brake pedal goes to the floor, but brakes do stop the truck

[brdhntr]

there is no leaks and the fluid was flushed and filled last fall. the lines have been bled and there is no air in the line. this is a more recent problem that seems to be getting worse. there is no leaking at the master cylinder as well. the brakes do stop the truck, you just have to push the pedal way in.

 

so, what do you think, bad master cylinder or booster? :dunno:

[bigd44889]

ya i'd say master cyclinder is going or rear wheel cylinder and fluid is in the drumb were you can't see it yet

[project88mj]

the brake is the middle pedal not the left one :smart:

 

 

 

 

jk

 

 

 

maybe bad booster? :dunno:

[bigalpha]

I second bad master.

 

If you swap out the master+booster, make sure you get the pushrod (the rod that connects booster to brake pedal) swapped out too, else you'll be scratching your balls with the brake pedal.

 

Ask me how I know.

[maddzz1]

Mine is doing something similar. No fluid leaking brakes are very soft and pedals goes to the floor. Brake light on dash comes on and stays on until i push the pedal down as far as i can then it goes off for a while. I am just gonna swap the booster and master for one from a 95-96 XJ, with those years you don't need to swap the push rod, just have to grind a flat edge into the round end.

[bigalpha]

Mine is doing something similar. No fluid leaking brakes are very soft and pedals goes to the floor. Brake light on dash comes on and stays on until i push the pedal down as far as i can then it goes off for a while. I am just gonna swap the booster and master for one from a 95-96 XJ, with those years you don't need to swap the push rod, just have to grind a flat edge into the round end.

 

So the pushrod from my 88 is the same length as one from a 95-96?

[maddzz1]

Mine is doing something similar. No fluid leaking brakes are very soft and pedals goes to the floor. Brake light on dash comes on and stays on until i push the pedal down as far as i can then it goes off for a while. I am just gonna swap the booster and master for one from a 95-96 XJ, with those years you don't need to swap the push rod, just have to grind a flat edge into the round end.

 

So the pushrod from my 88 is the same length as one from a 95-96?

 

 

Just the end is shaped different (the end of the 95-96 is round). So you grind part of it flat. Scroll down to the brake booster upgrade and then scroll down to the yellow part of that page: http://www.madxj.com/

[bigalpha]

Luckily, I got the master and booster for free, so I just need to get the push-rods swapped. Does it take a specialized place to do that?

[brdhntr]

ya i'd say master cyclinder is going or rear wheel cylinder and fluid is in the drumb were you can't see it yet

 

 

i checked for that. no leaking in the drums or at the calipers

[fiatslug87]

Hope this helps, from the '90 FSM.