Suspension geometry & cornering/handling - Toyota Yaris Forums

sheekeebut · 07-18-2014, 09:26 PM

This is for all you engineering specialists and track goers.

I've just lowered my sedan on Tein Street Basis coilovers, with what measures out to a 1.5" (38 mm) drop. Last week I checked under the car, and my front lower control arm height measures .70" (20 mm) lower at the inner bushing than at the ball joint. Therefore the arm points slightly upwards.

I know that this lengthens roll couple and lowers roll center, especially if the strut is straight up in terms of lateral angle. At the same time, I'm a little worried about it fudging up my camber movement(?) at spirited road twists.

So the questions:

1) Is the Yaris front strut angled laterally (logically inwards?) in any way? How much?
2) What ride height do you track goers tend to go for your overall cornering performance? Calculated and numerical data gathered for tuning, or just seat of your pants tuning?
3) What does a low or even below-ground roll center "feel" like at corners and bumps?
4) Short of getting adjustable ball joints and steering linkages, do I have to raise the ride height a bit (18 mm if struts straight up?) to get back to a lower-control-arm-to-strut angle of 90° or less to optimize performance? As in, does going over 90° mean having already gone beyond good camber and roll center characteristics?
5) Am I overthinking this?

sheekeebut · 07-27-2014, 02:05 PM

A week and a half, and no one's interested in answering any of the questions? Feels worse than just getting full-on flamed..

eablola69 · 07-28-2014, 03:31 AM

Quote:

Originally Posted by sheekeebut

A week and a half, and no one's interested in answering any of the questions? Feels worse than just getting full-on flamed..

#5, yes you might be over thinking it.

Flipper_1938 · 07-28-2014, 09:42 AM

As flimsy as the lower control arm is, if you trow it into a corner too hard....the lower arm is probably going to deflect and your alignment settings are for refernce only.

Bluevitz-rs · 07-29-2014, 10:10 AM

yes, over lowering the car will have negative impact on the camber geometry to a certain extant. But at 1.5" you shouldn't have much issues. The angle between the control arm and the strut is still probably less than 90°.

Rigaud · 07-29-2014, 07:38 PM

Quote:

Originally Posted by Bluevitz-rs

yes, over lowering the car will have negative impact on the camber geometry to a certain extant. But at 1.5" you shouldn't have much issues. The angle between the control arm and the strut is still probably less than 90°.

What about dropped say 2" or 2.5"?

Bluevitz-rs · 07-29-2014, 07:39 PM

I don't know. I don't have a Yaris.

malibuguy · 07-29-2014, 09:22 PM

Mines lowered 1.75~ and it handles awesome...however the ride is not so great

sheekeebut · 07-30-2014, 04:13 PM

Thanks for the feedback!

Mittelklasse · 08-09-2014, 06:17 PM

(1) Did you mean Steering Axis Inclination angle?
If so, then it is 11.30 degrees.

sheekeebut · 08-10-2014, 03:49 AM

Thank YOU Troll-Face-Avatar. You good sir (madame?) have just given me my next topic of research... And in comprehensively answering 1), you have given me the means to answer question 4) objectively.

After soon trying out a slammed-silly civic sedan, I may find my own answer to 3).

All that remains is 2). I think only two practical ways to get this:

Find people who race with coilovers.
Or
Start going to the track.

Hmm..

ilikerice · 08-10-2014, 09:22 AM

I race with coil overs. I have -2.5 camber up front. I lowered mine I believe 2.5-3 inches. I do not know exactly. I run megan coil overs witha 15x7 rim with 225-45 Hankook RS3 tires.

All my adjusting I have done has been how the car feels to me. I like my rear very loose. My tire pressures are 40psi in front and 55psi. This is for autocross. On track days, I drop it to 28psi front and 45psi in the back because the tires get A LOT hotter for longer periods of time.

If you look at my times here:
http://www.buccaneerregion.com/ce-7-14.html
This was my last event. It was a pretty fast event. I do not own a gopro, so I don't have any video of the course. If you are really wanna see how the course was layed out I can link a video for you. I killed the RAW time and Took 1st in Pax.

Each driver is different though. You need to play around with your settings on how you drive. What works for one person on the same car, may not work for another person.

sheekeebut · 08-10-2014, 08:27 PM

And with ilikerice's answer, thread has been concluded. Thanks all. If I remember, I'll add to this thread by describing my crazy low driving experience.

cali yaris · 08-12-2014, 02:38 AM

^ Oh?

ok, I won't post then.

sheekeebut · 08-12-2014, 04:16 AM

Oh, Garm over here holding out on me! Please, share some racing knowledge with the poor folk.

07-18-2014, 09:26 PM	#1
sheekeebut Minimalist Drives: 07 silver sedan Join Date: Jun 2014 Location: Mississauga, GTA, Toronto, ON Posts: 432	Suspension geometry & cornering/handling This is for all you engineering specialists and track goers. I've just lowered my sedan on Tein Street Basis coilovers, with what measures out to a 1.5" (38 mm) drop. Last week I checked under the car, and my front lower control arm height measures .70" (20 mm) lower at the inner bushing than at the ball joint. Therefore the arm points slightly upwards. I know that this lengthens roll couple and lowers roll center, especially if the strut is straight up in terms of lateral angle. At the same time, I'm a little worried about it fudging up my camber movement(?) at spirited road twists. So the questions: 1) Is the Yaris front strut angled laterally (logically inwards?) in any way? How much? 2) What ride height do you track goers tend to go for your overall cornering performance? Calculated and numerical data gathered for tuning, or just seat of your pants tuning? 3) What does a low or even below-ground roll center "feel" like at corners and bumps? 4) Short of getting adjustable ball joints and steering linkages, do I have to raise the ride height a bit (18 mm if struts straight up?) to get back to a lower-control-arm-to-strut angle of 90° or less to optimize performance? As in, does going over 90° mean having already gone beyond good camber and roll center characteristics? 5) Am I overthinking this?

07-29-2014, 09:22 PM	#8
malibuguy Obsessed with 1.5L Drives: '10 PW Yaris Sedan Join Date: Feb 2011 Location: Westminster, MD Posts: 908	Mines lowered 1.75~ and it handles awesome...however the ride is not so great __________________ -Greg...the Exhaust Freak. -10 PW sedan 107whp/110wtq, full exhaust, suspension bits, TRD LSD -06 Highlander 3mzfe Limited AWD -82 Malibu, 1uzfe swap -97 Tercel coupe, 1nzfe/4.31 -96 Tercel coupe, Turbo 5efe, autoX -96 Tercel 4dr

08-10-2014, 09:22 AM	#12
ilikerice Drives: 2010 black yaris Join Date: Oct 2010 Location: savannah, ga Posts: 2,868	I race with coil overs. I have -2.5 camber up front. I lowered mine I believe 2.5-3 inches. I do not know exactly. I run megan coil overs witha 15x7 rim with 225-45 Hankook RS3 tires. All my adjusting I have done has been how the car feels to me. I like my rear very loose. My tire pressures are 40psi in front and 55psi. This is for autocross. On track days, I drop it to 28psi front and 45psi in the back because the tires get A LOT hotter for longer periods of time. If you look at my times here: http://www.buccaneerregion.com/ce-7-14.html This was my last event. It was a pretty fast event. I do not own a gopro, so I don't have any video of the course. If you are really wanna see how the course was layed out I can link a video for you. I killed the RAW time and Took 1st in Pax. Each driver is different though. You need to play around with your settings on how you drive. What works for one person on the same car, may not work for another person. __________________ -Derrick- "Racing is important to men who do it well. When you're racing... It's life. Anything that happens before or after, is just waiting."

08-12-2014, 02:38 AM	#14
cali yaris ULTIMATE View User's Garage Drives: 07 Yaris Turbo Join Date: May 2007 Location: Canoga Park, CA Posts: 14,859	^ Oh? ok, I won't post then. __________________ Micro Image forums, online store and shop are now closed. It was a great eight year run, but it was time to focus on other things. I'm still selling parts on eBay under micro*image seller ID and customers can still make requests for anything specific.

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07-27-2014, 02:05 PM	#2
sheekeebut Minimalist Drives: 07 silver sedan Join Date: Jun 2014 Location: Mississauga, GTA, Toronto, ON Posts: 432	A week and a half, and no one's interested in answering any of the questions? Feels worse than just getting full-on flamed..

07-28-2014, 09:42 AM	#4
Flipper_1938 Drives: 2010 Yaris Sedan Join Date: Oct 2010 Location: Kentucky Posts: 529	As flimsy as the lower control arm is, if you trow it into a corner too hard....the lower arm is probably going to deflect and your alignment settings are for refernce only.

07-29-2014, 10:10 AM	#5
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	yes, over lowering the car will have negative impact on the camber geometry to a certain extant. But at 1.5" you shouldn't have much issues. The angle between the control arm and the strut is still probably less than 90°.

07-29-2014, 07:39 PM	#7
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	I don't know. I don't have a Yaris.

07-30-2014, 04:13 PM	#9
sheekeebut Minimalist Drives: 07 silver sedan Join Date: Jun 2014 Location: Mississauga, GTA, Toronto, ON Posts: 432	Thanks for the feedback!

08-09-2014, 06:17 PM	#10
Mittelklasse Problem, officer? View User's Garage Drives: '06 Yaris 5DLB 1.5 Join Date: Oct 2010 Location: Bangkok, Thailand Posts: 71	(1) Did you mean Steering Axis Inclination angle? If so, then it is 11.30 degrees.

08-10-2014, 03:49 AM	#11
sheekeebut Minimalist Drives: 07 silver sedan Join Date: Jun 2014 Location: Mississauga, GTA, Toronto, ON Posts: 432	Thank YOU Troll-Face-Avatar. You good sir (madame?) have just given me my next topic of research... And in comprehensively answering 1), you have given me the means to answer question 4) objectively. After soon trying out a slammed-silly civic sedan, I may find my own answer to 3). All that remains is 2). I think only two practical ways to get this: Find people who race with coilovers. Or Start going to the track. Hmm..

08-10-2014, 08:27 PM	#13
sheekeebut Minimalist Drives: 07 silver sedan Join Date: Jun 2014 Location: Mississauga, GTA, Toronto, ON Posts: 432	And with ilikerice's answer, thread has been concluded. Thanks all. If I remember, I'll add to this thread by describing my crazy low driving experience.

08-12-2014, 04:16 AM	#15
sheekeebut Minimalist Drives: 07 silver sedan Join Date: Jun 2014 Location: Mississauga, GTA, Toronto, ON Posts: 432	Oh, Garm over here holding out on me! Please, share some racing knowledge with the poor folk.