2008-2009 Lexus IS-F Brake Caliper Problems and Replacement

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most 2008-2009 Lexus IS-F caliper complaints come down to three things: a piston that sticks in its bore, a torn dust boot that lets water and grit in, or pads that wear unevenly because the pistons no longer move freely. The IS-F uses Brembo six-piston aluminum calipers up front and two-piston calipers in the rear, so a caliper problem is usually fixed by cleaning and rebuilding the caliper or by replacing it with a complete Lexus assembly, not by guessing with generic parts.

How the IS-F brake system is built

The IS-F was not a dressed-up IS 250. Lexus fitted it with a dedicated Brembo system built to its own engineering specifications, and it was the first Lexus production car with the Lexus name displayed on the calipers. The layout looks like this:

That hardware exists because the car needs it. The naturally aspirated 5.0-liter V8 is rated at 415 bhp and 371 lb-ft of torque, and the car shipped with a three-mode version of Lexus Vehicle Dynamics Integrated Management (VDIM) that uses the brakes for stability control. High-friction pads were fitted at all four corners from the factory.

A multi-piston fixed caliper does not float on slide pins the way a single-piston economy caliper does. The caliper body stays put and pistons on both sides of the rotor push the pads in. The upside is even clamping and a firm pedal. The downside is that there are more pistons, more seals and more dust boots, and every one of them has to move freely for the pads to wear evenly.

Common IS-F caliper problems and their symptoms

Sticking or seized pistons

This is the classic failure on a car that is now well over a decade old. Corrosion builds up behind a damaged boot, or old fluid lets the bore pit, and a piston stops retracting. Signs include:

• The car pulls to one side under braking, or drifts while coasting.
• One wheel is noticeably hotter than the others after a drive, and may smell of hot brakes.
• Heavier brake dust on one wheel than the rest.
• A pad worn at an angle (tapered) or one pad in the set worn much more than its partner.
• A blue or heat-checked spot on a rotor, or a new pulsation in the pedal.

Torn or hardened dust boots

Brembo notes that dust covers exist to stop liquid and dirt from getting into the piston seat, and that road salt and chemical degreasers used to clean the car are a major reason caliper rubber and metal parts deteriorate. On an IS-F that has lived in a salt state, or had its wheels scrubbed with harsh cleaners to fight brake dust, cracked boots are common. A torn boot is not an emergency by itself, but it is how a sticking piston starts.

Fluid seepage

The piston seals keep the brake fluid in and also pull the piston back slightly when you release the pedal. A seal that has hardened or a bore that has pitted can weep fluid. Look for wetness on the inside of the wheel, on the caliper body or on the pads. Fluid on the friction material means the pads are ruined and must be replaced along with the repair.

Uneven or rapid pad wear

Because the pistons share the load, one lazy piston changes how the pad contacts the rotor. Brembo points out that a blocked or dragging caliper causes residual braking torque, rotor overheating and early wear of both pads and discs. If you keep eating front pads faster than you would expect, check the calipers before blaming the pad compound.

How to diagnose a bad caliper

1. Check wheel temperature. After a normal drive with light braking, carefully compare each wheel with an infrared thermometer. One corner much hotter than its opposite side points to a drag.
2. Spin the wheel. With the car safely supported on stands and in neutral, a front wheel should turn with light pad contact only. A wheel that stops almost immediately is dragging.
3. Pull the pads and inspect. Measure the pad thickness at both ends and compare inner to outer pads. Tapered or mismatched wear tells you which pistons are lazy.
4. Look at every boot. A six-piston front caliper has six boots. Check each one for splits, and look for rust or crusty deposits around the piston edge.
5. Test piston movement. With the pads out, the pistons should push back smoothly and evenly. Never press the brake pedal with the pads removed, or a piston can be pushed out of its bore.

Also check the brake hose for that corner. A hose that has collapsed internally can hold pressure on the caliper and mimic a sticking piston.

Rebuild or replace?

You have two real options on an IS-F.

Rebuild the original caliper

If the bores are clean and only the seals, boots or a piston are bad, a rebuild is a good fix. Brembo caliper repair kits include pistons, piston seals and dust covers, and Brembo stresses cleaning the caliper, checking the pistons, seals and sliding parts, and using the correct dedicated grease on each item. On a fixed caliper do not split the two caliper halves; rebuild the pistons and seals through the bores. If a bore is pitted where the seal rides, the caliper is done and should be replaced.

Replace the caliper assembly

Lexus sells each IS-F caliper as a complete disc brake cylinder assembly, one per corner, with separate left and right parts. The genuine assemblies are listed for the IS-F with the 5.0-liter V8 from 2008 through 2014, so any year IS-F caliper of the correct side and axle is the same family of part. Replacing is the right move when a bore is pitted, a caliper has been damaged, or you want the car back on the road in one afternoon. Browse our brake calipers for other applications.

A single seized caliper on a lightly used car can be replaced alone, but inspect the other side of the axle carefully before you decide. If both sides show the same corrosion, do them as a pair.

What to replace at the same time

• Pads. Any pad that has run against a dragging caliper, or has touched brake fluid, goes in the trash. For the front six-piston calipers we carry several Hawk compounds built for this car: the quiet, low-dust Hawk Performance Ceramic Street front pads for the IS-F, the higher-friction Hawk HPS street pads, the street and track Hawk HP Plus pads, and the dedicated Hawk HPX motorsports pads for track days.
• Rotors. A dragging caliper overheats the disc. Check thickness against the minimum stamped on the rotor and look for cracks spreading from the cross-drilled holes. Browse brake rotors if yours are past service.
• Pad hardware. Replace pad retaining pins, anti-rattle springs and clips. See our brake hardware kits.
• Brake hose. If the hose on that corner is old or swollen, change it while the system is open. We stock brake hoses.
• Brake fluid. Opening the system is the perfect time to flush it. Use the fluid type printed on the reservoir cap and in the owner's manual, and bleed all four corners, not just the one you worked on.

How hard is the job?

For a confident home mechanic, replacing a caliper assembly is a moderate job. The fixed caliper unbolts from the knuckle, the hose comes off at the caliper, and the new unit bolts on. What makes it harder than an economy car is the size of the front caliper, the need to protect the painted finish, and the bleeding. Tighten the caliper mounting bolts and the hose fitting to the values in the factory service manual; do not guess on these.

Bleeding needs care. The system works with VDIM and ABS, and a multi-piston caliper can trap air in its bores. Bleed in the sequence given in the service information, and if the pedal stays soft after a thorough manual bleed, a scan tool that can run the ABS bleed routine may be needed. A rebuild is harder than a replacement because it requires clean conditions, careful piston removal on every bore, and the correct lubricants. If any of that sounds unfamiliar, have a shop do it. These are the brakes on a 400-plus horsepower car.

Frequently Asked Questions

Who makes the Lexus IS-F brake calipers?

Brembo. Lexus had Brembo build the system to its own specifications: six-piston aluminum calipers in front and two-piston calipers in the rear, with the Lexus name on the caliper bodies.

Do 2010-2014 IS-F calipers fit a 2008 or 2009 IS-F?

The genuine Lexus caliper assemblies are catalogued for the IS-F from 2008 through 2014 with the 5.0-liter V8. Match the side and the axle, and confirm with your VIN when ordering.

Can I just replace the pads if one caliper is sticking?

No. New pads on a sticking caliper will wear unevenly and overheat the rotor again. Free up or rebuild the caliper, or replace it, then fit new pads.

Is a torn dust boot dangerous?

Not immediately, but it lets water and dirt reach the piston, which is how pistons start to stick. Replace the boot, or rebuild the caliper, before corrosion sets in.

Which front pad should I choose for my IS-F?

For daily driving, a ceramic street pad is quiet and low-dust. If you drive hard on back roads, a higher-friction street pad bites harder. Motorsport pads are for the track and are not meant for cold daily use.

Sources

1. Supercars.net - 2008 Lexus IS-F - Brembo six-piston front and two-piston rear calipers, rotor sizes, Lexus name on calipers, engine output, three-mode VDIM
2. Lexus Parts Now - Genuine Lexus IS F brake caliper - calipers sold as complete sided assemblies per corner, fitment 2008-2014 IS F 5.0L
3. Brembo - Repair kits for brake calipers - causes of caliper wear, repair kit contents, dust cover and seal functions, lubrication practice
4. Hawk Performance - HB616Z.607 - front pad application for the Lexus IS F and ceramic compound characteristics