Mushy brakes? Worn out brake master? There are lots of options for improving your Toy’s brakes. You can easily swap in a master cylinder with a bigger bore or swap a dual diaphragm brake booster for your single diaphragm. We’ll talk about what to look for and how to ID the parts you need.
The Best Master Cylinder for Big Tires, Heavy Vehicles, and Better Braking
The best Toyota brake master cylinder for Toyota mini trucks and 4Runners is the Trail Gear FJ80 brake master cylinder. This is a stock FJ80 master cylinder. It has residual valves in the front and back, so it’ll work fine with either drum or disc brakes. It has a 1” bore, so it works fine with larger calipers. You’ll need to slightly rebend your brake lines and splice the fluid level sensor pigtail to make it fit, but its 75mm x 45mm bolt pattern means that it will bolt right up to your brake booster.
Our second choice is the stock master cylinder for a V6 Toyota mini pickup or 4Runner. This is a bolt-in mod that gets you the 1” bore master. This master cylinder is cheaper, but does not have the residual valves of the FJ80 master cylinder. You may or may not need to bend your brake lines and splice the fluid level sensor wiring. Pre-1989 minis and 4Runners will probably have to do both as the front brake line port and the wiring plug are both different:
The most desireable combo is a 1” bore master cylinder with a dual diaphragm brake booster. For most people this gives the ability to lock up the front brakes without too much pedal travel but also does not make the brakes feel stiff or overly sensitive. For Toyota trucks and 4Runners any 1”, 4 hole master cylinder will swap onto your brake booster (if you don’t already have a 1” bore master). Most dual diaphragm boosters will swap on, but early trucks and 4Runners will require a little more work.
If you have a problem with junkyard parts, remember: brake boosters rarely fail, but you can easily have a problem with a used master cylinder. Be sure to bleed your brakes properly.
Toyota Master Cylinders
Almost all Toyota master cylinders have M10x1.00 fittings. For the purposes of swapping, ABS or non-ABS doesn’t matter, but non-ABS masters tend to have a smaller bore.
2/3/4 hole flange brake master cylinder mounting
3 hole masters are in some Toyota cars and we’re mostly not interested in them.
2 hole master cylinders tend to be in recent Tacomas, Tundras, and 4Runners. We haven’t looked into it a lot, but it appears that there should be some possibilities of swapping in larger 2 hole brake masters on recently manufactured Toyotas.
4 hole master cylinders are the most common. As far as we can tell, they all have the same 75mm x 45mm bolt pattern.
Toyota Brake Boosters
There are several brake boosters that have come in Toys. The main variations are:
- single/dual diaphragm
- small/large diameter
- distance off firewall (with spacers)
- firewall bolt pattern
Dual diaphragm boosters are a significant upgrade for braking in most Toyotas that have larger tires, are heavier, or that have rear disc conversions. Dual diaphragm boosters provide more vacuum assist, which will decrease pedal effort. To identify them, dual diaphragm boosters are about 1” thicker (front to back) than single diaphragm boosters plus they a “step down” when viewed from the side. Recent Toyotas seem to be using an awful lot of single diaphragm brake boosters.
For certain swaps, the outer diameter of the booster is pretty important. Dual diaphragm boosters can have large and small diameters. On solid axle pickups and 4Runners the steering u-joint is larger than on IFS trucks. To clear the u-joint you can:
- Use a small diameter brake booster.
- Install a spacer behind the booster. The booster will often have a 1/4” aluminum spacer on the original vehicle that fits between the firewall and booster.
- Shim the steering column down. In the cab unbolt the steering column and stack a washer or two to shift the column down.
- Hammer the seam on the booster. This is sort of hacky, so only do it as a last resort.
On 1st Gen pickups (‘79-‘83) and possibly 4Runners, there are additional clearance issues with the clutch master cylinder. See below.
Distance off firewall (with spacers)
There appear to be 2 different spacers that fit between the booster and firewall. One is around 1 1/4”, the other is 1/4” They are both aluminum.
The thicker spacer is especially useful for clearing the clutch master in earlier Toys. 1st Gen trucks have very little room to fit a larger brake booster. The thick spacer requires longer studs on the back of the booster and will probably require you to lengthen the brake pushrod to compensate for the spacer thickness.
We think that a 3rd Gen 2WD truck booster might also fit without mods, but we’re not certain.
Most boosters that we are interested in swapping have the same firewall pattern. There are occasional exceptions with some cars, so if you plan to use a non-truck/4Runner booster, measure first.
Parts Scrounging Tips
- Non-ABS vehicles tend to have smaller diameter brake booster.
- Larger and heavier vehicles tend to have master cylinders with larger bores.
- 4WD tends to have a larger master cylinders than 2WD.
- 4 cylinders usually have a small bore.
- V6 vehicles usually have a 1” bore.
- Any dual diaphragm booster will fit a 2nd Gen truck.
- Dual diaphragm boosters are 1” thicker than single diaphragm.
- Dual diaphragm boosters have a step down when viewed from the side.
Look for small diameter boosters in:
- 2WD C&C chassis
- 3rd Gen 2WD trucks
- Turbo trucks and 4Runners
Toyota Brake Master Cylinder and Brake Booster Listing
Here is some info on some common Toyota master cylinders and boosters. Most of this information should be close to correct, but we’re sure that there are some missing factoids. You’ll see that some models came with more than one master cylinder or brake booster. This is because brake options were often attached to vehicle option. For instance, ‘90s and ‘00s V6-equipped Toyotas tend to have 1” master cylinders, 4 cylinder-equipped vehicles of had 13/16” or 7/8” master cylinders.
|Model||Year||Bore||Front/Rear brake type||# of Reservoirs||Fitting size||Flange bolt pattern||# of flange holes||Booster diameter/diaphragm||Notes|
|All Land Cruiser||1970-1975||1"||Drum/Drum||Dual||M10x1.00||4|
|FJ40/FJ55||1976-1980||7/8"||Disk/Drum||Dual||M10x1.00||4||North American spec|
|FJ45||1977-1980||1 1/8"||Drum/Drum||Dual||M10x1.00||4||Canadian spec|
|FJ80/FZJ80||All||1"||Disk/Disk||Single||M10x1.00||75mmx45mm||4||9.75"/dual||ABS and non-ABS masters are different. Bolt-in upgrade for '79-'95. Residual valves front and rear.|
|Toyota pickup and 4Runner||1981-1985||13/16"||Disk/Drum||Single||M10x1.00||75mmx45mm||4||8.5"/single/non-1 ton chassis, 10"/single/1 ton chassis,|
|Toyota pickup and 4Runner||1986-1989||13/16"||Disk/Drum||Single||M10x1.00||75mmx45mm||4||8.5"/dual, 9.5"/single||Suspect that dual diaphragm booster is extremely rare and may only come on specific vehicles like 2WD C&C.|
|Toyota pickup and 4Runner||1989-1995||7/8" or 1"||Disk/Drum||Single||M10x1.00||75mmx45mm||4||8.75"/dual, 9.75"/dual, 9.5"/single||V6 usually have 1" bore.|
|Toyota Cressida||1988-1992||1"||Disk/Disk||Dual||M10x1.00||75mmx45mm||4||9.75"/dual||ABS and non-ABS masters are different|
|Toyota Supra||1986-1992||1"||Disk/Disk||Single||M10x1.00||75mmx45mm||4||9.75"/dual||ABS and non-ABS masters available.|
|Toyota Supra||1992-2002||1"||Disk/Disk||Single||M10x1.00||75mmx45mm||2 or 4|
|Toyota Tacoma||1995-2005||1"||Disk/Drum||Single||M10x1.00||75mmx45mm||4||9.75"/dual, 8.75"/dual||ABS and non-ABS masters available.|
|Toyota Tacoma||2005-2015||13/16"||Disk/Drum||Single||M12x1.0||2 hole|
|Toyota 4Runner||1996-2002||1"||Disk/Drum||Single||M10x1.0||2||9.75"/dual||ABS and non-ABS masters available.|
|Toyota T100||1993-1998||1" or 1 1/16"||Disk/Drum||Single||M10x1.0||75mmx45mm||4||10.5"/dual, 9.75"/dual||ABS and Non-ABS masters available.|
|Toyota Tundra||1999-2006||13/16"||Disk/Drum||Single||M10x1.0||2||10 9/16"/single|
An excellent article on upgrading the brakes on a 4Runner.