paomien168

Hi everybody, newbie here. Anybody with a first generation LS400 that has brake problems? My 91 LS400 has a problem with a bad vibration in the brakes after a few thousand miles on the new brakes. It has 152K miles, and I've replaced the brakes a number of times already. however, it seems like a few thousand miles after the brake replacement, they start vibrating really badly when I step on the brakes. I'm not a crazy driver, I don't slam on the brakes, nor do I ride on them all the time. I've replaced them with OEM parts... is there an aftermarket brand that will prevent this? I also have a set of 16" wheels on them, which I don't think causes the problem either (standard is 15"). I've spoken to the parts manager at my local lexus dealer where I purchased the car 12 years ago, and he said first generation LS400's have that problem because of thin rotors.... any suggestions?!?!?

quick

The vibration is likely caused by worn rotors. If you mean that you've replaced your rotors and you have the problem recur, then I suggest investigating a set of aftermarket rotors.

If you haven't replaced your rotors, then I suggest you either get them machined by a reputable shop if possible or replace them.

Good luck.

paomien168

Thanks for your reply! I have been replacing the rotors, though, believe it or not, every time I replace the pads. I don't even cut them, I replace them. That's the bad part.. if I never replaced them then I deserve to have problems, but to have rotors only a few thousand miles old and have that kind of problem, it's no good!

kreativ

I have a '91 LS too, and the rotors (front pair) have only been replaced once since '91, and that's after being machined 3 times. So I'm not sure about your Lexus guy's "thin rotors" reasoning.
While I've never been impressed with this car's braking ability, I haven't had any problems with vibration.

My two main issues have been:
-squeaky brake pads, which they tell me is just because of the design. Apparently, after 12 years, Lexus has finally gotten around to improving the brake pads to eliminate the squealing noise. The set of OEM brake pads I have on the LS now still squeak occassionally.

-a slow pulsating sensation when I step on the brakes harder than normal. I thought it was ABS kicking in first, but the pulsing is way too slow and I'm not braking THAT hard.
I'm not sure how long this has been going on. It may have to do with warped rotors, but it doesn't bother me enough to have my rotors cut before I need to change brake pads.

I'm surprised you replace the rotors every time you change brake pads. I remember a pair of OEM rotors cost me $300+!

You could try aftermarket brake pads (EBC Greenstuff I hear is good) and a different set of Toyota rotors next time around.

You can get TRD (Toyota Racing) cross-drilled rotors for your LS for cheaper than the stock rotors.

Check this thread in the LS forums:
https://www.clublexus.com/forums/sho...threadid=43461

hyperopt

When was the last time you replaced/cut the rear rotors? Just cut my rear rotors and both my LS's and now braking is silky smooth. Yes, your dealer is correct when he said that the latter years of the first generation models have thicker rotors which are less prone to wrapping...but wrapping after a few thousand miles on new rotors are excessive.

Did you dial indicate the rotors when you placed them in and did you used the correct lug bolt tighenting patterns and torque?

GJSGS4

Make sure you are buying quality rotors. Many cheaper aftermarket rotors will warp after a few thousand miles or a couple of hard stops.

kreativ

Doesn't this mean that replacement OEM rotors are now all of the thicker variety for the first-gen LS?

hyperopt

Not necessarily. Need matching brake calipers to match with thicker rotors. Lexus improved the brakes on the latter years of 1st generation.

Pilot

The 90-92 front rotors are smaller in diameter and warp very easy. Always stick with OEM rotors and pads to have the highest quality. Lots of cheap cast iron rotors in the aftermarket parts, as well as cheap brake pads that are sure to squeal like a pig!
The 93 on up, have much larger rotors, but also 16inch wheels etc. I have no idea how big a job it would be to upgrade a first generation (90-92) LS400 to the larger rotors. The vibration is for sure a warped rotor. The only other thing you might try would be cross drilled after market rotors. A trick that works good to prevent warped rotors, is to never sit at a complete stop after moderate or heavy braking. If you creep the car forward a few inches every few seconds or so, you will not cause the bad warping. This is due to the heat being the highest where the pads are touching the rotor with the car completly stopped. It only takes a few inches of creeping forward to rotate the pads to another location, to stop the heat buildup in one area. Also after moderate to heavy braking, try to air cool the brakes with a steady speed for some distance without touching the brakes much. I have used this technique for many years on many different cars, and have not warped a rotor in a long time.
I always creep the car a few inches at all stops, and air cool as much as possible after moderate to heavy braking. The first generation LS-400 is well known to warp the rotors. This is why Lexus made them larger in diameter starting in 93. The 93 also has the newer A/C freon R134 and a passenger airbag. Anyone with a pre 93 and who wants another LS-400 should start with a 93 or newer to have all the second generation goodies, including larger brake rotors! Remember I am talking inches with the creeping, not feet!

Pilot
91 LS-400
01 RX-300

kreativ

Thanks for the tip on preventing warped rotors.

Sounds like he'd be better off going with a set of TRD cross-drilled rotors for his '91 LS next time. Given the fact that through Carson Toyota they're cheaper than the stock rotors anyways.