Your brakes are locking up because the master cyl. is not returning all the way and it is not letting the fluid return to the master cyl. It could be that your pedal is not returning do to lack of lube or binding for some reason or the pedal adjustment rod is to long or the rod from the booster to the master cyl. is too long. Check to see if you can pull the pedal back up when this condition acures if so lube the linkage. GM chassis have a bellcrank that changes the direction of the lincage and in the past they didn't have a lube fitting and caused this problem. If this is the case you can drill and tap this shaft for a grease fitting. I hope this helps and happy camping.
Reading your first post, you didnt say if they were just locking up going down the road or after you apply the brakes then they lock up.
I'm just grabing straws here, the bell crank thing, you should be able to feel that with your foot if its binding & wouldnt be that much of a task to check it out under the dash. Might be harder getting up from in between the seat, engine cover & dash than checking it over, so have someone on hand before you crawl down into there.
If you look in the brake lines right under the booster & master cylinder, just a few inches from the master cylinder there is a block in the lines, a connection point where all the brake lines hook together. You will notice there is a wire hooked to that block as well.
Now, its not real clear to me now, I know its there, but I'm thinking that block is the valve of sorts that distribs the same amount fluid presure out to each wheel. Could be a malfunction in that & not letting the fluid return to the master cylinder.
Heard of no brakes after all that work was done, but locking up, all 4 wheels, only way would be the connection hoses from the chassis over to the wheel like already noted, that valve in the lines or the master cylinder not releacing.
What you want to bet the bell crank deal, 83 model & probably been sitting more than its been drove, rusty to say the least.
Neil
C-Leigh Racing wrote: If you look in the brake lines right under the booster & master cylinder, just a few inches from the master cylinder there is a block in the lines, a connection point where all the brake lines hook together. You will notice there is a wire hooked to that block as well.
That's the proportioning valve. It is possible with old brake fluid and a lot of years it could be corroding inside. The wire goes to the 'Brake' light on the dash. If for some reason there isn't proper brake fluid to the front and rear brakes a valve moves and makes the switch turning on the light.
Exhaust leak or other heat source at MC or other brake parts.
Somebody put motor oil in the MC. (happened to my brother at a lube joint - similar symptoms)
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