Confidence Above 60 [mph - That Is]

CanadaCraig · December 28, 2003

Hi Guys!! :)

Have you already broken your promise to never eat again?! lol

As most of you know - I own a 1993 LS400. As most of you may also know - I just recently replaced all four Michelin X-One tires with brand new Bridgestone Turanza LS-V's. Nice tires - I think. [let me explain] My LS doesn't feel very secure above 60 mph. And feels even less secure [or 'pinned-down' or whatever you want to call it] the faster 'it' goes. From what I've been reading over the years [and here at the LOC] my LS should be 'rock solid' even at 120 and 130 mph. [maybe even all the way to its' 150 mph top speed] But it's not even 'rock solid' at 60. Is it because of the tires? I don't know. I don't THINK so - but I don't know. The new Turanza's are certainly better than the T-speed rated Michelin's - that much I do know. Although my LS has only 84,000 km's [just above 50,000 miles] it IS a 10 year old car. [bought new by the previous owner in September of '93] Could it be the shocks? [even IF they're not leaking or otherwise showing signs of failure] The car passes the 'bounce-test' and seems perfectly fine while driving in the city. It's just when I'm on the freeway [or highway] that I start to lose confidence in the car. What about the springs or bushings or whatever. What would cause my car - do you think - to feel insecure above 60 or so mph? Could it be the steering? I really can't figure this out. AND it's annoying me. I was hoping that the new tires would have 'cured' everything - but it hasn't. [although - like I said before - the new tires are certainly better than the old one's]

Any ideas?

Thanks.

Craig!! :)

jbsmithsa · December 28, 2003

There is something definitely wrong if it doesn't feel solid at 60. My 95 LS feels just as solid at 125 as it does at 60. I hit 100 today entering the freeway and the guy riding with me for the first time said he couldn't believe how fast it got there and how solid it feels.

I would have someone check the suspension real close. I am far from being a mechanic but there may be some steering linkage loose, sway bars out of whack, bad spring, bad alignment or something like that. Don't quote me on the specifics but I would definitely have a qualified mechanic check it out.

Good luck.

SRK · December 28, 2003

Hi Craig;

I had my car aligned locally by a shop that does all of my and my customers cars. They even let me help.

The result was a car that felt like it was on "tip-toes" at highway speed, to one that feels planted and stable. A four wheel alignment, done properly (and I can't stress how much properly counts) will transform the car. There are lots of shops that advertise "four wheel alignments" and they simply center the steering wheel.

Phone me if you still have my number or mail me off the board to get the name of the shop and an intro to the owner.

Rhys

RCRFAN3 · December 29, 2003

check air pressure in the tires, this car is at it best at 120 mph, It sounds like too much air

SW03ES · December 29, 2003

Lotsa things it could be but I agree with everyone here, it SHOULD feel very confident at ALL speeds. Start with the tire pressure, mechanics and tire places almost ALWAYS over-inflate the tires.

wwest · December 29, 2003

NOT the Turanzas!

I have run those on my 92 LS since 93. Got them for QUIETNESS.

Recommended them to all my Lexus friends.

Turanzas seem find at ~120MPH in MT and WY.

VBdenny · December 29, 2003

I put about 1500 miles on my LS over Chrsitmas. The car is rock solid all the time. I did get up to 100 a couple of times. My wife was reading and didn't notice. She gets upset if I go over 85. I have original size tires and GoodYear Aquatred III tires. It might be because your tires are new. New tires are often squirrly as they have a lot of tread at that point. The Aguatreds were horrible when they were new but with 20K on them, they aren't bad.

CanadaCraig · December 30, 2003

Thanks everyone!! :)

SRK - thanks - but the car just had a 4-wheel alignment - through Metro Lexus. I know they did it too - because NOW the steering wheel isn't perfectly centered - like it was before!! [grrr...] Is your alignment guy the same one Metro uses?

As for checking the tire pressure....

When the new Turanza's were put on - I specifically asked 'them' to make sure each tire had 35 psi. Looking back on that - it was a mistake. But the Michelin X-One's that WERE on the car had 35 psi so I figured.... well... I'm sure you know how that goes. Well anyways.. yesterday morning I checked all four tires. Each very cold tire had 36 psi. I let enough air out until all four had 32 psi. Now... what I'm about to say makes me a little bit nervous. And I say that because I still find it hard to believe that 4 psi could make such a difference. But it did. And does. Is that possible? It's actually a LOT better at 60 mph [and above] then it EVER was. [since I've owned the car - at least] Hopefully I'm not dreaming and it drives just as nicely tomorrow. [and everyday from now on!!]

Please go the tire & wheel section to read yet another tire question!!

Thanks again.

Craig!! :)

98 LS · December 30, 2003

Yes ........ it does matter that much!!!

I would bet that many if not most "tire issues" are related to improper tire pressure.

This is particularly evident on a very well balanced suspension like the LS. Changes in pressure of as little as 2 PSI are noticeable.

Over-inflation usually feels - jittery, jumpy ... a bit nervous and hard riding.

Under-inflation usually feels - mushy, imprecise and generally floaty.

Tire pressure influences the stiffness of the side-wall of the tire and has a critical effect on the ability of the tire to transmit the feel of the road to the rest of the car.

I would highly suggest starting with the recommended tire pressure for your model year as found on the glove box door.