Budget But Effective Rear Disk Brake Upgrade
 

EDIT: I no longer run this setup. I run a setup with electric parking brake calipers. Check it out here


I recently decided it was time to do a rear disc brake swap. I got tired of my brakes fading to nothing everytime I crossed a deep wash and packed the drums full of sand. I considered the kits available but I felt like they were all a little underenginered. Like everything was an expensive improvised solution. Plus, most of them don't have a solution for a properly functioning parking brake.

After looking around for quite some time, I found a few solutions but none of them were perfect. The best one I found was using Mustang GT calipers on Montero rotors with a home made bracket, washers for spacers, and custom made brake lines. Still no parking brake. I started with that overall design and just improved it with a few better off the shelf parts.

This should work on all pickups and 1st-3rd gen runners. Should work on tacos too. The bracket and parking brake cable will vary from truck to truck though.

I started with rear 94 Mustang SVT calipers. They are the same caliper as the GT but have a wider bracket for a wider rotor and thinner pads. SVT pads will fit GT calipers and rotors but not the other way around.

For a rotor I chose a 2004 4runner rear rotor. These are wider and vented unlike the Montero rotor. They happen to be the same width as the SVT rotors. Unlike the common Chevy rotor swap, these fit without any mods and can be had for less than $20 new.

For brake lines, I chose a rear hose for a 81 Nissan 200sx. This hose has a 10mm banjo on one end and a m10.1.0 inverted flare on the other. In other words, it fits the Mustang calipers and the Toyota hardlines. I bought these new for about $4 each.

I purchased everything from Rockauto. Total cost was about $250. Significantly cheaper than any of the available kits. I currently just have the stock parking brake cables attached to the calipers. They work but they have too much slack before they grab. I have a set of new mustang cables I'm going to splice together with the 4runner cables. I just haven't had the time yet.

To start I made a test fit in the wheel to see if this was even going to fit my 15s. Its tight but it fit. If they don't fit yours, there is a fair bit of meat on the caliper that can be ground off.

https://cimg9.ibsrv.net/gimg/www.yot...1470cc0d12.jpg


I then ruffed it up on the truck to see where the caliper will best fit. I chose to clock it back 22.5° this might vary depending on your truck. I chose here because it would clear all of the suspension components and the parking brake cables would fit. If you have leaf springs the options will open up a bit.

I mocked up everything on a spare axle I have. I pressed off the backing plate and reinstalled the bearing to the shaft. I then took a few measurements on the bolt holes and drew up a template in Sketchup.

https://cimg0.ibsrv.net/gimg/www.yot...b257591461.jpg

https://cimg3.ibsrv.net/gimg/www.yot...7d6a8519f1.jpg


Test fit

https://cimg6.ibsrv.net/gimg/www.yot...86432dce36.jpg

https://cimg7.ibsrv.net/gimg/www.yot...cff97470f0.jpg


Transferred the template to some 3/8" steel and torched it out.

https://cimg3.ibsrv.net/gimg/www.yot...fe633073d4.jpg

https://cimg5.ibsrv.net/gimg/www.yot...0f96752da9.jpg


I originally used bolts because I thought I would need them. In the end, I ground off about 1/8" of the knurled edge on the studs and reused them. They were the perfect length. If you cut the backing plate off instead of removing it all together, you will need to replace with bolts.

Here I have the caliper bolted on. I cut and reflared the brake line down by the retainer. The brake hose fit perfect here and squeezes behind the shocks really well.

https://cimg1.ibsrv.net/gimg/www.yot...4ce530effb.jpg


I had to grind a little bit of the bracket down to clear the rotor.

https://cimg6.ibsrv.net/gimg/www.yot...1b941d039f.jpg


Finally I got this side mounted up on the truck. Took it out with just this side done and ran the suspension through its cycles and made sure everything cleared.

https://cimg8.ibsrv.net/gimg/www.yot...cf784d3fab.jpg


Here you can see the factory 2nd gen 4runner parking brake cableattached. It needs to be in a sheath to work right but this was a proof of concept. Pickup and 1st/3rd gen side pull cables probably wont work. Either you can modify the bell crank to connect to the cables to the under side or convert to modified 2nd gen runner cables. You can also see how close of a fit it is with a 15" wheel

https://cimg9.ibsrv.net/gimg/www.yot...56caeba7c8.jpg

https://cimg4.ibsrv.net/gimg/www.yot...d6c28108b6.jpg


Here you can see I had a brake leak on the driver side. I damaged the caliper and didn't feel like trying to go through Rockautos return policy. I just went and bought a GT caliper from O'Reilly. They don't keep SVT calipers stocked, but as I said before, they are the same aside from the brackets. This gave me the opportunity to show the differences. The GT bracket on the left is open on the outside end where the SVT bracket on the right is closed.

https://cimg9.ibsrv.net/gimg/www.yot...1f4e59bcc9.jpg


You can see the GT bracket fits over the wider rotor still but its tight. And, with out a washer between the caliper bracket and the adapter bracket it touches the rotor. It can be made to work, but it's not ideal.

https://cimg6.ibsrv.net/gimg/www.yot...2c36378592.jpg

Clearance comparison with the SVT bracket.

https://cimg5.ibsrv.net/gimg/www.yot...1caf7f4e53.jpg

In the end, it works very well. I'm still using the stock 1" master cylinder. I had some issues with far pedal travel. I wound up bypassing the LSPV and the ABS actuator and it didn't fix the problem. It acted like there was air in the lines. It wound up being the cheap brake pads I used had too long of a piston alignment pin. The piston was pressing on just the pin and not the back of the pad. They would then rock back and cause the piston to travel to far. Changing out the pads for some nice Bendix ceramics fixed that problem and I have a nice pedal now.

I still have no proportioning valve. If I lay into the brakes, I can get all 4 to lock up 33s but the fronts always lock first, no matter the surface I'm driving on. They really are perfectly balanced. What you choose to do is up to you. I don't know how they will perform with ABS but I don't see a reason why they would interfere.

I will update again when I finally get a proper parking brake cable made. They work ok for now though so it's not on my list of top priorities.

Update
 

So, have had several years to evaluate this build. Would still recommend it with proper parking brake cables however, don't expect the parking brake to hold super good enough. I have got them working right but have always been a little displeased with how well the parking brake holds. Come to find out, that's just the nature of Mustang calipers. Found that out after snooping around some Mustang forums for a little while. Didn't know that at the time of the swap.

I've got some new plans though. I have always been super impressed with how well the electric (gross. I know) parking brakes seem to hold on newer vvehicles. I have been eyeballing pretty much every electric caliper that has come into work. Finally I think I found a good candidate. Had a 2021 silverado come in needing a new rear axle housing. Measured up every meaningful dimension I could think of and I think they will work well. The replacement axle housing came with brake hoses and electrical connectors so I managed to snag the old ones before it went to scrap. The hoses I think should work with the Toyota lines. Just ordered up a pair of loaded calipers for 160 shipped. I think this will be a worth while swap. Good for conversion because these electric brakes grip like no other and in my opinion, a little bit of wiring is easier than making custom cables. I'll report back once I know it's doable or not.

Thanks for posting. I'd like to convert my IFS pickup rear axle to full floater and disc brakes but I don't like the lack of a parking brake. Front Range Off Road has a kit now that uses FJ cruiser rear discs with drum parking brake. (Drotor kit) Too expensive for me. Plus it requires IFS hubs which I have but will widen the rear 3+". Maybe a good thing but I already did the IFS hub swap on my 85 SFA to widen it to match the rear. For the money ,I would be better off swapping larger axles in. Snowballs out of control fast. Looking forward to what you find with the electric parking brakes.

Update
 

Just found this thread today. this guy runs essentially the same configuration as mine. He made a thread about it about a year after I did however he claims to have originally done it in 2017 so apparently I didn't quite do something original :poop:. If you're interested in going this route, he sells it as a kit (or at least he was. Not sure if he still is) with laser cut brackets. Looks like he mounted the calipers at pretty close to the same angle I did mine so I think it'll fit the second gen just fine. Only thing that might not fit is the parking cables and bracket but I don't think it'd take much effort to make it fit the second gen. Would be a really good route to go if you don't want to make your own brackets.

https://www.toyota-4runner.org/3rd-g...rsion-kit.html

Sneak peak
 

Just a little sneak peak at the new brake setup. They required a LOT of grinding but they can be made to fit an 15" wheel. Wouldn't recommend on a 15" wheel. 17" wheels for sure though

https://cimg5.ibsrv.net/gimg/www.yot...d8fd5c084d.jpg