Hi Eddy, thanks for the post.

I don't know the stiffness of the front bar - it's a fair question.

I agree with your observations in all regards, which sort of suggests that the highly analytical SIAS technique may ultimately be required to sort through this puzzle.

Are you familiar with SIAS as an engineering approach?

Cheers,

Charlie

 

The more polite definition is:
Sample
It
And
See...

Charli

 

Charlie,
Just need the diameter and can approximate from there. Also, is it the convoluted shape that they put the R56 or is it more straight like the rear bar? Yes, I know, you need to dig the car out, put it on ramps and slid under it to see all of this....

So how much snow did you get?

 

Now that the snow has stopped... About 8" of nice white fluffy stuff that makes me feel strong when I shovel it.

I'll get the front bar dimension as soon as I can - but isn't material part of that calculation?

On a separate note, I ordered the Bilstein B8, the NM 22 mm solid bar, and the endlinks yesterday.

SIAS.

Cheers,

Charlie

 

The material property of importance is the modulus which is pretty much the same for all steels, about 30 Msi. The length of the bar is important too. But, if the bar is similar to that in the R56, then the spring rate is a combination of the moment of inertia (for the part in bending) and the polar moment of inertia (for the part in torsion). But the length is longer than the rear...

Hmmmm ..... I'll have to think this through

What was the question

If you can get me the diameter of the front bar, I'll figure something out.

I think, for autoX, the B8s and 22mm bar will do you well.

Personally, I wouldn't take it on the track, though.

 

I hear you.

The current setup (OEM Sport Suspension + the knuckles) stil has sufficient understeer so that I run 38/48 psi front and rear to loosen the tail.

I do hope that this setup will not require me to run such high pressures out back, and if so I may be giving up some of the safety net on off-ramps and such.

Some careful testing will be needed, and the challenge will be to get that done before 18 March.

At least there is a test & tune at Georgia Motorsports Park on the 17th, and so I'll try hard to get a slot.

Cheers,

Charlie

 

I have not yet tried my B8s. However, my '07 with my 20 mm RSB, stock S suspension and FSD it was easy to be on and off the throttle and get the rear to "jack" around. The problem I kept getting into was, if I wasn't fast enough to catch it, it would just keep coming around. On your car, the B8s may slow that down so it is more controllable. It is easy to change the settings on those bars, so soft for the street and hard for autoX.

Just be careful on the on-off ramps. Although your "skid pad" might be fun to play on.

I trust you will get there for March.

 

Oh yay - shiny bits!

Thanks to NM Engineering, and of course Thyssen-Krupp.





Time to get into the shop, and let the Mini of Peabody team do the installation and alignment.


Cheers,

Charlie

 

Due to the general excellence of the Mini of Peabody service team, and the lull that occurs in the depths of winter, I am now the proud and temporary custodian of a 4 door F56 (B38) with an automatic.

Less confusing than the 8 speed of the Clubman, and very much a Mini!

Meanwhile, and over the next few days, all the shiny bits will go onto Gollum III.

And then (weather permitting) we'll get a sense of whether it's possible to improve on the Sport Suspension.

All in due course.

Cheers,

Charlie

 

 

Minus twelve,



And the sea mist,




Coats the trees.





Cheers,

Charlie

 

-12 on the coast, that has to be brutal. There is nothing colder than cold air coming off the water; it goes through everything. A day for a wind breaker and wool sweater.

-14 here when I got up. Brrrrrr
Learned a new term today when I looked up your area a saw the National Weather Service advisory - Arctic sea smoke

Stay warm.

 

Great pictures, it was a balmy 25 with a wind chill of 14 for us this morning.

I've got a question and a thought ... I'm also in search of the best "street" setup for my MINI.

Your new shocks, I don't see coilovers. Are you staying with the standard springs and not changing the ride height?

I noticed you run with high rear tire pressures. When I started autocrossing last year, I also ran with high rear tire pressures for the same reason. It was after replacing the rear sway bar that I starting thinking differently about it. We do many things to our cars to make them act in a controlled fashion, why do something that might make the rear end slide around uncontrollably? Last couple of events I've been slowly reducing the pressure. Haven't got the wear marks where I want them yet.

Really enjoying following this thread Charlie. Good luck to you!

 

Pepper - Hope Charlie doesn't mind me helping with your questions and he is free to correct me if I am wrong. As for your first question, I would suggest checking the SCCA rules. I believe that in the stock class they allow the shocks and one sway bar to be replaced, but the springs must remain stock. Hence no coilovers.

As for you second question "why...make the rear end slide around uncontrollably?" Great question Are you familiar with airplane design at all? A Piper Cub is designed with all sorts of stability and it is really hard to make it go out of control. But it is not what you would call a highly maneuverable plane. On the other end of the spectrum are the fighter jets of the '60s that were design with very little stability. While these planes took a lot of pilot skill to handle, they were highly maneuverable. The same difference applies to the difference between an everyday street car and a highly maneuverable autocross car. There are a lot of dynamics that play into the maneuverability of a car. The MINI starts out at the wrong end of those dynamics. In particular, the dynamic of CG versus traction center. If the CG is ahead of the traction center (as in the MINI), the car is going to want to understeer. Understeer is the bane of a highly maneuverable car. Understeer can be addressed in a number of different ways and each will impart its own level of "uncontrollability". For example, adding camber to the front adds traction to the front without affecting the rear. Adding a rear sway bar moves weight from the front to the rear, but also reduces traction from the rear (think of it as a MINI 3-wheeling it around a turn). High pressure in the rear reduces traction in the rear. A highly skilled driver can make use of these characteristics on an autocross course to go quickly through it. A less skilled driver may just spin the car (not that I have evvvverrrr done that ). The thing is, however, on an autocross course things are totally in your control. Out on the street or on the track, there are a lot of things that are not in your control and a car that does really well on the autocross course is likely not the best to take on either the street or track. Even a highly skilled driver out on the street may be put into a situation where his/her actions are "right" for the situation but "wrong" for the car. Hence, designing street cars with a fair amount of stability for the less experienced drivers.

Hope this helps...
Charlie - how'd I do?

 

Damn!



What HE said!

Stand by for a little progress, and my own two bits. Thank you Eddie!

No debate, just further tales of this drunkard's walk towards the pillars of greatness.



Charlie

 

The greatest irony of the off season is that potentially significant improvements may be made, but there is nowhere to prove it!

Patience my son! Have faith.

So - having admitted that the loose nut behind the wheel is the primary factor in Autocross success, I like countless other motivated lemmings of similar ilk, decided to spend money to fix something that was not broken.

The not broken in this case is the fine Sport Suspension which graces the nether regions of Gollum III and has served valiantly during the 2015 competition season.

So - must I gild the lily, even though I am between jobs? A suicidal self indulgence and offering to the gods of speed?

Of course!

Thus we have pretty yellow and purple and silver bits down where no-one ever looks.

Like here:




and here:




culminating, courtesy of the excellence of Mini of Peabody (and by the way, let us welcome Colin to the unofficial Pit Crew - a man who shares my passion for motorsport) in an alignment which features balanced camber front to back.





It's subtle, but that is -1 degree on all four corners.

So - will the Bilsteins reduce the "pee on the hydrant" stance? Will the RSB create suicidal oversteer? Will the attempt to refine what was already good backfire on this perpetrator like some odious Oxford negative Karma?

Only time, good weather, and testing will predict.

Only the Dixie Tour will tell.

Pray for me!

Cheers,

PS: The keen crew at MoP is now officially upgraded from unofficial Pit Crew, all the way to Unofficial Sponsor. My cup runneth over... Thank you!

Charlie

 

Hey guys, Ive been thinking about RSB's, and since that is a recent discussion here, please allow me to ramble.

Since the sway bar/anti-roll bar is a torsion spring with levers on the end, there are two ways to adjust the spring rate: bar stiffness and lever length. Both of these aspects have been brought about in this thread and many others.

Also, since the sway bar rides in bushings that reduce friction, the bar is allowed to pivot relative to the chassis.

So what I've been wondering is: Would there be a significant difference if you had one side of the car in adjustment hole #1 and the other side in adjustment hole #2? My initial thought (panic) is that 'The Car is not Symmetrical, it can't be done'. Then I think about it a bit, and wonder if you would have a stiff side (say, turning left), and a softer response when turning right. But if the bushings are reasonably slippery, the physics should indicate that the overall stiffness of the bar is between Hole #1 and Hole #2. I say this since we are transmitting force from wheel to wheel, not wheel to chassis to wheel.

In other words, if Charlie finds that his new NM bar is too soft on the near hole, and too stiff on the far hole, is there a goldilocks option with staggered holes? I don't have any experience (I'm in the middle hole on my RSB, and I'm too ham fisted to recognize a detailed change like this on the street) in this type of setup, but I just thought it was an interesting idea. Maybe totally off base, but interesting.

Just a thought as I watch the snow flurries......

Have fun,
Mike

 

Actually...

The bar AS INSTALLED is configured the way you describe!

It is on the "medium" setting, by which I mean the left end-link is connected to the mounting point closest to the pivot axis of the bar (away from the bitter end), and the right end-link is connected to the mounting point furthest from the axis (and closest to the bitter end).

I wanted to start out full soft, but in this application the left bitter end of the bar is extremely close to the trailing arm, and Colin and I decided to make room by avoiding that last bolt hole entirely. It is interesting that this fitment issue occurred only on the left hand side.

In theory, the bar stiffness is thus the average of the full stiff and full soft measurements - in the order of 453 lb/in.

Which still seems very damned stiff to me, but remember this is SIAS engineering..



Cheers,

Charlie

 

Well folks, Gollum III is more like a go-kart than ever, and at least up to about 8 tenths the handling is benign.

But this ain't no Cadillac!

So far so good.

Cheers,

Charlie

 

The answer is yes and no as for installing the bar with one end stiff and the other soft.

If the bar is not moving, therefore everything has to be in equilibrium. As you say, this is just a cantilevered beam putting a torque on a rod. If you cut the rod section in half and fix that end in space then the torque resisting rotation is just F x L (force - F - times the length of the lever - L-). So, if the one side is 7" long and the force is 100 lbs, then the torque is 700 in-lbs at the center of the bar. Say the other side is 6" long, then the force to resist rotation from 700 in-lbs of torque at the center of the bar is 700/6 = 116.7 lbs. So on the 6" side the suspension has to travel a little bit further to allow it to develop 116.7 lbs force on the sway bar balance the distance traveled in the other direction on the other side of the car.

The net result will be that turning in one direction will produce different handling characteristics than turning in the other direction (eg: the one side will dip more than the other side). I am sure that in a truly sophisticated setup you might be able to make use of this kind of asymmetrical balance to the car (maybe with an infinitely adjustable bar). However, Charlie, I doubt that the mechanic who installed the bar in your car set the bar in an asymmetrical fashion on purpose. I would have them set the bar in the same location on both sides, at least for a starting point.

Honestly, I have never heard of cars being setup this way or any discussion about doing that. The shop who installed the RSB in my car set the bar in the same hole, both sides and these guys set up race cars.

 

Shocks are a bit stiff?

 

All my fillings are still in place.

So far.

The RSB floats in the bushings, which is why NM supports the asymmetrical end-link positions as an intermediate setting.

Note the chart in the installation guide.

Cheers,

Charlie

 

My apologizes to Mini of Peabody for implying that they didn't do it right.

I see that is what NM says, but I am not sure I understand how it works. I know the RSB floats in bushings but that doesn't change that it takes a different force on the ends of each end of the RSB to balance it out...something that I need to think more about.

In the meantime - Motor On and Enjoy

 

If you were ordering a base 2016 Cooper for GStreet--what would be the options? I am not seeing a Sport suspension option, other than the Dynamic Suspension on the MINIUSA site….

Thanks.

 

I'm afraid the answer that I used in 2014 is no longer possible, as I believe the Sport Suspension was not offered starting at some point in 2015.

Perhaps it was perceived as too stiff, and did not generate sufficient demand?

Cheers,

Charlie