By Core Brake Parts Tech Team — Circleville, OH warehouse
Most caliper problems on a 1993-1998 Toyota Supra come down to age: pistons that stick in their bores, torn dust boots, seeping seals and slide or hose problems that leave one wheel dragging. The fix is usually a replacement caliper (or a rebuild), fresh pads and rotors on that axle, new fluid and a proper bleed. Before you order anything, confirm which brake package your car has, because the twin turbo and non-turbo Supras do not share front calipers.
Which Calipers Your Supra Has
The fourth-generation (A80) Supra was sold in the US in non-turbo and twin turbo form, and Toyota fitted them with different brake packages. The US-spec twin turbo uses a 4-piston front caliper and a 2-piston rear caliper. The genuine Toyota twin turbo rear calipers are listed as 47750-14280 (left rear) and 47730-14270 (right rear). The front 4-piston caliper works with a 323 mm vented rotor that is 30 mm thick new, with a 28 mm minimum thickness, and that rotor is sold specifically for the 4-piston caliper.
The non-turbo car uses a smaller front brake package. That matters for two reasons: rotors and pads for one package do not fit the other, and the twin turbo calipers are a popular upgrade for non-turbo owners. Converting a non-turbo car to twin turbo front brakes takes more than the calipers. You also need twin turbo rotors, twin turbo pads, the fitting and shim kit, and 17-inch or larger wheels to clear the larger caliper and rotor.
| Item | Twin turbo (US spec) | Non-turbo |
|---|---|---|
| Front caliper | 4-piston | Smaller front package - confirm on the car |
| Rear caliper | 2-piston (47750-14280 LR, 47730-14270 RR) | Check the part number on your caliper |
| Front rotor | 323 mm x 30 mm, 28 mm minimum | Smaller rotor, not interchangeable with the 4-piston setup |
| Wheels needed | 17-inch or larger | Needs 17-inch or larger wheels to run the twin turbo front brakes |
The quickest check is to look through the wheel: count the pistons on the front caliper, and match the casting or part number on the old caliper before ordering. Many of these cars have also been modified over nearly 30 years, so do not assume a car still has the brakes it left the factory with.
Common Supra Caliper Problems and Symptoms
A caliper works hydraulically. When you press the pedal, fluid fills the caliper bore, the piston extends and clamps the pad against the rotor. When you release the pedal, pressure drops and the piston pulls back slightly on its square-cut seal. When any part of that cycle stops working, you get one of these symptoms:
- Pull to one side under braking. One caliper is not applying as hard as the other, often from a sticking piston or a restricted hose.
- Pull or drag when you are not braking. A piston is not retracting, so the pads stay in contact with the rotor.
- One wheel much hotter or dirtier than the others after a drive, or a burning smell from one corner.
- Uneven pad wear - one pad, or one side of the car, worn far more than the rest. On the 4-piston front caliper, a single stuck piston can also wear a pad at an angle.
- Fluid on the inside of the wheel or tire, or a dropping reservoir level. A leaking caliper needs attention right away.
- Soft or sinking pedal after a caliper has been opened or has been leaking, which points to air or a seal problem.
What Causes It
Age is the big one. Brake fluid absorbs moisture over time, and that moisture corrodes the piston and bore. A torn dust boot lets water and grit in from the outside and speeds the same process. A caliper that has sat for months in a garage, which is common with collector Supras, often seizes simply from lack of use.
Not every "stuck caliper" is actually the caliper. A useful test from a caliper remanufacturer's technical bulletin: if the piston will not release, open the bleeder. If the piston then retracts, the caliper is doing its job and something is holding pressure against it. The usual suspects are:
- A twisted or internally collapsed rubber brake hose acting like a one-way valve
- A kinked or damaged metal brake line
- A faulty proportioning or combination valve
- A faulty master cylinder
- A misadjusted booster pedal rod or master cylinder pushrod
- A brake light or cruise control switch that is out of adjustment and holding the pedal slightly applied
On a car this age, the flexible hoses are a frequent culprit. If you are replacing a caliper, it is worth replacing that corner's hose at the same time. We carry replacement brake hoses and brake lines.
Replace or Rebuild, and What to Replace With It
You have three realistic paths:
- Rebuild the original caliper with seals, boots and, if the bore is pitted, a new piston. This keeps the factory part but only works if the bore is clean.
- Replace it with a remanufactured or new caliper of the same type. This is the fastest way back on the road. Browse our brake calipers.
- Upgrade - for non-turbo owners, the twin turbo calipers with matching rotors, pads, the fitting and shim kit, and 17-inch wheels; for track use, an aftermarket big brake kit.
Whichever you choose, do the axle, not just the corner. A dragging caliper overheats its pads and rotor, and a leaking caliper contaminates the pads with fluid. Contaminated pads cannot be cleaned and must be replaced. Replace pads on both sides of the axle, and replace or measure the rotors against their minimum thickness. For the twin turbo front, that minimum is 28 mm on a rotor that is 30 mm new. Also plan on fresh hardware (clips, shims and pins) from our brake hardware kits.
If your pads and rotors are due on both axles, a complete kit saves ordering piece by piece. Our 1993-1998 Toyota Supra front and rear brake kit includes drilled and slotted rotors, ceramic pads and hardware for both axles. Calipers are not included, so you would pair it with calipers if yours are bad. Confirm your brake package (non-turbo or twin turbo) against the part you are removing before ordering, or browse brake pads and brake rotors on their own.
How Hard the Job Is
Replacing a Supra caliper is a moderate DIY job with basic tools, a flare-nut wrench for the brake line fitting, a torque wrench and a way to bleed the brakes. The basic steps:
- Loosen the wheel, raise the car on stands, and remove the wheel.
- Crack the brake line or hose fitting at the caliper, then plug or cap it to limit fluid loss.
- Remove the caliper mounting bolts and the caliper, then the pads.
- Inspect and measure the rotor; replace it if it is below minimum thickness, scored or overheated.
- Install the caliper with new pads and hardware, and torque the mounting bolts and banjo or line fitting to the values in the factory service manual.
- Bleed the brakes, starting at the corner farthest from the master cylinder unless the service manual says otherwise. The Supra has ABS, so follow the factory procedure if the ABS unit may have taken in air.
- Pump the pedal until firm before moving the car, then bed in the new pads.
Use a new sealing washer on any banjo fitting you disturb. Fill the system with the fluid grade printed on your master cylinder reservoir cap, and do not mix fluid types. If the old fluid was dark, flush the whole system rather than just bleeding the corner you worked on. A caliper remanufacturer recommends changing brake fluid every two years to help prevent early brake failure, and on a car that is used rarely, time matters more than miles.
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Shop Brake Calipers →Frequently Asked Questions
Do twin turbo and non-turbo 1993-1998 Supras use the same calipers?
No. The US-spec twin turbo uses a 4-piston front caliper and a 2-piston rear caliper with larger rotors. The non-turbo uses a smaller front brake package, and rotors and pads for one do not fit the other.
Can I put twin turbo brakes on a non-turbo Supra?
Yes, it is a common upgrade. Besides the calipers, you need twin turbo rotors, twin turbo pads, the fitting and shim kit, and 17-inch or larger wheels to clear the larger brakes.
Should I replace calipers in pairs?
If one caliper is leaking or seized and the other side is the same age, replacing both keeps braking even from side to side. At minimum, always replace the pads on both sides of the axle.
My caliper is stuck. Is it definitely the caliper?
Not always. Open the bleeder on the stuck corner. If the piston then releases, pressure is being held upstream, often by a collapsed rubber hose, a faulty valve or master cylinder, or a misadjusted pushrod or brake light switch.
What is the minimum rotor thickness for the Supra twin turbo front?
The 4-piston front rotor is 323 mm in diameter and 30 mm thick new, with a 28 mm minimum. Replace it once it measures below that, or if it is scored or heat-cracked.
How often should I change brake fluid on a Supra?
A caliper remanufacturer's technical bulletin recommends every two years. Moisture in old fluid is one of the main causes of corroded, sticking caliper pistons, especially on cars that sit for long periods.
Sources
- XAT Racing - OEM Toyota Supra TT Front Brake Caliper - 4-piston twin turbo front caliper; parts needed to convert a non-turbo car (TT rotors, TT pads, fitting and shim kit, 17-inch or larger wheels)
- XAT Racing - OEM Toyota Supra TT Rear Caliper - 2-piston twin turbo rear caliper, part numbers 47750-14280 and 47730-14270
- DBA 4000 T3 front rotor for Toyota Supra JZA80 - 323 mm diameter, 30 mm thickness, 28 mm minimum, for the 4-piston caliper only
- CARDONE - Brake Caliper Function and Symptoms of Common Failures - how caliper hydraulics apply and release the pads
- CARDONE ProTech PT18-0002 - Sticking Caliper Piston Cause and Solution - bleeder test, upstream causes of residual pressure, two-year fluid change recommendation
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