Thanks for your explanation Jackie! Proper ride height and toe in is key! It's crazy how some guys are changing the entire subframe to fix bumpsteer issues lol
Apex taxi should be and must be fast,safe,and consistent.. Maybe the stock config is just not good enough for them.. Because as they say,going full send is an understatement for them.. But i also feel robert taking the supra bump steer isue to dramatic. Not many people use that car like them. . he might be in a promotional mission for the swap kit
I still say the main reason they are feeling quote on quote instability in the rear is because of the rear rubber bushing deflection. SPL arms will cure probably 99% of this problem
Very interesting! I think what people are complaining about is compliance in the bushes that does lead to "involuntary, unpredictable bump steer". As you pointed out, this is extremely reasonable toe changes over such a range of travel. Good experiment!
Hi Jackie. Very good video. Thank you. However we must also account for the factory bushing flex which might occur under full braking, the forces that act on the suspension arm may cause the tires to toe out even further. I haven't done a full kinematic analysis and maybe it doesn't affect your car as much compared to a stock vehicle as I believe you have aftermarket bushings already ?
I remember my first track day in my AP1 S2000, Streets of Willow going clockwise at turn 11, I was accelerating hard out of turn 11 and then all of a sudden the rear started to step out and then it stepped out faster and I spun in front of 3 cars, thankfully I spun to the outside of the corner but that moment made me respect the S2000 a lot more lol. To be fair I was running on 6 year old Continental Control Contact All Seasons on stock AP1 wheels so that might have affected my handling slightly. I started cording right at the last session lol. Man I can't wait for another track day!
I've driven 2 G29 Z4's, can't comment on A90, but I'm guessing its not too far off, when I do the kick down I do feel the need to correct the car as it goes left or right. Probably needs some rear toe in
Very good critique of the A90 rear toe controversy. I have been at the performance game for decades and learned over time that factory suspension engineers spend months even years in the design and prototype stage of development. Changes to the original design need to be done by a "very" qualified person. Lowering, as you wisely, mention can be over done unless you like a boulevard Chevy with hydraulics and a loud sound system ...
It'd be interesting to see the toe changes under compression on an S2000, I'm planning on getting one soon and it'd be good to have some knowledge about that beforehand
So many youtuber lowering their car and has no issue.. Some even say the car drives better.. And normaly if we changes something in the supsension it is recomended to check the aligment,etc
I mean it all comes down to you really. I've heard mixed reviews but mainly most saying they don't even notice it or they haven't even discovered it and some saying it's probably there but they dont mind how the car drives anyway. I not them but id say it all comes down to your own perspective since there's many different pov's with this issue from what I'm hearing tbh.
@@carboydorifutoparty3976 i only know two guys/side who complained about this bumpstreer.. EAG and Apexs robert mitchel.. The other see it as normal.. At least not as bad as goin mustangs to crowd
dont lower your car beyond 20mm i recomend rsr down springs they lower the car about 15mm and give you about 20% stiffer spring rate put in camber plats up front -2 front and -1.8 degree rear camber a bit of toe in at the back with spl rear toe link and you pretty much solve all your bump steer issue teh car now handles track day even better.
They just released a video about it few days ago. Showing Verkline arms and subframe changes for their Supra. I hope they can check it out in the track to see if its really effective swapping.
Not going to lie I was considering buying a 2020 Supra but the whole bump steer issue got me thinking. Thanks to this video I feel much better about it. Do you know what Toyota did to the rear end of the 2021 Supra? Perhaps they addressed the toe to eliminate the bump steer?
I've only heard its more planted than the 20 mk5 but I've yet to hear anyone talk about the bumpsteer problems with them. The guys in the forums talked about it a bit but no one with a 21 has come up to say what's the comparison to the 21 vs 20 and how both drive.
@@carboydorifutoparty3976 I’ve driven them back to back quickly in canyons, but was not able to secure track time. There are some other subtle changes to the 21 which make it feel a bit different. The dampers are a touch firmer, and it has stiffer anti roll bars. I suspect the springs have a different rate as well. It’s easy to get either sideways on power. I wasn’t able to test limit behavior at the track, but in canyons the 21 inspires a bit more confidence. It’s subtle. Does it actually create more g load? I actually doubt it.
Could it be what some people are describing not completely to do with the suspension geometry? Is the factory electronic LSD programing reactive to slip angle, making the car less predictable at the limit? Is the lockup feature not as predictable because it's constantly changing? Almost all the latest M cars share this not identical but similar characteristic, except for the ones that have more aggressive early lockup programing like the GTS and CS models. There is some aftermarket tuning options for the ELSD that make the lockup event more aggressive and predictive. A good mechanical LSD like a Drexler/OS Giken is also an option. Is the subframe or diff mounted with rubber bushings? All of these things combined could make for an unpredictable car. I don't have a Supra but I've driven a few modern M cars on track.
I have H&Rs on mine, right from the get go, even with the stock springs, the rear would wander around under hard acceleration, it felt terrible. I took it in for another alignment & put a heap of weight in the rear on it whilst it had the computer/laser alignment gear on it & toe barely changed, so I gave up on rear bump steer issues for normal driving circumstances, We changed the rear camber & toe, now the car is much happier ;-)
i do alot of track day with my gr supra mt they really dont like going lower then 20mm on stock suspension and control arms i put in the rsr down springs 15mm lowering with about 20 stiffer spring rate with versus camber plate and spl rear control arms the car handles amazingly even stock pretty good but what happen is people put in 30mm+ lowering springs without doing proper camber and toe ajustments my friend also had similar issue when he put in the hks has kit and went for the slam look but when he kept the lowering to the recomended minimum lowering spec instead of the slam look the car handle much better i would stay clear away with springs that go lower then 20mm even the racing gt4 cars are only about 25-30mm lower then stock.
No clue if you'll know the effect of this or not but I wanna get the Eibach springs will that introduce the issues you talked about when lowering the car?
Misha from Apex Nurburgring should see this! They just replaced the whole subframe on their MK5 Supra to resolve this issue! Was it necessary? Maybe, maybe not lol
@@JackieDing86 Tape some grid paper on the wall first. The grid will let you see even minor changes in either direction, plus you can mark the lasers position as the suspension compresses and you can then have a reference sheet for future changes (note how far the sheet is from the car for repeatability, as the further away it is the more exaggerated the changes will be shown). Also, rather than putting the laser directly on the wheel, put magnets on the back of a mirror and stick it to the wheel (or take the wheel off and stick it to the hub/brake rotor if the wheel isn't magnetic), then shine a laser on the mirror so it reflects back onto the wall. This way the laser will not move up and down with the wheel, but only move when the angle of the mirror changes, obviously indicating camber/toe change. Make sure the mirror is perfectly flat, and long enough that the laser will shine on some part of it at all times during the full range of motion.
Bmw has always had their geometries under control since the mid 90s with the e36. I wouldn't expect the supra to have any inherent geometry flaws out of the box.
Bump steer is fixable, I've gone from 0.141in before and 0.014in after on a Autocross Camaro. makes a huge difference. but having bad bump steer on a $50,000 new car is an embarrassment keep in mind 1 degree is about 1/4in of toe change. suspension engineers target sub 0.010in of TOTAL toe change in race cars
Well, I was waiting for this one :) Upd - not exactly the right tool to perform the test, nor the results are very precise :))) Good overall recommendations though!
@@abdisyahrizal4313 Well they never said that before. Obviously you have not seen any of their videos nor know them personally. Should reserve your opinion on them before knowing them in depth.
@@faizalmohd9536 same goes for you mate.. You use maybe,i also use maybe.. The problem is they make it look like a fatal flaw,when it just the car stock charateristic. Its like hey its a deadly flaw,but we have a fix for you...... This is my opinion,just like yours,or like roberts opinion,everyone is free to share their thought
Thanks for your explanation Jackie! Proper ride height and toe in is key! It's crazy how some guys are changing the entire subframe to fix bumpsteer issues lol
Yeahh that's just overkill 😅
Some people like Robert Mitchell demand the best.
Maybe they know something more about car handling dynamic than many other normal day to day driving / weekend trackday people do. Just maybe...
@@seanm.collins9888 True. Why not. For safety & satisfaction reasons...
Apex taxi should be and must be fast,safe,and consistent.. Maybe the stock config is just not good enough for them.. Because as they say,going full send is an understatement for them.. But i also feel robert taking the supra bump steer isue to dramatic. Not many people use that car like them. . he might be in a promotional mission for the swap kit
its like breakfast for s2000 driver, HAH! so true. all these new cars haver it so easy.
Would be nice to see you both racing together in the s2000! big fan of both of you guys! IG-ap2.v1
I still say the main reason they are feeling quote on quote instability in the rear is because of the rear rubber bushing deflection. SPL arms will cure probably 99% of this problem
Very interesting! I think what people are complaining about is compliance in the bushes that does lead to "involuntary, unpredictable bump steer". As you pointed out, this is extremely reasonable toe changes over such a range of travel. Good experiment!
Hi Jackie. Very good video. Thank you. However we must also account for the factory bushing flex which might occur under full braking, the forces that act on the suspension arm may cause the tires to toe out even further. I haven't done a full kinematic analysis and maybe it doesn't affect your car as much compared to a stock vehicle as I believe you have aftermarket bushings already ?
if he’s full SPL, I know the one piece from the rear completely deletes a factory bushing in favor for a solid metal joint
Didn't understand does it have bump steer though
Yeah, it's confirmed, the A90 supra have a really good rear suspension, if you see the Z platform, they have massiva toe gain during compression.
I remember my first track day in my AP1 S2000, Streets of Willow going clockwise at turn 11, I was accelerating hard out of turn 11 and then all of a sudden the rear started to step out and then it stepped out faster and I spun in front of 3 cars, thankfully I spun to the outside of the corner but that moment made me respect the S2000 a lot more lol. To be fair I was running on 6 year old Continental Control Contact All Seasons on stock AP1 wheels so that might have affected my handling slightly. I started cording right at the last session lol. Man I can't wait for another track day!
Nice. So what was the net tow angle change that you've observed? (Hard to tell from the video)
We would recommend around .15 degree in each side, .3 total. For more powerful applications, 0.4 deg in would work as well.
@@JackieDing86 No, I meant what’s the kinematic toe change observed?
@@JackieDing86 would you know the mm equivalent?
people in Europe are changing the whole subframe to fix bump steer. Jackie is like hold my beer.
Wonderful context comparing to the S2000! Thanks for sharing your experience and the lessons you learned!
Thanks Jackie!
I've driven 2 G29 Z4's, can't comment on A90, but I'm guessing its not too far off, when I do the kick down I do feel the need to correct the car as it goes left or right. Probably needs some rear toe in
Jackie always wears his helmet for safety! Great vid as always!
lmao
Straight forward explanation ! To funny we see people with cars so low and all they can tell you is how mad it handles, yeah right mate! ! Not
Very good critique of the A90 rear toe controversy. I have been at the performance game for decades and learned over time that factory suspension engineers spend months even years in the design and prototype stage of development. Changes to the original design need to be done by a "very" qualified person. Lowering, as you wisely, mention can be over done unless you like a boulevard Chevy with hydraulics and a loud sound system ...
This is a nice way to start the day. So reasonable ride height & getting proper alignment is the key. TIL.
Great video. It'd be even better if you also repeat this on S2000 to see the difference..
It'd be interesting to see the toe changes under compression on an S2000, I'm planning on getting one soon and it'd be good to have some knowledge about that beforehand
Check out honed developments page on the s2000 bunpsteer kit
@@toddxhiggins I will, thanks 👍
This issue actually put me off getting a supra a year ago. Wish there was more transparency of the issue and how to fix it. thanks for your content.
So many youtuber lowering their car and has no issue.. Some even say the car drives better.. And normaly if we changes something in the supsension it is recomended to check the aligment,etc
I mean it all comes down to you really. I've heard mixed reviews but mainly most saying they don't even notice it or they haven't even discovered it and some saying it's probably there but they dont mind how the car drives anyway. I not them but id say it all comes down to your own perspective since there's many different pov's with this issue from what I'm hearing tbh.
@@carboydorifutoparty3976 i only know two guys/side who complained about this bumpstreer.. EAG and Apexs robert mitchel.. The other see it as normal.. At least not as bad as goin mustangs to crowd
dont lower your car beyond 20mm i recomend rsr down springs they lower the car about 15mm and give you about 20% stiffer spring rate put in camber plats up front -2 front and -1.8 degree rear camber a bit of toe in at the back with spl rear toe link and you pretty much solve all your bump steer issue teh car now handles track day even better.
is this Misha Charoudin channel?
No.
that video is a blatant ad
@@mas921 no it is not. Robert Mitchell have said these things about the A90 many months ago. Check his videos.
@@seanm.collins9888 i know, and back then I did reply to him about the toe kinematics
They just released a video about it few days ago. Showing Verkline arms and subframe changes for their Supra. I hope they can check it out in the track to see if its really effective swapping.
Not going to lie I was considering buying a 2020 Supra but the whole bump steer issue got me thinking. Thanks to this video I feel much better about it. Do you know what Toyota did to the rear end of the 2021 Supra? Perhaps they addressed the toe to eliminate the bump steer?
I've only heard its more planted than the 20 mk5 but I've yet to hear anyone talk about the bumpsteer problems with them. The guys in the forums talked about it a bit but no one with a 21 has come up to say what's the comparison to the 21 vs 20 and how both drive.
@@carboydorifutoparty3976 I’ve driven them back to back quickly in canyons, but was not able to secure track time. There are some other subtle changes to the 21 which make it feel a bit different. The dampers are a touch firmer, and it has stiffer anti roll bars. I suspect the springs have a different rate as well. It’s easy to get either sideways on power. I wasn’t able to test limit behavior at the track, but in canyons the 21 inspires a bit more confidence. It’s subtle. Does it actually create more g load? I actually doubt it.
@@revmatchtv yeah I’ve read/seen reviews where steering feel has improved also which is big as well.
@@chrisguerrero7690 Yes, it’s true. There is more resistance as the g forces load up. I’ve got a review on my channel.
I do want to lower my supra. What ride height would you recommend then?
Could it be what some people are describing not completely to do with the suspension geometry?
Is the factory electronic LSD programing reactive to slip angle, making the car less predictable at the limit? Is the lockup feature not as predictable because it's constantly changing? Almost all the latest M cars share this not identical but similar characteristic, except for the ones that have more aggressive early lockup programing like the GTS and CS models.
There is some aftermarket tuning options for the ELSD that make the lockup event more aggressive and predictive. A good mechanical LSD like a Drexler/OS Giken is also an option.
Is the subframe or diff mounted with rubber bushings? All of these things combined could make for an unpredictable car.
I don't have a Supra but I've driven a few modern M cars on track.
Does the “bump steer” contribute to the Supra’s ability to slightly lose traction to slide( added playfulness)
I have H&Rs on mine, right from the get go, even with the stock springs, the rear would wander around under hard acceleration, it felt terrible. I took it in for another alignment & put a heap of weight in the rear on it whilst it had the computer/laser alignment gear on it & toe barely changed, so I gave up on rear bump steer issues for normal driving circumstances, We changed the rear camber & toe, now the car is much happier ;-)
i do alot of track day with my gr supra mt they really dont like going lower then 20mm on stock suspension and control arms i put in the rsr down springs 15mm lowering with about 20 stiffer spring rate with versus camber plate and spl rear control arms the car handles amazingly even stock pretty good but what happen is people put in 30mm+ lowering springs without doing proper camber and toe ajustments my friend also had similar issue when he put in the hks has kit and went for the slam look but when he kept the lowering to the recomended minimum lowering spec instead of the slam look the car handle much better i would stay clear away with springs that go lower then 20mm even the racing gt4 cars are only about 25-30mm lower then stock.
No clue if you'll know the effect of this or not but I wanna get the Eibach springs will that introduce the issues you talked about when lowering the car?
Very educational. Thank you,
Interesting experiment and quite instructive 👍
0:58 im an ap1 driver eating breakfast rn
Misha from Apex Nurburgring should see this! They just replaced the whole subframe on their MK5 Supra to resolve this issue! Was it necessary? Maybe, maybe not lol
Jackie replaced rear arms with SPL parts. Pretty much what Apex did. Robert is talking about the stock set up
He should do the same test on a stock car
New cars op, me in my mr-s with McPherson and dual endlink pleb suspension
Great content - I like this stuff!
Would be nice to see an actual bump steer gauge being used for accuracy instead of turn plates....
Wasn't able to secure the gauge in time but very happy to redo the test later down the line
You come to PHD Racing to get an education. Well done Jackie!
Excellent expériment ! Thanks
Awesome content
you should do the same thing on the s2k
I would love to try
Isn’t bumpsteer sometimes a function of the engineering? Like, it can be desirable if tuned right..
Edit: Ope, you touched on that later in the vid
I love all the weight reduction in the Supra, but I see one place you’ve got some weight to lose... time for a haircut!!
Leave mighty car mods songs to mighty car mods... other than that keep it up, cheers
Good info!
so its true, it does toe out a bit then toes in.
Yes. But i think the point here is, don’t run the car 2 inches higher than stock, or 2 inch lower than stock.
@@BoostdPanda I agree. No need to switch out the subframe.
Dude your pants are cool as
It's good to see Master Ding refute rumous lmao
THANK YOU for SHOWING the measurements! "the other guys" in Europe "hyperbole'd" the whole thing!
But even the standard car on the street wants to kill you with the bumpsteer.
Redo w/ a laser flat against the wheel
Shining on the wall, or use a proper bump steer gauge.
We considered laser against the wall but the camber gain is gonna be way more aggressive and overshadow than the toe change.
@@JackieDing86 Tape some grid paper on the wall first. The grid will let you see even minor changes in either direction, plus you can mark the lasers position as the suspension compresses and you can then have a reference sheet for future changes (note how far the sheet is from the car for repeatability, as the further away it is the more exaggerated the changes will be shown). Also, rather than putting the laser directly on the wheel, put magnets on the back of a mirror and stick it to the wheel (or take the wheel off and stick it to the hub/brake rotor if the wheel isn't magnetic), then shine a laser on the mirror so it reflects back onto the wall. This way the laser will not move up and down with the wheel, but only move when the angle of the mirror changes, obviously indicating camber/toe change. Make sure the mirror is perfectly flat, and long enough that the laser will shine on some part of it at all times during the full range of motion.
Bmw has always had their geometries under control since the mid 90s with the e36. I wouldn't expect the supra to have any inherent geometry flaws out of the box.
Bump steer is fixable, I've gone from 0.141in before and 0.014in after on a Autocross Camaro.
makes a huge difference.
but having bad bump steer on a $50,000 new car is an embarrassment
keep in mind 1 degree is about 1/4in of toe change.
suspension engineers target sub 0.010in of TOTAL toe change in race cars
"it's a feature"
Well, I was waiting for this one :)
Upd - not exactly the right tool to perform the test, nor the results are very precise :)))
Good overall recommendations though!
We will attempt to secure the right tool for the job, this one is really more of an visualization to provide a little more info and context.
That hair haha
You wouldn't have a problem if you have 4 wheel steering. Haha
Was that half a degree?? Is that even a reason to complain? The suspension deformation under load is going to give more then that lol
Jeez Jackie, you needa get a haircut my dude!
That's the plan for today, lol
Jackie has a fro.... yo
7 persons dislike because they own new supra
probably gunna hate on the weight and bmwness next
I can't imagine anyone could seriously complain about a 3400 lbs curb weight
@@ARCNA442 You never know man XD
Anything above 3000 I don't want it. Luckily Jackie shown us getting there is very possible
Or maybe they know something more than you Jackie. Just a thought.
Maybe they sell the kit,lol
@@abdisyahrizal4313 No they don't. It's verkline.
@@faizalmohd9536 yeah until they say,go to their wbsite and enter xxxx to get xx discount
@@abdisyahrizal4313 Well they never said that before. Obviously you have not seen any of their videos nor know them personally. Should reserve your opinion on them before knowing them in depth.
@@faizalmohd9536 same goes for you mate.. You use maybe,i also use maybe.. The problem is they make it look like a fatal flaw,when it just the car stock charateristic. Its like hey its a deadly flaw,but we have a fix for you...... This is my opinion,just like yours,or like roberts opinion,everyone is free to share their thought