Toyota Supra, Ruined by Bump Steer?!?!

xBADCOMPANYx

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I am running the HKS height Adjustable Sleeve over's, The springs have a higher rate. Doesnt matter because the car had the same bump steer anddddd Numb steering feel before the upgrades. Now with the upgrades...car is enhanced, feels tighter but the issues are still there. No reason to go deeper into modifying a car in my case if the steering is NUMB and Bump steer is there. The entire Subframe in the car needs to be reworked. SPL Kinematics will help but to a certain degree.
Like you said, "this car isnt meant to be seriously tracked out of the gate" - This is somewhat true, but ive been tracking cars, different cars for over 16 years now and this platform is not the best out of the box by any means! Mazda Miata's out of the box, especially the newer RF's are Leagues ahead from this chassis when it comes to how a car should feel on the circuit. Even the Subaru BRZ/FRS feel much more livelier, you can FEEEEEEEEL what the car is doing....that is what its about!
on the HKS kit, raising the car a few mm front and rear recovers that numb feeling you described... most cars that get lowered for appearance suffer from a slower feeling... if you're already messing with suspension, an alignment is a given and will also help the way the car feels. a few track guys and myself are running higher than HKS otb setting.
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Supra Werty

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I am convinced this is 99% bushing deflection and possibly some tire deflection you guys are feeling. Tightening everything up with full spl should virtually eliminate the unwanted movement
 

Rndustries

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Kinda read through the thread. Had to make an account cause Iā€™ve had 7 track days with the Supra.

3 at buttonwillow 2:01
2 at chuckwalla one CW and One CCW 2:05/2:04 respectively
2 at Big willow 1:45

mods:

starting after 3rd Trackday,

W5 pads
Te37SL with r888r
Rbf660

Just like people complained about the body roll, I use the weight transfer and the bump steer to turn the car...

all about driver preference.

he even admits heā€™s known to be biased to Porsche's and Mclarens.

No opinion: Donā€™t trust a dude like that based on his word and take the car out.
 

autopc25

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Kinda read through the thread. Had to make an account cause Iā€™ve had 7 track days with the Supra.

3 at buttonwillow 2:01
2 at chuckwalla one CW and One CCW 2:05/2:04 respectively
2 at Big willow 1:45

mods:

starting after 3rd Trackday,

W5 pads
Te37SL with r888r
Rbf660

Just like people complained about the body roll, I use the weight transfer and the bump steer to turn the car...

all about driver preference.

he even admits heā€™s known to be biased to Porsche's and Mclarens.

No opinion: Donā€™t trust a dude like that based on his word and take the car out.
You have a 2020 or 2021?
 

autopc25

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I am convinced this is 99% bushing deflection and possibly some tire deflection you guys are feeling. Tightening everything up with full spl should virtually eliminate the unwanted movement
I think the guys from Apex in the video said something about bushing deflection.

It does not seem to be entirely bushings or deflection. I think they say there are bad alignments or variances from the factory. That and poorly engineered suspension geometry from the factory. They also mentioned lowering the car can cause problems. The rear suspension issue may not really an issue until someone lowers their car. I thought I read or herd some of the issues are amplified when people lowered their cars. The suspension geometry changes as the car is lowered so the issues are more obvious when lowered.

SPL components would probably help. Probably great for a race car or dedicated track car. But there are tradeoffs for a daily driver or street car. Noise, vibration, harshness and comfort. And continuous maintenance of the links. Not to mention the cost.
 

Bflood

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SPL components would probably help. Probably great for a race car or dedicated track car. But there are tradeoffs for a daily driver or street car. Noise, vibration, harshness and comfort. And continuous maintenance of the links. Not to mention the cost.
As a daily I might feel differently however I like the tradeoff.. Also, it's not as drastic as you might think. It livens the car up with little to no added vibration or discomfort (depending on road quality) SPL says you can go a long time between bushing replacement and when it's time to replace, maintenance costs are low. Up front cost isn't cheap but can be had for $3k if you shop around.
 

handsoffsam

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Going to make a separate post soon with a my opinionated review, but I lapped very hard today in my 21 bone stock turning competitive consistent times (the stock pads are useless but thatā€™s to be expected) and had zero issues with bump steer on a track that has some nasty uneven brake zones. The only thing I did from factory was throw an alignment on it that matched my style. This was also after a previous day in the full wet without issue. There is nothing unpredictable about this car or inherently dangerous.

For those reading at home debating purchasing this car because of ā€œbump steer,ā€ dont. This is such a non-issue that Iā€™m surprised it gained this much traction in the first place. If youā€™ve driven a stock AP1 s2000 or e36, this is not even remotely close to that.

My two cents, more thorough review to come.
 

Pacchin55

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Going to make a separate post soon with a my opinionated review, but I lapped very hard today in my 21 bone stock turning competitive consistent times (the stock pads are useless but thatā€™s to be expected) and had zero issues with bump steer on a track that has some nasty uneven brake zones. The only thing I did from factory was throw an alignment on it that matched my style. This was also after a previous day in the full wet without issue. There is nothing unpredictable about this car or inherently dangerous.

For those reading at home debating purchasing this car because of ā€œbump steer,ā€ dont. This is such a non-issue that Iā€™m surprised it gained this much traction in the first place. If youā€™ve driven a stock AP1 s2000 or e36, this is not even remotely close to that.

My two cents, more thorough review to come.
They made changes to the suspension with the 2021 models to eliminate the bump steer, specifically the bump stops and damper tuning. Still a very real thing for the stock 2020 suspension.
 

Raehan

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I canā€™t say I have seen this at all, not sure why. I run the car at BIR and once at VIR. I tend to brake late and hard. VIR has lots of high speed track leading into some pretty impressive corners and BIR has a long, banked to flat turn from 1 to 2 and then a modest slow into 3 followed by a more than 90 degree turn into 4 that requires some serious braking. There is a short straight from 11 to 12 followed by hard braking and sharp left handed after which you have a brief acceleration before entering 13. I havenā€™t experienced any of this. Friend had a 2010 vette grand sport that was really unstable until he had a front and rear alignment after which car was much better. Iā€™ve had Supra up to 130 before braking. I havenā€™t bumped up against limiter due to HP issues but may after some tuner mods this spring. At least now I understand bump steer and I wonder why some people have issues with it and not others in essentially the same car.
 

1slow_mk5

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Going to make a separate post soon with a my opinionated review, but I lapped very hard today in my 21 bone stock turning competitive consistent times (the stock pads are useless but thatā€™s to be expected) and had zero issues with bump steer on a track that has some nasty uneven brake zones. The only thing I did from factory was throw an alignment on it that matched my style. This was also after a previous day in the full wet without issue. There is nothing unpredictable about this car or inherently dangerous.

For those reading at home debating purchasing this car because of ā€œbump steer,ā€ dont. This is such a non-issue that Iā€™m surprised it gained this much traction in the first place. If youā€™ve driven a stock AP1 s2000 or e36, this is not even remotely close to that.

My two cents, more thorough review to come.
What specs did you set your alignment to?
 

handsoffsam

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What specs did you set your alignment to?
I only changed front and rear toe from stock. Front: 0mm (mine was incredibly out of whack from the factory) / Rear: 1mm total (roughly .5 per side).

I haven't driven a 20 to compare, but the 21 pushes a lot to me even with this setup but that could be a result of the changes between model years. Even with the push it was still a riot to wring out - was surprised when I looked at the AiM and saw what it was clocking stock.
 
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As far as I'm concerned if the dude that races these things professionally says it isn't a problem, it isn't a problem.
they say its uncontrollable but a good alignment takes this away
my car is already doing times with porshce gt3 at my local track and i dont have this issue
glad to anounce that I will be part of the Drivers participating in the Imsa GS with the Supra Gt4

frist practice will be in daytona in January
 
 




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