'm doing pretty well but I will be going to Cross coilovers soon.

Alright, that's respectable. I had a suspicion that I'd be getting myself into a front-heavy car... I just didn't want to believe it, LoL. It's just that I've never owned a car that's worse than 51/49, so even 58/42 seems terrible to me. But yes, it's one of those FWD vs RWD things.

Also, I should point out that I do already have a 22mm rsb. The PO had it set on the middle setting, which is where it is now. I haven't been out to do any balance testing yet, so I can't report on my satisfaction with it. I do notice that TSW springs are the same rate front and rear... Coupled with a 22mm rsb, is this enough to get decent lift-throttle rotation? My logic tells me to prefer a slightly heavier rear spring, especially considering the weight distribution...

Yes, you can and will get rotation with trailing throttle... :)

In our opinions (and via lots of testing), there's no reason to run a stiffer spring in the rear of the R50/R52/R53 platform.

You sound like you want to be a drifter or somthing, the mini will never be a RWD car.

How much off throttle rotation do you want?

My car with TSW springs and a 25.5 hollow Hsport bar (same as a 22mm) will compleatly rotate to the point that it will loop out if you really want it to. This is not desireable on a race track, only for slow speed like Auto-X and even that is pushing it.

FWIW, our Cooper and Dr. Mike's Cooper S will perform flawless 4-wheel drifts in the right circumstances... I was doing some this weekend at the autocross on a fast, left-hand, 270 degree sweeper in the off-camber section - once I hit the on-camber section and rolled back into the throttle, it hooked right back up as there was a lot more lateral grip...

In a totally neutral car, rotation is easy to induce, as are nice, long, lurid 4-wheel drifts... :)

However, there are a lot of people out there running too much rear swaybar with very tail happy cars that just don't know it yet - in a lift situation, it can cause snap oversteer (which is a very, very bad thing). In quick transition situations (e.g. like slaloms), it can cause quite the tank slapper. Those cars have a VERY fine line between oversteer and snap oversteer, IMHO. I've been in a few of those cars and man, here's to hoping those guys/gals don't lift completely, mid-corner, at the wrong track (especially ones with lots of Armco) or the wrong road. On more than one occassion, I've sent people into the paddock to soften up the rear swaybar for fear they were going to hurt themselves, the car, or someone else... I'd wager the Dragon has eaten a couple of cars with the exact same issue.

IMHO, get the springs right first (we did) and use the rear swaybar for fine tuning. Most people with a 22mm rear bar find that the soft or mid setting works more than adequately. We still prefer 19mm H&R rear bars over anything else, no matter what struts/springs/shocks you're using.

Forgive me, but I must admit I'm pretty biased. It's just that I've forged my driving style on RWD and oversteer... I like to be able to turn the car with the gas, so it really irks me when a car little other than plow (*cough Subaru cough*...). HOWEVER, if I can get good lift-throttle rotation, I'll likely be pretty well dialed in to drive the car as-is... My primary autoX car is unfortunately plagued with an open diff, so I actually end up using mostly lift throttle to rotate the thing anyhow, despite the fact that it's RWD.

So yes, ignore my anti-FWD narrowmindedness. I'm sure that will all go away as soon as get to really test the limits of this thing.

Part of being a good driver is being able to adapt to all car types, be it FWD, RWD or AWD, and even front vs mid vs rear engine.

Take it as an opertunity to learn a new style of driving. :thumbsup:

Just keep in mind on your quest for more rotation that being such a short wheelbase, as txwerks said, the car literly will be gripping, then snapping into oversteer in the blink of an eye, and it's not as slow a process where you have a bit of time to think as longer wheelbase cars that you might be used to. I used to drive a 240sx so I understand where you are coming from don't worry!

I will say this is the first real time that I have hammered on the Cooper with the Quaife LSD up front on a tight course that necessitated having an LSD - it just sucked me around the tight stuff and I kept the hammer down. An LSD makes SUCH a HUGE difference on an FWD car!

To initiate rotation, all I have to do is breathe off the throttle and then roll it back in - car rotates and then takes off like a rocket!

Yeah, after test driving a bone-stock non-LSD MCS and getting wheelspin on what I thought was a very gentle application of throttle off a very gentle corner, I made sure that every car I seriously considered had LSD. Thank goodness too, since these little things make WAY more low end torque than I expected.

I should be used to the short wheelbase - my 240Z has about the same wheelbase, plus heavier rear springs (compared to front) and proportinally more weight at the rear vs the MINI. It can be a bit sketchy in the rain, but that's more down to my 1/16" tread depth Azenis I think :wink:

Thats a great way of putting it. And I would have to agree with you as well on the 4 wheel drift though I have noticed that it almost seems like a rear wheel drift that utlilizes throtle massage as a means of keeping the car in a (somewhat controlled) state of oversteer, if that makes any sense.