Rear Disc Swap
 

Rear Disc Brake Swap

Vehicles: 86-95 Pickup or 4Runner

This swap: '91 4Runner, SAS with rear leaf swap

I found the factory Toyota drum brakes to be cumbersome, difficult to work on and prone to getting packed with all sorts of unfriendly elements once out on the trails. I made a mental note that the next time I needed to disassemble my rear axle for maintenance I would look into upgrading the rear brake system to discs. When my ARB locker started to leak I decided there was no time like the present.

There are many different ways to do this swap and I researched the options thoroughly before diving in. I found there were many threads with parts of the puzzle, but few showed the whole process. That is exactly what I have tried to do here. Present all the bits and pieces along with the steps involved so others can use this information should they attempt such an upgrade.

As a warning, braking systems are nothing to be taken lightly. It is not only your own safety but that of other road and trail users you must take into consideration. The following is how I did my swap, and is not the only way, but simply one way. I would strongly suggest against attempting such a swap unless you are fully confident in your mechanical abilities and thoroughly understand the process.

No short cuts should be taken. Responsibility for success is solely your own. :soap:

A few notes:Here is a quick overview of the steps involved:

Order parts
Order or find your GM calipers
Remove LSPV
Eliminate ABS routing (if applicable)
Remove rear axles
Remove drum brake assemblies
Remove backing plates
Install caliper brackets
Install rotors, calipers, hard and soft lines
Replace master cylinder
Install proportioning valve
Bleed brake system
Road test and adjust


Step 1: I chose to purchase the caliper brackets and rotors from Sky Manufacturing (http://www.sky-manufacturing.com/toyota.htm) You can get the rotors on your own, but you will have to have the centers turned out to accept the Toyota axle center. This dimension can vary between model years, so measure accurately. I felt the price from Sky for modified rotors was reasonable and would save me some time.

From Sky I bought the following:

TOY-RDB-001 (Qty 1pr): disc caliper brackets and hardware
TOY-RDR-001 (Qty 1pr): modified Chevy rotors

This is what UPS brought me from Sky Manufacturing:

Attachment 172714

Step 2: Sky's kit is designed to work with calipers from a 79-85 Monte Carlo or Cadilac Eldorado (your personal research may reveal other options as well) Either front or rear calipers will work.

During my research, I was unable to find any successful write-up mating the GM parking brake rear calipers to the stock Toyota parking brake cable and lever. Evidently, there is a significant amount of tension required for the GM parking brake to work, and would require modifications of the Toyota parking brake lever and control cable. Not impossible, but not covered in this write up. I would however be interested in learning how it can be done, so let me know if your give it a try.

I ended up finding some front calipers from an '85 Cadillac Seville.

'85 Seville calipers and bolts:

Attachment 172715

Tip: Bring the Sky caliper brackets with you to the salvage yard to confirm caliper compatibility.

Tip: These calipers require a 3/8" allen wrench to remove. Without one, you will have a frustrating salvage yard experience to say the least.

Tip: While at the salvage yard, it will be helpful to get several different sections of hard-line from Toyota vehicles. For example, you'll find these necessary when connecting the proportioning valve to the master.

What I ended up walking away with (note extra junction block in middle of pic):

Attachment 172716

Step 3: Master cylinder. There are many options for the master, but the most swaps use one from a Toyota FJ80. A recommended source for this master is WabFab Offroad (www.wabfab.org) or username "waskillywabbit" here on Yotatech. Although I chose another route, he was very helpful in regards to answering questions I had about a disc swap and would highly recommend him as a source for the necessary parts.

For my swap, I happened across a master from a '88 Toyota Supra. These vehicles come equipped with four wheel disc brakes and the master has a 1" bore. The salvage price was to low to pass by, and the part has worked out very well. The bolt pattern from this Supra master to the 4Runner booster is identical and does not require an adapter, just bolts right in place. I'd imagine the same would hold true for truck boosters as well. As an added bonus, the original 4Runner reservoir cap and sensor fit on the '88 Supra reservoir. :great:

'88 Supra master cylinder:

Attachment 172717

Note: Research your master cylinder options. There are many different manufacturers to choose from although some may require adapters to mate to your vehicles brake booster.

Note: The master and booster you choose to use can and will affect final braking performance. You may need to experiment with different combinations to achieve the results you desire.

Very detailed info on boosters and masters: http://home.4x4wire.com/erik/4runner/brakes/

Step 4: In order for the final brake system to work properly, you will need to add a proportioning valve that will allow for manual adjustment of brake line pressure between the front and rear calipers. It is challenging to work with both standard and metric threaded lines as well as mate the several different types of flaring each manufacturer has used. I purchased the proportion valve and necessary adapter fittings from Summit Racing (www.summitracing.com)

From Summit Racing I bought the following:

EAR-989538ERL (Qty 2): Adapter -3 AN to 10mm x 1.0 Inverted Flare
EAR-916103ERL (Qty 2): -3 AN Female to 1/ 8 in. NPT Male
SUM-G3905 (Qty 1): Brake Proportioning Valve, 1/ 8 in. NPT, Single Inlet/ Outlet

With these parts, you can adapt the 1/8" NPT fitting on the prop valve to the Toyota 10mm x 1.0 inverted flare found on the factory brake lines.

It all assembles like this:

Attachment 172719

Tip: While placing your order from Summit, pickup a set of "SpeedBleeders" for the front and rear calipers. They are very slick and make the brake bleeding process extremely fast and simple.

SpeedBleeder part numbers:
RUS-639560 (Qty 1pr): 10mm x 1.0 Thread, 35mm length (Toyota)
RUS-639580 (Qty 1pr): 10mm x 1.5 Thread, 30mm length (GM, calipers may vary)


Step 5: Rear soft lines. As mentioned before, the trickiest part of this swap can be meshing all the standard and metric components together. You'll find even the GM calipers themselves come with a mix of metric and standard threads, all the ingredients for a major headache. There is however the perfect brake line. The answer is a brake line for a '80 - '82 Nissan 200SX. These brake lines have a standard banjo fitting on one end, and a female 10mm x 1.0 IF fitting on the other. They will mate the factory Toyota hard lines to your new GM caliper! Very sweet. :great: You will also need longer banjo bolts (the new 200SX banjo is thicker than the GM) and two pair copper compression washers. I chose to get these parts from NAPA (http://www.napaonline.com)

From NAPA I bought the following:

38149 (Qty 2): 1980-82 Nissan 200SX brake line
82700 (Qty 2): 10mm x 1.5 banjo bolt

NAPA brake lines and bolts:

Attachment 172720

Tip: You may wish to purchase the brake pads for your calipers from the same source you get your lines.

Tip: I had some difficulty in locating the copper compression washers. Make note that they are needed and will not be included with either the brake lines or banjo bolts mentioned above. They are shown in the picture for reference only.

Step 6: ABS and LSPV system. Not all '86-'95 Toyota's came equipped with ABS. Mine did, but had essentially been deactivated with the removal of the speed sensor on my rear diff some time ago. With this swap, I decided to remove the rest of the system as well. The following is a diagram of the brake line routing that was found in my '91 4Runner.

ABS Diagram:

Attachment 172721

Tip: Diagram shows "T" and 90 degree junction fittings referenced throughout this writeup.

Without going into to much detail as to how the LSPV and ABS systems operate, my goal was to remove the LSPV and related ABS components and simplify the system. The LSPV would no longer connect the front and rear brake systems together and each would operate separately instead.

If your vehicle is equipped with ABS, you will notice a 90 degree junction as well as a "T" junction mounted to the PS frame rail. The "T" allows line pressure to feed both the front calipers as well as add to the rear braking power as dictated by the LSPV. I wanted to terminate this connection and decided to eliminate the "T" by replacing it with another 90 degree fitting.

Original PS junction block, single 90 degree and single "T" fitting:

Attachment 172722

To achieve this, I found an additional junction plate from a similar Toyota pickup. I cut off the "T" fitting and replaced it with the extra 90 degree elbow from the donor vehicle.

Modified PS junction block, double 90 degree fittings:

Attachment 172723

Tip: You can plug the "T" with a bolt or choose to weld up the hole entirely to achieve the same result.

As you can see, I now had the ability to run one brake line from the master to both the rear calipers, and one brake line directly to the PS front (DS front is fed directly from master already). The original lines in and out of the ABS/ PS block were abandoned. I now had two unused lines running from this junction block to the LSPV at the rear of the vehicle, one of which I would use to run the rear feed from the master.

Step 7: Removal of LSPV. The LSPV has three lines. Two coming in from the front of the vehicle and one going out to the rear drum brakes. This allows the LSPV to control rear brake pressure as well as receive alternating pressure from the ABS circuit. At this point, I disconnected all three lines from the LSPV and removed it from the vehicle. You will need to evaluate which of the two lines leading from the PS junction block will be easier to attach to your new 90 degree fitting. I found the line marked "F" on the LSPV was the easiest for me to work with, so I connected that line to the 90 at the junction block and the other to a stainless flex housing that I could route down to the rear axle.

Tip: Stainless flex line can be purchased from WabFab (www.wabfab.org). One end needs to be female to tie into existing brake line that was once attached to the LSPV, the other end will be male to thread into the existing "T" junction block on the axle housing.

Step 8: Removal of axles and drum brakes. Basically, it's out with the old drums and in with the new rotors. If you have ever done a rear brake job on these vehicles you should be familiar with most of the process. With vehicle securely off the ground on your trusty jackstands, remove the wheels. You'll be looking at something like this.

Final look at your drum brakes:

Attachment 172724

If you need clarification, there are several steps here that can be found in a Toyota factory or Haynes manual. Basically, you will need to remove the parking brake, drums, brake hardware, pads and pull the axles out of your housing. At this point, you should have two axles and a bare backing plate attached to each.

Axle, drum brake hardware removed (cut line shown):

Attachment 172725

Step 9: Remove backing plates. In my research, I found many options to remove the backing plate. Cutting, torching, pressing off the bearings and removing said plate, etc. Since I had replaced the axle bearings within the last six months I just decided to cut the backing plates off with them still attached to the axle. This step was actually much easier than I thought and my trusty DeWalt 5" angle grinder was more than up to the task. :great:

Image of cut lines:

Attachment 172726

Backing plate just slides right off:

Attachment 172727

Tip: If your bearings are old this is the time to replace them. Unless you have access to a press, you will probably have to source this work to a local automotive machine shop. When they reassemble the axle, just instruct them to leave the backing plates off.

Tip: Now is the time to replace the axle housing inner seals as well as the large external housing O-ring.

Step 10: Re-install axles, mount caliper brackets. Sky sends their kit with hardware. I found that the four original axle studs would do the job just fine and would not require me to press the studs out of the axle. However, for additional security I would recommend purchasing the necessary metric nylock nuts instead of using the factory nuts. Since these photos, I have replaced mine with nylock versions.

Axle back in place, caliper bracket installed:

Attachment 172728

Upper view. (note remnants of backing plate):

Attachment 172729

Caliper and rotor installed:

Attachment 172730

Caliper and rotor installed (lower view):

Attachment 172731

Step 11: Master and proportioning valve install. Depending on the master you have decided to use, these steps might be slightly different. For the purpose of this write up, I'll stick with the '88 Supra master I chose to go with. Basically, I just unbolted the original and re-bolted the Supra master in its place. I was able to use the original reservoir cap so I didn't have to splice the sensor wires, they just plugged right back in. Using some of the extra Toyota brake lines I had scavenged before (told you they would come in handy :D ) I routed, twisted and installed the Summit prop valve next to the master controlling the rear circuit.

Summit Proportioning Valve:

Attachment 172732

Tip: Be sure to bench bleed your new master before install

Tip: A metric double flaring tool can be used to shorten or modify the factory brake lines. These old lines can become hard and difficult to work with however.

Step 12: Securing brake lines. You will need to keep hard lines from undue stress and secure them accordingly. This is a judgment call and will vary from every application. Your goal is to not stress the hard lines in anyway, especially in a repetitive manner as this will fatigue the lines and cause them to fail. I chose to run my soft caliper lines under the springs, and to weld a tab to the housing where they connected to the hard lines.

Finished product:

Attachment 172733

Note: This 4Runner has had a rear leaf conversion. Stock 4Runner coil suspension may require different line routing.

Tip: I purchased additional lengths of hard-line from my local auto parts store. It may be possible to re-flare or re-route original lines to achieve the same goal.

Step 13: Bleed the system. Start from farthest to closest. Basically, RDS, RPS, FPS, FDS. Those "SpeedBleeders" you paid extra for will already be showing their value. Dare I say they almost make bleeding your brakes fun? :hillbill:

Step 14: Check and double check all your fittings, hardware, fluid level and brake pressure before your leave the safety of your garage. Check for leaks. Make sure your pedal holds pressure and that all air has been evacuated from the system. Be prepared for your brake system to exhibit different behaviors than stock.

Step 15: Adjust proportioning valve. Ideally, you want to try this new brake system out on a desolate dirt road at low speeds. There is a strong possibility that your rear wheels will lock easily before you get the prop valve adjusted to where you want it to be. Keep this in mind and drive accordingly. The correct setup would be to have the front brakes lock just before the rears do.

Tip: Most people state that the minimum amount of rear flow is about perfect

Tip: The Summit prop valve decreases fluid flow by turning knob counter clockwise, which seemed counterintuitive to me.


I am very happy with this upgrade. For once I actually feel like the vehicle stops with confidence. With the addition of 35" tires, armor, winch and various mods it's nice to have the additional power slowing me down. I am looking forward to the ease maintenance the disc setup will afford me in the future. :great:

:bigclap:

:guitar:

another round of :bigclap: thats a nice write-up....

Overall great job.
One thing though is where you have the hardline to soft line connection located.
It's too low and unprotected on the rear axle and you will have problems with it like that.
Suggest changing the location, maybe moving it up higher, or adding some armor to it.




:)
Fred

I agree. I have been contemplating armor or relocation to above the axle.

Is you avatar the entrance to Upper Woodpecker ?




:)
Fred

Yes, WoodPecker. Windshield Rock I think it's called.

Wow, that is great. I expect to see this in the tech section soon. Very good write up. You really put a lot of thought and prep into it.

dang good write up. Very nice job.

Yup, that's what I though, right at the entrance to Upper Woodpecker.
Been there a lot.

Here's a photo of me going through it in the Jeep.
Been though it a lot and never touched:

http://www.fredtj.com/images/photos/LWUW/dscf0004.jpg



Devils Back, Upper Woodpecker:

http://www.fredtj.com/images/photos/LWUW/dcp_2437.jpg


Here I am cresting Devils Back in Upper Woodpecker:

http://www.fredtj.com/images/photos/LWUW/dscf0044.jpg


And here I am heading up the Fire Hole in Upper Woodpecker:

http://www.fredtj.com/images/photos/LWUW/fredt5.jpg



And a shot from the bottom of me going up the Fire Hole, Upper Woodpecker:

http://www.fredtj.com/images/photos/LWUW/fredd9.jpg




:)
Fred

Thanks for the compliments everyone. Hopefully it will help someone out in the future.

FredTJ... that Firehole is intimidating, but maybe one day I'll work up the nerve. Maybe we'll see you in a Toyota next time on those lines. :hillbill:

You will see me in a Toyota from now on.
I have a '95 4Runner that I'm starting a buildup on...

The Fire Hole is fun.
Going up it isn't the "hard" part. It's getting out at the top.
It tends to be pretty snarly at the top.
We run all the obstacles in Upper Woodpecker evertime we run it.


:)
Fred

Nice write up.... Wish I had the parts to do this.... Too bad someone didn't make brackets for Toy callipers..... But again nice job...

Don't they? That's what I thought too...I was wrong. I'm planning to do the Toy caliper route too. I've got toy calipers and rotors laying around anyways, plus I think that SFA toy brakes would be a good compliment to front V6 brakes.


Very nice job on the write up, nice and through. What do you plan on doing for an e-brake, or seeing that it looks like a pretty much trail rig, are you even worrying about it?

Even though it looks more like a trail rig, it is my daily driver. Only vehicle I own actually. :hillbill:

E-Brake... probably a transfer case brake. I am looking at getting some GM calipers with parking brake, but I have heard it is difficult to make those work right.

If you manage to rig up a T-case brake with a V6 t-case, you defonitly need to do a write up!

I guess I'll have to install that dual ultimate crawler sitting in my garage before I do the T-case brake. Poor, poor me. Such a busy weekend ahead. 217:1 here I come! :hillbill:

Although, looking at the Sky and All Pro kits, I don't really see why it is so hard to mount one on a V6 case. Both kits have plates that match the 4CYL case, so why couldn't one modify or make their own plate to match the V6 case?

I am sure I am missing something, or a lot of somethings.

I think the issue with mounting it to the 6cyl case is the lack of seperate housings. All t-case brakes I've seen mount to the case by replacing the stock housing bolts with longer ones and mounting the brake to that. I havn't looked at the V6 case too close, but I don't think it has mounting points like that.


You don't want to instal that dual ultimate crawler...sheer junk. Don't worry, I'll take it off your hands for you.

Incredible write up Steve. Right down to the last detail...that is going to help out quite a few people I imagine, including myself some day.

would this work for the 2wd trucks? could i use the brackets? thanks

I am not personally familiar with the way the 2WD's are set up. Sky Manufacturing may be able to tell you if the brackets would work. In theory, the rest of the swap would be very similar if not exact.

Parking brake for V6
 

Elvota. What do you do for an E-brake at the moment?

I was comparing my V6 transfer case with some pictures from the All Pro Parking Brake Review on 4x4 wire. The cases are very similar but have a few small differences that make bolting the All Pro system up to it impossible. Since I am so curious I called All Pro and asked why they didn't offer a bracket for the V6 model. The explanation I received was that they never got around to doing one. I also asked if they knew of anyone who makes brackets that would fit the V6 and they did not know of anyone.

However I think that someone with the right skills and tools could easily make a bracket that would work or modify the All Pro bracket to work.

If anyone has done this let us know. I am wanting to install one of the All Pro parking brake and would be willing to pay for a bracket proven to work.

Right now I use a electric E-Brake which works amazingly well, but does no good as a backup system since it requires the hydro system to be intact for operation. Also, I don't use it long term due to the battery drain. Really does a great job on the trail though. Holds easily at 20 degrees... probably even steeper if traction is there.

This is the one I got:
Biondo line lock: SBR-LL
http://store.summitracing.com/partde...0&autoview=sku

I needed some adapters as well.

EAR-989538ERL
EAR-916103ERL
EAR-592032ERL

Here is how it looks with adapters before install:
Attachment 172734

I mounted all this around where the LSPV originally was, so just before the flex line down to the rear axle.

Pic of unit mounted (pardon the Moab mud :hillbill:):
Attachment 172735

As far as a transfer case brake goes, that is what I plan for the future. I did a Crawler install so I now have 4CYL cases. I am not aware of a V6 adapter, although I know a lot of people on YT would like to see one.

I'll be keeping this line lock regardless of future E-Brake mods. It works really well, very simple to use and I would highly recommend it even for vehicles currently running a mechanical brake. I can engage the switch which holds the vehicle, then creep out the clutch until I am about to stall... then just add gas and hit the switch to release the brakes. Very easy and allows starts on even the steepest sections of trail. :great:

Oh simpy swap to an auto tranny and not have to worry with all that silly stall, not enough feet, line locks, etc. ;) ;)




:)
Fred

Great writeup! Thanks! So judging by the beginning of the thread, this will not work on an '85 4Runner? What are the differences in the 85 vs. 88 rear drums?

I was thinking the same thing. Maybe it is a clearance issue with the leaf springs. The 85 axle is 3" narrower (1 1/2" each side)

^^ that makes sense, but if a drum can fit, I would think a disk could... maybe it's the calipers and lines that get in the way?

Not necessarily. I was just listing the vehicle I did the swap on. I don't have a direct understanding of whether or not such a swap would work on other vehicles.

My bet would be that it will work, but I'd ask Sky Manufacturing... they should know for sure in regards to the compatibility of their brackets in regards to different axle widths and such.

This is an outstanding writeup, I followed it to add rear discs to my rock buggy, it makes the job incredibly easy.

The only thing I have to add is that if you want a brake line clip for:

"38149 (Qty 2): 1980-82 Nissan 200SX brake line"

It is a Nissan line and you will need a Nissan Clip, the old and new Toyot5a clips are too small.

The Nissan Clip for this line is part number: 46206-M0200

I used two line locks, one for the front and one for the rear. Axed the All-Pro T-Case brake.

So now I have Toyota hard line going to a Nissan soft line which them go to a GM caliper. :banger:

Hi All, I would like to know if anyone knows if there is a way you could take the parts for this off say a newer model Toyota(possibly salvage) and do the same setup...?

Something that would be bolt-on Toyota parts and include an E-Brake...?

Thanks
RRIND

yes and no. I have a rear disc setup, like elvotas (you can find my writeup here on yotatech ..or click the link in my sig, you'll find a link).

Theres basically two options, full floater conversion (frontrange offroad) and keep with all toyota parts.. which you would use 4cyl or v6 86-95 calipers. Or Elvota and what I did, the more cost effective, and performance effective method, gm calipers, gm rotors. It just makes sense if you're keeping semi-floaters.

You could theoretically fit anything you wanted to but you're lookn at some very custom fabrication.

and even still, i think only landcruiser, tundras?? use rear disc setups. Tacomas sure dont, at least my bro's 2009 TRD sure as hell has drums (wtf i said haha) ...

and im not sure if tundras/LC's use 5.5-6 wheels so im just blowing hot air here.

but... im sure you could fab anything you wanted =)

but gotta ask yourself... is it worth the hassle?

btw, cadilac and i think supras have rear-discs..with ebrakes but the supra brakes work with the full-floater conversion and the caddy calipers from what ive read are a beeatch to connect to our parking cable setup.

T-case brake, gm calipers, gm rotors, locker. Done son!

besides, they look sexy =P

http://www.dojodesign.com/toyota/pic/mounted.jpg

Using the t-case mounted e-brake set up, do you find that the vehicle rolls an inch or two before it feels like the e-brake holds?

I have the spidertrax t-case mounted ebrake on my suzuki samurai and I get a little bit of roll before it catches. I'm told that is a symptom of the "slop" in my drive train.

How true is that and is this the same for toyotas?

I have a tcase brake on my 85 4Runner and the vehicle holds firm...no slop. I purchased the used one Steve had up for sale to put on my 85 ext cab.

:guitar:

um, you could get some slop ... what lil play there is in the third member, then however much the rear springs twist. For me its hardly noticeable. My only complaint is getting enough force on the disc to hold the truck. I played around with mine quite a bit and got it as best I could but you still gotta rip on the parking handle to get it to hold firm, but it will hold firm.

Also, my guess with the older rear axles, there might not be enough room between the leaf springs for the bracket and caliper and room for the brake line (my brake line barely bends enough to as is) .. without running it below the leaf spring where it can get damaged.