Toyota 4x4 Brake Master Cylinder and Brake Booster Specs

Mushy brakes? Worn out brake master? There are lots of options for improving your Toyota'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.
Table of Contents

  • 4 Ways to Get a Parking or Emergency Brake on Your Toyota Mini or 4Runner
  • Toyota Extended Brake Lines
  • Toyota Axle Widths

  • The Best Master Cylinder and Brake Booster Combo

    The most desirable 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” bore, 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 may require a little more work unless you use a turbo booster.

    You can find brake master cylinders and brake boosters in junkyards or through our links below.

    The Best Master Cylinder for Big Tires, Heavy Vehicles, and Better Braking - 1" Bore with Residual Valves

    Toyota FJ80 1" Brake Master Cylinder with Residual Valve - Pigtail Side
    The 1" bore FJ80 master cylinder has a plug on the right side that you'll need to splice into your wiring harness.
    Toyota FJ80 1" Brake Master Cylinder with Residual Valves - Port Side
    The Toyota FJ80 brake master cylinder has residual valves that easily work with disc or drum brakes. This is our choice for a more powerful, better master cylinder.

    The best Toyota brake master cylinder for Toyota mini trucks and 4Runners is the 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 Budget Choice - 1" Bore Stock V6 Toyota Brake Master Cylinder

    Toyota 1" Brake Master Cylinder - Dorman M39996 - No residual valves
    The Dorman brake master cylinder works fine with a stock-style disc/drum setup. If you plan to go with rear discs, we recommend the FJ80 master cylinder.

    Our budget 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 rear brake residual valve of the FJ80 master cylinder - it won't work quite as well as the FJ80 with rear discs. 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 Best Brake Boosters for Big Tires, Heavy Vehicles, and Better Braking - Dual Diaphragm

    A dual diaphragm brake booster will give you better pedal feel and create more vacuum assist. This helps you stop your heavy Toyota whether you're daily driving or on the trail.

    Dual Diaphragm Brake Booster from '89-'95 Toyota 4Runners and Trucks, 4WD

    Toyota '89-'95 4WD Dual Diaphragm Brake Booster
    This brake booster has the short firewall studs that most people need for their Toyota.

    For most 4Runners and minis, this is the dual diaphragm brake booster you're looking for. It has short studs, the correct 4 bolt master cylinder bolt pattern, and it will contribute significantly to having more powerful brakes that can stop heavy rigs on big tires.

    If that doesn't work for you, try the 2WD version:

    Toyota '89-'95 2WD Dual Diaphragm Brake Booster
    This 2WD has long studs on the firewall. This can be used with the aluminum spacer that comes on some Toyota minis and 4Runners.

    The 2WD version of this booster has longer studs, but is otherwise similar to the 4WD version.

    Small Diameter Dual Diaphragm Brake Booster from '86-'87 Toyota Turbo, 2WD and 4WD

    Toyota '86-'87 Turbo Dual Diaphragm Brake Booster
    This brake booster is perfect for 1st Gen Toyotas that need to clear the steering shaft and clutch master cylinder. Other dual diaphragm boosters may fit, but only with modifications to the booster and steering shaft.

    This booster should bolt in to most 1st Gen Toyotas without modifications. If you use a larger booster you'll likely have clearance issues with the clutch master cylinder and/or the steering shaft. A word of caution: Apparently not all of the turbo boosters are dual diaphragm, so try to make sure that it's listed in the description or that it actually is thicker like a dual diaphragm before you buy.

    Your truck may have a thick aluminum spacer between the firewall and booster - you don't need it with this booster.

    We think that a 3rd Gen 2WD truck booster might also fit without mods, but we’re not certain.

    Toyota Brake Master Cylinder Info

    Almost all Toyota master cylinders have M10x1.00 brake line 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 brake master cylinders are in some Toyota cars and we’re mostly not interested in them.

    2 hole brake 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 brake master cylinders are the most common. As far as we can tell, they all have the same 75mm x 45mm bolt pattern. This means that any 4 hole Toyota brake master cylinder will fit in place of another 4 hole master.

    Toyota Brake Booster Info

    There are several brake boosters that have come in Toys. The main variations are:

    • Single or dual diaphragm
    • Small or large diameter
    • Distance off firewall (with spacers)
    • Firewall bolt pattern

    Single/dual diaphragm

    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.

    Small/large diameter

    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 and sometimes the steering shaft. Some 1st Gen owners relocate the steering shaft with extra u-joints and a heim joint. Also see spacer options 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 diameter 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.

    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 Specifications

    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
    FJ40/FJ60/FJ62/FJ70 1981-1989 7/8" Disk/Drum Single M10x1.00 4
    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.
    Turbo Toyota pickup and 4Runner 1986-1987 Disk/Drum Single M10x1.00 75mmx45mm 4 Small diameter dual, some single Bolt-on for 1st Gen trucks.
    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 1981-1986 15/16" Disk/Disk Single M10x1.00 75mmx45mm 4 8.5"/dual
    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
    Toyota Tundra 2006-2014 15/16" Disk/Drum Single M12x1.0 2


Tyler Branham

Tyler came out of the womb with a Birfield in one hand and a stick of 6010 in the other, ready to weld any piece of trail-busted steel back together. He has wheeled, broken, and modified a variety of rigs, from Toyotas to Jeeps to Fords to Chevies. He likes doing long distance overland travel and would happily spend every night in the bed of a pickup under the stars.

Last updated: September 5, 2019