FJ80 SF to FF Disc Brake swap questions (1 Viewer)

Joined
Mar 8, 2015
Messages
358
Location
Elverta, CA 95626
OK, 'Mud community, I've searched & read for the last few YEARS and still haven't come to a real conclusion on this.

Hopefully somebody here can FINALLYclear some of this up.

I have a 1991 3FE FJ80 (Disc/Drum brakes, w/o ABS)

However, I have a Full Float disc brake E-Locked rear axle, from a '93, sitting in the garage, waiting to be installed.
IMG_20190612_145927.jpg

Because my 80 is my daily driver, I need to be sure I get the correct parts ahead of time, in order to minimize down time.

My primary concerns are

1)Determining which Master Cylinder to run -

-- Disc/Drum VS Disc/Disc - 2lb VS 10lb residual valves (although this MAY not be a MC issue - see below)

-- Non-ABS VS ABS (if this matters)

-- Port orientation - One of the threads I read through recently on 'Mud, stated the FJ80/3FE models have a Rear Port/Front Brake, Front Port/Rear Brake layout - with both ports coming out of the SIDE of the Master; the 1FZ ABS models ALSO have the Front Port/Rear Brake layout - BUT the front port comes out of the TOP of the Master, while the rear port comes out of the SIDE; Finally, the 1FZ Non-ABS models are Front Port/Front Brake, Rear Port/Rear Brake layout - with both coming out the SIDE of the Master Cylinder. Unfortunately, the 91 does NOT have the curly-Q coil in the metal brake lines, off of the Master, like the ABS trucks do; this limiting the ease of flopping ports/lines, F to R.

2) LSPV - Is there a CRITICAL difference between the 91 (Disc/Drum) and the later (Disc/Disc) proportioning valve? Does the LSPV just need to be adjusted when swapping the rear brakes from Drum to Disc; or does it need to be replaced with the other version? It was suggested, by one of the "go to" Cruiser parts suppliers that the residual valves MAY actually be part of the LSPV and NOT in the Master Cylinder; which is contrary to everything I have found anywhere on the different Masters. ALTHOUGH, this WOULD explain why places like Marlin say the "FJ80" Master Cylinder that they sell will work for the various years of Hilux and 4-Runners, whether they have Disc OR Drum rear brakes. However, there doesn't seem to be a clear answer on WHICH FJ80 (or FZJ80) Master Cylinder it is that is being offered for the Mini's.

3) Brake Hoses - is there a difference in the fittings in the frame side of the rear brake hose? I have a set of extended SS brake hoses for the FZJ, will these fit the 91 frame fittings; or do I need to get different hoses/change the frame side fitting/get some kind of adapter?

So, I am turning to the community, in hopes that someone who has actually DONE the Semi-Float Drum brake to Full-Float Disc brake axle swap can share some insight into WHAT their setup is.

And PLEASE leave the speculation & "well the manual shows" lectures OUT of it. I have already done LOTS of research on the subject, but there doesn't seem to be any consensus on WHAT the "go to" setup is.

I'm trying to get feedback from those that have ACTUALLY performed this swap and WHAT their FINAL configuration was. Since it seems most did the swap, then weren't happy with the braking & began changing components (some of which didn't really have any affect).

SO THIS is what I want to know - WHAT components left you satisfied with your braking AFTER swapping from the SF Drum axle to the FF Disc axle?

- Master Cylinder (91/92, 93-94 Non-ABS, 93+ ABS FZJ)

- Hard Line modifications for Master fitment

- LSPV (91/92, 93+, removed/bypassed)

- Brake Hoses - frame to axle (91/92, 93+, Custom)

- Any additional insight on this swap that may be helpful
 
Joined
Jun 20, 2007
Messages
509
Location
Provo, Utah
The LSPV can stay. No adjustment needed. I removed mine on my '91 and have been happy having it gone, but if yours is working, there's no need to remove or adjust it. I personally would go with a T100 (w/o ABS) for the master cylinder. A little more sensitive, grabby brake feel is afforded by the slightly larger master (personal preference here). HTH
 
Joined
Mar 8, 2015
Messages
358
Location
Elverta, CA 95626
The LSPV can stay. No adjustment needed. I removed mine on my '91 and have been happy having it gone, but if yours is working, there's no need to remove or adjust it. I personally would go with a T100 (w/o ABS) for the master cylinder. A little more sensitive, grabby brake feel is afforded by the slightly larger master (personal preference here). HTH
I've thought about the T100 Master, but read somewhere that the large diameter = more volume but less pressure and I hadn't found anything in terms of real feedback on how that works & what it takes to set it up.

Like I said, my 80 is my only vehicle at the moment. Now, family is relatively close, so I can borrow something for an emergency parts run; but this has gotta be a Fri evening - Sun evening swap, so I can drive it to work on Mon morning.

I'm not in a position to tear it down for weeks, while I figure out what is needed.

Are you actually running the T-100 master?

If so, what year (I noticed the 93/93 T-100 shows the same master as the 92/92 FJ80; which is also the same on the 2nd gen 4Runner - at least according to the local parts store website)

And WHAT was involved in mating that T-100 master to the 80 hydraulics?

Are the ports oriented the same?

Are they in the same (relative position)?

Or did you have to splice/make up new hard lines?
 
Joined
Jan 6, 2012
Messages
8,674
OK, 'Mud community, I've searched & read for the last few YEARS and still haven't come to a real conclusion on this.

Hopefully somebody here can FINALLYclear some of this up.

I have a 1991 3FE FJ80 (Disc/Drum brakes, w/o ABS)

However, I have a Full Float disc brake E-Locked rear axle, from a '93, sitting in the garage, waiting to be installed.View attachment 2619505
Because my 80 is my daily driver, I need to be sure I get the correct parts ahead of time, in order to minimize down time.

My primary concerns are

1)Determining which Master Cylinder to run -

-- Disc/Drum VS Disc/Disc - 2lb VS 10lb residual valves (although this MAY not be a MC issue - see below)

-- Non-ABS VS ABS (if this matters)

-- Port orientation - One of the threads I read through recently on 'Mud, stated the FJ80/3FE models have a Rear Port/Front Brake, Front Port/Rear Brake layout - with both ports coming out of the SIDE of the Master; the 1FZ ABS models ALSO have the Front Port/Rear Brake layout - BUT the front port comes out of the TOP of the Master, while the rear port comes out of the SIDE; Finally, the 1FZ Non-ABS models are Front Port/Front Brake, Rear Port/Rear Brake layout - with both coming out the SIDE of the Master Cylinder. Unfortunately, the 91 does NOT have the curly-Q coil in the metal brake lines, off of the Master, like the ABS trucks do; this limiting the ease of flopping ports/lines, F to R.

2) LSPV - Is there a CRITICAL difference between the 91 (Disc/Drum) and the later (Disc/Disc) proportioning valve? Does the LSPV just need to be adjusted when swapping the rear brakes from Drum to Disc; or does it need to be replaced with the other version? It was suggested, by one of the "go to" Cruiser parts suppliers that the residual valves MAY actually be part of the LSPV and NOT in the Master Cylinder; which is contrary to everything I have found anywhere on the different Masters. ALTHOUGH, this WOULD explain why places like Marlin say the "FJ80" Master Cylinder that they sell will work for the various years of Hilux and 4-Runners, whether they have Disc OR Drum rear brakes. However, there doesn't seem to be a clear answer on WHICH FJ80 (or FZJ80) Master Cylinder it is that is being offered for the Mini's.

3) Brake Hoses - is there a difference in the fittings in the frame side of the rear brake hose? I have a set of extended SS brake hoses for the FZJ, will these fit the 91 frame fittings; or do I need to get different hoses/change the frame side fitting/get some kind of adapter?

So, I am turning to the community, in hopes that someone who has actually DONE the Semi-Float Drum brake to Full-Float Disc brake axle swap can share some insight into WHAT their setup is.

And PLEASE leave the speculation & "well the manual shows" lectures OUT of it. I have already done LOTS of research on the subject, but there doesn't seem to be any consensus on WHAT the "go to" setup is.

I'm trying to get feedback from those that have ACTUALLY performed this swap and WHAT their FINAL configuration was. Since it seems most did the swap, then weren't happy with the braking & began changing components (some of which didn't really have any affect).

SO THIS is what I want to know - WHAT components left you satisfied with your braking AFTER swapping from the SF Drum axle to the FF Disc axle?

- Master Cylinder (91/92, 93-94 Non-ABS, 93+ ABS FZJ)

- Hard Line modifications for Master fitment

- LSPV (91/92, 93+, removed/bypassed)

- Brake Hoses - frame to axle (91/92, 93+, Custom)

- Any additional insight on this swap that may be helpful
I swapped in a disc brake lspv just because I was concerned about if the ratio of pressure at different ride Heights might be different than the drum brake lspv ratio. Brake lines were the same. Ebrake cable needed the ends shortened and then I crimped on aluminum crimps from home Depot. I also installed fresh lspv linkage hardware from the dealer. I used a 93 abs master. I'm not real happy with the pedal feel, it's a little soft. Vehicle stops fine though.
 
Joined
Mar 8, 2015
Messages
358
Location
Elverta, CA 95626
The T100 master part # is ADVICS BMT139. From a 1995 one-ton T100 w/o ABS.
Are the ports oriented the same as the FJ80 / ABS FZJ80 -- Inverted - F port = rear brakes, R port = front brakes

Did you have to modify the hard lines off of the Master Cylinder to fit this one?
 
Joined
Feb 10, 2013
Messages
247
I cant speak about the locker part by I have done the axle swap into my 92.

Its a direct fit. You do not need a new master cylinder, you do not need new brake lines unless you want them.

You DO NEED the e brake cable from the donor axle and you will need the sway bar brackets that attach the sway bar to the axle from the donor vehicle as the holes are in different spots.

Removal and replacement can be done in a day.
 

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