Brake Pulsation?

[kuziwk]

i bought a lexus ls400 1992 with 200 000 miles on it, i have all the repair records and the record of a previously diceased owner. Anyways the car was fine in the city under heavy braking but on the highway at above 60mph when i brake the wheel and pedal vibrate bad. The car has records of the rack and pinion being replaced and struts or something like that, the brake rotors were replaced at 12000 miles ago, are they warped again? it is to my knowledge the car was parked for 6-8 months prior to the previous owners death, is it possible there is build up from sitting? or do the bushings need to be replaced? Im also worried i wont pass the out of province vehicle inspection

[SRK]

Although the 92's have the smaller brakes, and they do warp rotors, it's entirely possible that there are rust patches on the rotors where the pads sat when the car was off the road. Especially if it was stored outside. Drive it for a while, and the rotors will clean up with use and more than likely the vibration will disappear. Might tight a few hundred kilometers to fix itself.

The vehicle inspection will not find a problem with the brakes like that. Most inspections are a joke.

[kuziwk]

Although the 92's have the smaller brakes, and they do warp rotors, it's entirely possible that there are rust patches on the rotors where the pads sat when the car was off the road. Especially if it was stored outside. Drive it for a while, and the rotors will clean up with use and more than likely the vibration will disappear. Might tight a few hundred kilometers to fix itself.

The vehicle inspection will not find a problem with the brakes like that. Most inspections are a joke.

well im from alberta, canada and i need an out of province inspection which is very detailed and than a safety inspection. Im hoping they are not warped and im aware of the smaller brakes and on the 205 width tires, however for $1600 i figure you cant go wrong. I drove the car and i was sold, i had someone else drive it and they said its a bit loose i didnt notice anything but i drive a 2005 dodge neon so there is HUGE difference it quite remarkable how this car drives, unfortunatley the long weekend prevents me from being able to get the car regestered and inspected :( so i have to wait till tues too see.

[curiousB]

I agree with SRK. Inspection is typically safety related. If the brakes are all working and stop the car you generally pass. Pulsing brakes isn't as much a safety issue as an annoyance and potential creator of other problems down the road.

Usually warped rotors are an issue as you slow down and you really feel it in the steering wheel. High speed vibration is usually wheel balance and not linked to touching the brakes. So its a bit strange to me.

Some talk on this forum of worn suspension bushings creating strange front end problems. Maybe someone else with direct knowledge of that symptom can chime in.

[kuziwk]

I agree with SRK. Inspection is typically safety related. If the brakes are all working and stop the car you generally pass. Pulsing brakes isn't as much a safety issue as an annoyance and potential creator of other problems down the road.

Usually warped rotors are an issue as you slow down and you really feel it in the steering wheel. High speed vibration is usually wheel balance and not linked to touching the brakes. So its a bit strange to me.

Some talk on this forum of worn suspension bushings creating strange front end problems. Maybe someone else with direct knowledge of that symptom can chime in.

well i took the car for a drive tonight on the range road, it really is a fine machine but yea whenever i press on the brakes at 60 mph it pulsates the brake, steering wheel, and i noticed the shifter as well it really makes me nervous and almost makes the car unstable. I really did my research on these cars, went out and bought expecting to prove my parents wrong that buying a lexus with high miles makes me smarter than the uniformed people missing out (they were not thrilled at the least). My 2005 dodge neon did this but mostly just from the brakes and wheel not the whole car. Also when the car starts the interior lights kinda flicker a bit when i turn them on, i think the alternator is about to go, can i use any Toyota alternator from a junk yard? Im more worried about the breaks as i fell in love with the car the moment i drove it but this pulsating is really annoying.

[SRK]

So have you put 200k on the car since my post? Are you listening? Drive the car gently, use the brakes. If the pulsations don't go away, have the rotors turned and fix the problem that way.

Have you performed at least a voltage check on the alternator? Are you prepared to diagnose the car rather than complain? You got a good deal, you like the car, now fix it.

Whose giving you advice locally? If the alternator is not performing have it rebuilt - you won't find them in wrecking yards, and why would you think that's the best way to go?

Stop questioning your decision to buy the car and get on with it.

[kuziwk]

So have you put 200k on the car since my post? Are you listening? Drive the car gently, use the brakes. If the pulsations don't go away, have the rotors turned and fix the problem that way.

Have you performed at least a voltage check on the alternator? Are you prepared to diagnose the car rather than complain? You got a good deal, you like the car, now fix it.

Whose giving you advice locally? If the alternator is not performing have it rebuilt - you won't find them in wrecking yards, and why would you think that's the best way to go?

Stop questioning your decision to buy the car and get on with it.

yea i have a multimeter i guess i can seach up how to do a voltage test, yes rotors can be turned hopefully going away. Thanks.

[fsuguy]

Hi,

It may be that the rotors are worn excessively (beyond specifications - rotor/hub run-out) and therefore resulting in the vibrations you are experiencing. If it is not the thickness issue, then it may be the rust causing the vibration. If your rotors are worn out, it is possible that the replacements were not the OEM (or OEM quality) ones. See the Lexus section in the following link on brake vibration: http://arrc.epnet.com/autoasp/framerq.asp.

Hope this helps

Mike

[Hanging In There]

i bought a lexus ls400 1992 with 200 000 miles on it, i have all the repair records and the record of a previously deceased owner. Anyways the car was fine in the city under heavy braking but on the highway at above 60mph when i brake the wheel and pedal vibrate bad. The car has records of the rack and pinion being replaced and struts or something like that, the brake rotors were replaced at 12000 miles ago, are they warped again? it is to my knowledge the car was parked for 6-8 months prior to the previous owners death, is it possible there is build up from sitting? or do the bushings need to be replaced? Im also worried i wont pass the out of province vehicle inspection

A pulsating brake pedal is almost always caused by an issue with brake rotors/drums. With 80K miles on them it is reasonable to expect some rotor issues. If it were my vehicle I'd take it to a trusted repair shop and have the rotors resurfaced. If resurfacing would leave the rotors below factory specs, then new rotors are in order. Correctly done this should eliminate your pedal pulsing issue.