Need help with brake job! FJ60 or FJ40 calipers? (1 Viewer)

[Zeus0623]

Howdy Friends,

Its time for a brake job on the 40. Front brakes keep locking up. I am thinking the calipers may be compromised but also curious to know your thoughts on other culprits? I have been told that I have a FJ60 front axle. What is the best route to go on replacement calipers/rotors/pads (mainly calipers)? Do I just punch in 1972 FJ40 in Rock Auto or should I be using 60 parts?

Thanks!

 

[OGBeno]

60 and 1/1975 and later calipers are the same. 47730-60021/47750-60021

 

[charliemeyer007]

I would do rotors, pads and calipers. If your rubber hoses are old I would change them too. I had one go bad on the inside and acted like a diode and wouldn't let the pressure release - it ruined everything on that side.

 

[pb4ugo]

60 and 1/1975 and later calipers are the same. 47730-60021/47750-60021

Wouldn't a 1/1975 have drum brakes?

 

[OGBeno]

Wouldn't a 1/1975 have drum brakes?

Sorry, correct. 9/1975 and later. Thanks for the catch!

 

[Zeus0623]

Awesome! Thanks guys. To confirm, I could use late model FJ60 calipers? Similar to my 1983 FJ60 for instance?

Also, no rubber lines. All braided steel.

Do calipers make the most sense or should I look at the master cylinder too? I have wanted to replace it for a while but also want to address the core issue first (if possible).

 

[Zeus0623]

Does this look right?

 

[Mark WV]

I may be mistaken, but I believe you will find that your braided stainless steel brake lines are just normal rubber lines under all the braids, and thus are subject to internal breakdown/delamination.

If in doubt, change it out….

 

[Zeus0623]

I may be mistaken, but I believe you will find that your braided stainless steel brake lines are just normal rubber lines under all the braids, and thus are subject to internal breakdown/delamination.

If in doubt, change it out….

Ok, so dumb follow-up question but just checking; should I run late model FJ60 brake lines? I’m assuming yes. Thanks!

 

[B y r o n]

You say the front brakes keep locking up, do you know if the drum brake residual valve was removed from your master cylinder? Maybe updating your master to match your brake setup would help. What brakes are you running on the back, drum or disc?

 

[pb4ugo]

It appears you have the stk frt end with a disc brake conversion with probably 60 knuckles. The brake lines appear to be 40 stuff from 76 to around 78.

Does your rotor spin with slight resistance? If it's hard to turn or not at all without a tool, then the calipers might be locking up. You should be able to look at the brake pads to determine how much material is left on them. See if the caliper pistons will retract. If they do retract a calipers are probably good.

 

[Zeus0623]

You say the front brakes keep locking up, do you know if the drum brake residual valve was removed from your master cylinder? Maybe updating your master to match your brake setup would help. What brakes are you running on the back, drum or disc?

The plot thickens! I am running drums on the rear. Not sure if the residual valve was removed??? I posted a photo of the master cylinder setup above if that helps?

 

[Zeus0623]

It appears you have the stk frt end with a disc brake conversion with probably 60 knuckles. The brake lines appear to be 40 stuff from 76 to around 78.

Does your rotor spin with slight resistance? If it's hard to turn or not at all without a tool, then the calipers might be locking up. You should be able to look at the brake pads to determine how much material is left on them. See if the caliper pistons will retract. If they do retract a calipers are probably good.

Thanks for the insight. Rotors spin with slight resistance when the wheel is off. However, the brakes lock up under only small amounts of pressure. Almost every time I brake now things lock.

 

[pb4ugo]

When calipers go bad they start sticking and are applying pressure constantly with no pedal pressure. Making sure the frt residual has been removed is a good place to start. What is the condition of the rear brakes? Are they adjusted properly? How's the brake pedal height? Rear brake adjustment effects the brake pedal height. Are any of the wheel cylinders pistons frozen? Your fronts might be locking up because the rears are not working properly or at all.

 

[Zeus0623]

When calipers go bad they start sticking and are applying pressure constantly with no pedal pressure. Making sure the frt residual has been removed is a good place to start. What is the condition of the rear brakes? Are they adjusted properly? How's the brake pedal height? Rear brake adjustment effects the brake pedal height. Are any of the wheel cylinders pistons frozen? Your fronts might be locking up because the rears are not working properly or at all.

This is interesting insight. Brake pedal has always been VERY high, however the locking up has only gone on for about a year now.

I ordered all the equipment for the front to take care of that. Will see if this fixes the problem but then may also drop it off at a local shop to check out the rears. I am no expert on drum brakes...

 

[texcwa]

When I did my 60’s knuckles swap on my 72 40, I believe I just used standard Chevy calipers. I also swapped out my 40’s Master with a FJ80 master (single reservoir) that bolted right onto the existing brake booster. Still have rear drum and never had an issue over the last 15 years with a need for a proportional valve.