ntsqd
technerd
You will need one or the rears will lock-up way before the fronts are even close.
Which Brake Booster? (1 Viewer)
- Thread starter IBFJ62
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
That's what you need to do when you convert to disk in the back. Here is how I did it on my FJ40.
- Thread starter
- #23
I like that, nice and easy access. My plans were/are to use the vented larger rotors and calipers up front, and the stock solid rotor setup in the rear, along with the proportioning valve, I was thinking it might 'even' things out for brake pressure.
I'm sure I'm not alone, but unfortunately my rebuild seems to get done in windows of opportunity, a little here, a little there.. I'm trying to get the brake scenario worked out before an impending kitchen remodel.. The input and info is greatly appreciated.
I'm sure I'm not alone, but unfortunately my rebuild seems to get done in windows of opportunity, a little here, a little there.. I'm trying to get the brake scenario worked out before an impending kitchen remodel.. The input and info is greatly appreciated.
Front Range Off Road has a kit for their full float rear brakes that uses the FJ Cruiser rear D-rotor brakes. If it wasn't so expensive, I'd probably try it.
There are more FJ's showing up in the bone yards so maybe keep an eye out for an axle or at least the brakes.
There are more FJ's showing up in the bone yards so maybe keep an eye out for an axle or at least the brakes.
ntsqd
technerd
Also need to look at if the m/c has a residual pressure valve (RPV) in the rear brake system. Typically those hold about 10 psi in the rear brake system to keep the strong springs in the drums from pulling the shoes too far away from the drum itself. Some calipers/systems work fine with those in place. Others need it removed.
Usually the RPV is under the sealing cone in the m/c. That is how domestics do it anyway. Removing that cone means tapping the hole to whatever size screw is appropriate and pulling the cone out by gently running the screw in until the cone is free. Remove the plunger and spring from behind the cone and then reinstall it. In other m/c's there is an adapter of sorts threaded into the m/c body. Usually those have a thin hex on them and won't be too easy to remove.
Usually the RPV is under the sealing cone in the m/c. That is how domestics do it anyway. Removing that cone means tapping the hole to whatever size screw is appropriate and pulling the cone out by gently running the screw in until the cone is free. Remove the plunger and spring from behind the cone and then reinstall it. In other m/c's there is an adapter of sorts threaded into the m/c body. Usually those have a thin hex on them and won't be too easy to remove.
dohcdelsol93
snoogans
I built my 86 4 runner to be a daily driver. 4 wheel disks were a top priority. I mostly do city driving but over the past year I've had to do much more highway commuting so I'm very thankful I did the upgrade especially with as much rain as we've gotten.
I started with the 4 position calipers, matching rotors and dual diaphragm booster. I then installed the caddy style rear disks. The fj80 master wouldn't pump enough fluid and made the pedal squishy. I installed the GM 1 ton master with the adapter to the dual diaphragm booster and now the brakes are perfect. A Wildwood adjustable prop valve dials in the braking.
I run 285/70/17 tires.
As for the parking brake, they are as good if not slightly better than the stock transfer case parking brake that I had on my old fj40. It works but I wouldn't trust it on a grade. I keep a small plastic set of wheel chalks in an inside storage compartment. I've never had to use them but they are there if we ever rent a mountain cabin and the parking area is on a grade. Brake drums provide more surface area making them superior for parking brakes.
This October will be 2 years of daily driving this rig, I've put nearly 20,000 miles on it so far. I had to adjust the parking brake once. They are self adjusting. I drive daily so the parking brake gets set and released daily, many times. The only issue I had with it was right after putting it on the road, one started dragging. I'd blame it on a faulty caliper but it was more likely me pulling it apart and reassembling it incorrectly. I installed another caliper and have not had another issue or had to adjust since.
The force it requires to set proper tension on the parking brake requires whoever is pulling that parking brake handle to have some strength. My significant other wouldn't be able to set it.
If this would have been built for her rig instead of mine id have either installed a lever style parking brake allowing it to be pulled up to engage or a foot pedal engagement. I still might do that in the future, I'm entering my mid 40s now and realize some of the hobbies I have will need to be put on easy mode in the coming decades.
I started with the 4 position calipers, matching rotors and dual diaphragm booster. I then installed the caddy style rear disks. The fj80 master wouldn't pump enough fluid and made the pedal squishy. I installed the GM 1 ton master with the adapter to the dual diaphragm booster and now the brakes are perfect. A Wildwood adjustable prop valve dials in the braking.
I run 285/70/17 tires.
As for the parking brake, they are as good if not slightly better than the stock transfer case parking brake that I had on my old fj40. It works but I wouldn't trust it on a grade. I keep a small plastic set of wheel chalks in an inside storage compartment. I've never had to use them but they are there if we ever rent a mountain cabin and the parking area is on a grade. Brake drums provide more surface area making them superior for parking brakes.
This October will be 2 years of daily driving this rig, I've put nearly 20,000 miles on it so far. I had to adjust the parking brake once. They are self adjusting. I drive daily so the parking brake gets set and released daily, many times. The only issue I had with it was right after putting it on the road, one started dragging. I'd blame it on a faulty caliper but it was more likely me pulling it apart and reassembling it incorrectly. I installed another caliper and have not had another issue or had to adjust since.
The force it requires to set proper tension on the parking brake requires whoever is pulling that parking brake handle to have some strength. My significant other wouldn't be able to set it.
If this would have been built for her rig instead of mine id have either installed a lever style parking brake allowing it to be pulled up to engage or a foot pedal engagement. I still might do that in the future, I'm entering my mid 40s now and realize some of the hobbies I have will need to be put on easy mode in the coming decades.
Last edited:
ntsqd
technerd
I've been watching the Cad p-brake topic across multiple forums and mailing lists (remember those?) for literally decades. Your Cads are by far and away the exception to the norm. I'd guess 1 out of 10-30k, roughly.
Keep the brake fluid fresh. Once you have enough moisture in the fluid the self-adjusting mechanism will cease to do that. Once that happens nothing known will restore that function for any significant period of time.
Keep the brake fluid fresh. Once you have enough moisture in the fluid the self-adjusting mechanism will cease to do that. Once that happens nothing known will restore that function for any significant period of time.
dohcdelsol93
snoogans
You should be flushing every brake system every 3-4 years in all your vehicles as normal maintenance . DOT 3/4 absorbs water and while DOT 5 doesn't it still gets moisture in the system, it just doesn't mix with the water like 3/4 does, it pools in the low parts of a dot 5 brake system. When it comes to improperly cared for/neglected braking systems I'm more worried about dragging brakes due to stuck brake pistons or rusty lines than I am a parking brake that is no longer self adjusting.
Also, pretty sure that there are well over 30k factory GM vehicles that ran these style calipers.
ntsqd
technerd
Yes, there were. How many of those are still on the road that still have functioning parking brakes? But that's not what I was referring to and you know it.
By keep the fluid fresh I mean every year, two years at most. I dealt with a DOT 5 system that had lived in the Puget Sound area, I know all about what a bad idea that fluid is. Got an object lesson in it. Good for show cars where they're worried about the paint, and very little else.
My two years of intensive Brake Design Immersive Education tells me that the basic design is a bad idea. I watched and tried to help two very capable mechanic/fabricator friends, one of whom has a Master's in Mechanical Engineering and the other a PHd in Hard Knocks, struggle to keep those p-brake functions working. I've watched way too many to count on the various forums go through that same struggle to think that the Cad calipers are a viable option. Your lone exception isn't going to change my mind. I'm glad that they work for you, but you're really the extreme outlier on this.
By keep the fluid fresh I mean every year, two years at most. I dealt with a DOT 5 system that had lived in the Puget Sound area, I know all about what a bad idea that fluid is. Got an object lesson in it. Good for show cars where they're worried about the paint, and very little else.
My two years of intensive Brake Design Immersive Education tells me that the basic design is a bad idea. I watched and tried to help two very capable mechanic/fabricator friends, one of whom has a Master's in Mechanical Engineering and the other a PHd in Hard Knocks, struggle to keep those p-brake functions working. I've watched way too many to count on the various forums go through that same struggle to think that the Cad calipers are a viable option. Your lone exception isn't going to change my mind. I'm glad that they work for you, but you're really the extreme outlier on this.
dohcdelsol93
snoogans
Once again I'm not trying to sell you on the set up, responses like this and needlessly starting arguments is why I asked you to stop posting in my build thread.
The OP asked about rear disk conversions and master cylinder upgrades. Since these upgrades were done to my personal vehicle and I went through 3 Toyota master cylinders before finding the cheap GM 1 ton waz the one that worked best I wanted to share my costly trial and error experience with the OP
Again, my personal experience with my personal vehicle, not my buddies vehicle or my other highly educated buddy.
No offense to the engineers on this site but I've been working on outdoor power equipment for over 20 years now, I get more engineers than any other profession that legally shouldn't be allowed to own a tool box.
If you think self adjusting disk calipers are difficult to maintain you really wouldn't have liked the world of 4 wheel drums brakes.
A replacement caliper for my rear disk set up is less than 60 bucks and takes maybe half an hour to swap/gravity bleed. If I've neglected my brake calipers to the point I have internal or even external rust issues I'm not rebuilding them.
- Thread starter
- #31
Well hell, I thought I was going down a somewhat well trodden path, looks like it's more seat of the pants flying! This brake confusion is causing me to hit a bit of a wall on my slow-mo restoration.. I guess some more research is needed! Always a bummer to buy parts that don't end up working, but I figure it's a learning curve for when I get over to redoing my FJ62.. Definitely appreciate the in-depth analysis!
- Thread starter
- #32
This link was helpful when upgrading my '85.
Toyota 4x4 Brake Master Cylinder and Brake Booster Specs
Mushy brakes? Worn out brake master? Read here to find out about larger bores, dual diaphragm boosters, and better stopping for big tires on your Toyota.www.roundforge.com
This is great info. Just ordered the Cardone 53-2785 for a 2wd with the long studs. Will report when I've got it in my grubby hands and can install.. Thanks!
ntsqd
technerd
I was a mechanic and fabricator for decades before I became an Engineer. I agree with there are some Engineers who should not legally be allowed to pick up, much less own a wrench. I work with a bunch of them and it's scary at times.
I started off-road with my avatar. If there were 4 wheel drum brakes out there harder to keep in adjustment I can't imagine what they might be.
I was right there next to the "PHd" working on the truck like it was my own. BT, DT, seen what a pita those calipers will become and have no desire to see anyone else follow that path.
You're not trying to sell me on them because you know I'll never buy, but that doesn't stop you from trying to sell others on a poor design that is mismatched in size. Even the so-called "Metric" calipers have a piston that is just too big. You can dial them way down with a p-valve, that's true. Wouldn't it be better to use a caliper closer to the correct size and only need to tune the system a little bit?
Stay safe in that power plant. I worked in one for almost a year. There's 10,000 ways to die in one, and none of them are pretty. As it happens I know a man who worked at Coolwater when it went BAD. That's a scary thing to hear about, can't imagine living through it.
dohcdelsol93
snoogans
I'm running the smaller bore eldorado "style" calipers, not the honking 77-79 model eldorado calipers that were a needed upgrade for one ton axles on full size pickups and SUVs. With the GM 1 ton MC I have my prop valve dialed down about 25-30%, not sure how thats a CON on a custom brake set up.
My DD Toyota before the 4runner was a 67 fj40. I don't think the LC has self adjusting drums until @81. After about 4 years of fine tuning every couple months I finally swapped axles and installed 60 hubs/4 runner 4 piston calipers. I can a assure you from personal experience it was more time consuming than the one time I had to adjust my current brake set up once in 18 months. Just in case you're not familiar with them the 40 of they vintage had 4 wheel drums. You had to jack up each wheel one at a time and adjust until the brakes started to drag, then back off. Take it down the road and see if she would stop in a straight line. If not, repeat process to fine tune brakes. Since you could push the adjusters in either direction you hope you guessed the proper direction to spin the first time. I did not always guess right the first time.
- Thread starter
- #35
Ok, so here's the Cardone 53-2785. It fits, but it's tight! Your steering angle might be a little different, I've got it set up with crossover steering and a newer style steering box, but the angle should be relatively similar. I pre-bent all the hydraulic lines from the originals (don't laugh too loud, it's my first attempt at the miserable things), so it actually fits the stock arrangement fairly well. By the dimensions, it doesn't seem like it would be that much larger than the stock unit, overall about an inch wider in diameter, but it's just more substantial all around. As you can see, the clutch reservoir was the one hang up. I ended up bending back a tab and a half of the 'lip' on the back of the booster and it gave it just enough clearance. Not a lot of space, but it seems like it should work. Now you guys have me seriously considering going back to the stock drum/e-brake arrangement in the rear.. Does anyone have experience with the dual brake booster/1" MC combo with the slotted rotors and V6 calipers in the front/ stock drum rear?? Thanks
ntsqd
technerd
No experience with that. The closest that I come is the stock '88 4rnnr brakes, which are close, but not close enough.
FWIW it looks like the slip in the steering shaft might be one (?) spline off. Ideally those U-J's want to be in phase too. I hope to hell that you're never turning that shaft at the speed of a drive-shaft, so the importance is much lower. But if the steering feels a little wonky you might start there.
FWIW it looks like the slip in the steering shaft might be one (?) spline off. Ideally those U-J's want to be in phase too. I hope to hell that you're never turning that shaft at the speed of a drive-shaft, so the importance is much lower. But if the steering feels a little wonky you might start there.
This is the common setup for those of us that have gone with FJ60 rotors, V6 calipers, and the 90-95 booster. Works just dandy.
If you want to see how I did it without rear disk....just to have an additional idea, Check my sig for the build thread BUT know I still have not tested my combination.
