MASTER THREAD: Comprehensive Road-Course Modification Guide — Optimizing the 3 for the track

[Lunares]

And the overall quality of the MPP toe and Camber arms is just amazing. They look great particularly combined with the coilovers. Looking forward to getting the traction and trailing arms to finish off the rear suspension.

I'm just disappointed they arent adjustable and apparently no plans to make them so because then "people could mess up adjusting their suspension", or so I was told in the other thread

 

[TexasTeslaRacing]

Ordered Thursday delivered Friday. Fast as they are in Austin. Adjustable traction and trailing arms. On first inspection quality appears to be good. Should be installed this week so I’ll let you know how it goes.

 

[beastmode13]

I'm just disappointed they arent adjustable and apparently no plans to make them so because then "people could mess up adjusting their suspension", or so I was told in the other thread

MPP arms are 100% adjustable. I have able to dial in my rear camber and toe with MPP arms.

 

[dfwatt]

MPP arms are 100% adjustable. I have able to dial in my rear camber and toe with MPP arms.

I think he was probably referring to the trailing and Link arms not the tow in and Camber arms which of course have to be adjustable or otherwise they're useless!

 

[Lunares]

MPP arms are 100% adjustable. I have able to dial in my rear camber and toe with MPP arms.

Yes, as per @dfwatt I meant the new traction and trailing arms not upper camber and toe

 

[ItsMeOK]

Whiteline Adjustable Sway Bar End Links

Can someone explain this more? And link to the ones that we would use?
Do these go on the end of the UP sway bar an allow for more adjustment than the 3 holes?

 

[Ryephile]

Yes, as per @dfwatt I meant the new traction and trailing arms not upper camber and toe

The traction/trailing arms aren't adjustable because there's no rational reason to adjust them, unless you have a compelling need to adjust your wheelbase millimeters at a time.

Can someone explain this more? And link to the ones that we would use?
Do these go on the end of the UP sway bar an allow for more adjustment than the 3 holes?

No. Adjustable drop-links allow you to zero out the anti-roll bar preload after corner balancing your coilover setup, assuming the anti-roll bars you're running are inducing a bias to your corner weights. They also allow for intentional preloading of the anti-roll bars if your chassis setup guy has decided asymmetrical setup works best for the particular track you'll be at next (rare for road-course, absolutely unhelpful for street use).

Basically, if you don't have coilovers, haven't corner balanced your car, and then determined your ARB's aren't "flat", adjustable drop-links aren't helping your setup.

 

[Lunares]

The traction/trailing arms aren't adjustable because there's no rational reason to adjust them, unless you have a compelling need to adjust your wheelbase millimeters at a time.



No. Adjustable drop-links allow you to zero out the anti-roll bar preload after corner balancing your coilover setup, assuming the anti-roll bars you're running are inducing a bias to your corner weights. They also allow for intentional preloading of the anti-roll bars if your chassis setup guy has decided asymmetrical setup works best for the particular track you'll be at next (rare for road-course, absolutely unhelpful for street use).

Basically, if you don't have coilovers, haven't corner balanced your car, and then determined your ARB's aren't "flat", adjustable drop-links aren't helping your setup.

Traction arm adjustment is used to compensate for the bump steer introduced by the upper arm changing length for camber

Bump steer - Wikipedia

 

[TexasTeslaRacing]

Traction arm adjustment is used to compensate for the bump steer introduced by the upper arm changing length for camber

Bump steer - Wikipedia

I have been looking forward to installing traction arms ever since I lowered and installed coilovers. The very next day I noticed bump steer while aggressive driving mid corner. Doesn’t feel stable in some turns.

 

[Ryephile]

Traction arm adjustment is used to compensate for the bump steer introduced by the upper arm changing length for camber

Bump steer - Wikipedia

The traction arm doesn't meaningfully dictate the toe curve, especially in a circumstance where the traction arm is rubber bushed and the toe arm & LCA are spherical bearing. If you're trying to say you want to change the toe curve (to what?), you'd need to change the mounting points [and thus length] of the toe arm, not the length torque arm. Also, changing camber doesn't change the toe curve, just static toe. This is why when you do an alignment you set camber first and then toe.

 

[MountainPass]

Thank you @Ryephile for bringing the knowledge!

The misinformation out there is sickening sometimes, but this man just brought the truth down and we must thank him for it.

Companies and enthusiasts alike are always commenting about the traction and trailing arms for bump steer adjustment, and it DOES NOT WORK. It ends up rotating and/or moving the knuckle - which will just do some of the following undesirable things:

• Increase axle fore/aft offset, prematurely wearing out axles or blowing up axles (I have some stories about racing Genesis Coupes where the axles kept failing after 30+ minutes and guess what the root cause was? - the traction / toe arms were too long, the wheel was too far back, and the axle was running out of travel on the outside of the CV joint and creating a ton of friction, binding and eventually, failing)
• Rotating the knuckle - when you change the length of either the traction or trailing arms, the knuckle will rotate forwards or backwards. This will create bind in the anti-roll bars, and may even cause components to hit (the anti-roll bar will hit the lower arm if it is extended too much)
• Mis-match wheelbase side to side
• Over-extending or compressing the knuckles, resulting in axle failure if there is not enough CV joint travel

As @Ryephile mentioned, if you want to adjust the bump-steer of the platform, you need to do this by adjusting the pickup points - or location of the toe arm. This is a very advanced topic and is really not needed for the Model 3 at this stage. Until all of the rubber has been removed from the back of the car, compliance back there is the main culprit for an unstable and twitchy rear end.

Once the rear suspension is solid, if there is still entry instability (from toe-out in suspension droop), then alterations to rear bump-steer can be investigated. Again, adjustable rear traction and trailing arms WILL not be the place to do this.

Yes those arms may affect bump steer, but it's like saying you can make adjustments to your toe by adjusting camber. It's a backwards way of doing things and to prevent people from getting into trouble and having countless potential issues, we decided to make our arms OE length and non-adjustable. Yes it takes a bit more machine setup time and requires larger blocks of aluminum, but it's worth it to do it this way in our minds.

Sasha

 

[TexasTeslaRacing]

Installed many new parts on the 3 last week. Overall I'm happy with the parts quality and can really feel the difference with more negative camber. The trailing and tractions arms are set at OEM length. Jury is still out of the new arms make a difference. The race shop could only adjust -2.88 negative camber on the front. I was hoping to see -3.0+. For those who want to know what the different shim lengths did to my front camber, here they are.

6mm Shim -2.00
2mm Shim -2.48
No Shim -2.88

Schroth QF Pro was a breeze. I didn't bend back the headrest like other have done and came out great.

Next up are the MPP Spring Arms and Lower Control Arm bushings.

 

[Ryephile]

Installed many new parts on the 3 last week. Overall I'm happy with the parts quality and can really feel the difference with more negative camber. The trailing and tractions arms are set at OEM length. Jury is still out of the new arms make a difference. The race shop could only adjust -2.88 negative camber on the front. I was hoping to see -3.0+. For those who want to know what the different shim lengths did to my front camber, here they are.

6mm Shim -2.00
2mm Shim -2.48
No Shim -2.88

Schroth QF Pro was a breeze. I didn't bend back the headrest like other have done and came out great.

Next up are the MPP Spring Arms and Lower Control Arm bushings.

Thanks for sharing. What ride height are those camber numbers at? (axle centerline to apex of fender please)

The spherical bearing rear toe and camber arms will slightly improve consistency going into, through, and exiting corners at or near the limit. Around town you might not notice any change at all.

 

[beastmode13]

6mm Shim -2.00
2mm Shim -2.48
No Shim -2.88

Thanks for sharing these valuable data. Would you happen to record the toe at each of these shim settings?

 

[SD_Engnr]

Thanks for sharing. What ride height are those camber numbers at? (axle centerline to apex of fender please)

The spherical bearing rear toe and camber arms will slightly improve consistency going into, through, and exiting corners at or near the limit. Around town you might not notice any change at all.

I believe he was referring to whether or not the rear traction and trailing arms will make a difference. Likely the same result that you mention though.

 

[TexasTeslaRacing]

Thanks for sharing these valuable data. Would you happen to record the toe at each of these shim settings?[/QUOT

first pic is 6mm, second 2mm, and last no shims.

 

[MountainPass]

It might be too late now, but you can loosen those top 4 bolts for the upper suspension assembly and push it towards the center of the car for additional negative camber. The holes for those bolts are quite big. The 3 nuts for the dampers looked centered in their holes, which would indicate you can push the assembly in further!

 

[Ryephile]

I believe he was referring to whether or not the rear traction and trailing arms will make a difference. Likely the same result that you mention though.

You're right, I had it in my head he was referring to the rear camber and toe arms. Going spherical with the traction/trailing arms will also improve on-track consistency, the main drawback is NVH transmission of road imperfections into the subframe dramatically increases. There's also a possibility of losing grip on rough and choppy surfaces [at the limit] as there's no rubber to take the edge off the impacts. For example, this is why the Camaro ZL1 1LE is uses spherical bearings everywhere *except* the front and rear torque links.

So, if you're chasing those final tenths on the track, spherical trailing/torque arms make sense after you've already taken care of the basics [coilovers, camber, brakes, tires], however IMO for a road car, or even a track car where you're predominantly on rough tracks, the negative outweighs the benefit.

 

[TexasTeslaRacing]

It might be too late now, but you can loosen those top 4 bolts for the upper suspension assembly and push it towards the center of the car for additional negative camber. The holes for those bolts are quite big. The 3 nuts for the dampers looked centered in their holes, which would indicate you can push the assembly in further!

Thank you! I will try that once the Spring Arms and bushings arrive. If I loosen those bolts to the center can I get negative camber above -3.5? What is the max you have been able to dial in?

 

[Lunares]

You're right, I had it in my head he was referring to the rear camber and toe arms. Going spherical with the traction/trailing arms will also improve on-track consistency, the main drawback is NVH transmission of road imperfections into the subframe dramatically increases. There's also a possibility of losing grip on rough and choppy surfaces [at the limit] as there's no rubber to take the edge off the impacts. For example, this is why the Camaro ZL1 1LE is uses spherical bearings everywhere *except* the front and rear torque links.

So, if you're chasing those final tenths on the track, spherical trailing/torque arms make sense after you've already taken care of the basics [coilovers, camber, brakes, tires], however IMO for a road car, or even a track car where you're predominantly on rough tracks, the negative outweighs the benefit.

I am split on the NVH. Some say it's awful, others say they dont care. My preference is to get all 4 arms done at one time to save on installation cost, but am worried I will be in the too much NVH camp!