What is the difference between a FZJ80 and a 4Runner Master Cylinder? (1 Viewer)

[GRM]

As the title states: what is the difference between a FZJ80 master cylinder and a 90's 4runner 1" master cylinder?

The reason why I ask the question is that I recently swapped my '86 Pickup rear axle (drum brakes & 15/16 wheel cyl) for a disc brake '96 FZJ80 rear axle. The truck currently runs a 90's Cab and Chassis Pickup 1" master and dual diaphragm booster off a u-haul truck. The brakes felt great with the old drums and feel good now. As I tune the brakes, I want to ensure that there isn't something mechanical I am overlooking (such as the wrong residual valve in a master cyl).

What I have noticed is these issues:

• The pedal feel is great when driving, but when I hit the brakes hard, I can get the pedal to the floor
• When pumping the brakes, the engine starts to stumble (WD40 in the brake booster check valve fixed 80% of this issue)
• The brakes were very mushy when the proportioning valve was set for drum brakes. Then as I reduced the pressure to the rear calipers, the pedal became stiffer.

While I tune the brakes, I want to make sure the internals of the drum brake and the disc brake master cylinders are the same. Can anyone confirm this for me? Is there a residual valve in the master cylinder? I did a bit of research and found that the 4runner and the non-abs fzj80 use the same master cylinder in the aftermarket. But that doesn't mean they are the same from Toyota.

Thanks for your help.

 

[pappy]

FZJ80 is designed for a 4wheel disk truck. The 4Runner is designed for disk/drum trucks.

 

[GRM]

So whats the difference? Do they have different residual valves in them?

From Toyota- visually they are different because they have different reservoirs. But the cylinder kit (04493-60210) are the same for both 4runner and non-abs Land Cruiser.

Also, a Beck/Arnley 072-9077 (Master Cyl w/o Reservoir) is the same for both 4runner and non-abs Land Cruiser.