Supra Bump Steer fix...

DavesMK2JZ

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Let’s not forget all the rubber bushings in the rear suspension under load. The flex alone will affect the rear toe regardless of articulation.





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antonio88x

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Just some clarifications on our thoughts:
Does the Verkline kit help with reducing bump steer? Yes, it is engineered to.
Does the Supra come from factory with bump steer? Yes, it is designed to have bump steer, this car handles with a real sense of agility and requires a driver's full attention.
The car 'loses rear toe in' on corner entries, which really helps the car rotate into these corners. It doesn't understeer, at all. On a tighter, twistier track, this can be thrilling and really easy to control, a little loose on the entry, grips up (more toe in) as you exit the corner. But at autobahn speeds or the fearsome Nurburgring, I can also see how it can be unnerving. Especially if Apex is using the car as a rental for customers of all skill levels.

For the majority of us, I think a reasonable ride height and a little more rear toe in will go a long way. If you absolutely hate the Supra moving around under you, well, the Verkline kit is there as an option for you. This is my honest opinion.
I totally read this in your voice :p
 

BA9092

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Would an adjustable front sway bar benefit on the street/highway by introducing some understeer?

The local performance shop that did my alignment threw in a bit of toe-in all around and I love it now. They also track a Supra that they purchased last year and have over a decade of experience with BMW. The owner recommended I try an adjustable front sway bar before doing anything else, even if I don't track it.
 

VA90

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This feels a little bit like a solution in search of a problem. I'm sure this is a good production, but like others have said, I think a bit of rear toe-in would probably suffice.
 

A-I

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Bump steer can be engineered in to the handling of a car or it can be an 'error' via incorrect engineering.
But I can't see how Toyota would have wanted bump steer for a road car, so I have to think it must be an error on their part. (Especially as they knew owners would want to lower their cars with aftermarket products - where bump steer toe angle will be more pronounced).

For a street car you want stability and predictability, and especially both of those for safety on the highway.
For example, say you were driving along a freeway and you are following a line of traffic and accelerate to overtake, reaching a speed of say 75mph, when all of a sudden there are much slower vehicles ahead and you need to brake heavily and possibly need to steer in to an emptier lane at the same time. (A situation that happens a lot on highway driving and more so in rush hour times when traffic can suddenly build up).
....Any amount of bump steer is going to cause real problems for the driver, especially a typical average driver or even one that is used to sports cars.

I just can't see Toyota placing a reasoning of "lively handling" for say track driving above a reason for safety on everyday street driving.

I guess the main question is how bad is the bump steer - I am commenting from a racing background and also from a position of non-ownership at the moment, but keeping an eye on the MkV in case they bring out a manual gearbox option. ;)
 

Rocksandblues

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hasn't presented itself in my 2021 and 4 track days this fall.
Plan to track at least once a month 2021 season and i want bigger brakes and more rubber. But it is either a non to minor issue with the 2021 Supras or it reveals itself closer to the cars limits and beyond my ability- so far.
 
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A-I

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Road surface (wet/dry), tram-lines, power/acceleration, tire wear, even tire tread pattern can make a difference in how much bump steer a car will experience on weight transition to and from the rear axel.
It may be the case that it only becomes apparent with stickier tires, uprated brakes and uprated engine output which would all provide more weight transfer?

Be good to get more feeding back with their experience to build up a better picture.
 

Bflood

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Without replacing the subframe, there are plenty of people saying this is a capable track car with just a couple provisions - with times to prove it. To me, it's right in line with the wind buffeting issue.. if you feel as though it's a problem, then fix it.
 

Ultimateone

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Without replacing the subframe, there are plenty of people saying this is a capable track car with just a couple provisions - with times to prove it. To me, it's right in line with the wind buffeting issue.. if you feel as though it's a problem, then fix it.
Agreed, it's strange with the non owners posting these Youtube videos when you have someone like Jacki Ding, a forum user and winning Global Time Attack racer proving people wrong with the A90 platform.
 

Bflood

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That misha guy bitched about the Supra early on saying the ONLY fix would be revised subframe - fast forward, sub frame comes to market and continues to bash the car because, I suspect, there are enough people wanting to hate on the this car - making it good click-bait.
 

DesmoSD

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Bump steer can be engineered in to the handling of a car or it can be an 'error' via incorrect engineering.
But I can't see how Toyota would have wanted bump steer for a road car, so I have to think it must be an error on their part. (Especially as they knew owners would want to lower their cars with aftermarket products - where bump steer toe angle will be more pronounced).

For a street car you want stability and predictability, and especially both of those for safety on the highway.
For example, say you were driving along a freeway and you are following a line of traffic and accelerate to overtake, reaching a speed of say 75mph, when all of a sudden there are much slower vehicles ahead and you need to brake heavily and possibly need to steer in to an emptier lane at the same time. (A situation that happens a lot on highway driving and more so in rush hour times when traffic can suddenly build up).
....Any amount of bump steer is going to cause real problems for the driver, especially a typical average driver or even one that is used to sports cars.

I just can't see Toyota placing a reasoning of "lively handling" for say track driving above a reason for safety on everyday street driving.

I guess the main question is how bad is the bump steer - I am commenting from a racing background and also from a position of non-ownership at the moment, but keeping an eye on the MkV in case they bring out a manual gearbox option. ;)
Do you really think Toyota engineers would have ignored something of this manner during testing? I'm sure they felt it but I see it more of a limitation with the components that was provided to Toyota. Not to spark the debate of BMW parts Zupra but previous BMW Z4's had this issue.
 

Jah29

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Do we really think this is Toyota’s Problem? I think it is probably a bmw Z4 problem, but people aren’t really tracking those as much and it’s undiscovered. Is there a way to compare the part numbers for the rear subframe and control arms for the supra and it’s twin Z4? I expect them to be the same parts, but would like to know if they really are.

Also M3/M4 people have been re-coding the settings for the LSD. I think it was the first year of the standard M4 that was unstable and the problem was vastly improved by re-flashing the diff settings from the M4 GTS. That description was from memory, so I might have something wrong. The point I’m making is the BMW differential is programable, and has different “tunes” that can make the car more or less unstable.
 

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