Sponsored

Solved: Literal Bump Steer

i3igpete

Well-Known Member
Joined
May 16, 2022
Threads
44
Messages
1,254
Reaction score
1,485
Location
Chicago
Car(s)
2023 3.0L 8AT
I did make a change and install rear traction links recently, but they're installed at the factory arm lengths (at least, within a 60-degree turn).
Sponsored

 

concept

Well-Known Member
First Name
Dave
Joined
Sep 1, 2023
Threads
23
Messages
1,125
Reaction score
796
Location
Southern CA
Car(s)
2024 Supra 45th, Mikan 2008 Mazda MX5 PRHT manual
Those of you who have coilovers: Do they eliminate bumpsteer? I don't think I've ever owned a sportscar WITHOUT it. However, the Miata folks sure do love Ohlin coilovers.
 
OP
OP
Kujiwara

Kujiwara

Well-Known Member
Joined
Aug 17, 2022
Threads
3
Messages
175
Reaction score
224
Location
Vancouver, BC, Canada
Car(s)
23 Supra AT Stratosphere, GLI32, SVT Cobra
Those of you who have coilovers: Do they eliminate bumpsteer? I don't think I've ever owned a sportscar WITHOUT it. However, the Miata folks sure do love Ohlin coilovers.
Coilovers can reduce the amount of suspension travel which help limit bumpsteer by doing that but you are not changing the geometry. S2k, Mx5 and supra all lose toe-in during extension by design for turn-in, but that requires very specific driving style to fully appreciate and may still be annoying to some extent during street driving
 

razorlab

Well-Known Member
First Name
Bryan
Joined
Oct 2, 2021
Threads
29
Messages
8,568
Reaction score
16,797
Location
Hudson Valley, NY
Car(s)
Not a Corvette.
Those of you who have coilovers: Do they eliminate bumpsteer? I don't think I've ever owned a sportscar WITHOUT it. However, the Miata folks sure do love Ohlin coilovers.
Can actually make it worse, and for a lot of people on this forum, it probably does since everyone likes to slam the hell out of their cars.
 
OP
OP
Kujiwara

Kujiwara

Well-Known Member
Joined
Aug 17, 2022
Threads
3
Messages
175
Reaction score
224
Location
Vancouver, BC, Canada
Car(s)
23 Supra AT Stratosphere, GLI32, SVT Cobra
Can actually make it worse, and for a lot of people on this forum, it probably does since everyone likes to slam the hell out of their cars.
Makes sense, we have slight toe changes thru most of the suspension travel, but towards the extremeties it changes more drastically. And the ones slamming there cars usually hits bump stops fairly often and doesnt help with staying on the road
 

razorlab

Well-Known Member
First Name
Bryan
Joined
Oct 2, 2021
Threads
29
Messages
8,568
Reaction score
16,797
Location
Hudson Valley, NY
Car(s)
Not a Corvette.
Makes sense, we have slight toe changes thru most of the suspension travel, but towards the extremeties it changes more drastically. And the ones slamming there cars usually hits bump stops fairly often and doesnt help with staying on the road
The rear gets really pissed off if you lower it significantly.
 

concept

Well-Known Member
First Name
Dave
Joined
Sep 1, 2023
Threads
23
Messages
1,125
Reaction score
796
Location
Southern CA
Car(s)
2024 Supra 45th, Mikan 2008 Mazda MX5 PRHT manual
Can actually make it worse, and for a lot of people on this forum, it probably does since everyone likes to slam the hell out of their cars.
How much lower is your setup?
 

noogie

Well-Known Member
Joined
Jun 7, 2023
Threads
11
Messages
219
Reaction score
154
Location
US
Car(s)
23 Supra
has anyone confirmed how much bump travel the rear has? if not much to begin with and you lower it further, you'll hit the bump stop more often and cause loss of rear traction.
 
OP
OP
Kujiwara

Kujiwara

Well-Known Member
Joined
Aug 17, 2022
Threads
3
Messages
175
Reaction score
224
Location
Vancouver, BC, Canada
Car(s)
23 Supra AT Stratosphere, GLI32, SVT Cobra
Update: Rear bump steer fully disappeared after 1 change...

So as you know from earlier, I got it aligned properly and it has improved the rear bump steer situation over mid sized potholes, more effect was in equalizing the behaviour between left and right side. But still some bump steer none the less.

I got camber plates installed a few weeks ago and realigned again a few weeks ago same 0.17/18ish deg per side in the rear, similar bump behaviour as before, maybe a little worse since I increased rear camber from -2 to -2.3 at the same time.

ANDDDD THENNNN.. I switched to winter tires, 19x9.5 square on 245/40R19 and the bump steer just disappeared completely, such a big change the wife noticed.
The winter setup is a little lighter than stock (Super speed RF05RR) and ET10, flush to fenders with the current camber settings.

Despite taking my best efforts to ensure the alignment was done correctly and maintained well in the past 13k km, the was significant inner edge wear (indicatie of toe out), but as confirmed by two different shops, before and after alignment was both toe-in in the rear. Only the first 500km when i bought the car, it was found there was very slight total toe out. I feel like perhaps there is some tire defect or PSS's tire properties just dont do well in the back of this car..

My square summer setup should be arriving soon, APEX ML10-RT 19x10.5 ET35 (ET23 after spacers) all around, and 275/35 ECS02, will report back how that affects the rear axle in May.

Another setup I'll be trying later next year is using a Square OEM Rear setup and running 275/35 CRS or A052 all around.
 
OP
OP
Kujiwara

Kujiwara

Well-Known Member
Joined
Aug 17, 2022
Threads
3
Messages
175
Reaction score
224
Location
Vancouver, BC, Canada
Car(s)
23 Supra AT Stratosphere, GLI32, SVT Cobra
Update:

New summer street setup installed, 19x10.5 all around with 275/35 Indy 500s, no significant bump steer except for the nastiest bumps. Similar observations with the winter tires.
Image - 2025-06-05T005402.325.jpg

Conclusion: Either PSS is just not my cup of tea or the set I had was defective causing noticable bump steer in the rear.

Will keep updating this thread with other tires i install in the future to have a list of tires for people with sensitive bums like me, next set to be added here is likely A052, CRS or P1
Sponsored

 
 








Top