Chassis rigidity improvements

[VA90]

I just drove a new Porsche Cayman GTS in the back roads and the suspension and chassis was on another level. I then drove my Supra on the same road and noticed the stock suspension felt a bit bouncy over bumps compared to the Cayman, feeling a bit under damped. I could also feel some chassis bending in the Supra over the larger bumps. This has got me thinking of what I can do to approach the dynamics of the Cayman.

Can a set of coilovers get the damping to Cayman levels?

Does chassis bracing help with chassis dynamics? Has anyone done back-to-back driving tests of the CUSCO front struts tower brace? Does it help? How about the rear power brace? I can also bolt in a stiff harness bar, or maybe a half cage. Are these components strong enough to make a difference?

Lot to unpack here. Let's start with your use case: how are you primarily using your Supra and for what situation(s) are you trying to optimize the suspension? Daily driving? Back roads? Track? With the exception of the SPL arms (which are probably a good idea no matter what) that (+ budget) will inform what you should do.

I'd also challenge you to spend more time in the Supra and diagnose what you are trying to solve for. Is it too much body roll? Do you not like the turn-in? Something else? I think you want to be thoughtful and specific about what you're hoping to accomplish.

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[jtsang25]

The 2021+ bars are aluminum, not steel. Do you have any additional braces on your 2020?

Seriously analyzed my comment based on me calling it steel and not aluminum. My bad for not memorizing all the materials on the car.

 

[Superooo]

The chassis bend feeling is when I hit a 2-3 inch bump on one corner at about 50mph. You can feel the shockwave travel from the front of the car to the back of the car and from one side to the other very quickly, unsettling the car instead of just absorbing the bump. As mentioned before, this could be caused by the bushings too. I experience a similar sensation, albeit significantly more pronounced in my 2018 Subaru Crosstrek, which I’ve driven pretty hard for 60k miles and abused the suspension. In that car you can definitely feel the chassis flexing.

Since the Supra is a second car and my commute is very short, I’d like it to be mostly a canyon carver. I live 10 minutes away from the Santa Cruz mountains and hit the back roads at least once a week. After having had the car for 2 years, I feel like it’s quite soft now.

My main gripe with the handling of the Supra is the high frequency (5+ Hz) bouncing when going over bumps or even when changing directions. During fast direction changes, it feels like the suspension is under damped (or the bushings are too soft and basically not damped). Mid-corner bumps that would not unsettle the Cayman cause the Supra some significant headaches, especially on the back axle. It feels like the damping and spring rates aren’t a great match on that axle. My guess is also that the variable dampers have significant non-linearities, causing some bumps to be absorbed pretty harshly.

The static mid-corner body roll isn’t too much of a problem as I’m pretty smooth and just let the car settle into a turn. It would definitely be a plus if the body roll was reduced though.

I’m definitely not looking for a smooth GP circuit race car, but I’d like a more nimble and responsive handling while still keeping the GT ethos of the Supra.

 

[suicidaleggroll]

The chassis bend feeling is when I hit a 2-3 inch bump on one corner at about 50mph. You can feel the shockwave travel from the front of the car to the back of the car and from one side to the other very quickly, unsettling the car instead of just absorbing the bump. As mentioned before, this could be caused by the bushings too. I experience a similar sensation, albeit significantly more pronounced in my 2018 Subaru Crosstrek, which I’ve driven pretty hard for 60k miles and abused the suspension. In that car you can definitely feel the chassis flexing.

Since the Supra is a second car and my commute is very short, I’d like it to be mostly a canyon carver. I live 10 minutes away from the Santa Cruz mountains and hit the back roads at least once a week. After having had the car for 2 years, I feel like it’s quite soft now.

My main gripe with the handling of the Supra is the high frequency (5+ Hz) bouncing when going over bumps or even when changing directions. During fast direction changes, it feels like the suspension is under damped (or the bushings are too soft and basically not damped). Mid-corner bumps that would not unsettle the Cayman cause the Supra some significant headaches, especially on the back axle. It feels like the damping and spring rates aren’t a great match on that axle. My guess is also that the variable dampers have significant non-linearities, causing some bumps to be absorbed pretty harshly.

The static mid-corner body roll isn’t too much of a problem as I’m pretty smooth and just let the car settle into a turn. It would definitely be a plus if the body roll was reduced though.

I’m definitely not looking for a smooth GP circuit race car, but I’d like a more nimble and responsive handling while still keeping the GT ethos of the Supra.

I felt the same with mine. There’s this one corner by my house, it’s an upward sweeping right hand turn with a few small bumps in the middle. My WRX on snow tires is comfortable going 40-45 through it without much drama to give a reference point, you can feel a little bit of understeer but that’s about it.

The Supra felt nervous at 45, moreso than my WRX on snow tires, and at 50 it felt like the rear was going to give out on every one of those bumps. Like you said, any small bump in the rear felt like a shockwave that unsettled the entire car. Springs helped a bit, as did sways and an alignment, but not nearly as much as I felt they should, that uneasiness was always there. The full set of SPL arms fixed it though, it’s now comfortable cruising through that turn at 55+ without a care in the world, and the bumps just feel like regular bumps.

Of course it was probably just 2-3 of the arms that really did it, but since I did them all at once I couldn’t say which one(s).

 

[NitroYellowMKV]

The full set of SPL arms changes the feel dramatically and removes the slop when hitting bumps. I’ve done springs, F/R sways, and the full set of SPL arms, and the arms made far and away the biggest difference in removing that disconnected/floaty/bouncy feeling of the stock suspension.

pls share ur alignment specs...

 

[Superooo]

How is the NVH after going to solid bushings?

 

[FLtrackdays]

Friend of mine drove this Saturday, WRL at Barber and won. It was a 9 hour race and he split the driving time with another guy. He did say the Supra is “no joke”. His words, not mine. Guess that jinxed him. This is who won the following day:

I can only speak for myself. It doesn’t take a lot to get the Supra buttoned down. Sway bars and SPL bits are a huge improvement, imo. With @suicidaleggroll on this. My car feel absolutely incredible after those additions. I would start with sway bars 1st. They’re a very inexpensive upgrade I really think you’d like @Superooo

Point being, for tens of thousands le$$, you can really get your Supra quite capable on track & even compete with the Porsches you’re speaking of

 

[suicidaleggroll]

pls share ur alignment specs...

 

[NitroYellowMKV]

I really wanna do the SPL arms. I think the stock floaty feeling under quick steering and slight float under direction changes on full throttle is really getting to me… even just doing a pull on the highway I feel the looseness in the back end

 

[razorlab]

Rear traction and toe arms with a good alignment pretty much evaporates all the rear oddities with the 2020.

 

[Nocturnal LE]

Rear traction and toe arms with a good alignment pretty much evaporates all the rear oddities with the 2020.

Both the rear traction links and the rear upper arms are most critical? I want to upgrade, but SPL sells so many different components it is hard to identify best price to performance benefit. They also have rear toe links, swaybar endlinks, and bumpsteer adjustable tie rod ends.

 

[razorlab]

Both the rear traction links and the rear upper arms are most critical? I want to upgrade, but SPL sells so many different components it is hard to identify best price to performance benefit. They also have rear toe links, swaybar endlinks, and bumpsteer adjustable tie rod ends.

Rear toe arms do the same as the toe links. The term toe links are usually reserved for the front as it's literally a link at the end of the steering rod ends. At the rear, it's a full bar from the subframe to the hub.

In the rear, I only have the SPL traction bars and toe arms, and the weird mid corner bump upsetting the car dynamic is completely gone. The two top bars (upper arms) are still OEM.

 

[Nocturnal LE]

Rear toe arms do the same as the toe links. The term toe links are usually reserved for the front as it's literally a link at the end of the steering rod ends. At the rear, it's a full bar from the subframe to the hub.

In the rear, I only have the SPL traction bars and toe arms, and the weird mid corner bump upsetting the car dynamic is completely gone. The two top bars (upper arms) are still OEM.

ahh ok that's good then... looks like that install can be done pretty easily

 

[razorlab]

ahh ok that's good then... looks like that install can be done pretty easily

Really easy. Hardest part is aligning the OEM lower spherical when re-installing.

 

[sams2k]

i have a 22 model, i also was feeling the same when the car was stock.
i did -
cusco front and rear sway bars
megan racing rear toe arms
power flex front radius arm to chassis bush with caster adjustment
a good alignment
my car feel amazing now and i can drive it so much faster in the back roads compare to stock.
another thing i really notice is that the traction is working much better and let me drive much faster and not turning on as fast as before, in back roads i always drive with traction half off(one push on the button).
the car still feel great and very comfortable in daily use.

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