Si's Helical LSD - Locking and Unlocking in fast turns

[sibanez]

Just curious... Is upgrading to a bigger FSB specific to the OP because of how much power he is running? where as stock power would be okay with just a RSB? I only ask because due to regulations in GS most everyone i see changes the Rear vs the Front with good results. May have answered my own Q but im guessing this is a trade off you have to make to qualify for GS... where as if you could, you'd install the bigger FSB as well for optimal performance?

The front sway bar is important on these cars.

For example, people who autocross the 8th gen Civic SI tend to upgrade the FSB instead of the rear. The front sway bar helps keep the tires planted, ensuring power is put down equally.

Street class autocross only allows on sway bar change. On the 10th, it appears that the fastest drivers are going with a bigger RSB to help improve turn-in. You have to keep the FSB, but I have no idea why you would want to remove it, anyway. Without it, the car isn't going to power out of turns as well, and you'll lose a lot of high-speed stability.

STH autocross rules allow you to change both sway bars and the few 10th gens I've seen are running both.

For the new SCCA TT series, you can swap both sway bars, springs and shocks (but can't run coilovers). The HPD package is popular for 8th gen Civics.

I've found that a CTR rear sway bar and running 5-7 pounds more air pressure in the rear helps. Some people reverse stagger, running 225/45/17s in the back and 255/40/17s in the front. I prefer a square setup, but the faster guys are all reverse staggered.

OP mentioned that he was worrying about the FSB inducing understeer. These cars rotates well with a bigger RSB, he's trading stability and power delivery for a little bit of turn-in . . . not worth it, especially when you have to come out of the turn.

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[Yonder]

The front sway bar is important on these cars.

For example, people who autocross the 8th gen Civic SI tend to upgrade the FSB instead of the rear. The front sway bar helps keep the tires planted, ensuring power is put down equally.

Street class autocross only allows on sway bar change. On the 10th, it appears that the fastest drivers are going with a bigger RSB to help improve turn-in. You have to keep the FSB, but I have no idea why you would want to remove it, anyway. Without it, the car isn't going to power out of turns as well, and you'll lose a lot of high-speed stability.

STH autocross rules allow you to change both sway bars and the few 10th gens I've seen are running both.

For the new SCCA TT series, you can swap both sway bars, springs and shocks (but can't run coilovers). The HPD package is popular for 8th gen Civics.

I've found that a CTR rear sway bar and running 5-7 pounds more air pressure in the rear helps. Some people reverse stagger, running 225/45/17s in the back and 255/40/17s in the front. I prefer a square setup, but the faster guys are all reverse staggered.

OP mentioned that he was worrying about the FSB inducing understeer. These cars rotates well with a bigger RSB, he's trading stability and power delivery for a little bit of turn-in . . . not worth it, especially when you have to come out of the turn.

With your current setup, have you encountered any symptoms like OP has with your CTR RSB?

 

[sibanez]

With your current setup, have you encountered any symptoms like OP has with your CTR RSB?

The 10th generation Civic SI has a lot of mechanic grip that is evident during HPDE and autocross runs. I have my negative camber maxed out up front, the factory front sway bar and the CTR bar in the rear. The car rotates predictably and puts power down smoothly. It's very sharp in transitions and slaloms, and the LSD can nicely the car through turns, if you don't go too crazy with the throttle.

I've never experienced what OP is reporting, but I kept my front sway bar on and not running a tune. Once you put a tune on these cars, I think a bigger FSB is needed to keep the tires planted, that's usually the trick for autocross or track use.

It's good that OP is experimenting with different settings and changes. Sway bars are interesting because they basically increase spring rate and there is a lot of debate about what works and what doesn't.

For most FWD cars, bigger rear sway bar will boost rotation and a bigger front sway bar will increase grip and keep the car planted.

 

[teders]

Reading through topics in the tracking section of civicx, and this topic came across my eyes. I'll share my observation, which seems to be exactly the opposite of what OP saw.

So to start off, my Si sedan is not stock. its currently pushing about 320 wheel, has fortune 500 coilovers, and 17x9 RPF1s. I'm on Michellin pilot sport AS3+, and also have my alignment dialed in for street/daily as that is the majority of what i do, so basically the OEM ranges on toe and camber. It's my daily driver first and foremost, with occasional track use. To that end, for the last 6 months i've been attending some winter trackcross events and have not at all felt the need for more mechanical grip up front. Quite the opposite actually. I've been noticing the back end wants to loosen up much sooner than the front, especially in long high speed turns. It has become my meter for determining how close i am to "the line", and is a very predictable limit which i try to avoid. Most notably in those long sweeper turns; as soon as i feel like the rear is getting light and moving a little too much (oversteer), i ease up off the throttle. If the rear feels planted, i ease into the throttle and never feel the front end ploughing wide. The car is more prone to oversteer and the back has slipped out a few times, but i've been able to catch everything so far and sort of dance the car back into a straight line. Have honestly NEVER felt any understeer.

Like i said, the events i've been going to have been trackcross during winter time (40s-50s though), so it could just be an issue of not enough heat getting to the rear tires. After all, each run only lasts about a minute and then the car sits for 10-15 minutes before going again.

 

[CanadiaegeanBlue]

How I came to the earlier conclusion, and what may have been regarded as an extreme opinion is from having a highly experienced track driver, Dave from Speed Academy in this case verify what I was feeling too. You can hear it audibly in the video, and when Dave told me he experienced something similar in a stock 10th Gen Si on the same track, but not with a CTR that's what I pointed it to.

I'm making quite a lot of suspension changes this season, will try various tire PSI, and then attempts the same turns in different manner to see what helps. Turn 1 isn't the smoothest, and it could just be the track surface. I'm also planning on attending other events at other road courses this year so let's see how it all performs

 

[eye-5]

I would check your spring rates and shock travel. I autocrossed and tracked an RSX Type S a long time ago 2005-2008. I found very stiff spring rates and no front sway bar was the best for putting down power and turn in. I did have a Quaife LSD in it as they were open diff from the factory. I also found a reverse stagger to be fastest. I think I was running 245s up front and 225s in the back.

 

[burgermeister]

I have zero experience tracking FWD cars.

Still, I would think a bigger front anti roll bar would be detrimental in a FWD car. A stiffer bar will unload the inside front tire more than a less stiff bar - this seems directionally incorrect. Lots of cars lift front tires - old 911's readily do it on street tires, E36 BMW's will do it with slicks. They deliberately bias the roll stiffness distribution to the front so the driving tires stay on the ground. VW Rabbits tend to lift a rear tire instead. I would think a Civic should do the same - lift a rear before a front.

Helical LSDs, from what I understand, cease to work as an LSD if the inside wheel lifts off the ground.

As to roll stiffness distribution - has anyone measured, or calculated, it for their Civic, stock or otherwise?

 

[L8apex]

I have zero experience tracking FWD cars.

Still, I would think a bigger front anti roll bar would be detrimental in a FWD car. A stiffer bar will unload the inside front tire more than a less stiff bar - this seems directionally incorrect. Lots of cars lift front tires - old 911's readily do it on street tires, E36 BMW's will do it with slicks. They deliberately bias the roll stiffness distribution to the front so the driving tires stay on the ground. VW Rabbits tend to lift a rear tire instead. I would think a Civic should do the same - lift a rear before a front.

Helical LSDs, from what I understand, cease to work as an LSD if the inside wheel lifts off the ground.

As to roll stiffness distribution - has anyone measured, or calculated, it for their Civic, stock or otherwise?

Your roll stiffness logic is correct. And yes, older 911s will lift a front wheel while cornering, but I think a lot of that has to do with their extreme rear weight bias.

But what I’ve seen on here from owners tracking these cars, is that the extra roll stiffness benefits the front Macpherson strut design. Due to the lack of camber gain with this suspension, static camber goes to positive very quickly with body roll. Unlike dual wishbone suspensions that keep the contact patch (relatively) flat as the body rolls.

Disclaimer, I have not tracked this car, but I used to in my EK. So someone please correct me if I’m wrong.

 

[teders]

Your roll stiffness logic is correct. And yes, older 911s will lift a front wheel while cornering, but I think a lot of that has to do with their extreme rear weight bias.

But what I’ve seen on here from owners tracking these cars, is that the extra roll stiffness benefits the front Macpherson strut design. Due to the lack of camber gain with this suspension, static camber goes to positive very quickly with body roll. Unlike dual wishbone suspensions that keep the contact patch (relatively) flat as the body rolls.

Disclaimer, I have not tracked this car, but I used to in my EK. So someone please correct me if I’m wrong.

You're not wrong, at least not about the camber. When i was within the factory alignment specs (less than 1 deg negative camber in the front), i would hear a TON of tire squeal as the vehicle would roll to the outside edge , overloading the outer edge of the tires. Just 2 deg negative camber was enough to clear that up.

With regard to the entire topic of this thread, the Si and Type R share the exact same helical LSD. So i think that the basis of OP's anecdote with Dave from speed academy might be too subjective. I think that any perceived differences in handling characteristics between the Type R and Si are going to be more a function of the Type R's dual axis strut geometry than a difference in LSD tech.

 

[burgermeister]

I think dual axis struts are designed to minimize the offset between the steering axis and the center of the wheel, which in turn minimizes torque steer.

lots of roll stiffness and lots of negative camber makes sense. I would distribute the additional roll stiffness between front and rear rather than add it solely to the front.

 

[CanadiaegeanBlue]

Hello all, been some time since I

You're not wrong, at least not about the camber. When i was within the factory alignment specs (less than 1 deg negative camber in the front), i would hear a TON of tire squeal as the vehicle would roll to the outside edge , overloading the outer edge of the tires. Just 2 deg negative camber was enough to clear that up.

With regard to the entire topic of this thread, the Si and Type R share the exact same helical LSD. So i think that the basis of OP's anecdote with Dave from speed academy might be too subjective. I think that any perceived differences in handling characteristics between the Type R and Si are going to be more a function of the Type R's dual axis strut geometry than a difference in LSD tech.

Hello all, been some time since the last update. I made a few changes last year after not being satisfied with the setup in 2019. List of changes in 2020:

- Reverted to factory dampers with Whiteline Springs
- Added the Whiteline 27mm Front Sway Bar
- Added the Whiteline Anti Lift Kit
- Upgraded from the Whiteline 22mm Rear Sway Bar to the 26mm Rear Sway Bar

Front Camber -0.8, Rear Camber -1.8, Toe 0 all around, Anti Lift Kit adds about 1 degree of positive Caster over factory piece.

With the addition of the Front Sway Bar and Anti Lift Kit, and reverting to stock dampers with springs (I can accept responsibility for perhaps not having set the past coilovers up right), the car's handling has dramatically improved! No weird locking/unlocking of the diff or bouncy suspension, the car just turns in, grips and shoots out of the corners! Even on the road I'm enjoying how much more feedback I get from the wheel from adding the ALK.

Here's the last outing at a different track this time. I also went to the same track from my original post a week after this footage, and the car handled a lot better than it did in 2019. The tires (Continental Extreme Contact Sport) although fantastic for street and light track use tend to get greasy after 4 laps, and start understeering at the limit. Lack of negative camber also doesn't help at the limit so I'm looking forward to the adjustable ball joints.



Changes proposed for Spring-Summer 2021:
- Switch to Swift Spec-R Springs. The Whiteline Springs strike a great balance between daily and trackable, I'll be ready to go more aggressive mid-summer after a few more outings on the Whiteline
- Add Whiteline Adjustable Lower Ball Joints. Tested these on @Thusee's Si, the added camber will certainly help negating some understeer at the limit
- Wheels and Tires: awaiting delivery of Enkei PF09 18x9 ET42 with 265/35R18 Toyo R1R tires

@L8apex @teders @burgermeister thank you for chiming in, I've definitely been learning a lot as I took the build more in this direction, studying suspension geometry more, and testing various setups for my shop the last year

 

[teders]

Hello all, been some time since I


Hello all, been some time since the last update. I made a few changes last year after not being satisfied with the setup in 2019. List of changes in 2020:

- Reverted to factory dampers with Whiteline Springs
- Added the Whiteline 27mm Front Sway Bar
- Added the Whiteline Anti Lift Kit
- Upgraded from the Whiteline 22mm Rear Sway Bar to the 26mm Rear Sway Bar

Front Camber -0.8, Rear Camber -1.8, Toe 0 all around, Anti Lift Kit adds about 1 degree of positive Caster over factory piece.

With the addition of the Front Sway Bar and Anti Lift Kit, and reverting to stock dampers with springs (I can accept responsibility for perhaps not having set the past coilovers up right), the car's handling has dramatically improved! No weird locking/unlocking of the diff or bouncy suspension, the car just turns in, grips and shoots out of the corners! Even on the road I'm enjoying how much more feedback I get from the wheel from adding the ALK.

Here's the last outing at a different track this time. I also went to the same track from my original post a week after this footage, and the car handled a lot better than it did in 2019. The tires (Continental Extreme Contact Sport) although fantastic for street and light track use tend to get greasy after 4 laps, and start understeering at the limit. Lack of negative camber also doesn't help at the limit so I'm looking forward to the adjustable ball joints.



Changes proposed for Spring-Summer 2021:
- Switch to Swift Spec-R Springs. The Whiteline Springs strike a great balance between daily and trackable, I'll be ready to go more aggressive mid-summer after a few more outings on the Whiteline
- Add Whiteline Adjustable Lower Ball Joints. Tested these on @Thusee's Si, the added camber will certainly help negating some understeer at the limit
- Wheels and Tires: awaiting delivery of Enkei PF09 18x9 ET42 with 265/35R18 Toyo R1R tires

@L8apex @teders @burgermeister thank you for chiming in, I've definitely been learning a lot as I took the build more in this direction, studying suspension geometry more, and testing various setups for my shop the last year

Good stuff man, love reading about other track focused builds on here. Nobody around me wants to take their Si or even Type R to the track, all they care about are windshield banners, smoked side markers, and stance. Just shoot me already.

I've also been learning a lot about suspension geometry. I paid for a motorsport suspension alignment course through racecrafthq.com. Its good to know the how changes to things like wheel size/offsets, ride height, tire pressure, etc will have on things like roll center, bump steer and scrub radius. I'm now taking their Data Analysis class and already learning things from my own data on track.


*****


I'm curious what made you want to switch back to the factory dampers. Since i changed to Fortune Auto coilovers, i havent looked back. Maybe if you had the setup that i have you wouldn't have wanted to switch back either. My only issues in the last year have had to do with overheating the factory brakes, so since then i've upgraded to the 27won BBK. So far so good, but the real test will be this upcoming weekend. I think i'll go update my build thread...

 

[CanadiaegeanBlue]

Good stuff man, love reading about other track focused builds on here. Nobody around me wants to take their Si or even Type R to the track, all they care about are windshield banners, smoked side markers, and stance. Just shoot me already.

I've also been learning a lot about suspension geometry. I paid for a motorsport suspension alignment course through racecrafthq.com. Its good to know the how changes to things like wheel size/offsets, ride height, tire pressure, etc will have on things like roll center, bump steer and scrub radius. I'm now taking their Data Analysis class and already learning things from my own data on track.


*****


I'm curious what made you want to switch back to the factory dampers. Since i changed to Fortune Auto coilovers, i havent looked back. Maybe if you had the setup that i have you wouldn't have wanted to switch back either. My only issues in the last year have had to do with overheating the factory brakes, so since then i've upgraded to the 27won BBK. So far so good, but the real test will be this upcoming weekend. I think i'll go update my build thread...

It definitely isn't cheap going this route. I see a few Type R's, and the occasional Si at the tracks here. I've been hooked since my first outing, and now with my shop I've been focusing more and more on chassis and suspension. That site looks like a great resource, I will explore it more.

Here is a great playlist from a shop that happens to be local to me,

I had K-Tuned Coilovers, the ride was pretty choppy unfortunately and they seized up after less than a year's use. Also for my shop I do prefer to test everything so in order for me to make a major push on suspension I went with the complete Whiteline setup, and it's been great. In a few months I'll try out Swift Springs. After I've maxed out the potential with factory dampers, I will look into coilovers again - HKS and Fortune Auto are at the top of my list.

The factory brakes were definitely not up to the task so I got a Brembo retrofit kit from the Gen Coupe. Tried that for 2 years, really good. Only cons are a bit of pad overhang, and confirming wheel fitment is quite a challenge. @Thusee has been running the 27won BBK, it's a stellar kit so just for comparison's sake I'm getting the relatively unknown StopTech BBK in Silver.

 

[teders]

very cool, you'll have to let me know how the stoptech bbk kit is

 

[natethegreat]

Hello all, been some time since I


Hello all, been some time since the last update. I made a few changes last year after not being satisfied with the setup in 2019. List of changes in 2020:

- Reverted to factory dampers with Whiteline Springs
- Added the Whiteline 27mm Front Sway Bar
- Added the Whiteline Anti Lift Kit
- Upgraded from the Whiteline 22mm Rear Sway Bar to the 26mm Rear Sway Bar

Front Camber -0.8, Rear Camber -1.8, Toe 0 all around, Anti Lift Kit adds about 1 degree of positive Caster over factory piece.

With the addition of the Front Sway Bar and Anti Lift Kit, and reverting to stock dampers with springs (I can accept responsibility for perhaps not having set the past coilovers up right), the car's handling has dramatically improved! No weird locking/unlocking of the diff or bouncy suspension, the car just turns in, grips and shoots out of the corners! Even on the road I'm enjoying how much more feedback I get from the wheel from adding the ALK.

Here's the last outing at a different track this time. I also went to the same track from my original post a week after this footage, and the car handled a lot better than it did in 2019. The tires (Continental Extreme Contact Sport) although fantastic for street and light track use tend to get greasy after 4 laps, and start understeering at the limit. Lack of negative camber also doesn't help at the limit so I'm looking forward to the adjustable ball joints.



Changes proposed for Spring-Summer 2021:
- Switch to Swift Spec-R Springs. The Whiteline Springs strike a great balance between daily and trackable, I'll be ready to go more aggressive mid-summer after a few more outings on the Whiteline
- Add Whiteline Adjustable Lower Ball Joints. Tested these on @Thusee's Si, the added camber will certainly help negating some understeer at the limit
- Wheels and Tires: awaiting delivery of Enkei PF09 18x9 ET42 with 265/35R18 Toyo R1R tires

@L8apex @teders @burgermeister thank you for chiming in, I've definitely been learning a lot as I took the build more in this direction, studying suspension geometry more, and testing various setups for my shop the last year

I appreciate these long write ups about track prepped SI's, it has such a good potential to be a decent track/daily driver for quite a bit less than a type R. Next route to a more track focused setup seems to be back to coilovers and possibly a weight reduction ? I wonder how much weight could be lost if you took out the back seats and passenger. Titanium exhaust possibly too. Would like to see your car on those new Enkei's the PF09's look sweet.

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