Touring vs Sport suspension

[frazzer]

My decision was made on how it'll corner. Gleaned from all the videos and chats, the Touring suspension offers more feedback on how much traction there is as it gently rolls into an entry - though less feedback through the wheel to sense what the tyres are doing. Yes I've done track days and all that, but being honest with myself, this would suit me better not having the experience to feel the limits as well when cornering flat.

 

[eclat2emira]

My decision was made on how it'll corner. Gleaned from all the videos and chats, the Touring suspension offers more feedback on how much traction there is as it gently rolls into an entry - though less feedback through the wheel to sense what the tyres are doing. Yes I've done track days and all that, but being honest with myself, this would suit me better not having the experience to feel the limits cornering flat.

Great minds...

 

[Porter]

OK so I thought through this in some detail and really considered the suspension geometry of the car and the opportunity costs of different tuning approaches. The phrase that jumped out at me from Gavan Kershaw's comments in the TST Podcast regarding the difference between the suspensions was "hub control". The Touring suspension has less of it. Or rather, it trades off hub control for ride comfort. How much? We don't know. But I've tried to make some guesses.

I'll walk you through my thought process. Here's the front suspension on the Emira, for reference:

It's a double wishbone car front and rear, with unequal length wishbones, but not extremely unequal. They are fairly similar in length. Double wishbone is great in that it keeps camber very well controlled during vertical bump events, but a challenge in that it experiences camber shift during cornering whenever the body rolls, because whenever it tilts, the body pulls the lower control arm inward and pushes the upper control arm outward. The differing lengths of the upper and lower arms are designed to partially mitigate this camber loss as the body rolls.

Like so:

So as body roll occurs during cornering events, it loses camber on the outside wheel and gains it on the inside wheel, which is the opposite of what you would want for grip. This can be masked or counteracted somewhat by having sufficient static camber (alignment), particularly in the rear, and also a significant amount of caster (steering axis angle) which causes camber gain on the front axle as steering is increased. But ultimately, it's a compromise in both cases. You need to have enough combined camber compensation to keep the tire's contact patch close to level during maximum lateral G forces at both front and rear, and if one axle ends up more well-compensated than the other it changes the balance of handling (oversteer/understeer) at the limit. And the more body roll you have, the more extreme your camber compensation needs to be in order to maintain grip at the limit, while also balancing the compensations appropriately front/rear to retain neutral handling (or something near it).

So, the compromise to be struck on this type of suspension is between A) more suspension travel (lower combined spring rate) which contributes to body roll... and B) less suspension travel (higher combined spring rate) which lowers body roll and prioritizes control over the hub angle and the tire's contact patch during high-G cornering events. By combined spring rate, I mean the combination of the rate of the primary springs and also the anti-roll bar which is a modifier for spring rate during cornering. Comfort on normal road imperfections can be similar between the higher and lower rate setups if the damper is tuned well, but the car equipped with higher primary spring rates will have less suspension travel to work with and therefore won't cope as well with large impacts like potholes. Large bumps mid-corner will be more likely to induce traction loss in the stiffer car.

Higher spring rates effectively lower the roll moment, making the camber loss significantly lower during cornering, so a car with stiffer suspension doesn't need (as) high static camber settings to achieve consistent control over the angle of the tire's contact patch. A car with the softer "Touring" suspension would still not use extreme camber settings from the factory, because that's not a recipe for tire longevity, so it's to be expected that it would roll more onto the outside edge of the tire during fast driving. The rest shouldn't change much... the steering feel should be largely similar, and the car should be absolutely just as rewarding to drive fast, but the handling limits will be a bit lower and the balance of handling will not be as strictly consistent.

So to sum up, my own best guess based on all available info thus far...

• Touring will be more plush on the road, and will have lower handling limits but likely a little more "seat feel" as the body moves around more, and will chew up tires a little faster if you're driving aggressively on twisty roads or on track. This choice is an ideal compromise if your exploration of the dynamic limits will likely remain somewhere below 7/10ths. The lower absolute limits may also make the car more fun for the driver that experiments a bit further, because the handling limits are explorable at lower speeds and will likely be more progressive when encountered.
• Sport will have slightly firmer ride with higher absolute handling limits, with more precise and consistent handling at the limit of lateral grip, and will likely preserve the tires a little better if your pattern of use is very dynamic. Avoid potholes. A better choice if your exploration of the dynamic limits will extend to 9/10ths, whether on track or on mountain roads. Handling limits when reached may be more sudden, since the tire is being worked more comprehensively.
• Still unknown: whether the 80 variations of the Goodyear tire were iterated to address the particulars of the Touring suspension (which will tend to load the edge), or the Sport suspension (which won't as much), or to compromise for both.

If you'd like to play directly with the effect that body roll has on this geometry, there's a live demo applet here that lets you shift the body of a double wishbone car and see the effect on camber angle. I've mocked up some wild ass guesses at the geometry of an Emira, front and rear. At some point I'd like to get the exact geometry measurements of an Emira and build a proper suspension model on there to show it exactly, but for now this super rough, very incorrect version will have to do. It does show the effect of body roll on camber though.

• Emira Suspension Model - Front Guess
• Emira Suspension Model - Rear Guess

I hope all this helps someone else think through it. Recognizing that there's an inherent opportunity cost tied specifically to body roll for double wishbone cars has helped me place it appropriately in the hierarchy of compromises.

Thanks!
Jason Porter

 

[eclat2emira]

OK so I thought through this in some detail and really considered the suspension geometry of the car and the opportunity costs of different tuning approaches. The phrase that jumped out at me from Gavan Kershaw's comments in the TST Podcast regarding the difference between the suspensions was "hub control". The Touring suspension has less of it. Or rather, it trades off hub control for ride comfort. How much? We don't know. But I've tried to make some guesses.

I'll walk you through my thought process. Here's the front suspension on the Emira, for reference:
View attachment 4210

It's a double wishbone car front and rear, with pretty close to equal-length wishbones. That's great in that it keeps camber perfectly controlled during vertical bump events, but a challenge in that it experiences camber shift during cornering whenever the body rolls, because whenever it tilts, the body pulls the lower control arm inward and pushes the upper control arm outward.

Like so:
View attachment 4208

So as body roll occurs during cornering events, it loses camber on the outside wheel and gains it on the inside wheel, which is the opposite of what you would want for grip. This can be masked or counteracted somewhat by having sufficient static camber (alignment), particularly in the rear, and also a significant amount of caster (steering axis angle) which causes camber gain on the front axle as steering is increased. But ultimately, it's a compromise in both cases. You need to have enough combined camber compensation to keep the tire's contact patch close to level during maximum lateral G forces at both front and rear, and if one axle ends up more well-compensated than the other it changes the balance of handling (oversteer/understeer) at the limit. And the more suspension travel you have, the more extreme your camber compensation needs to be in order to maintain grip at the limit, while also balancing the compensations appropriately front/rear to retain neutral handling (or something near it).

So, the compromise to be struck on this type of suspension is between A) more suspension travel (lower combined spring rate) which contributes to body roll... and B) less suspension travel (higher combined spring rate) which lowers body roll and prioritizes control over the hub angle and therefore the tire's contact patch during high-G cornering events. Comfort on normal road imperfections can be similar between the two if the damper is tuned well, but the car equipped with higher spring rates will have less suspension travel to work with and therefore won't cope as well with large impacts like potholes. Large bumps mid-corner will be more likely to induce traction loss in the stiffer car.

Higher spring rates effectively lower the roll moment, making the camber loss significantly lower during cornering, so a car with stiffer suspension doesn't need extreme camber settings to achieve more consistent control over the angle of the tire's contact patch. A car with the softer "Touring" suspension would still not use extreme camber settings from the factory, because that's not a recipe for tire longevity, so it's to be expected that it would roll more onto the outside edge of the tire during fast driving. The rest shouldn't change much... the steering feel should be largely similar, and the car should be absolutely just as rewarding to drive fast, but the handling limits will be a bit lower and the balance of handling will not be as strictly consistent.

So to sum up, my own best guess based on all available info thus far...

• Touring will be more plush on the road, and will have lower handling limits but likely a little more "seat feel" as the body moves around more, and will chew up tires a little faster if you're driving aggressively on twisty roads or on track. This choice is an ideal compromise if your exploration of the dynamic limits will likely remain somewhere below 7/10ths. The lower absolute limits may also make the car more fun for the driver that experiments a bit further, because the handling limits are explorable at lower speeds and will likely be more progressive when encountered.
• Sport will have slightly firmer ride with higher absolute handling limits, with more precise and consistent handling at the limit of lateral grip, and will likely preserve the tires a little better if your pattern of use is very dynamic. Avoid potholes. A better choice if your exploration of the dynamic limits will extend to 9/10ths, whether on track or on mountain roads. Handling limits when reached may be more sudden, since the tire is being worked more comprehensively.
• Still unknown: whether the 80 variations of the Goodyear tire were iterated to address the particulars of the Touring suspension (which will tend to load the edge), or the Sport suspension (which won't as much), or to compromise for both.

If you'd like to play directly with the effect that body roll has on this geometry, there's a live demo applet here that lets you shift the body of a double wishbone car and see the effect on camber angle. At some point I'd like to get the exact geometry measurements of an Emira and build a suspension model on there to show it exactly:

Suspension Geometry Calculator

Quickly and easily see the affect movement has on your suspension set-up and adjust on the fly using the drag and drop editor.

www.racingaspirations.com

I hope all this helps someone else think through it. Recognizing that there's an inherent opportunity cost tied specifically to body roll for double wishbone cars has helped me place it appropriately in the hierarchy of compromises.

Thanks!
Jason Porter

My goodness, I feel like I have just been to suspension school! Thank for those great insights, I've always understood certain basics (effects of camber, castor, etc) but the rest has always felt a bit "dark arts". Well it's all quite bit less dark now thanks to your excellent info - much appreciated!

 

[Wowwitsgau]

OK so I thought through this in some detail and really considered the suspension geometry of the car and the opportunity costs of different tuning approaches. The phrase that jumped out at me from Gavan Kershaw's comments in the TST Podcast regarding the difference between the suspensions was "hub control". The Touring suspension has less of it. Or rather, it trades off hub control for ride comfort. How much? We don't know. But I've tried to make some guesses.

I'll walk you through my thought process. Here's the front suspension on the Emira, for reference:
View attachment 4210

It's a double wishbone car front and rear, with pretty close to equal-length wishbones. That's great in that it keeps camber perfectly controlled during vertical bump events, but a challenge in that it experiences camber shift during cornering whenever the body rolls, because whenever it tilts, the body pulls the lower control arm inward and pushes the upper control arm outward.

Like so:
View attachment 4208

So as body roll occurs during cornering events, it loses camber on the outside wheel and gains it on the inside wheel, which is the opposite of what you would want for grip. This can be masked or counteracted somewhat by having sufficient static camber (alignment), particularly in the rear, and also a significant amount of caster (steering axis angle) which causes camber gain on the front axle as steering is increased. But ultimately, it's a compromise in both cases. You need to have enough combined camber compensation to keep the tire's contact patch close to level during maximum lateral G forces at both front and rear, and if one axle ends up more well-compensated than the other it changes the balance of handling (oversteer/understeer) at the limit. And the more body roll you have, the more extreme your camber compensation needs to be in order to maintain grip at the limit, while also balancing the compensations appropriately front/rear to retain neutral handling (or something near it).

So, the compromise to be struck on this type of suspension is between A) more suspension travel (lower combined spring rate) which contributes to body roll... and B) less suspension travel (higher combined spring rate) which lowers body roll and prioritizes control over the hub angle and the tire's contact patch during high-G cornering events. By combined spring rate, I mean the combination of the rate of the primary springs and also the anti-roll bar which is a modifier for spring rate during cornering. Comfort on normal road imperfections can be similar between the higher and lower rate setups if the damper is tuned well, but the car equipped with higher primary spring rates will have less suspension travel to work with and therefore won't cope as well with large impacts like potholes. Large bumps mid-corner will be more likely to induce traction loss in the stiffer car.

Higher spring rates effectively lower the roll moment, making the camber loss significantly lower during cornering, so a car with stiffer suspension doesn't need (as) high static camber settings to achieve consistent control over the angle of the tire's contact patch. A car with the softer "Touring" suspension would still not use extreme camber settings from the factory, because that's not a recipe for tire longevity, so it's to be expected that it would roll more onto the outside edge of the tire during fast driving. The rest shouldn't change much... the steering feel should be largely similar, and the car should be absolutely just as rewarding to drive fast, but the handling limits will be a bit lower and the balance of handling will not be as strictly consistent.

So to sum up, my own best guess based on all available info thus far...

• Touring will be more plush on the road, and will have lower handling limits but likely a little more "seat feel" as the body moves around more, and will chew up tires a little faster if you're driving aggressively on twisty roads or on track. This choice is an ideal compromise if your exploration of the dynamic limits will likely remain somewhere below 7/10ths. The lower absolute limits may also make the car more fun for the driver that experiments a bit further, because the handling limits are explorable at lower speeds and will likely be more progressive when encountered.
• Sport will have slightly firmer ride with higher absolute handling limits, with more precise and consistent handling at the limit of lateral grip, and will likely preserve the tires a little better if your pattern of use is very dynamic. Avoid potholes. A better choice if your exploration of the dynamic limits will extend to 9/10ths, whether on track or on mountain roads. Handling limits when reached may be more sudden, since the tire is being worked more comprehensively.
• Still unknown: whether the 80 variations of the Goodyear tire were iterated to address the particulars of the Touring suspension (which will tend to load the edge), or the Sport suspension (which won't as much), or to compromise for both.

If you'd like to play directly with the effect that body roll has on this geometry, there's a live demo applet here that lets you shift the body of a double wishbone car and see the effect on camber angle. I've mocked up some wild ass guesses at the geometry of an Emira, front and rear. At some point I'd like to get the exact geometry measurements of an Emira and build a proper suspension model on there to show it exactly, but for now this super rough, very incorrect version will have to do. It does show the effect of body roll on camber though.

• Emira Suspension Model - Front Guess
• Emira Suspension Model - Rear Guess

I hope all this helps someone else think through it. Recognizing that there's an inherent opportunity cost tied specifically to body roll for double wishbone cars has helped me place it appropriately in the hierarchy of compromises.

Thanks!
Jason Porter

That photo you linked indeed looks like the arms are equal length. But doesn’t an unequal length design with a shorter upper arm negate those disadvantages you listed and instead promote more negative camber gain during cornering? I’m confused as to why Lotus would go through the trouble to design and use double wishbones but utilize a compromised equal length setup

 

[Porter]

That photo you linked indeed looks like the arms are equal length. But doesn’t an unequal length design with a shorter upper arm negate those disadvantages you listed and instead promote more negative camber gain during cornering? I’m confused as to why Lotus would go through the trouble to design and use double wishbones but utilize a compromised equal length setup

It's not actually equal length, I just used that image for illustration purposes. I'll actually swap it out, now that you mention it. I have a version that shows unequal length but it's not quite as conceptually clear.

If you look closely at the photo of the Emira front suspension, the mounting points for the lower control arm are further inboard than the ones for the upper control arm, and the outer ball joint at the hub for the lower arm is further out than the upper one as well. The upper control arm attaches to a tab on the hub that is probably 30mm inboard from the location of the lower ball joint. I captured this as well as I could in the dynamic model that I linked at the bottom.

But to answer your question... this design has a relatively minor difference in the upper and lower radius. It doesn't negate the camber loss entirely, it just partially mitigates it. It almost certainly doesn't have camber gain during roll events, just slightly less loss. During bump compression without body roll, it should have a very minor amount of camber gain.

 

[Den]

After much deliberation and watching reviews (not that I take much notice or rely on them!), I have decided to get the Sports Chassis with the CUP tyres. After all, it is a Sports Car . The car will hopefully never see a wet road and is a weekend toy with possibly the odd summer long distance trip. I don't think the ride will be as harsh or rattle as much as my current M100 or previous Mk3 Focus RS? I have until early July before my configuration is locked but hopefully will get a test drive beforehand?

 

[hagen111]

When talking spring rates…isn’t it the case that these are highly defined by suspension geometry and the resulting roll centers vs center of gravity? And this is very specific for Lotus’ as they apply a principle of a ‘breathing car’ …and relatively low/soft springs? Can you elaborate?

 

[hagen111]

I am also of the opinion that it is best to opt for the specificly designed flavours; either tour+conti or sports+cup2… and not start mixing these up. Either you like strawberry or you like chocolate icecream.

 

[kitkat]

I am also of the opinion that it is best to opt for the specificly designed flavours; either tour+conti or sports+cup2… and not start mixing these up. Either you like strawberry or you like chocolate icecream.

I’m going with sports suspension and the goodyears for delivery because I fully expect to have a second set of track wheels with whatever tires I want. It’s not like I’m going to push the car to where it this combination might be flawed on the street.

I don’t like the cup 2s and plan on dialing in my own alignment that meets my balance of road and track and not necessarily Lotus’ balance.

 

[xen]

I am also of the opinion that it is best to opt for the specificly designed flavours; either tour+conti or sports+cup2… and not start mixing these up. Either you like strawberry or you like chocolate icecream.

 

[Cutting42]

View attachment 6377

That is just wrong, nearly clicked the report button ;-)

 

[Evotion]

I have decided to get the Sports Chassis with the CUP tyres. After all, it is a Sports Car . The car will hopefully never see a wet road and is a weekend toy with possibly the odd summer long distance trip.

That is my feeling.
For others, especially as a daily, the Touring will be one to go for.

We might never know the answer to this unless somebody spends a day, in both versions, over the same roads, back to back.

 

[Leonard]

I wish they had just done adjustable dampers. With a spring rate difference of 5% I can't see why it's an issue in regards to purity of feel

 

[TomE]

That is my feeling.
For others, especially as a daily, the Touring will be one to go for.

We might never know the answer to this unless somebody spends a day, in both versions, over the same roads, back to back.

And even then it will depend on the type of road, road surface quality and the driver's preferences and abilities.

Several of the reviewers have mentioned the Sports setup is more bumpy and fidgety at lower speeds on mixed roads, which might annoy you if that makes up a big part of your driving. At higher speeds and on better roads there won't be a significant difference.

 

[TomE]

I wish they had just done adjustable dampers. With a spring rate difference of 5% I can't see why it's an issue in regards to purity of feel

It is noticeable. I drove an Evora S (same as Touring) and an Evora GT410 (same as Sports) back to back over the same route and could easily tell the difference. My wife, who has no interest in cars, noticed it from the passenger seat too.

 

[Leonard]

It is noticeable. I drove an Evora S (same as Touring) and an Evora GT410 (same as Sports) back to back over the same route and could easily tell the difference. My wife, who has no interest in cars, noticed it from the passenger seat too.

But surely adjustable dampers could do both with little difference to ride. Porsche PASM is night and day between normal, sport and sport plus with the same springs and is also continuously working no matter what mode u are in. Just seems like the obvious option for a wider reaching Lotus. Not sure y Gav says its a compromise when it's just valves and a reservoir with an ecu

 

[NicolasB]

That is my feeling.
For others, especially as a daily, the Touring will be one to go for.

We might never know the answer to this unless somebody spends a day, in both versions, over the same roads, back to back.

Like Harry did? 😄

 

[Jonhklee]

Like Harry did? 😄

It’s a Lotus, compliance came from the lightweight and use of passive dampers…. Something tells me the Touring is the more lotus setup as a road car.

 

[kitkat]

I wish they had just done adjustable dampers. With a spring rate difference of 5% I can't see why it's an issue in regards to purity of feel

Cost and weight probably?

Personally I’ll likely just be putting a set of custom 3-way adjustable dampers in. That way I can dial out some high speed compression if I feel like the car is too much for the road.

Something else I’ve always wanted to play with is a standalone DSC kit so I can tune my own dampers electronically.