Unnecessary Roughness
11-20-14, 07:37 AM
#1
I'm having hell with my SC400. All new front suspension. The only original parts are the factory springs. MKIV control arms and new kyb shocks. Tires and wheels are factory size and tires are new. The problem is a horrible tire noise like feathered or cupping tires but they're not. Rotating and balancing has no effect. It's getting another alignment in the morning. Also the car is absolutely bone jarring rough over bumps. The guy at the alignment shop was like "this is the roughest riding Lexus I have ever been in". It feels like there is no give in anything. Has anyone else had this problem? There are no suspension mods on this car. I'm about to set it on fire or maybe worse, let some kid buy it.
Last edited by gtsfire; 11-20-14 at 07:40 AM.
11-20-14, 01:20 PM
#3
New rack with new tie rods. New KYB shocks (for an SC) and they are mated with the factory Lexus springs.
11-20-14, 05:09 PM
#5
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Gtsfire I hear you. My shocks were shot so I had them replaced with just some stock Monroe's. Rear of the car rattles like crazy when driving slow. Also recently put Supra lcas on and the car rides very hard. Did not have either problem prior to replacement
11-20-14, 08:27 PM
#6
I don't know but it's just very, very frustrating. This is my fourth SC. It's the nicest one I've had and flew to Florida to buy it. It's also the one that's given me the most problems and is by far the roughest of them all.
Something else too. I bought the car with 99800 miles on it. It now has 153k. I've had to put two tranny mounts on it and I think this one if going bad also. So much clunking going on under the gear shifter again. I just had two brand new flex disks put on the other day too. Those fkn things aren't cheap. I replaced the motor mounts a year ago.
Something else too. I bought the car with 99800 miles on it. It now has 153k. I've had to put two tranny mounts on it and I think this one if going bad also. So much clunking going on under the gear shifter again. I just had two brand new flex disks put on the other day too. Those fkn things aren't cheap. I replaced the motor mounts a year ago.
11-21-14, 10:55 AM
#7
its probably the mk4 control arms that are bothering you. they have much stiffer rubber. most people keep the stock upper arms though maybe the whole combination of new bushings up top and the stiffer bushings down low are doing it. give it some time to break in it might feel better. I didn't even know it was possible to have a harsh ride on the stock 16's with new tires. maybe something they missed is off under there.
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11-21-14, 11:35 AM
#8
In my experience with my old SC400; it had polyurethane bushings all around, PBM coilovers, and it rode and drove fine with 19" wheels on. But soon as I put on the Supra MKIV 17" wheels, it had the worst ride ever, exactly how you described it. Felt like there's no give whatsoever with the suspension, bone jarring over uneven roads, it felt like it was gonna come apart to be honest because of how much shock you can feel from the road. But as soon as I put the 19" wheels back on again, it drove and rode as smooth as it was again. I'm not saying it might be your stock wheels or tires, but that was my experience.
11-24-14, 10:48 AM
#9
Your tires are most likely the culprit. The cheaper or no name brand tires tend to use lower quality super hard rubber compound that have very little give and can cause that rough ride. You raised a flag when you stated that your car has horrible tire noise. That's a signature of el cheapo tires from China. I know because I had a set that were installed on my car when I first picked it up, The dealer just stuck on a set of the cheapest tires they had just so they could say it has all new tires. The ride was rough, grip sucked, and worst of all, had terrible tire noises and vibrations. Those all went away when I replaced all the tires with a nicer set of Continentals. My Bridgestones have been amazing as well, completely changed the ride quality as well as noise levels inside the car.
11-24-14, 11:24 AM
#10
It's not the tires and I don't put cheapos on my cars. They've been rotated/balanced multiple times with no change in the noise and it still sounds like right front. I took the stockers off and put my MKIV TT wheels on there (with brand new tires), had another alignment done and zero change in the noise. I found it suspicious that around the same time the noise began, clunking under the console started. In 53k miles I've put two tranny mounts on and it's looking like number three is about to be put on. Flex disks are brand new and motor mounts have 30k miles on them so don't go there. So I just dropped another Ben Franklin on a mount from Lexus. This car, although the nicest of the four I've owned, has been the single most biggest pain in the *** and wallet. On the flip side of forgotten how good these cars look with TT wheels. 
But I've decide if I'm going to own a car that's a maintenance nightmare it better well have some serious *****. So I got this also. 
But I've decide if I'm going to own a car that's a maintenance nightmare it better well have some serious *****. So I got this also. 
Last edited by gtsfire; 11-24-14 at 11:27 AM.
11-26-14, 07:07 PM
#13
Steel belted radials. I said I didn't put cheapo tires on it. Knowing the exact brand is irrelevant unless you're looking for some reason to be critical. The problem is handled it was the transmission mount...again. I'm done with this car and it'll be for sale locally after the holidays.
Last edited by gtsfire; 11-27-14 at 05:46 PM.
11-26-14, 08:24 PM
#15
Shot in the dark here but...
I had a similar issue with my car when doing Bilstein fronts and lower arms. After hearing such incredible reviews I didn't understand why I was having such a bouncy ride on Bilsteins.
The fix?
Adjustable swaybar end links.
Apparently theres some kind of asymmetry built into the front suspension (the car never had a front collision of any sort so that's what I attribute it to) and correcting the uneven ride height via Supra arms plus Bilsteins put preload on the sway bar.
As a quick and dirty test, disconnect the sway bar up front on both sides and take it for a spin. If it gets better, there's your answer.
I had a similar issue with my car when doing Bilstein fronts and lower arms. After hearing such incredible reviews I didn't understand why I was having such a bouncy ride on Bilsteins.
The fix?
Adjustable swaybar end links.
Apparently theres some kind of asymmetry built into the front suspension (the car never had a front collision of any sort so that's what I attribute it to) and correcting the uneven ride height via Supra arms plus Bilsteins put preload on the sway bar.
As a quick and dirty test, disconnect the sway bar up front on both sides and take it for a spin. If it gets better, there's your answer.