Schirmer Kinematics

[72dan]

Originally Posted by nigt3

Dropped car off over winter to team Schirmer and got his cage and carbon parts fitted

Looks awesome!

[slowdown_dan]

When you buy a Shirmer car is there some sort of agreement in place that you don't the pull wheels off and start taking measurements, pictures, and general disassembly to see where the unicorn splooge is hiding?

[Redd]

Originally Posted by butte2butte

When you buy a Shirmer car is there some sort of agreement in place that you don't the pull wheels off and start taking measurements, pictures, and general disassembly to see where the unicorn splooge is hiding?

... And if there isn't, can you pull wheels off and start taking measurements, pictures, and general disassembly to see where the unicorn splooge is hiding? 😁

[gnoy26]

Originally Posted by roastbeef

They get down and dirty. Very impressive stuff.

ive been following their build as well and i think their cars have stages, this probably being their highest stage kinematics.

not all cars are the same and most depends on the owner / budget

but it would be safe to assume that all stages would be full monoball and as the stages go up more and more bespoke parts go in and less bolt on more chassis/cage welding and lightening

[gnoy26]

this particular car by team schirmer did a full welded cage and lightening however if u looked at the kinematics it uses most of the stock monoball parts, and all of the parts that arent monoball are replaced.

so as u can see from pictures (another 2 pics of team schirmer m2 for reference)

all rubber bushes are all swapped out

example:
rear sway bar end link
rear upper arms
rear trailing arm bushes
front sway bar end link *probably cuz the originals are too long

conclusion, weight vs full monoball vs budget. id first replace all rubber bushes to monoball, then if some stock parts need replacement upgrade to SPL monoball arms for adjustability and weight then a full lightweight process on the chassis side. and like @72dan said nothing beats weight, it helps with wear and tear, agility, performance. everything

[omgzirra_exe]

the only thing i want off this entire thing.. is that 22gal fuel tank

[tlrid3r]

As you can see I believe the "secret to schirmer kinematic is roll center correct front and rear.

It's the only think they focus on differently than most other tuners. Every single car they touch has geometry correction. Not just plain lowering and alignment.

[bbnks2]

Originally Posted by tlrid3r

As you can see I believe the "secret to schirmer kinematic is roll center correct front and rear.

It's the only thinking they focus on differently than most other tuners. Every single car they touch has geometry correction. Not just plain lowering and alignment.

yeah there is nothing that special in those pictures. Just all upgraded control arms with spherical bushings. The only thing kinematics related is the true rear coilover (with a custom lower camber arm which may have a custom lower mounting location). Up front they have some roll center correction. It's not like they are relocating pickup points or anything real crazy. No custom hubs (on this car) or custom subframe. I see all stuff the avg person can bolt on to a car with the money and quite a few already have cars set up to this level of prep or higher.

I personally just finished up pressing sphericals into my M3 guide rod and trailing arms. Much cheaper then upgrading to aftermarket adjustable arms just to get spherical joints. The rear feels way less "rigid" now is the only way I can explain it. It just articulates and follow the road/front steering input so much better than stiff rubber joints that load up when compressed instead of articulating freely.

[Biginboca]

So as best I can tell the rear roll center correction is the lowering of the lower camber arm (spring arm) attachment point with this black offset insert pressed into the hub/spindle?





And the front roll correction is just using offset tie rod ends like the SPL and Turner ones?

[derbo]

Originally Posted by Biginboca

So as best I can tell the rear roll center correction is the lowering of the lower camber arm (spring arm) attachment point with this black offset insert pressed into the hub/spindle?





And the front roll correction is just using offset tie rod ends like the SPL and Turner ones?

I think effectively you would need to lower all bushings for the arms.

http://www.mk-motorsportteile.de/epa...oducts/corre9x

MK seems to make offset bearings for all bushings on the bottom.

To answer your question on your front roll center, yes, tie rod ends + the thrust and control arms have extended bolts to offset it. The other option for us is the Strom Uprights that replace the entire spindle to fix the geometry. Stroms retain OE arms without much issue. Clearance on aftermarket arms with Strom has been known to be tight for certain 18" rims.

[bbnks2]

Originally Posted by derbo

I think effectively you would need to lower all bushings for the arms.

http://www.mk-motorsportteile.de/epa...oducts/corre9x

MK seems to make offset bearings for all bushings on the bottom.

To answer your question on your front roll center, yes, tie rod ends + the thrust and control arms have extended bolts to offset it. The other option for us is the Strom Uprights that replace the entire spindle to fix the geometry. Stroms retain OE arms without much issue. Clearance on aftermarket arms with Strom has been known to be tight for certain 18" rims.

That's the first time I've seen a bushing like that. Pretty cool.

It's really hard to find any kind of data on rear multi-link suspension. Needs to be 3D modeled to really see how things change in compression and roll and how moving the lower arm pickup point by 1/4" will change much if anything.

[derbo]

Originally Posted by bbnks2

That's the first time I've seen a bushing like that. Pretty cool.

It's really hard to find any kind of data on rear multi-link suspension. Needs to be 3D modeled to really see how things change in compression and roll and how moving the lower arm pickup point by 1/4" will change much if anything.

I'm sure it does but definitely how much is the given question. I get that the aim of these kits to try to keep the angle of the arms relatively the same as the stock suspension while lowering the CG.

I definitely see it that if you are correcting front roll center and bumpsteer, the rear should be be considered too somehow.

[gnoy26]

Originally Posted by derbo

I think effectively you would need to lower all bushings for the arms.

http://www.mk-motorsportteile.de/epa...oducts/corre9x

MK seems to make offset bearings for all bushings on the bottom.

To answer your question on your front roll center, yes, tie rod ends + the thrust and control arms have extended bolts to offset it. The other option for us is the Strom Uprights that replace the entire spindle to fix the geometry. Stroms retain OE arms without much issue. Clearance on aftermarket arms with Strom has been known to be tight for certain 18" rims.

very interesting, i always thought that was to allow more camber and not to adjust rollcenter. the way its positioned in the picture its definitely to compensate the lowered height.

[leftfootbr8king]

It's 100% to correct roll center and bump steer. Millway in Sweden has a solution just the same as MK, and does it for around half the price.

[//steve\\]

Originally Posted by leftfootbr8king

It's 100% to correct roll center and bump steer. Millway in Sweden has a solution just the same as MK, and does it for around half the price.

Yup! Definitely isn't something new but doesn't seem like anyone stateside is running it.

[tlrid3r]

I have invested a bit of time and effort to create this for myself. Rear axle roll center correction and bump steer like schirmer cars. This is 16mm of roll center correction. This is the kinetics schirmer speaks of. I took inspiration of what is current available, but create my own design, CAD and measurements.
It can be done and replicated. I'll be testing it out soon.

[roastbeef]

so with these kits, the goal is to have the arm mounted in a way to have it flatter at ride height, so in compression, it doesn't "straighten" out and push the spindle outward, scrubbing the tires? is that a decent understanding of the benefit?

[tlrid3r]

Originally Posted by roastbeef

so with these kits, the goal is to have the arm mounted in a way to have it flatter at ride height, so in compression, it doesn't "straighten" out and push the spindle outward, scrubbing the tires? is that a decent understanding of the benefit?

Correct. But to add it also has to do with the moment arm motion and vehicle center of gravity.
The car will have a more compliant ride handling and increased mechanical grip because its like having a stiffer spring with out the draw back of a stiffer spring.
Here is a simple video explaining it. Those where the calculations I had to understand.

[tlrid3r]

I have the strom Motorsport front upright and with the mechanical grip up front greatly increased. Prior to the uprights,the car went from a neutral to oversteer. I run 295 square. But I was going through a lot of tire. Because roll center in the front was off. With the uprights roll center was corrected. Thus the improvements on grip. I was impressed so I wanted to try the same with the rear. If I can go back to neutral feeling and increased grip also improved tire wear. I'm happy. I ran 1:39 at laguna. If I can manage to beat 1:39 I think it's a success.

[roastbeef]

cool. the fall line rear lca's have camber shims, but that doesn't take care of the subframe side. is there any advantage to running both?

[Redd]

How low do you need to be to require roll center correction?

[tlrid3r]

Originally Posted by Redd

How low do you need to be to require roll center correction?

Im not a expert, just an engineer with an interest and looking for a solution to our platform. It's not just about being lowered or not. It's that lowering exacerbates this negative affect exponentially. Because it all adds up. Loading into a corner, riding the berms all impact roll center when you most demand it.
High spring rates can help but the car may be great a one track and not the other. Because proper suspension articulation is what provide mechanical grip. But the word articulation is not use to say that more movement is better.
Simply put, if your car is lowered and your roll center is in the proper place. The moment arm with have a less leverage on moving the chassis, your 600lbs spring may be sufficient where your would need 1000lbs spring with improper roll center.
Than to add on top of that. Camber loss, bump steering due too improper motion. Roll Center correction should fix all that.

My design and from what I can see from the limitation of the rear subframe (with-out major modifications of cutting into the subframe) all other providers of roll center correction kit can only correct a max of a 25mm drop from factory height.