Toyota Supra, Ruined by Bump Steer?!?!

[JakeM]

From his explanation, I think if you take away some of the suspension travel by dropping it and adjusting the toe alignment then you should be able to reduce it.

He said just that. You can reduce it but you cannot eliminate it, in his opinion, without upgrading the rear suspension entirely.

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[roadtripper]

JT, I doubt this is causing accidents and don't think any one needs to worry about it if traveling sane speeds! My car is extremely stable under most conditions. I have experienced some weird handling on bad roads sometimes above 120 mph. I went for a great 400 mile drive today and played a little on a remote road. Got her going pretty good on a bumpy mountain road and she handled well, Had to shut her down because a car was coming in the distance. I don't think its any where as bad as the guy in the video claims. But, Any improvement we can figure out here will be welcome. Better is always good. I have thought about it dozens of times if I made the right choice buying the car or if another car would be better. Every time I conclude I love the car and can't think of any other car under 100k that I would prefer! Any race car engineers out there with insight?

 

[roadtripper]

I don't know how it works or what it does, Can the active rear suspension have anything to do with this? Will shutting off the the traction control help troubleshoot this? Never had active suspension on a car before. One of my motorcycles has it but its on two wheels, Much different

 

[jtsang25]

JT, I doubt this is causing accidents and don't think any one needs to worry about it if traveling sane speeds! My car is extremely stable under most conditions. I have experienced some weird handling on bad roads sometimes above 120 mph. I went for a great 400 mile drive today and played a little on a remote road. Got her going pretty good on a bumpy mountain road and she handled well, Had to shut her down because a car was coming in the distance. I don't think its any where as bad as the guy in the video claims. But, Any improvement we can figure out here will be welcome. Better is always good. I have thought about it dozens of times if I made the right choice buying the car or if another car would be better. Every time I conclude I love the car and can't think of any other car under 100k that I would prefer! Any race car engineers out there with insight?

I love the car despite some of the quality issues. Can't think of anything for a better bang for your buck thats not used.

 

[mas921]

I'll need to see the toe curve to be convinced that bumpster is the culprit. JackieDing posted a story on his Instagram that his shop is measuring it, i hope he publishes the whole thing. because; its a 5 way multilink, everything affects everything when the 5 arms are moving.

Keep in mind that MotorTrend reports that Toyota has "fixed it" in the 2021MY,(start reading after the interior shot) which has a revised rear bump stops and retuned diff, no mention to any suspension bushings or geometry changes in the 2021MY:

Where the 2021 changes really make themselves known is on a good winding road. Gone is the tail-wagging-the-dog sensation of the 2020 Supra. In its place is finally a planted, composed sports car. The Supra's chassis now settles nicely into a bend and tracks predictably, its firm but never harsh active suspension helping the Toyota feel planted and balanced.

Since you're now no longer chasing the Toyota's rear end, you can actually focus on your steering inputs.

in the clip he has a JRZ sticker on the front fender, i guess the bumpstops are out of the equation then, so it boils down to the active diff programming.

 

[XtremeMaC]

https://www.supramkv.com/threads/toyota-supra-ruined-by-bump-steer.5377/
@Guff Merge Please

 

[JakeM]

I'll need to see the toe curve to be convinced that bumpster is the culprit. JackieDing posted a story on his Instagram that his shop is measuring it, i hope he publishes the whole thing. because; its a 5 way multilink, everything affects everything when the 5 arms are moving.

Keep in mind that MotorTrend reports that Toyota has "fixed it" in the 2021MY,(start reading after the interior shot) which has a revised rear bump stops and retuned diff, no mention to any suspension bushings or geometry changes in the 2021MY:



in the clip he has a JRZ sticker on the front fender, i guess the bumpstops are out of the equation then, so it boils down to the active diff programming.

If this is the case, I hope we have access to reflash or we can have the dealer flash the 2021 code into our vehicles.

Either way I'll be watching their "progress" on their car as well as taking in feedback from several other sources. Right now it's not a huge concern for me, but down the road when I start pushing the car I really want to sort the car as best as possible.

 

[JakeM]

https://motoiq.com/the-ultimate-guide-to-suspension-and-handling-bump-steer-toe-steer/

Bump Steer

Steering precision and stability are both affected by bump steer. Bump steer is steering input independent of what the driver is doing with the steering wheel created by the suspension moving through its stroke in response to bumps and cornering induced body roll. It is caused by the suspension links moving in different arcs than the steering linkage as the suspension follows its stroke.

A common cause of bump steer on the popular McPherson strut front suspension car is that the lower control arm and the steering tie rod are out of plane and pivoting on a different axis. The difference in the arcs is the amount of bump steer that results. Usually, the further from the design ride height a car is, the worse the bump steer will be as the difference in angles becomes more extreme.

If a McPherson strut suspension has the inner tie rod in line with the lower control arm pivot, bump steer is greatly reduced.

On this race car, a spacer was made to fit in between the steering rack and the inner tie rod to move it outwards which placed it in line with the lower control arm pivot point. This alone got rid of 80% of the bump steer. With the stock steering, this car had a severe issue with bump steer.

This is all great information but it in no way provides a solution to the problem at hand and the example is of toe in the front suspension.

 

[Racevideo]

I'm not a professional driver but I drove my Supra today at speeds which would be abnormally fast on the road. I entered a nice sweeping turn with an irregular surface. I could not get the car unsettled. I had a '98 Viper GTS that I used to take around the same curve. I could not imagine making any sudden changes with the Viper once you were set up for the curve. Correct me if I'm wrong but it seems these problems are a nuisance on the road but only become serious on a track.

 

[JakeM]

https://www.supramkv.com/threads/toyota-supra-ruined-by-bump-steer.5377/
@Guff Merge Please

Sorry I hadn't seen this thread.

 

[Charlie]

This is an issue I've noticed with loading the car into high speed corners and letting off throttle. It gives a wiggle in the rear end. Feels unsafe and unstable. BUT I think this is normal for RWD cars especially ones with lots of torque and a short wheel base. I've experienced this in Miatas as well. I watched the vid, and imo I don't think it's a flaw at all. It's just the nature of abruptly coming off throttle on a RWD car, the suspension will become unsettled.

I live in the Sunshine Coast Queensland Australia and have had my Supra's suspension tweeked by Murray Coote who was a reining rally champion here for decades. He is a recgonised suspension guru and now runs MCA Suspension. When he drove the car the first thing he said is that the bump stop on the springs doesn't allow enough travel, especially in high speed corners and he ajusted it accordingly. I also had a set of KING springs custom made to complete the set up. The result is absolutely perfect. Murray would have the specifications for the springs he made for me and some information of the other changes if you were interested in ordering a set of springs. I kept the standards shocks because I am a fan of the dampening set up on the car. Murray contact details are +61 7 54948177.His website link is https://mcasuspension.com/

 

[JakeM]

I live in the Sunshine Coast Queensland Australia and have had my Supra's suspension tweeked by Murray Coote who was a reining rally champion here for decades. He is a recgonised suspension guru and now runs MCA Suspension. When he drove the car the first thing he said is that the bump stop on the springs doesn't allow enough travel, especially in high speed corners and he ajusted it accordingly. I also had a set of KING springs custom made to complete the set up. The result is absolutely perfect. Murray would have the specifications for the springs he made for me and some information of the other changes if you were interested in ordering a set of springs. I kept the standards shocks because I am a fan of the dampening set up on the car. Murray contact details are +61 7 54948177.His website link is https://mcasuspension.com/

Will he ship to the US?

 

[Brian Clarke]

Bump Steer kits have existed for years though. Drive a GD Chassis Subaru and you'll get it too. You can tune it out.

 

[Charlie]

Will he ship to the US?

Yes

 

[Powaup]

Thank you for sharing this, my conclusions are that the more you lower your car the higher the chance of experiencing bumpsteer but this can be fixed by having a space on the control arm (or new control arms as mentioned in the video)

The good thing is that all these solutions aren't that hard to fix, they'll take time and it sucks that owners will need to dish $ out to fix the problem, but every car has a weird flaw (e9x has rod bearings, e46 has the fractured chassis problems etc..) and if this is the only problem then that's good news

https://motoiq.com/the-ultimate-guide-to-suspension-and-handling-bump-steer-toe-steer/

Bump Steer

Steering precision and stability are both affected by bump steer. Bump steer is steering input independent of what the driver is doing with the steering wheel created by the suspension moving through its stroke in response to bumps and cornering induced body roll. It is caused by the suspension links moving in different arcs than the steering linkage as the suspension follows its stroke.

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