Lexus082

I am really trying to bring back the ride quality in my sc400. Anyone's SC ride smoothly and quietly over not so smooth roads? I'm trying to bring back that Lexus ride quality as if the car was brand new. I plan to use all oem parts and this time I want to install the oem lexus front lower control arms instead of the Supra arms.

I noticed after I removed the rear hub assembly, I could swing the upper control arm up and down very easily with no resistance. (This is just with the ball joint disconnected...) I just thought it was pretty loose. Just thought I would mention that as well.

mitsuguy

iTrader: (2)

you want OEM ride quality, well, start replacing any and all bushings that are even questionable... you are going to want new shocks all the way around, and since you are doing new shocks, might as well find a new set of OEM springs as well...

ball joints will not affect ride quality unless they are loose / worn, in which case they need replaced regardless of ride quality issues...

front lower control arms are first, then front upper control arms... then rear lower control arms / strut rods and then rear upper control arms... next do sway bar bushings... in the rear, might also be worthwhile to replace any chassis mount bushings, and in the front, engine mounts contribute to ride harshness as well...

do all of that and you will be at 95% of OEM ride quality... the other 5% you will probably never get back just due to age of car and other things like worn seat springs and such...

captainsc

iTrader: (1)

IDK if this matters to you or if you need them, but I have OEM SC400 springs with only 80k on them. I'll sell them cheap if you are in need of them.

mitsuguy

iTrader: (2)

forgot to mention, put stock size wheels back on (16") and go with a quality 225/55-16" tire from Bridgestone, Michelin, etc... tire quality makes a huge impact on ride quality...

edit: and alignment... it'll obviously be needed with suspension part replacement, but alignment will have an effect on ride harshness as well...

MrYoshi

If you want to have the OEM feeling all over again, you can just go ahead and keep your SUPRA LCA (doesn't make that much difference from stock) and get BRAND NEW OEM shocks. I'm on HKS Hipermax III w/ SUPRA LCA right now and my car feel like OEM, even lil better because my old shocked was blown.

JohnEd

iTrader: (1)

Mitsu,

That comment about engine mounts intrigues me. I can't quite figure that one out and to be honest, I don't really need to. I'll go with your recommendation....check them. The only way I know of to check them is to watch them from under the car while a helper applies throttle in DRIVE with the wheels locked. Watch the mounts for play/movement. One should be in compression and should not move even if it is severed. The other will "open up" and move if it is bad. Then how do you do the other engine torque and check for movement? Wouldn't the third mount back on the tranny also give you vibration under throttle?

Thanks for your help,

John

mitsuguy

iTrader: (2)

Sometimes an engine mount will get hard and won't absorb the engine shakes and rattles at all... the type of mounts that we have are a little different than many other cars... when they go bad, they typically don't let the engine move that much when torquing the engine like you may assume they would... instead, they just transfer engine vibration, and one other thing I have noticed, they also let the engine move under suspension compression... a bump in the suspension transfers into the body, which transfers into the engine - the engine will sometimes transfer it back into the body if the mounts don't do their job to absorb it... not every car, but i have noticed it on a few in a bad kind of way...

the trans mount typically doesn't go bad on these cars, though if it would, it would definitely cause a vibration unrelated to road shock...

GSteg

iTrader: (15)

Engine mounts are definitely needed on the V8s (I6s seems to be darn smooth regardless since they dont have much end-to-end vibrations like V-configurations.). It's one of the best things I did to my car (GS400, but 1uz-fe none the less). This alone will make your car feel like new again.

JohnEd

iTrader: (1)

Cody,

Mt replacement sounds like a "must do" to me on my 93 SC400. Thank you for that. Does anybody have a "good" source for these. I am sure the Lex dlr will be high.

Thank you,

GSteg,

What year is the GS400 that gets 31 MPG? My 93 SC gets 27 if I set the cruise control at 70. I didn't think anyone would believe that. I have heard that the stock SC300 gets worse than a 400 but you can't prove this by me.

Again; what year?

Thank you,

John

mitsuguy

iTrader: (2)

no clue on the gs400, but my SC consistently got 26-28 mpg on the highway, and on a 3 hour stretch of road at an average of 90 mph, I averaged right at 27 mpg... 93 SC400... it all has to do with maintenance and how you drive... I also get better gas mileage when I control the throttle versus when the car does cruise control...

GSteg

iTrader: (15)

I have a 1999 model. I maintain my car thoroughly, and I drive with control. I dont speed and I try to avoid braking as much as possible. Cruise control is better for me because the roads out there aren't as great so every time I hit some kind of rough roads, my foot will be dancing around. Tire pressure is 35-36psi on OEM wheels all around which is fine because my car still rides soft.

GS400s come with 5spd auto and a 3.26 final drive. I know the SC4s didn't get a 5psd until 1998 so your 93 may be spinning at a higher RPM. At 70mph, my engine is only at 2400rpm. However with City and Highway combined, I'm at ~24mpg, which isn't too bad.

Lexus082

Do you guys think there will be a difference in ride quality then if I replaced the springs 220,000 miles (15 years old) with new oem springs?

I re-built my front suspension about two years ago with new shock mounts, oem shocks, sway bar bushings and end links, spring insulators, spring bumpers & supra lower control arms. I did not replace the upper control arms or the springs. Maybe the springs are affecting the ride quality. I guess its worth a shot. I would rather spend the money necessary to get it close as possible.

mitsuguy

iTrader: (2)

what is it doing or not doing?

what kind of tires (size, speed rating, brand, model?)

Lexus082

Its just a really rough & loud ride going over poor bumpy roads. Pretty much every other car I've been in rides alot better. Its alot worse when there's a spot in the road where the wheel kinda drops a 1/2" or so following the road its a pretty rough drop and I get this loud thud. Even though its only 1/2" or so its pretty ridiculous. Its like I have no suspension at all.

In other cars especially brand new cars the tire would drop down 1/2" following the uneven pavement surface but it would be a very smooth and quiet process like its suppose to be...

Tires are 225 55 16 Yokohama Avid V4S

I have also replaced the engine and transmission mounts.

gephross10

did you change out your wheels? i know in some cars if you use low profile wheels the ride isn't suppose to be as quiet.













if you really wanted a quiet ride you could always go to walgreens and buy some earplugs for 2 dollars