Suspension help. Rear end shimmy still.

fmorelli

Colonel
Staff member
Aug 11, 2017
2,120
Virginia
Nice that you can do that. My local Firestone wont touch my car.
Hell my local garage who has done inspections (VA) for 20 years on my cars won't touch my car. They are basically afraid of the car and can't get under it. Crazy.

I'm not a big fan of letting Joe Schmoe do my alignments. I have a guy with good equipment, that knows what he's doing. I pay him what it costs, and it is not a fast process.

Filippo
 

R.G.

Lieutenant
Nov 17, 2016
658
Henderson, NV
Firestone's in my area do not have correct equipment to attach to wheels

Look for shops that specialize in alignments. Ask guys that track their cars as they usually all use the same local shops.
Here's a pic of the alignment tool used by local specialist in V town
 

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ShocknAwe

Lieutenant
Jan 24, 2018
606
SC
Hell my local garage who has done inspections (VA) for 20 years on my cars won't touch my car. They are basically afraid of the car and can't get under it. Crazy.

I'm not a big fan of letting Joe Schmoe do my alignments. I have a guy with good equipment, that knows what he's doing. I pay him what it costs, and it is not a fast process.

Filippo
Oh. I use my local indy performance shop. Dude does good alignments using the full range of adjustability given by all parts. It's worth the money and time.
 

Optigrab

Corporal
Sep 19, 2018
133
Other than the dealership i normally look for a shop with a hunter machine. I believe they can do BMW alignments without ballasts. As far as i know the dealership uses some type of ballast when they do an allighment
 

MDORPHN

Corporal
Jan 28, 2018
119
For a quality alignment you need both good equipment that's been recently calibrated and a tech skilled in doing alignments. Since I track my car, I always have ballast placed on the driver's seat equal to what I weigh when suited up.

Neil
 
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Rob09msport

Captain
Oct 28, 2017
1,164
Monroe CT
Your so lucky to have that guy as friend he really knows his shit and isnt out to make a buck I offered to pay him for helping me set up my suspension and he didn't want. Meanwhile he took more time then the ones that sold it to me .
 

fmorelli

Colonel
Staff member
Aug 11, 2017
2,120
Virginia
Your so lucky to have that guy as friend he really knows his shit and isnt out to make a buck I offered to pay him for helping me set up my suspension and he didn't want. Meanwhile he took more time then the ones that sold it to me .
Good to hear, Rob. He does need to make a buck, like we all do. But he knows his stuff, gives a damn, and takes his time with people. Honestly that makes it harder to make a buck ... but it is the reason why I and others spend our money with him lol. He's also doing a lot of work with Ohlins USA right now focused on filling out the BMW offerings, so for me kinda the go to guy for that.

I had the car at a buck fifty with the top down and it was rock solid with plenty left in the motor. I'm really happy with where the suspension is at. Ready for bigger turbos, clutch, and single barrel. I have a E46 rear end, which is easier to deal with than the E90 rear. Probably going to do a much stiffer rear subframe mount when the turbos go in.

Filippo
 

Rob09msport

Captain
Oct 28, 2017
1,164
Monroe CT
Good to hear, Rob. He does need to make a buck, like we all do. But he knows his stuff, gives a damn, and takes his time with people. Honestly that makes it harder to make a buck ... but it is the reason why I and others spend our money with him lol. He's also doing a lot of work with Ohlins USA right now focused on filling out the BMW offerings, so for me kinda the go to guy for that.

I had the car at a buck fifty with the top down and it was rock solid with plenty left in the motor. I'm really happy with where the suspension is at. Ready for bigger turbos, clutch, and single barrel. I have a E46 rear end, which is easier to deal with than the E90 rear. Probably going to do a much stiffer rear subframe mount when the turbos go in.

Filippo
I should have worded it differently I meant he isnt just trying to take people's money when alot are.
 
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[email protected]

Corporal
Platinum Vendor
Jun 4, 2018
136
Hope I can help some here...

What is the intended use of the car? mostly street, mostly road course, or an even split of both?

Shock mounts:
I would stick with stock for the upper mount. The BMW mounts are bump rubber elastomer material. They are actually quite good. Urethane is a horrible component for suspension material. That's a story for another day. The lower shock mount is the abomination. I am in the middle of designing something better but I'm sure someone sells an articulating bearing version which is what I recommend. However, you are already planning to swap the rear lower control arm (good move) so this doesn't apply.

Rear Spindle Ball joint:
This is already a ball joint from the factory with a nice dust boot. It is NOT a bushing. Not much gain there switching to a spherical bearing.

Rear Trailing Arm Set:
Like @ShocknAwe said... this has no benefit. The factory arm is more than adequate and is designed to bend in the case of an accident and not puncture the gas tank.

Camber Plates:
I definitely recommend the Vorshlag camber plates.

Toe Arm:
Definitely go with the Rogue toe arms. The M3 version will not work but I think you already noted that.

Upper Wishbone, Guide Arm:
As for the upper wishbone and guide arm, this depends on the intended use of the car. The Rogue ones are good if you need the adjustment. If you don't need more than factory camber the OEM M3 arms are a good choice.

Random Note:
Maybe I'm misunderstanding what people mean but this is meant for the e46, not the E9X
https://www.ecstuning.com/b-genuine-bmw-parts/rear-control-arm-right/33326781626/

Basically, the E90 rear suspension is very complicated, too much to really cover here but I'll make a few notes... Suspension geometry plays a huge role on how the car feels under load (acceleration, braking, cornering). The Non M suspension is meant to have certain toe settings under certain conditions, hence all the rubber bushings. It was actually designed to be neutral in cornering and then understeer when at the limit. Below is the toe curve of the rear suspension where red is static, blue is cornering and green is braking. Unfortunately, I don't know what is is under acceleration which is what most people complain about. I'm in the middle of trying to figure it out plus many other geometry differences in detail (winter project)

bump curves.JPG


When you go and change things you change these curves. Not saying its a bad thing just making a point. Its also worth noting that simply putting the m3 arms (lower control arm, wishbone and guide arm) doesn't get you the M3 suspension. The rear spindle has different pickup points than the non M. The rear subframe has different pickup points for the toe arm (hence why the M3 arm is longer) and the rear lower trailing arm (Anti dive). Another note... if you replace every rubber bushing with a ball joint the rear suspension (M or Non M) will be locked into place. If you do get it to move its because an arm is bending.

Anyways, back to the point, once you do all of the items in the rear it may take a while to find a static toe setting that will then work when the suspension is loaded based on your wheels, tires, shocks, ride height, etc. The factory toe settings for the M and Non M will not apply. Someone correct me if I'm wrong but total toe in the rear of an M3 should be 10' and Non M 18'. I'd start with 13' (.21 degrees) total toe in rear and go from there.
 

ShocknAwe

Lieutenant
Jan 24, 2018
606
SC
Phenomenal post @[email protected] !

I'll add one comment to the rear upper RSM, the Dinan RSM is a medium durometer rubber, also allows for 10mm more shock travel to keep you off the rear bump stops for a tiny bit longer. I absolutely agree in not recommending polyurethane. I actually don't recommend using Poly anywhere in the suspension.
 
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[email protected]

Corporal
Platinum Vendor
Jun 4, 2018
136
The only issue with any rubber, poly, etc shock mount, even the BMW ones, is that when the suspension moves up and down, it follows an arc which then puts a side load on the piston shaft if it is not allowed to pivot. This is why I recommend keeping the BMW upper mounts to everyone. They are good in compression/rebound but flex easy to reduce that side load.

As for poly bushings, it is horrible as a suspension component in any location. Poly has slow elasticity meaning when you deform it, it does not want deform or return back to its original shape quickly. Therefore you cannot bond the poly to the inner and outer sleeves as it would just rip apart. Instead what you have to do is not bond it and let it slide against the inner and outer sleeves which is why you have to grease them. Then what happens is the grease traps dirt and grit and turns itself into sandpaper.

This pivoting causes friction which is the enemy to suspension design. This is why all manufacturers use either rubber bushings or ball joints. Rubber bushings are bonded to the inner and outer sleeve therefore have no friction only a spring rate which is easy to account for in suspension design. Ball joints obviously have negligible friction.

Poly also has low plasticity meaning it deforms easy and will not return back to its original shape. So in the case where a bushing is not pivoting (subframe bushing) it still is not good.
 

Optigrab

Corporal
Sep 19, 2018
133
Hope I can help some here...

What is the intended use of the car? mostly street, mostly road course, or an even split of both?

Shock mounts:
I would stick with stock for the upper mount. The BMW mounts are bump rubber elastomer material. They are actually quite good. Urethane is a horrible component for suspension material. That's a story for another day. The lower shock mount is the abomination. I am in the middle of designing something better but I'm sure someone sells an articulating bearing version which is what I recommend. However, you are already planning to swap the rear lower control arm (good move) so this doesn't apply.

Rear Spindle Ball joint:
This is already a ball joint from the factory with a nice dust boot. It is NOT a bushing. Not much gain there switching to a spherical bearing.

Rear Trailing Arm Set:
Like @ShocknAwe said... this has no benefit. The factory arm is more than adequate and is designed to bend in the case of an accident and not puncture the gas tank.

Camber Plates:
I definitely recommend the Vorshlag camber plates.

Toe Arm:
Definitely go with the Rogue toe arms. The M3 version will not work but I think you already noted that.

Upper Wishbone, Guide Arm:
As for the upper wishbone and guide arm, this depends on the intended use of the car. The Rogue ones are good if you need the adjustment. If you don't need more than factory camber the OEM M3 arms are a good choice.

Random Note:
Maybe I'm misunderstanding what people mean but this is meant for the e46, not the E9X
https://www.ecstuning.com/b-genuine-bmw-parts/rear-control-arm-right/33326781626/

Basically, the E90 rear suspension is very complicated, too much to really cover here but I'll make a few notes... Suspension geometry plays a huge role on how the car feels under load (acceleration, braking, cornering). The Non M suspension is meant to have certain toe settings under certain conditions, hence all the rubber bushings. It was actually designed to be neutral in cornering and then understeer when at the limit. Below is the toe curve of the rear suspension where red is static, blue is cornering and green is braking. Unfortunately, I don't know what is is under acceleration which is what most people complain about. I'm in the middle of trying to figure it out plus many other geometry differences in detail (winter project)

View attachment 17129

When you go and change things you change these curves. Not saying its a bad thing just making a point. Its also worth noting that simply putting the m3 arms (lower control arm, wishbone and guide arm) doesn't get you the M3 suspension. The rear spindle has different pickup points than the non M. The rear subframe has different pickup points for the toe arm (hence why the M3 arm is longer) and the rear lower trailing arm (Anti dive). Another note... if you replace every rubber bushing with a ball joint the rear suspension (M or Non M) will be locked into place. If you do get it to move its because an arm is bending.

Anyways, back to the point, once you do all of the items in the rear it may take a while to find a static toe setting that will then work when the suspension is loaded based on your wheels, tires, shocks, ride height, etc. The factory toe settings for the M and Non M will not apply. Someone correct me if I'm wrong but total toe in the rear of an M3 should be 10' and Non M 18'. I'd start with 13' (.21 degrees) total toe in rear and go from there.
Can some of the mentioned issue be eliminated by swapping in the m3 subframe?
 

Hydra Performance

Sergeant
Free Vendor
Jan 31, 2017
252
I cant speak to arm mounting locations but I do know it is quite a bit lighter than the stock subframe
You sure about that? According to RealOEM there is a 2.6kg difference between the two in favor of the non-M subframe, and that's not counting the additional bolt-on braces the M-cars have
 

Torgus

Captain
Nov 6, 2016
1,041
Boston
Hope I can help some here...

What is the intended use of the car? mostly street, mostly road course, or an even split of both?

Shock mounts:
I would stick with stock for the upper mount. The BMW mounts are bump rubber elastomer material. They are actually quite good. Urethane is a horrible component for suspension material. That's a story for another day. The lower shock mount is the abomination. I am in the middle of designing something better but I'm sure someone sells an articulating bearing version which is what I recommend. However, you are already planning to swap the rear lower control arm (good move) so this doesn't apply.

Rear Spindle Ball joint:
This is already a ball joint from the factory with a nice dust boot. It is NOT a bushing. Not much gain there switching to a spherical bearing.

Rear Trailing Arm Set:
Like @ShocknAwe said... this has no benefit. The factory arm is more than adequate and is designed to bend in the case of an accident and not puncture the gas tank.

Camber Plates:
I definitely recommend the Vorshlag camber plates.

Toe Arm:
Definitely go with the Rogue toe arms. The M3 version will not work but I think you already noted that.

Upper Wishbone, Guide Arm:
As for the upper wishbone and guide arm, this depends on the intended use of the car. The Rogue ones are good if you need the adjustment. If you don't need more than factory camber the OEM M3 arms are a good choice.

Random Note:
Maybe I'm misunderstanding what people mean but this is meant for the e46, not the E9X
https://www.ecstuning.com/b-genuine-bmw-parts/rear-control-arm-right/33326781626/

Basically, the E90 rear suspension is very complicated, too much to really cover here but I'll make a few notes... Suspension geometry plays a huge role on how the car feels under load (acceleration, braking, cornering). The Non M suspension is meant to have certain toe settings under certain conditions, hence all the rubber bushings. It was actually designed to be neutral in cornering and then understeer when at the limit. Below is the toe curve of the rear suspension where red is static, blue is cornering and green is braking. Unfortunately, I don't know what is is under acceleration which is what most people complain about. I'm in the middle of trying to figure it out plus many other geometry differences in detail (winter project)

View attachment 17129

When you go and change things you change these curves. Not saying its a bad thing just making a point. Its also worth noting that simply putting the m3 arms (lower control arm, wishbone and guide arm) doesn't get you the M3 suspension. The rear spindle has different pickup points than the non M. The rear subframe has different pickup points for the toe arm (hence why the M3 arm is longer) and the rear lower trailing arm (Anti dive). Another note... if you replace every rubber bushing with a ball joint the rear suspension (M or Non M) will be locked into place. If you do get it to move its because an arm is bending.

Anyways, back to the point, once you do all of the items in the rear it may take a while to find a static toe setting that will then work when the suspension is loaded based on your wheels, tires, shocks, ride height, etc. The factory toe settings for the M and Non M will not apply. Someone correct me if I'm wrong but total toe in the rear of an M3 should be 10' and Non M 18'. I'd start with 13' (.21 degrees) total toe in rear and go from there.
I cannot thank you enough for your input. Any chance you can sell me KWs or are you only an Ohlins dealer?
 
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