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      12-25-2018, 05:01 PM   #221
ornicar
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Originally Posted by Orb View Post
One of the best suspension write ups I have ever seen.....awesome details!!

I was looking at the CG plated when I came across this thread. I will defiantly will make my own. They obviously did no testing or calculations.

Question for the poster:
Did you account for the CG OEM spring perch deflection under load. I measured about 10 mm for the OEM spring perch. I suspect this came out a wash or close to it.

As for the rear spring compressing on a curved axis. I did a non linear analysis in Ansys and the spring rate does increase anywhere from 15-40%. This is dependent on spring wire diameter, spring length and stroke position so not a straight forward answer. I resolved the issue with the a sealed articulating spring perch placed between the helper spring and main spring. The soft helper spring works well at taking up translation by deforming as well. This made a very noticeable improvement and ride quality was a night a day difference especially over rough roads.


Hello,

i am into "constituing" a rear coilover set for my 125i:


- Main spring Eibach 7" Length ; 2,25" ID ; 650 Lb/inch rate ; PN : 0700.225.0650

- Tender Spring Eibach 2,68" Length ; 2,25" ID ; 300 Lb/inch rate ; PN : 0175.225.0300

- HPA Height Adjuster or another good quality one. I appreciate this one because you can fitting a thrust bearing to avoid stress in the spring

https://www.hpashop.com/HPA-E82-E9x-...st-e82-e9x.htm

I have one question:

Does anyone know where i can buying this ball joint coupler "sealed articulating spring perch" in 2,25 Diameter?

TY
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      12-25-2018, 06:05 PM   #222
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Quote:
Originally Posted by ornicar View Post
Hello,

i am into "constituing" a rear coilover set for my 125i:


- Main spring Eibach 7" Length ; 2,25" ID ; 650 Lb/inch rate ; PN : 0700.225.0650

- Tender Spring Eibach 2,68" Length ; 2,25" ID ; 300 Lb/inch rate ; PN : 0175.225.0300

- HPA Height Adjuster or another good quality one. I appreciate this one because you can fitting a thrust bearing to avoid stress in the spring

https://www.hpashop.com/HPA-E82-E9x-...st-e82-e9x.htm

I have one question:

Does anyone know where i can buying this ball joint coupler "sealed articulating spring perch" in 2,25 Diameter?

TY
I believe ground-control makes one that articulates
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      12-26-2018, 03:41 AM   #223
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Thank you.

Yes i see it, i seems to be a quality product...by the way i didn't find some reviews of these products.

https://groundcontrolstore.com/colle...eight-adjuster

Mechanicaly speaking i am asking what will happen in the main/helper linking?

During drop phases i am not sure that the helper will have enough "force" to re-aligned the main spring.

See Fe1rx Graph.

That is why the Orb ball joint which is located between Main & Helper seems better to me (i am not sure by the way).

If the GC articulating perche is really smooth (-->low friction, so force to moove it) i think it will be OK.

Is it a nylon ball joint?

otherwise these GC articulating perches may not be compatible with helpers?

For more compliance i really wanted to use helpers, so that is why i ask many questions

& Sorry for my poor english speaking, it is not easy to explain mechanical topics , and it is more difficult when it is not in his first language.
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      01-22-2019, 04:05 PM   #224
I am Jacks N54
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Originally Posted by fe1rx View Post
REAR SUSPENSION
1) Installed a 20 mm H&M rear anti-roll bar.
2) Installed TRW upper arm and guide arm.
3) Installed custom rear toe arm.

http://www.1addicts.com/forums/showt...1079383&page=2

4) Installed Powerflex upper shock mount.
5) Changed my rear springs from Swift 120 N/mm to 140 N/mm.

FRONT SUSPENSION
1) Installed custom built camber plates and shock spacers to adjust ride height and reduce spring preload (documented earlier in this thread).
2) Installed new Swift Z65-176-060 (60N/mm) front springs to replace last-year's springs, which had been coil bound and had lost some of their original height.
fe1rx, thank you for this thread. I've read it start-to-finish 3 times now and learn something new each time. A bit of a shame it took a dive at the end with the posturing, but I still find it to be an incredible resource.

I was curious about your rear spring rate move up from 120 N/mm to 140 N/mm along with the increase to 20mm rear sway bar. Seems like a big jump. Would you mind sharing the results and thoughts behind that?
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      01-26-2019, 04:57 PM   #225
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I'll take that as a no.

That rear suspension pivot angle is crazy! Looking at these two products to reel it in

https://www.akgmotorsport.com/produc...e9x-spherical/

https://www.hypercoils.com/perches/
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      01-26-2019, 10:41 PM   #226
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Quote:
Originally Posted by I am Jacks N54 View Post
fe1rxI was curious about your rear spring rate move up from 120 N/mm to 140 N/mm along with the increase to 20mm rear sway bar. Seems like a big jump. Would you mind sharing the results and thoughts behind that?
I was running OE front and rear bars with 60 N/mm front springs and 120 N/mm rear springs and wanted a bit more roll stiffness so that the car took a set faster. I also wanted move the limit handling a bit more towards neutral so I threw all the additional stiffness at the rear.

I found the car still easy to drive (nannies off) at the limit with the stiffer rear springs and rear bar so don't feel I have overdone things. That said, the stiff rear bar won't work well without an LSD (although adding a stiff front bar as well might make it ok - I just don't think the car needs more total roll stiffness than I currently have).

My comments are based on the car's primary function being as a track car.

I have recently gone to spherical bearings at every suspension joint, plus solid rear subframe bushings. I won't have a chance to track the car in that configuration until the Spring, so can't offer any opinion about those changes yet.
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      01-26-2019, 10:52 PM   #227
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Quote:
Originally Posted by I am Jacks N54 View Post
I'll take that as a no.

That rear suspension pivot angle is crazy! Looking at these two products to reel it in

https://www.akgmotorsport.com/produc...e9x-spherical/

https://www.hypercoils.com/perches/
I am not sure that the hypercoil perches will accommodate the degree of articulation that occurs at the rear springs. These perches appear to be designed for a true coil-over application where there is less angular misalignment.

The lower shock mounts can't hurt for a track only car but will likely increase NVH in a street driven car. I presume the only motivation is to get rid of some of the bending in the rear shock. Personally I don't see a lot of benefit. Although there is a fair bit of articulation at the strut attachment, the OE mount seems to be able to deal with it without too much bending moment being passed into the shock (in my opinion).
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      01-27-2019, 06:38 PM   #228
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fe1rx thank you for responding. This is all great information - answers exactly what I was looking for. I appreciate it.

Your assumption is correct on reducing rear bending. I looked around and found Turner offers something similar, but with a reported minimal NVH increase https://www.turnermotorsport.com/p-5...r-shock-mount/. I'll likely go with those and use your spring rates to get me towards a livable dual-duty compromise.

Cheers!
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