Ls400 Brakes

[BillyC]

Just bought a 1991 LS400 with the following problem. Often, but not every time, when the brakes are applied there is a pop or thump sound. It seems to be coming from the right front, but since I can't make it happen at will, it is difficult to localize. If the car has been backed up and then the next time the brakes are applied as the car moves forward is when it appears to happen. Anyone had a similiar experience or any ideas on this subject? Thanks in advance.

BillyC 91LS400

[VBdenny]

Just a guess but there aren't too many things that make that noise. Perhaps one of the inner 14mm caliper bolts has come loose or was never einistalled. This causes the inner part of the caliper which holds the brake pads to rotate outward. I posted pictures of the caliper in the gallery. I also have a powerpoint presentaion I made when I did mine. Email me if you would like it. Luckily, they're really easy to fix.

[BillyC]

Thanks VBdenny, I'll check it out. The former owner said that the front brakes were redone by the Lexus dealer in Huntsville, Al, about 6 weeks ago.

BillyC 1991 LS400 - North Alabama

[BillyC]

Checked the brake calipers - all bolts are there and everything is tight. Other ideas?

Thanks,

BillyC 1991 LS400

[VBdenny]

Well, you might try this check. After driving the car for awile, put your hand on the rims and see if one is hotter than the other, If the caliper piston hangs up, it might be causing it to stick. I doubt this is the problem if it seems to be coming from both sides. Remember than when braking, a strain is put on other suspension parts. Perhaps a strut, or control arm is weak and shifting when the load changes? I know the upper control arms and ball joints on these cars wear out at 120000 or so. I also had my torsion bar bushing replaced. Mine make no sound when I brake but i have enough other stuff broken to keep me busy. You'd think that maybe Lexus could hook up a tech with this forum to give us a little insight. Sure would be nice. At least we have each other to diagnose problems. Try to identify when and under what conditions you hear the noise as someone might recognize what it is.

Good luck

Denny

[pgross]

Just went thru a problem that might be relevant. My tires were wearing funny and I could not trace it down. Finally a dealer found a worn (but the key here is not badly worn) upper control arm) which seems to have helped the tire wear problem.

BUT - I realized that the whole time, I was feeling a catch in the brakes during each deceleration. I feel stupid, but never associated the two.

Check the wear on the tires. My tires wore not by cupping, but in a choppy way where the outside treads on both sides made the rubber wear straight down from the snipe so that each tire on the front had a sharp edge that presented itself to the road, and was really noisy. Maybe (hopefully) your is not that bad, but whether or not this is a problem, if it is suspension related, you might see evidence on the tires.

Phil

[tansupplyman]

I call the 'snipe' : feathering.

It has been present on my tires for about 40 years !!!! goes with driving.

It is corrected by 'X' rotation[regardless of what the book says] every 5000 miles. that way it corrects until the next 5000.

Most places you buy tires from will rotate free at that milege--if it is a good place.

[pgross]

Actually had rotations and allignments till I was blue. Proof is that after the fix, the tires are starting to wear true and round.

Just want to make the point that noise, if it comes from suspension, might be seen as a wear problem in the tires.

Phil

[VBdenny]

Just remember you can't X rotate the tires on the Gen 1 LS 400's because the rims are designed for either left or right side. There are also some tires that can only be rotated ib one direction as well.

Intereting that you said the control arms were "somewhat" worn. My dealer told me mine were "weak" but okay. If they had put a lubrication point on these they probably would have lasted forever.

[jzz30]

try replacing your upper and lower ball joints. the lower ones really go bad to the point where you can push it in and out with your finger. I changed my lower arms amd ball joint a couple months ago but im going to do my uppers soon I got one arm in but the dealer screwed up the order and didnt get the other side so i have to wait. and the new arm is steel not magnesium. which kind of makes it sound cheap but i guess they had to do that cause it was just too weak.