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 Posted: Jul 25, 2019 04:16PM
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All of which is great .. IF you understand the consequences of the changed geometry.

I would suggest buying one of the many books on basic suspension design/setup.  What you are looking for are “layman’s” explanations as to what will happen as you change roll centre location, camber changes etc etc ..  Once you work out *what* you want to achieve then you will have to look into *how* this might be done... 

Just knowing can be fun even if the doing (redrilling suspension pickup points, revised suspension components etc etc) is beyond your capabilities/desires.... or is even possible.

Cheers, Ian

 Posted: Jul 24, 2019 04:20PM
 Edited:  Jul 24, 2019 04:25PM
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2D is fine for optimizing a Mini front, just assume the inner arms ride on horizontal (parallel to each other and parallel to the ground) planes.
Pick an origin.  In a forward-looking-aft view, start with the X,Y locations of the 8 pivot points (your static measurements of the car sitting on flat ground).  Then calculate...tie (constrain) one of the model's outer pivots to its related inner pivot with a fixed length (the length of the arm) and then move the inner (all four substrate pivots) model...move that model in roll, or roll plus droop, or roll plus bump, whatever.  The new position of the constrained inner pivot defines its new X,Y and therefore the arm angle to its constrained outer pivot, so now you solve for the outer constrained pivot X,Y.  Now find out where the other outer pivot has to be so that it remains attached (constrained) to its upper inner pivot.  The brute force method is to swing the two arcs defining the other arm and outer pivot and find out where they intersect.  In the 70s we did it with Fortran, I could do it today in Excel, you could find freeware if you wanted to look at clickbait all day. This is all just fun math, however, if you are not ever going to actually modify the car.

 Posted: Jul 23, 2019 02:03AM
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GB
Camber, castor, rideheight, & toe all change during cornering.  If you really want to get into it you'll have to either 3D model the suspension on the computator or do some empirical measuring by filming and replicating wheel movement while stationary.

There's probably more time in you than the car, but twinkly bits do help.

 Posted: Jul 19, 2019 09:14PM
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Quote:
Originally Posted by Rosebud
Quote:
Hmm… I really rather not mess with the upper arms. What would be the result if I installed the roll center adjusters on the lower arms and didn't modify the upper arm angles? Increased camber during cornering perhaps? 
Bump. Anyone?

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Jul 16, 2019 06:30PM
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Quote:
Originally Posted by scooperman
It is more difficult to restore the upper arm angle while lowered.…
Hmm… I really rather not mess with the upper arms. What would be the result if I installed the roll center adjusters on the lower arms and didn't modify the upper arm angles? Increased camber during cornering perhaps? 

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Jul 16, 2019 06:13PM
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Quote:
Originally Posted by 1963SV2
…Mini racer once told me that one of the basics in setting up a Mini suspension was to ensure that outer end of the lower arm was lower than the inner ...or, at worst, the same height.  Otherwise the front roll centre will drop below ground level. Which is not a good thing   Looking at my own car, you'd have to go pretty low before the angles go wrong...

It will be interesting to hear what you find out/ how the experiment goes...

Cheers, Ian
As my car sits now in the garage, the lower arms are pretty much parallel to the floor. It's obvious that any further weight on the front wheels (as in cornering) will cause the outer ends of the arms to be above the inner ends. So, it sounds like I could benefit from roll center adjusters. I'll get a set and report back. Unfortunately, my local autocross track just lost its lease and closed it's doors after 30 years. Without the ability to check my lap times, I suspect it will be difficult to make an accurate assessment. But, we'll see.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Jul 16, 2019 03:34PM
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mildly lowered stock suspension has a roll center under the car before roll, and then during roll the center moves.  If it moves far away from under the center, up, down, left, or right, the car reacts accordingly.  Bumps, droops, turns, changes in traction, all now have a long moment arm with which to move the car.   A severely lowered Mini's roll center quickly disappears during corner entry, ends up somewhere between Mercury and the Sun. 

The part you linked does drop the lower ball joint and helps to restore the lower arm to suitable angle.  It reduces the camber gain but the upper arm will still be wrong. It is more difficult to restore the upper arm angle while lowered.  We used to modify the subframes so the inner pivots of both the upper and lower arms could be moved.  I had 3 positions for the upper arm and two for the lower.




[url=https://imgur.com/LyYWXe1][/url]

 Posted: Jul 15, 2019 11:18PM
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Many years ago, when I started thinking about similar issues, there was a book on suspension design ("Race Car Suspension"???) by a guy called Carrol Smith.  It went into all sorts of issues; one being roll centres and axis ..and their effect on vehicle handling.

An old and bold (and very successful) Mini racer once told me that one of the basics in setting up a Mini suspension was to ensure that outer end of the lower arm was lower than the inner ...or, at worst, the same height.  Otherwise the front roll centre will drop below ground level. Which is not a good thing   Looking at my own car, you'd have to go pretty low before the angles go wrong...

The rear design keeps the roll centre height pretty much at the same height whatever the suspension height. As well as individual roll centre height, the front to rear angle of the roll axis (which joins the individual roll centres) affects handling.

As you lower the car, the inner end drops while the outer remains where it is. Those "adjusters" will move the outer end lower.  

Looking at the pics on the website I would be concerned that the bottom end of the joint would end up lower than the wheel rim ..which is illegal here .. and not a good idea anywhere.  Hopefully the designers allowed for this and the bottom of the extension will not interfere with the tyre if an under inflated tyre bends inwards under hard cornering....

It will be interesting to hear what you find out/ how the experiment goes...

Cheers, Ian

 Posted: Jul 15, 2019 02:46PM
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Has anyone had experience with roll center adjusters [link]? Sez they're recommended for lowered cars. 'Rosebud' is about as low as she can go w/o rubbing. What and to what degree of difference can I expect?

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports