Fj80 booster + T100 master + 4Runner calipers + Fj60 drums

GMSilk_Fj60

SILVER Star
Joined
Jun 26, 2004
Messages
176
Location
Central MD
 
 
The title describes my set up.

Fj80 booster + T100 brake master + 4Runner calipers + Fj60 drums

I put it all together and took it for a drive. It feels good for a bit then the brakes started dragging. About 10 miles into my drive I start down a large hill and smoke the front calipers. Small fire on some excess grease for a hot second. Let the truck cool down and the brakes felt much better. Anyone have any idea how to better set up the new brake hardware?
 

60Works

60 Series Iron Works
Joined
Sep 28, 2009
Messages
1,482
Location
NH
 
 
Go back to all OEM with an FJ-62 or 4 Runner booster. 4 Runner calipers gain you nothing. T100 master reduces braking pressure.

Does the 80 booster have a check valve? The OEM 60's is internal. If the 80's isn't, you will need to add one.
 

GMSilk_Fj60

SILVER Star
Joined
Jun 26, 2004
Messages
176
Location
Central MD
 
 
From my research fj80 booster has a check valve and is an upgrade over the 60 booster.

I went the 4Runner brake route because I could find them locally and they bolt up. I’ve read many of the posts for and against the upgrade but it’s still something I’d like to try.

It is my understanding that the math behind the braking performance relies on fluid volume and the size of the piston that’s being pushed.

I had some significant braking issues and figured I could use this opportunity to move to a system where I could more easily find parts. Fj60 parts are always a special order. The above mentioned parts are not. I’d like to get this combination adjusted if possible. I always have OEM but this is a new idea I’m playing with. Thanks for the advice.

I’m going to try adjusting the brake booster adjustment screw again...
 

Tapage

Club 4X4 Panamá
SILVER Star
Joined
Apr 4, 2003
Messages
23,531
Location
Panamá
 
 
 
I had that very same setup at one point on Tencha .. rear discs was a definitely improvement over drums ( although my drums were in very bad old shape ) then I move to hydro booster ..
 

60Works

60 Series Iron Works
Joined
Sep 28, 2009
Messages
1,482
Location
NH
 
 
If the booster pin protrusion adjustment solves your problem, please post the dimension. Toyota's SST for setting it is a go-no go gauge with no numbers given. It will help anyone else with the T100 master.

If the pin is causing the calipers to drag, logic would suggest that the hill is incidental to the overheat. You might try testing if the wheel spins freely with the engine running.

On second thought, descending with engine braking will produce very high vaccuum which might effect drag if the pin is protruding too far or the pedal Clovis too far out.

Are you running with unusual weight or large tires?
 
Last edited:

GMSilk_Fj60

SILVER Star
Joined
Jun 26, 2004
Messages
176
Location
Central MD
 
 
Interesting thought about the downhill vacuum. Hopefully I’ll get to do more by this afternoon. Updates ahead...
 
Joined
Apr 14, 2008
Messages
5,587
Location
North of LA California
 
 
The FZJ80 booster has 2lb residual valves front and rear. Rear drum brakes ususally want 10 lb residual valves from all the reading i've done the past few weeks.

Can we see a picture of your 4runner caliper(s)? Odd they would drag. Did you rebuild or buy remans? Grease on the pad pins should allow the pads to move freely.
 

GMSilk_Fj60

SILVER Star
Joined
Jun 26, 2004
Messages
176
Location
Central MD
 
 
Ok. Got everything working.

The Fj80 booster has a longer plunger into the master than the fj60. It requires tuning (almost entirely threaded in). A way to test the length without fighting the tight thread with thread lock is to unbolt the master and slip a few washers on the studs. I immediately had middle range brake pedal play. The 10lb residual valve I left on the assembly FYI (see photo).

I have to say, once dialed in (set the rear drums correctly!) and space the booster shaft correctly, this is probably the best braking 60 I’ve had... and I’ve had a few...

2116C636-82EA-4DEC-B1F3-3EBC77F71394.jpeg
 
Top Bottom