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How to Replace 98 GS300 Brake Master Cylnder Booster Unit

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Old 05-05-12, 07:47 PM   #1
Mick2
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Default How to Replace 98 GS300 Brake Master Cylnder Booster Unit

My car has 195,000 miles and somewhere in my master cylinder i have been hearing a loud squeal that sounds like a dolphin when pressing or releasing the brakes. This used to occur only in freezing temperatures but over the last 2 years this has become worse and will do it when 100 degrees. For the past 5 years my brakes feel a little mushy as if needing bleeding.

I asked a Lexus dealer about it this week and was told the electronic actuator is probably about to fail and will lose my breaks. The replacement labor and parts is not worth it and would like to change this myself with a used one. Does anyone have knowledge on how to replace the unit and how hard it is to do? Thanks.
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Old 05-05-12, 10:23 PM   #2
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I used to have the same problem with mine, very annoying hearing that sound everytime you pressed on the brake pedal. Bought a used master cylinder/ABS pump unit and think I paid no more than 150 for the labor.
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Old 05-06-12, 09:37 AM   #3
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remove the 4 lines from the unit itself
unplug all electrical connectors and sensors
remove the pin going through the brake pedal
remove the 4 bolts holding the booster to the firewall (inside the car)

pull the booster assembly out

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Old 05-06-12, 08:09 PM   #4
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Thank you very much. I think I will track down a used one and attempt replacing it. Appreciate the help!
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Old 05-06-12, 09:45 PM   #5
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most people upgrade to 01+

do some searches
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Old 05-07-12, 12:30 PM   #6
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So then.... do 01+ master cylinder assemblies replace the current unit without modification?
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Old 06-08-12, 07:58 AM   #7
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i dont know if it needs modification i would think not, but the 01 plus is better
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Old 06-08-12, 11:46 AM   #8
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Thanks for all your help. I bought a 1999 ABS unit out of a salvage yard for $450. There was really nothing complicated about removing and installing it but it took 3-4 hours because I had a hard time getting the right angle on the 4 firewall bolts. Once installed I had it towed to a Lexus dealer who bled the system for $112. Other local mechanics said they would not bleed the brakes and that I had to have a dealer do it. My brakes work better now than they ever did. The salvage guy said the 98 and 99 models are well know for faulty ABS systems and finding a cheap used one is getting a more difficult.
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Old 06-08-12, 12:21 PM   #9
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why didnt you choose to go with the 01 and up?
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Old 06-08-12, 12:27 PM   #10
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I'd like to remove my ABS all together....
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Old 06-08-12, 07:48 PM   #11
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I had read about using newer ABS units but when I went to the salvage yard the guy told me only 98 and 99 ABS brakes were compatible so that's why I went with the 99 model. I didn't have time to look into it more and just bought it. I hardly knew what I was doing anyway.
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Old 06-08-12, 09:07 PM   #12
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Quote:
Originally Posted by speedaddic View Post
I'd like to remove my ABS all together....
I did. best thing I did!

http://www.clublexus.com/forums/susp...nd-master.html
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Old 06-09-12, 05:51 AM   #13
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Quote:
Originally Posted by speedaddic View Post
I'd like to remove my ABS all together....
this guy used a supra one
http://www.clublexus.com/forums/gs-s...ter-build.html
i have a supra one thomas, but it has abs or else i would trade you
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Last edited by sinistervr; 06-09-12 at 05:56 AM..
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Old 03-09-13, 11:18 AM   #14
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if you do end up replacing your master cylinder/brake booster components can I buy the old broken ones from you ?

Please pm me
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Old 06-07-13, 10:18 PM   #15
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Quote:
Originally Posted by AMSMIKE View Post
remove the 4 lines from the unit itself
unplug all electrical connectors and sensors
remove the pin going through the brake pedal
remove the 4 bolts holding the booster to the firewall (inside the car)

pull the booster assembly out

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
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I need help anyone who have a brake booster for a GS300 and they are selling it let me know ASAP 1347-545-8231 thanks
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Old 06-07-13, 10:18 PM
 
 
 
 
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2000, 300, 98, booster, brake, change, cylinder, fix, gs, gs300, lexus, master, pedal, problem, release, removing, replacing

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