JDR76

A couple clarifications I would add to the above is that the GSh has never been offered with AWD. They are all RWD. Also, they all have the CVT, so there are no 6 speed or 8 speed transmissions in the GSh.

peteharvey

All I can add is that the 2016-20 GS450h's used their own line of springs - separate from RWD and separate from AWD.
However, GS450h's use the same shock absorbers as GS200t/300/350.
The 2016-20 springs and shock absorbers are "softer" than the originals used in 2012-15.

Meanwhile, both RWD and 45h used the same front and rear roll bars; the AWD uses the same rear roll bar, but must use a different front roll bar for AWD.
Anyhow, while 2016 GS200t/350/450h's added stiffer front roll bars, the 2018 GS300/350/450h's added stiffer rear roll bars too.
How do I know the new roll bars are stiffer?
Because I tried to fit them on my 2015 RWD, and Lexus said they are too big to fit and needed bigger brackets etc.

Thus, the 2016-20 GS300/350/450h is a general concoction of: stiffer chassis with more laser weld points, and stiffer roll resistance, but actually softer springs and softer shock absorbers for more compliancy and more float.
I suspect that the software that controls AVS shock absorber valving from 0-50 mph is actually softer in the 2016-20 GS300/350/450h than the 2015 GS350 RWD.
I don't know how that affects driving in the snow.

Gina450h

Thanks PeteHarvey, your original table and info was terrific. Latest discussion with mechanic he isn’t so sure it is the change in the front end sway bars, because I clarified that what spooks me about this is that the slipping I feel is in the front wheels and I never let it get into a sway.

Rather, I immediately back off even the sofestt touch on accelerator. Im just noticing that I have to go as much as 10mph slower on certain road conditions in the 2018 versus my 2015. Since I live in Michigan this definitely affects my driving/purchases; it’s also a safety factor as I’m not sure everyone would notice this front wheel slippage (I was trying to pass an Amazon Prime semi yesterday and simply couldn’t because the front end/wheels felt unstable). I had to drop back until a different road surface presented a few miles up).

I’ll send you a PM I just shared with your friend who posted your table; my first car at 16yo out of drivers training was a manual 8cyl AMC Javelin (driving lessons from some responders aside I do know what I’m doing on bad road conditions). It may be best to give up on figuring out this issue (perhaps would take a test driver and engineer on a straightaway in Shibetsu track. It’s a real phenomenon. We are at the point of simply buying a new car and giving this one to a family member (with warning about highway driving the 2018 in sub-freezing). Anyway I’ll send you my PM to other expert; I only wish the 2018 model was as good as the 2015 on treacherous roads. 👍

Knucklebus

If it is the front end getting loose and you are not AWD, it can't be much other than tires. Also, at 65MPH on snowy roads, you are being reckless, regardless of what those around you are doing. I've been driving on snow and ice since 1978 and I would not consider going that fast.

Second, with that much weight in the rear (200lbs of salt mentioned earlier), you might be shifting the balance too far rearward. A hybrid already has additional weight with the batteries.

DaveGS4

iTrader: (2)

Quoting this again as it appears it was not read.

Lwerewolf

Sway bars take spring force from the unloaded tire and transfer it over to the loaded tire. Since tire grip gains falls off at higher load levels, they effectively reduce maximum grip, at least as far as equal tire loading is concerned - maintaining optimum camber, preventing excessive roll for... reasons.. is another story.

Knucklebus

But under snow and ice conditions, there is no significant lateral grip to force loading/unloading enough for the stiffness/softness of anti sway bars to be a deciding factor in the OP's traction issues between the various years. The car will merely slide sideways before the bars reach a point of action... unless you are intentionally doing donuts.

Lwerewolf

The bars are always acting, unless the car is standing still on a perfectly level surface (and everything underneath is as straight as possible). Race cars use very little/no sway, primarily to shift "handling" characteristics or to control roll for camber purposes (if they can't/don't wanna achieve that with springs alone, for whatever reason). Snow rally setups often don't have sways at all.

Knucklebus

The OP was saying the two different model years were behaving differently. The difference between the bars will be negligible in snow were you can't build up lateral loads enough to make the anti sway bars do much. The car will slide before any lateral load can be generated. That's how you wind up in a ditch. A snow rally does not appear to be what the OP is talking about.

Im2bz2p345

@Gina450h - I received your PM, but unfortunately cannot respond because you have PMs disabled? Rather than getting a sporty sedan, I personally would consider an AWD vehicle for you area with quality snow tires outfitted for your next vehicle.

~ im2bz2p345

peteharvey

2016 GS200t/300/350/450h RWD’s had stiffer front roll bars.
2018 GS300/350/450h RWD’s had stiffer rear roll bars.
The stiffer the roll bars, the more the front and/or rear ends behave like a non-independent solid beam axle!
Theoretically, if a roll bar could be 100% rigid, it would turn the front/rear end into a dead/live axle!

Theoretically, dead/live non-independent axles won’t grip as well over bumpy surfaces.
Straight line stability may not be as good over bumpy surfaces either.
I’m not sure if being more “like” a solid beam axle will affect snow driving?

2016-onwards springs were softer for 200t/300/350 RWD, but I never drove refreshed 2016-20 450h, so I don’t really know, because the 450h’s used their own coil springs.

However 450h always used the exact same shock absorbers as 200t/300/350 RWD, and I know for sure that 2016-20 shock absorbers were softened because I own both the original earlier parts and the later updated parts.

Theoretically, downsizing from 19" 235/40R19 to 18" 235/45R18 will help your traction in snow.
I'm not good with snow, but I thought snow preferred softer suspension and softer tires.


You can actually try replacing the front and rear stabilizer bars.
They're less than $200 each, plus a few hours of labor.
48811-30800 Genuine Lexus Bar, Stabilizer, Front (lexuspartsnow.com)
48805-30070 Genuine Lexus Bar Sub-Assy, Rear Stabilizer (lexuspartsnow.com)
You may have to actually replace the brackets or clips that fasten the thinner 2015 front and rear roll bars.

I have 2015 4.4GS350 RWD which run 2019-20 RWD coils, with 2016-20 shock absorbers with the exact same part numbers as your 2018 OEM GS450h, but I use the thinner and softer OEM 2015 front and rear stabilizer bars just like your old 2015 GS450h, and it works beautifully; a little softer and more compliant than a 2019-20 OEM GS350 RWD with thicker front and rear stabilizer bars.
Do keep in mind that GS450h’s use their own coil springs compared to 200t/300/350 RWD’s, and that the refreshed 2016-20 GS450h’s used different coils compared to original 2013-15 GS450h’s.

spineman

Hello everyone. I didn't know if I should start a new thread, but this is about winter. I have also searched for information/problems with power steering to no avail except for water in p/s fluid. This morning (18 degrees) I started the car with remote start and when I got in to drive to work the steering wheel was completely locked, frozen. I;ve noticed this a few times when under 25 degrees or so I feel choppiness in power steering while driving. Anyone else experienced this? Is there a fluid to be checked or changed with the electric power steering?

Knucklebus

There is an angle sensor and an ECU for the steering. Any codes getting thrown?

When you say frozen, do you mean as in still locked like when the car is secured for the night. If that is the case, you should feel it give slightly between the locking mechanism. If it is frozen, like a block of ice with no movement at all, it is probably something else that will take further troubleshooting.

spineman

Haven't checked codes yet. I will when I get home. I mean frozen. Wouldn't move at all then broke free but still was acting erratic on the way to work. At lunch drove perfectly (27 degrees)

Where is the motor on the column?

Knucklebus

Could it be you have ice built up in the underside? The rack is just above the belly pan.