1975 FJ40 Brakes

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Hi I have a 75 FJ40 it has front discs and rear drums, I have owned it a few years and the brakes have never worked well, I have done the following steps to troubleshoot.
Adjusted rear brake drums, several times, initially I thought this was problem, brakes are set with minimal clearance
recently found a leak on front "splitter" on driveshaft, tightened that up and bled brakes, this occurred after sitting all winter, fluid drained out
Bled Brakes
Pulled off vacuum, line, booster helps or assists so figure it works.
The front discs, have torn rubber on calipers, but don't appear to be leaking, rear drum brakes are pretty new, will ensure I still have pressure in system and look for leaks when I get home tonight.


Symptom is brakes work, but hard to press, I can manage if I pay attention, but get nervous when I let others drive as they might not be used to pressing this hard. I also have a 77 FJ40, that has never given me any issues with brakes, I am starting to think it might be master cyclinder and proportioning valve, but don't understand that set up. My 77 is stock, works great, 75, I thought had wrong master cylinder, but appears to be made by aisin for fj40s, could use some help if master cylinders and proportioning valve are worth investigating as a problem, attached are pictures, red one is 77 and green is 75, the problem one.

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pb4ugo

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If brakes are hard to push it usually is the brake booster. In your pic the green ones vacuum line is not hooked up. A stk 75 40 came with 4 wheel drum brakes.
 
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to push it usually is the brake booster. In your pic the green ones vacuum line is not hooked up. A stk 75 40 came with 4 wheel drum brakes.
I did pull the vacuum line, to see if it was doing anything, I think it was working ok as brakes were softer without it hooked up, it also held vacuum. Must of been upgraded to disc brake's along the way> If you can think of anything else I should check on booster please let me know, after reading whatever I could find, was thinking I would pull master cylinder, and check engagement from booster, or look at pedal linkage, doesn't seem out of ordinary but think it's worth a look as I don't think that is original style master cylinder.

I'm starting to think it's not proportion valve, as if everything was good and that was problem rears would lock up first or at least that's what I think after reading up whatever I could find.
 

pb4ugo

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Just looking at your pics, the master is not original to the 40. It maybe ok. I think in your latest response you say the brakes were softer without it hooked up. I'm guessing you miss spoke. Does the idle change when you depress the brake pedal? You mentioned torn boots on the calipers, have you check to see if the frt wheels spin freely.
 
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Just looking at your pics, the master is not original to the 40. It maybe ok. I think in your latest response you say the brakes were softer without it hooked up. I'm guessing you miss spoke. Does the idle change when you depress the brake pedal? You mentioned torn boots on the calipers, have you check to see if the frt wheels spin freely.
Never noticed a change in idle with pedal pressed I can check tonight, wheels did spin freely.

The master looks like it is Aisin for newer vehicles,
 

Skreddy

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The master looks like an 80 series master or some variant. I would pull the master and check the pushrod depth. I would also check the pushrod from pedal to booster. If you’re unfamiliar with either of those, I or someone else can post up more details.
 
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hard pedal is usually no boost.
is it hard the entire stroke of the pedal or does it go easy for a bit and then get hard?
not knowing what master that is from could also be an issue, is it for a disc/drum setup or 4wheel disc? generally the front does most of the braking versus the rear
does the pedal move easily when bleeding the brakes?
 
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The master looks like an 80 series master or some variant. I would pull the master and check the pushrod depth. I would also check the pushrod from pedal to booster. If you’re unfamiliar with either of those, I or someone else can post up more details.
 
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Well thanks for the help guys extended the little ram on booster and behind the pedal, and I got pretty decent brakes even good, tires are pretty big so I do t think it will be as good as the 77 but pretty happy, thanks again.

Now I have to figure out how to get a gas tank in Canada for the 77😁

Cheers
 

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