ls400geek

.. on my 98 LS400.

When braking at 80 mph or so, the car vibrates. My boyfriend believed it was due to the front rotors, so we ordered replacements, along with new pads.

He replaced the front rotors and pads today. The car still has that same vibration when braking at 80 mph. So it didn't appear to accomplish anything. Any ideas as to what is causing this vibration? It doesn't happen when braking say at 60 mph.

Also, I am not 100% sure, but it appears that VSC is no longer working, as of today (after the front rotor/pad change). I slam on the brakes pretty hard and the antilocking mechanism isn't working-- I don't feel safe now. Any ideas?

Thanks,

Jennifer

k7q

iTrader: (37)

check the strut rod bushings.

sam12345

iTrader: (1)

Could be any suspension part. On the abs, your boyfriend probably broke the abs sensor wire during the install. Is your abs light on on the dash?

RA40

iTrader: (6)

How many miles on car? I agree about inspecting the strut rod bushings. These are often due for replacement by 80K miles.

Regarding the ABS check for any error codes. Make sure that the ABS sensor is properly connected-intact. When you applied the brakes did it lock-up? If you are feeling the pulsation through the pedal or steering wheel then the ABS may still be functioning but due to the worn bushings it feels worse like the rotors may have warped/runout.

ls400geek

The bushing that goes into the strut bar? I have the 98 toyota service manual .

Page SA-32 (Front Strut Bar Components)

If it's on that page is it in the lower left hand corner? I don't see a part number for it but there is a photo of the bushing.

Thanks,

Jennifer

dicer

Sounds like ABS to me. Take out abs fuse and see if it still does it.

k7q

iTrader: (37)

http://img.eautopartscatalog.com/live/L2012140256OES.JPG

Don't have a manual, but the front strut rods look like this. It's connected to the front lower control arms

midwest2

Jen,

Slamming on the brakes "pretty hard" isn't going to tell u if the abs is working. You need to apply the brakes sufficiently that the wheels skid. Either pavement or a gravel road will do. If your wheels lock up and you feel no abs pulse in the brake pedal, then I'd say it isn't working.

For what it's worth, my 96 vibrates when I brake at high speeds too, and I've gone through most of the front end. For me, I just don't often have the occasion to need to slam on the brakes at 80 mph.

fixmiester

Braking at high speed creates different suspension dynamics (oscillations) than low speed. You may simply have front tires that are not balanced for that speed, or are slightly out of round, and begin oscillations when the suspension is compressed during braking, which changes the dampening factors. Try changing the front tires to the rear, and see if things change.

ls400geek

The ABS is working fine.. I was wrong about it. I felt the pulsations recently.

However I am still getting vibrations when braking at 80 mph. My boyfriend thinks it's coming from the back. (It seems to me it is coming from the back as well). He's suggesting I change the back pair of rotors now... I already changed the front and that didn't help. Fortunately he can do all the work though and I got the pair of rotors for only $63 and $20 for the pads.

I do know I have a brand new set of tires and this problem existed before with the old set of mismatched tires. The old set of tires had a couple slow leaks (part of the reason I changed to a new set)... and now the new set has one slow leak in the right rear, that only happens in very cold weather (like 20-30 degrees or less F). My boyfriend said in the past it is possible that the rim is warped and that the bead on the new tire isn't sitting perfectly on it. Perhaps, it is warped and is the source of the vibration as well? (i.e. when braking at high speeds).

OMAHA

Here's my 2 cents......I have a 1994 LS400......I replaced all four tires(Pirellis), rear rotors (Brembo), rear brakes (Toyota), front lower ball joints (Beck Arnley).....still have front vibration when braking....took car to Midas, was told front rotors are WARPED. I'm replacing them this weekend with new rotors & brakes.....hopefully this will do it!

timmy0tool

iTrader: (7)

the OP replaced the front rotors already. i suspect the pads were not properly bedded in. you need to bed the pads onto the rotors during the break in period. do a couple of slow-downs from 60mph to 5mph (never coming to a complete stop) to bed.

ls400geek

We didn't know to "bed" them.. this is the first time both of us have heard about this. I watched some videos on the process on youtube and they go along with what you say.

But my question now is, can we bed them now after they've been used for a few months? Or should I buy new pads (only about $21) and bed them?

Jennifer

SonicC

My initial though was what the previous poster mentioned in: they weren't bedded in...which means your rotors are slightly warped now.

Unfortunately you can't go back and just bed them in now, because there's already a transfer layer (albeit bad one) built up on your rotors. On the positive side of things, you don't need new rotors...you can go to local O'Reilly's or similar shop and get your rotors turned/resurfaced for about $30 for a pair. Once you get that done, install them back, then go online and look up a general bedding in procedure for the pads you have. They are NOT all the same. For example, Hawk pads generally need to be warmed up quite well, but doing so on Duralast pads will end up with glazed/warped rotors. You don't need to replace pads, unless they started chipping, cracking, or something like that.

Legender

And at only $20 for rear brake pads.. . you may have the same problem in the future. Not all pads are created equal and you want to make sure you purchase pads that will wear down and not cause the rotors to wear down. I'm not aware of high quality pads that only cost $20... I could be wrong and am prepared to be corrected. Personally I have very good luck with wagner thermoquiet pads on the front and the rear. I know the new front pads for my LS cost over $40 from O'Reillys... maybe I just paid too much.