Rear Disk Brake Conversion Pt 1

WrenchTech said:
I am still wondering why the original poster cut the brake backing plate and left a peice of it on the bearing cup. I can't see what use that bit of sheet metal serves. Go to the post.

Or see the image here
Click to expand...

Sorry I have been away for a bit with work. But I'm back :hello:

The main reason I cut the backing plate instead of pressing everything off then back together is that First, it is easier and Secondly, though it is a small amount 1/8th inch maybe, I think that it could throw off the alignment and depth of the axle seating into the center section, or the ring for the ABS might not be in align with the sensor properly.

hope that makes sense.

Sam
 
Rockdawg84 said:
Sorry I have been away for a bit with work. But I'm back :hello:

The main reason I cut the backing plate instead of pressing everything off then back together is that First, it is easier and Secondly, though it is a small amount 1/8th inch maybe, I think that it could throw off the alignment and depth of the axle seating into the center section, or the ring for the ABS might not be in align with the sensor properly.

hope that makes sense.

Sam
Click to expand...

I found that the sheet metal has no effect on the positioning of the axle or the ABS ring. The sheet metal is outside of the stack of parts. It only affects the seating depth of the studs. When you take away the sheet metal the studs sit a little deeper in the bearing cup but there's no bad effect from that. I have a press and the tool for pressing the axle shaft and the bearing and my stuff was all apart anyway so was easy for me to get rid of that remaining piece of sheet metal. I think you can get the metal out without pressing the bearing and the ABS ring. You would just have to press out the four studs and when the sheet-metal was loose but still trapped between axle flange in the bearing cup you might be able to cut it with a grinder with cutting wheel or a heavy shear, or even a cutting torch or plasma, if you have those tools.

I got a rotor, brake caliper and some quarter inch steel flat stock late last week. I hope to make a bracket next couple days. I got the caliper at a local wrecking yard. Once I get the bracket worked out and see evidence that this is going to work I will order some remanufactured calipers and a second rotor from Rock Auto.
 
Last edited:
Rockdawg84 - ​​​​​​I just noticed that the third generation runner has a LSPV (load sensing proportioning valve) as part of the rear brake plumbing. Did you leave that unchanged with the disc brake upgrade?
 
WrenchTech said:
Just playing around with Sketchup I tried modeling a bracket based on what I've seen here in this thread and also what I've seen of a commercial product that trys to do a similar thing. I came up with this. Of course I don't know how thick the stacks of washers are in the set up that is the subject of this thread. I'm estimating 3/8” (0.375”). My prototype here is basically a sandwich of two layers, a 3/8” spacer and the quarter inch mounting plate

brake_backet_model.png
Click to expand...

http://www.toyota-4runner.org/3rd-gen-t4rs/247329-2000-limited-sleepydad-build-2.html#post2866745

Take a look at what I came up with? Been running it for maybe 4 months now and it’s been great.
 
WrenchTech said:
Rockdawg84 - ​​​​​​I just noticed that the third generation runner has a LSPV (load sensing proportioning valve) as part of the rear brake plumbing. Did you leave that unchanged with the disc brake upgrade?
Click to expand...

Not all do - it’s just the 2wd models IIRC
 
sleepydad said:
http://www.toyota-4runner.org/3rd-gen-t4rs/247329-2000-limited-sleepydad-build-2.html#post2866745

Take a look at what I came up with? Been running it for maybe 4 months now and it’s been great.
Click to expand...

Nice work. And way to document your process. As a carpenter, it was a bonus for me to see the multi-disciplinary approach where woodworking skills come to bear on the prototyping of machine parts. That link you included to the engineering is insane with detail. No one can say you didn't do your homework. You have convinced me to bail out on the Mitsubishi rotor. The Toyota rotor is less costly and more widely available, not to mention that it is a vented rotor as compared to the solid Mitsubishi rotor and also available with an e-coat option for corrosion resistance.
 
WrenchTech said:
Nice work. And way to document your process. As a carpenter, it was a bonus for me to see the multi-disciplinary approach where woodworking skills come to bear on the prototyping of machine parts. That link you included to the engineering is insane with detail. No one can say you didn't do your homework. You have convinced me to bail out on the Mitsubishi rotor. The Toyota rotor is less costly and more widely available, not to mention that it is a vented rotor as compared to the solid Mitsubishi rotor and also available with an e-coat option for corrosion resistance.
Click to expand...

Thanks, my hope was maybe somebody else would find the info helpful. The 3rd gen community here is terrific IMO. I still need to figure out the ebrake thing. I Think by just adding an extra connection point to the mustang calipers ebrake plate the stock 4runner cable should work. I just need to find some time...
 
BigDs9pdHammer said:
Does anyone have done the Trail Gear rear brake upgrade?
I know it does not have the e-brake connector but is the T-case mounted disk parking brake a good option too?

https://www.lceperformance.com/T-Case-Mounted-Disc-Parking-Brake-1979-1995-4wd-p/1055480.htm
Click to expand...

It fits 84-95 gear drive 4cyl transfer case equipped pickups and 4Runners ( V6 and automatic applications are not available ) and can be used with drum or disc rear brakes.

I'm not saying it would not work but I'm 100% sure that means custom fab work and maybe a new hole cut in your floor?
 
IMG_4488.jpg


I am finally getting around to making some parts for this brake conversion. I am going with the SleepyDad version, using 4th gen 4runner rotors and late '90s Mustang calipers.

I found that I could make the drawings for the parts in the free, open source drawing program called Inkscape (it's like Adobe Illustrator). I could draw the part to the dimensions I wanted and get those dimensions to print to paper with a pretty good amount of precision. Then I just cut what I need from paper and use spray adhesive to stick it on the metal. I check the work with a caliper as I'm going along, but so far the paper Has proved to be quite accurate and is a real help in doing the layout for the machining work that is involved, which amounts to drilling six holes, including one hole drilled with a holesaw to four inches in diameter.

I got a fantastic deal on the steel. I picked up about 4 square feet of the 3/8 eighths inch steel for four dollars at my wonderful local recycling center, where they recycle every thing from household goods to industrial and agricultural equipment. The place is a veritable goldmine for a guy like me.
 
BigDs9pdHammer said:
Does anyone have done the Trail Gear rear brake upgrade?
I know it does not have the e-brake connector but is the T-case mounted disk parking brake a good option too?

https://www.lceperformance.com/T-Case-Mounted-Disc-Parking-Brake-1979-1995-4wd-p/1055480.htm
Click to expand...

I'm running the GM "G" Body rear calipers on a rock assault first gen rear housing, Right now I'm running front calipers on it, because that's what I sourced at the time. I had to add an adjustable proportioning valve to the rear in my situation it did two things, made it drivable, it was so rear bias you almost couldn't touch the pedal without bringing the rears to full lock, and it firmed up the pedal. I run the valve completely closed, giving me about 45% of what they are good for.

Also the driveline E-brake is a tight fit, and only fits a first gen gear driven case, I had one, on another single case rig, the rotor hit the floor when flexed in certain situations, and would not clear the floor of the third gen at all with dual cases.

For reference I removed the ABS system completely So not sure how ABS would correct having a ton more rear brake, I've read most of the thread, Sorry if that's been addressed.

And without ABS and rear disc on 37's it just brings the rears to skid as you nearly come to a stop. I don't remember if it stops better or worse.


Hope this gives another point of reference
 
kolelt said:
What about swapping the whole axle ?
Click to expand...

That is a good question. I haven't been able to find any information about how wide the FJ cruiser axle is. It rides on coil springs and has links. I'd be willing to bet all that stuff is in wrong place for a third GEN runner. It also has an 8" or 8.2 inch differential, not much of a gain in strength for all that work. I hope someone else can tell us how wide it is.
 
WrenchTech said:
That is a good question. I haven't been able to find any information about how wide the FJ cruiser axle is. It rides on coil springs and has links. I'd be willing to bet all that stuff is in wrong place for a third GEN runner. It also has an 8" or 8.2 inch differential, not much of a gain in strength for all that work. I hope someone else can tell us how wide it is.
Click to expand...

Something tells me that even if the arms are not in same place. That it’s cheaper to get brackets and weld them for it. Also our rear ends are 8”.
 
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