Body sway during hard breaking on the freeway.

Does anyone experience a Body sway during hard breaking on the freeway after installing a lift kit. Bilstein 6112 Strut & Spring Assembled clip#7 3 inch lift + Rear B8 5100 Shocks Set, Old Man Emu Rear Coil Spring Kit 2 inch lift. for 2010-2023 Toyota 4Runner With KDSS 4WD With KDSS. No KDSS spacer installed or UCA. Alignment is done after lift installed. Without alignment done handling is pretty bad.

 

Welcome from Wisconsin! No body sway here, we don't have KDSS, we do have UCA's, modified alignment specs (according to Toyota) 3" front-2" rear, spacers.... like an arrow.

 

Welcome, could be tire air pressure, try pressuring up a few psi over sidewall rating and see what that feels like.

 

I haven't had to brake hard since I installed my lift, but I've experienced body sway with stock suspension. Had to drop from around 70 to 0 as quick as possible - felt like i was on a ship rolling back and forth on rough seas. Felt like the brakes were alternating braking power to stop me as quick as possible but also fight the body roll.

I also have KDSS but have to think that probably helps more than it hurts with this sway. Although a lift may cause this to be more pronounced (raised center of gravity), I think the issue of body roll during hard braking at freeway speeds is normal when trying to stop these bricks on wheels.

 

I run stiff sidewall LT tires on 20" rims and OEM suspension, never a bit of body roll and straight as an arrow when stopping.

 

I have a similar setup, KDSS, 6112/5100, 2.3" (maybe the 2nd or 3rd clip position), 1.5" heavy load Bilsteins coils, and I have BDS UCA's.

Mine feels better than stock in almost every way.

Definitely get the alignment done ASAP

 

Mine is too under normal conditions. I've only felt the roll once and it was unnerving.

When I say hard braking at high speeds, this was emergency panic braking with other vehicles swerving into the emergency lane because they couldn't stop in time. I was actually impressed with how quickly the 4runner stopped (no emergency lane for me) and even though the rolling felt unnerving, you could tell there was a great ABS doing its job.

 

Not sure, on my last Ironman FCP video I turned my Limited with no KDSS pretty hard to another road from main road and it was very much in control.

In the dirt road section also I took a "u" curve on a bumpy section and it was very stable as well. Under the vehicle cameras show how much work front and rear shocks did to maintain the smoothness to inside of the vehicle. (KDSS may not have that smoothness offroad but on pavement it should have good control for a tall vehicle like a 4runner)

 

Welcome from Arizona!

 

Welcome to the forum, from SoCal!

 

I have dobinson Ims dampers and their springs , about 2.5/1.5 lift. KO2’s C load stock size on stock wheels. I do not have KDSS.

It feels very nice and controlled during normal maneuvering. It even feels pretty good during spirited driving. Firmer than stock, but also comfortable too.

During emergency braking at highway speeds, it’s a different story. My setup has good straight line behavior during emergency braking, even though it’s more sensitive to steering inputs. However, if you brake hard enough, long enough, physics means the front suspension will continue to compress to the bottom of suspension travel, regardless of how nicely aftermarket shocks can control the compression. It doesnt dive as quickly as stock because I have good compression damping, but it will eventually pitch just as deep as a stock setup. Also, Since the rear is also lifted a bit, this could also mean the rear shocks have the potential of topping out sooner than a stock setup as well. A topped out rear suspension can mean very quick snap oversteer if you also need to steer. And since the steering is on the fast side, it can get dicey quick.

My 4runner can be downright scary when combining braking hard and long, AND maneuver by steering. Basically, if you are clipping along at 80mph, and need to stop NOW and avoid something in the way at the same time…HUGE potential for loss-of-control!

Just imagine all that weight on the front wheels, being more top-heavy than stock, and the rear wheels barely having any weight on them! Whether stock or with aftermarket shocks, I think the 4runner and other similar vehicles need to be treated with a lot of respect when traveling at high speed. Flipping over or snap oversteer because you are trying to avoid something at high speed can often turn out worse than focusing on staying straight during max braking, and scrubbing off as much speed as possible, and just accepting you’re gonna hit something. We got good brakes, so hard braking can at least get us down into survivable speeds should there be an impact.

Somebody had mentioned a while back…what do you tell the insurance when they ask why you didnt swerve? First, I don't think insurance is contingent on an answer to that. Secondly, maintaining control of a vehicle lets you make decisions, even if those decisions only affect the kind of impact you’ll have. Accepting an imminent collision and braking hard to reduce the impact energy is better than swerving, colliding anyway, but in an uncontrolled manner (with side of vehicle taking the impact, rolling the vehicle, or bouncing and hitting more things/other vehicles after the initial collision.

Hard impacts with a speed delta (velocity change due to impact) of 50 mph or lower are generally survivable if the car’s structure takes the impact head on. Not so much if it’s sideways or if the vehicle is on it’s side. Speed deltas above 50mph are usually bad news no matter what. So as a general rule, when we drive these things, we really should focus on scrubbing speed first and, then gently trying to affect direction of vehicle as speed and vehicle dynamics allows.

KDSS should allow a higher potential for safe steering in emergency situations, but once those back tires get light, they will be the limiting factor in maintaining control.

Stability control should in theory help, but Im not sure if that system knows enough to reduce braking on the rear wheels when the are unweighted to reduce potential for oversteer, or if it just responds after it senses the yaw from oversteer, which by then is too late.

I’ll say this though, I did not feel that stability control was gonna catch me during one particular panic stop situation. It felt like old-school vehicle dynamics were ruling.

 

Welcome from the center of the bourbon universe.