Hey everyone, I've got a mystery problem with the brakes on my '78 40.
Some history...
-original MC was leaking and replaced with a new OEM unit from Toyota Dealership.
-After about 2 years of daily use, one day I go down the road, as usual, need to slow down (going about 30mph.) I barely even touched the pedal and my front brakes immediately locked up, squeeled, and scared the crap out of me! Jacked it up and the fronts were locked, but rears were turning as they always had. Managed to crawl back 300 feet to my draiveway....I've driven the rig with great brakes for the past 6-7 years, up until the first MC failure (leaking.)
So, since then, here's what I've done...
1-replaced mc
2-replaced front calipers, pads.
3-bled, bled, bled, and more bleeding.
4-checked for excessive exhaust heat near any brake lines
Here are things I have not done...
1-replaced '78 booster (seems fine, no vac. or brake fluid leaks.)
2-adjusted push rod
3-adjust rear drums
4-replace all brake lines (no visible leaks, ballooning anywhere.)
Some more info...
currently no E-brake or any of the oem E-brake setup (drum, etc.) because now it's got an H55F, etc.
This is where it gets interesting.
Now, start it up and just going back and forth enough to hit the brakes 8-10 times, and the fronts lock up TIGHTLY! The day before, I was driving it like normal, and the next morning, surprise! WTF!?
I pop the hood and crack the FRONT brake's hard line where it enters the MC
and immediately I can hear the pressure release and obviously see/feel it happen, too. It seems to keep doing this indefinitely, and before they lock up, they are so touchy I'd likely go into the dash if I used the pedal "normally."
Myself, and my mechanic have bled this thing PLENTY.
There are no leaks I can see in the lines. Pressure is building up, returning to the MC, but not releasing. The MC is from Advance Auto and pretty much looks just like my OEM one.
Here are some possiblities we've come up with so far...
1-faulty MC from Advance Auto?
2-faulty booster?
I'm not positive, but it really seems to be isolated to the front brakes, they are the only ones locking up, etc. Has anyone been through something like this before or have any ideas about what is wrong? I searched, but after about an hour of reading posts that didn't really match, I decided to just ask...
Thanks for reading
JR
Some history...
-original MC was leaking and replaced with a new OEM unit from Toyota Dealership.
-After about 2 years of daily use, one day I go down the road, as usual, need to slow down (going about 30mph.) I barely even touched the pedal and my front brakes immediately locked up, squeeled, and scared the crap out of me! Jacked it up and the fronts were locked, but rears were turning as they always had. Managed to crawl back 300 feet to my draiveway....I've driven the rig with great brakes for the past 6-7 years, up until the first MC failure (leaking.)
So, since then, here's what I've done...
1-replaced mc
2-replaced front calipers, pads.
3-bled, bled, bled, and more bleeding.
4-checked for excessive exhaust heat near any brake lines
Here are things I have not done...
1-replaced '78 booster (seems fine, no vac. or brake fluid leaks.)
2-adjusted push rod
3-adjust rear drums
4-replace all brake lines (no visible leaks, ballooning anywhere.)
Some more info...
currently no E-brake or any of the oem E-brake setup (drum, etc.) because now it's got an H55F, etc.
This is where it gets interesting.
Now, start it up and just going back and forth enough to hit the brakes 8-10 times, and the fronts lock up TIGHTLY! The day before, I was driving it like normal, and the next morning, surprise! WTF!?
I pop the hood and crack the FRONT brake's hard line where it enters the MC
and immediately I can hear the pressure release and obviously see/feel it happen, too. It seems to keep doing this indefinitely, and before they lock up, they are so touchy I'd likely go into the dash if I used the pedal "normally."
Myself, and my mechanic have bled this thing PLENTY.
There are no leaks I can see in the lines. Pressure is building up, returning to the MC, but not releasing. The MC is from Advance Auto and pretty much looks just like my OEM one.
Here are some possiblities we've come up with so far...
1-faulty MC from Advance Auto?
2-faulty booster?
I'm not positive, but it really seems to be isolated to the front brakes, they are the only ones locking up, etc. Has anyone been through something like this before or have any ideas about what is wrong? I searched, but after about an hour of reading posts that didn't really match, I decided to just ask...
Thanks for reading
JR