Onasled and all,

Congratulations on your great handling and performance. Maybe some day I too................, but enough dreaming. Your good experiences with the front bar did get me thinking.

There is a lot of debate about the pros and cons of a stiffer front bar. The Seattle area local track rats who swear by a stiffer front bar, seem to be those who drive track oriented MINI's, all lowered, and, it seems, most with coil over suspensions that are really lowered. An article on suspension geometry in the August 2005 issue (August issue available at your news stands in June?) of Sports Compact Car magazine caught my eye and addresses the methods to adjust the suspension when the chassis is significantly lowered (3/4" to 1") . Based on the article, I think that those of us with lowered chassis experience increased handling problems from chassis roll and driving performance improves with anti-roll fixes. Drivers with stock height cars don't have to fight the roll problem in the same way. I think that a lot of the debate about the usefullness of a stiffer front bar depends on driver preference and whether the chassis is lowered or not.

The article describes the disproportionate lowering of the chassis roll centers (front and rear) compared to the lowering of the center of gravity with chassis lowering. The major lowering of the roll center increases chassis roll which can interfere with cornering and steering. Read the article, it is sobering. The fixes on the list include altering the geometry of the suspension components, a stiffer front sway bar, and stiffer springs. The stiffer sway bar and springs can be good solution.

I experimented with raising the roll center of my MINI about 2", using the methods detailed in the article. I found the front roll stiffness to be markedly increased, just with the altered geometry and with the stock front bar and the H&R springs, as the article predicts. Won't track the car until July 12, so really don't know if these suspension changes will translate into improved track performance.

The bottom line is that all the discussion about the merits of anti-roll bars and other suspension component changes probably should involve a more in depth understanding of each particular cars suspension geometry. Unfortunately, most of us don't have an easy way to know these things and we often fly blind. Food for thought. Read the article.

Regards,
John Petrich in Seattle

 

Based on the article, I think that those of us with lowered chassis experience increased handling problems from chassis roll and driving performance improves with anti-roll fixes. Drivers with stock height cars don't have to fight the roll problem in the same way.

John,

Exactly!!! I did not read the article but what is being discussed is ROLL COUPLE.

If you lower a car to a point where the verticle distance between the center of gravity and the roll centers increases, the car will roll more! If you lower your car an inch, the center of gravity will be lower by an inch, but the roll center may be lower by two inches, for example. The center of gravity acts as a pendulum about the roll center. Increase the length of this lever arm and the car rolls with more force, period! The reason(s) we do not observe this readily IS, as I wrote twice earlier, we've employeed heavier springs and dampers and bigger roll/sway bars. Now, weight will transfer more abruptly despite the addition of the above mentioned mods, which the article may or may not have stated. This can become a real problem in severe transient, competative conditions - an all-out race.

Where a MacPhearson strut is concerned, adding a bit of negative camber can potentially shorten roll couple...if I remeber, this will help to raise the roll center. I would have to check this with regard to the Mini.

I know I throw this crap out there every now and again, but guys/gals, this one is important. If you do not observe the relationship between center of gravity and roll centers, you will be chasing down handling problems despite having done everything else correctly. You may never know the difference...but if you begin to track your car at very advanced levels this will become obvisous.

I am about to pay big $$$ to find front and rear centers of gravity as this is the missing link in setting up a car. I just need to be sure of the methodology used; if I cannot get accurate measurements, the info is meaningless. If I'm successful, I will post this info.

I'm not trying to be an *** about this. But trust me, it's important. You can simply lower your car a 1/4" - 3/8" and save lots of trouble without worrying about roll couple - or leave at stock ride height. I did this with one car and it handled quite well.

If you're lowering for looks, that's a different story.

Michael

 

Meb,

I agree 100%. Using graphical methods, I computed that in my case, the 3/4" chassis lowering resulted in an estimated 2 1/2" lowering of the roll center. Did the lowering with the H&R springs. My perception at the time was the modification "helped" chassis control, probably the result of the 25% increase in spring rate. After I raised the roll centers back up, approximately 2" or less, I realized that I had lost a fair amount of front roll stiffness by lowering the chassis and slowed the chassis "set" in turns. I regained some of this roll stiffness by raising the roll center nearer to the center of gravity. Less "roll couple".

We'll see how it actually plays on the track. Now, I chasing bump steer since I altered the geometry lower "A" arm attachments.

Regards,
John Petrich in Seattle

 

just to push Meb's button, i found this:

https://www.northamericanmotoring.co...ht=roll+center

 

I will invest in a front bar, when it is released from M7, maybe August Peter said

190 bucks and looks good too

 

That's kind of steep for a front bar. The H-Sport is $135-ish.

 

I've looked at the sway bars and cannot for the life of me understand why a bar with more complicated bends costs less than a bar with four simple bends? Notice the price on the H-Sport rear swaybar is over $200! Ouch. Both come with zirc fittings






Anyhow, I think all this talk of lowered roll centers and stuff will make me think twice about not getting the front sway bar. Maybe this package is in my future...

 

Oh thanks John, rub it in. I'm sort of embarrassed by my second or third reply...can't remember which one. The reason? Well, I wasn't very clear about why I argued against changing the roll center's relationship with the entire suspension as a package. Too often I have little time to respond in depth, I missunderstand the context or I'm just plain sleepy... We'll see how it actually plays on the track. Now, I chasing bump steer since I altered the geometry lower "A" arm attachments.

Regards,
John Petrich in Seattle

John - I was going to ask you about this. A PM is on the way

Michael

 

dominicooper,

I'm not suggesting anyone avoid a front bar, you may find it very beneficial. I'm suggesting you simply understand what happens when you lower a car; 'things' other than the center of gravity will be affected. you may very well find that in the great compromise of suspension tuning, a larger roll couple is okay for you if you can find a way to control it. This happens all the time. Suspension tuning can be an awful lot of fun if you have a better idea of the potential changes - read opportunities - that occur. Onasled is having a great time with his front bar and his Mini!

 

meb, actually I at first wanted to get the full package from h-sport, then some said (in other threads) the front sway wasn't going to do much for me on the street. So then I decided I wasn't going to get it. Now that I see this thread, I think I will be reconsidering the "not getting it". I guess my use of a double negative in the previous post was misunderstood. Sorry. I will definately be getting a front sway bar if I go with the lowering springs from h-sport. If I remain at stock ride height, then I won't get the front one. But since I want the better handling springs, I suppose I might need the front sway bar to help keep the front from swaying too much and also will give me the ability to select from the two settings.

 

It's all a compromise. You're better off with adjustable coilovers. Although these are more expensive, you can corner weight your car, and, pick your own ride height, avoiding some of the above mentioned crap. H-Sports I've read, do not lower the car much?

Go with the front bar, but be aware that choosing sway bars diameters is usually a fine tuning thing; they are really meant to fine tune balance and responsiveness, not control roll, the position held by springs, and the rate of roll, by dampers.

You may find a 22mm rear bar and the H-Sport front bar a good combo. Dunno how big the H-Sport front bar is nor the size of the stock front bar. A little understeer can be a welcome thing especially at high speeds.

If you watch Onasled's videos, he is definately not fighting with the steering wheel; partly his smoothness, and, the car appears to be very easy to control at speed. It's easy to get a poorly set-up car out of sorts transitioning from turn one into the only left-hander. He seems to nail it really well.

 

The H-Sport front bar is only 16-27% stiffer than stock (27mm hollow~25mm, stock is 25mm). This is why it's mostly a track modification. It will allow you to run a bit stiffer in the rear so the car corners evenly.

 

Kapps, thanks.


Dominicooper, by the way, if you choose the H-Sport springs, try to choose a damper that is adjustable. Dampers/shocks control the spring's rebound and compression characteristics. The compression stroke essentially controls the motion of unsprung mass - suspension components. Rebound controls the energy absorbed in the spring as the sprung mass moves around - the rest of the car supported by springs. If the damper's rebound control is too high, it will not allow the spring to return to its 'mean' or normal position quickly enough. This will make the car feel sluggish. The opposite is true too; if a spring is too strong for a damper, it will never settle down. I offerd this because the H-Sport's front rates are a bit light. If you add strong, non-adjustable dampers you may be unhappy.

One of the reasons I like to purchase springs and dampers designed by one company is the spring and damping rates are matched. There are still compromises, the ones designed in by the manufacturer. You cannot escape these, however, unless you work for Ferrari and have the ability to custom make anything, cost nearly no-object. FYI

 

I've been running the H-Sport front bar (27mm) for over a year now - street and autocross (no track) -- I had the bar for 6 months before I installed it. I've got to say I like it - my car has a lot of grip in the corners.

To put this into context, I currently have PSS9's (1 yr), RDR camber plates, h-sport rear control arms (4), h-sport rear sway bar, and a quaife. I usually get 2 to 3 (sometimes more) alignments a year. I currently run the front bar on soft, the rear bar in the middle, but for 6 mos last year I ran both on stiff just to try it and see. I am still learning how to drive and consider that a journey with lots of road left to travel. I am average at autocross and don't really care how well I do in the standings as long as I have fun, learn, and continue to improve/push my limits. I started autoxing 3 months after I got my MCS; my wife started co-driving with me last year.

I actively read these forums, but sparingly contribute. I am no engineer, but I have found through trial and error what works for me suspension wise. I like the stiffer front swaybar.

David

 

I love my front bar, too. Shortly after installing the Sport rear bar, I started experiencing oversteer. (This is a Cooper, with the base stock suspension.)

Oversteer was fun for a while: I could feel it slipping and easily put it back under control. What wasn't fun was doing it around a blind turn.

So I installed the front bar. Oversteer was severely limited, and steering feels very responsive and balanced.

I'm running soft on the front, and hard in the rear. Of course, adding the springs really made the car feel connected to the road, and very "huggy" on corners.

I think anyone adding a stiffer rear bar should at least consider the front. It's a PITA to install, but well worth the effort.

 

I have the front bar sitting on the bench waiting to be installed, after reading all this I cant wait.

I am still learning and trying to increase my skill level like the rest of you.

The rear bar on the car was set on the soft setting and it seemed fine, pretty neutral. Now that I have increased my ability somwhat I found the car understeering more so I switched the rear bar to the middle setting and it seems like the car understeers even more than before? I know it sounds odd but the only suspension change was the setting on the rear bar. I also have pss9's on th e car and love em!

 

Absolutely loved watching you eat those porches up. I especially like the track. I spent many weekends there watching some fantastic racing. What class are you racing in? I am going to my first driving school next Monday with Bertil Roos@ VIR. Hope to be racing a MINI in the future.

 

Bringing back an old thread.

I've got a Cooper, with a hodge-podge of suspension parts on it now. I've got the JCW suspension upgrade's springs and dampers, a helix / RDR 3-way adjustable rear sway bar (I've seen it listed as both 21mm and 22.5mm), but the stock Sports Suspension (not SS+) front swaybar.

I'm not planning on doing anything right away, I have some upcoming track time to play with what I've got right now.

My rear swaybar is on its softest of three settings. Assuming I find the handling (oversteer / understeer) to my liking as is, what happens if...

Put a bigger front swaybar in and move the rear swaybar to a stiffer setting (middle hole)? I'm going into serious guessing mode here. If the relationship between the front swaybar stiffness and rear swaybar stiffnes remains (about) the same, but both increase, what happens? Less body roll, but the same oversteer / understeer characteristics? Would that mean that more speed would be needed to get to the point where oversteer / understeer occured (whichever it happens to be), but it would be the same in terms of over/under? That might be desirable.

These thoughts arise because the front bar is now the last part that has not been upgraded (of the major pieces).

onasled, I guess I'll see you at NHIS at the end of the month.

If I'm wrong, and it's too confusing to explain what would really happen, just tell me I'm wrong.

 

Just got the front bar in and te car definitly corners FLATTER ! the bar is on th esoft setting up front and middle in the rear. Now I need to find a good place to really test it. I need an open track day !

 

How about that traction condition - inside rear wheel - you noted in another thread? Front bar help or make it worse?

 

I havent really checked but it seems to be a little less. The car definitly goes around the frwy on ramps flatter. I think this was well worth th eeffort and I still have the stiffer setting if its not stiff enough now.

For the price of the front bar its money well spent in my opinion.