Brakes locking up...out of the blue
#1
Brakes locking up...out of the blue
1969 442 stock brake setup, disc front, drums back. Converted to slicone brake fluid several years ago.
Recently, a firm tap (not even a hard stop) on the brakes can make them lock up. Not sure if it's the front or back that are locking up but think it's the back. A softer pedal will not lock up.
There is a metering valve under the master cylinder and a distribution block underneath in back of the driver wheel well...all stock...and stock disc and drum brakes, lines, etc.
Brake booster is original and has never been opened up...n either have the metering valve or distribution block.
Brake warning light comes on at start and then goes off (correctly).
Any ideas?
Thanks
Recently, a firm tap (not even a hard stop) on the brakes can make them lock up. Not sure if it's the front or back that are locking up but think it's the back. A softer pedal will not lock up.
There is a metering valve under the master cylinder and a distribution block underneath in back of the driver wheel well...all stock...and stock disc and drum brakes, lines, etc.
Brake booster is original and has never been opened up...n either have the metering valve or distribution block.
Brake warning light comes on at start and then goes off (correctly).
Any ideas?
Thanks
#2
Read this thread on rebuilding brake distribution block. Not sure if this is the culprit though as my warning light is not coming on except at start as it's supposed to.
https://classicoldsmobile.com/forums...estion-164804/
https://classicoldsmobile.com/forums...estion-164804/
#9
That is where I am going to start including thorough inspection of brakes/pull the wheels, etc., but no leaks on the floor or on the inner wheels.
This came out of the blue and it is a lock up. Something definitely changed.
Just trying to come up with a plan to check the most likely culprits...clogged up cylinders/lines (witch i doubt because I went through them in past 5 years), distribution block, metering valve, vacuum booster (all originial)???
Start with the basics though.
This came out of the blue and it is a lock up. Something definitely changed.
Just trying to come up with a plan to check the most likely culprits...clogged up cylinders/lines (witch i doubt because I went through them in past 5 years), distribution block, metering valve, vacuum booster (all originial)???
Start with the basics though.
#11
Does the car sit for a long period of time ? You may want to "test" the brakes for "grabbing" a few times after you pull onto the street. Perhaps rust formed inside and that is causing them to grab. A few slow speed stops will help before you take off.
If you feel them get less sensitive, then you solved the problem. Your rear drums are more likely to grab than the front discs.
If you feel them get less sensitive, then you solved the problem. Your rear drums are more likely to grab than the front discs.
#13
Thanks. That's first on the list. The car does sit a lot ~ 7 months and then maybe gets 500-1000 miles in the summer/fall months.
Last summer it was driven very little...so...maybe that's the explanation.
Last summer it was driven very little...so...maybe that's the explanation.
#14
Father time can do it but I do not see sporadic use having any effect. If the brake hoses are original, they need to be changed out anyway. I experienced this myself once with 40 year old original hoses. Just a light touch on the brake pedal would cause the rear tires to lock up.
#15
Problem solved (I hope)...took OLDSter Ralph's advice...took it out for a drive and worked the brakes pretty good. Locked up once first time then no more...they seem to have quit grabbing...at least after they got warmed up.
I'll try again fresh/cold tomorow.
Thanks Ralph and thanks to others for responses.
Andy
I'll try again fresh/cold tomorow.
Thanks Ralph and thanks to others for responses.
Andy
#16
You don't have to do it every time you drive it, just when it has sat for a longer period of time. A few (2-3) low speed stops can be helpful to test the brakes and know they're operating properly, any time.
Thread
Thread Starter
Forum
Replies
Last Post
Oldsmaniac
Brakes/Hydraulic Systems
23
June 9th, 2022 03:09 PM