Brakes that drag or pull

Question

What is the car actually doing?

Brakes. If the car is not safe to drive, do not drive it. Nothing on this page is a substitute for the workshop manual or for a competent inspection, and a brake fault that has been diagnosed still has to be repaired properly.

Dragging and pulling get talked about together and they are not the same fault. Dragging is a brake that will not release. Pulling is two brakes that are not applying equally. The causes barely overlap.

One thing to establish before starting: the E-Type's rear brakes are inboard, mounted either side of the differential rather than at the wheels. That makes them harder to see, harder to bleed and hotter in normal use than outboard brakes, and it means a rear fault behaves differently from a front one.

Answer this

• All four wheels drag. The car feels slow and everything gets hotGoes to: Everything dragging. Is there free play at the top of the pedal?
• One wheel or one corner drags, or gets much hotter than the othersGoes to: One corner dragging
• It pulls to one side when I brakeGoes to: It pulls under braking
• It pulls to one side all the time, braking or notGoes to: It pulls all the time, so this is not a brake fault
• The handbrake will not releaseGoes to: The handbrake will not release
• The rear brakes get very hot but the fronts seem normalGoes to: The rear brakes running hot

Question

Everything dragging. Is there free play at the top of the pedal?

This one question separates the two common causes. Press the pedal gently with your hand and feel for a small amount of movement before any resistance begins.

If the pedal begins working immediately, with no free travel at all, the master cylinder piston may not be returning far enough to do its job.

Answer this

• No free play. The pedal acts the instant it movesGoes to: The master cylinder is not returning fully
• Normal free play at the top of the pedalGoes to: The servo, or the fluid itself

Finding

One corner dragging

Why this follows. A single binding corner means pressure is either being trapped on its way back from that caliper, or that caliper is not releasing mechanically. There is a quick test that tells you which.

The commonest cause on a car of this age is a flexible hose that has failed internally. The lining delaminates and forms a flap that lets pressure through when you brake and will not let it back out, so the hose behaves as a one-way valve. A hose in that condition looks perfectly sound from the outside, which is why it is so often missed.

What to do

• Raise the affected wheel and confirm the drag by hand.
• Slacken the bleed nipple on that caliper. If the wheel frees immediately, pressure was trapped upstream of the caliper, and the flexible hose or the master cylinder is the suspect rather than the caliper itself.
• If the wheel does not free when the pressure is released, the caliper or its pads are binding mechanically. Look for a seized piston, corrosion in the caliper bore, or pads binding in their carriers.
• On a rear corner, check the handbrake mechanism for that side separately, because it acts on the same disc through its own linkage and can seize on its own.
• Check the flexible hose regardless of age if the car's history is unknown. Internal failure is not visible externally.

Read further: Brake hydraulics and the servo, The inboard rear brakes

Finding

It pulls under braking

Why this follows. Pulling under braking is unequal application. One side is doing more work than the other, either because it is gripping harder or because the other side is gripping less.

What to do

• Check for a contaminated friction surface. Oil from a leaking caliper, a hub seal or, at the rear, the differential will glaze a pad and change its behaviour. Contaminated pads are replaced, not cleaned.
• Check for a partially seized caliper on the side the car pulls away from, since a brake that is not applying pulls the car towards the side that is.
• Check the flexible hose on the weaker side. A restricted hose delays and reduces application on that corner.
• Check the pads are the same material on both sides. Mismatched pads across an axle pull, and it is a surprisingly common finding on a car with an undocumented history.
• Check the discs for uneven condition, scoring or heavy rust on one side only.
• Rule out the suspension and steering before condemning the brakes, since worn bushes allow geometry to change under braking load and produce the same complaint.

Read further: Brake hydraulics and the servo, Torsion bars and the front suspension

Finding

It pulls all the time, so this is not a brake fault

Why this follows. A car that pulls when you are not braking is telling you about its tyres, its geometry or its steering. The brakes are not applied, so they cannot be the cause.

This node exists because the complaint is so often brought to the brakes first. The tree sends you out of the brakes deliberately.

What to do

• Check tyre pressures first, and check them cold. Unequal pressures across an axle pull.
• Check the tyres are the same make, model and age across each axle, and check for uneven or one-sided wear.
• Check for a tyre with a displaced belt, which pulls constantly and passes every visual inspection.
• Check the front geometry, and the torsion bar settings, since ride height affects the geometry on this car.
• Check the steering rack, its mountings and the track rod ends for wear and for movement.
• Check the wheels themselves and, on wire wheels, the splines and the hub condition.
• Check for a dragging brake on one side as a last step rather than a first one, using the one corner branch of this tree.

Read further: Torsion bars and the front suspension, The steering rack and its mountings, Wire wheels and splines

Finding

The handbrake will not release

Why this follows. On an E-Type the handbrake works on the inboard rear discs through its own pads and its own mechanism, separate from the footbrake hydraulics. That means it can seize entirely on its own while the hydraulic brakes are in perfect order.

The inboard position is the difficulty. The mechanism sits beside the differential, under the car, where road dirt and water reach it and where nobody inspects it, and access for adjustment or repair is poor. It is a service item that gets neglected precisely because it is hard to reach.

What to do

• Check the cable and its linkage for corrosion and for a seized run, working from the lever back.
• Check the lever mechanism itself and its ratchet.
• Check the pads and the mechanism at each rear disc. It is possible for one side to seize and not the other, which also shows up as a single dragging corner.
• Check the self-adjusting mechanism, which stops adjusting when it corrodes and then holds the pads in contact.
• Be realistic about access before starting. Work on the inboard rear brakes is confined and awkward, and on some jobs the practical route is to drop the rear suspension unit, which turns a small job into a large one.

Read further: The inboard rear brakes

Finding

The rear brakes running hot

Why this follows. The inboard rear brakes sit beside the differential, out of the airstream, so they run hotter than outboard brakes would in the same use. Some rear heat is the design rather than a fault.

What matters is whether the heat is symmetrical and whether it is extreme. Both rears warm after use is expected. One rear much hotter than the other is a fault, and so is heat sufficient to boil fluid.

There is a second consequence of the inboard layout that is worth knowing. The rear calipers are the hardest points in the system to bleed properly, so they tend to hold the oldest fluid in the car. Brake fluid absorbs water over time and water lowers its boiling point, so the hottest part of the system is also the part most likely to be carrying the fluid least able to take heat.

What to do

• Compare both rear corners against each other rather than against the fronts.
• If one side is much hotter, treat it as a single dragging corner and use that branch.
• Check when the fluid was last changed throughout, and whether the rear calipers were genuinely bled rather than topped up.
• Check the handbrake mechanism, since a partly seized handbrake heats the rear discs without affecting the fronts at all.
• Check for differential oil reaching the pads, which contaminates them and changes their behaviour as they heat.
• Do not assume an uprated pad or disc solves it. Establish first whether the heat is normal for the use, asymmetric, or caused by a drag.

Read further: The inboard rear brakes, Brake hydraulics and the servo, The rear axle and limited-slip differential

Finding

The master cylinder is not returning fully

Why this follows. The master cylinder must return far enough for its piston to uncover the compensating port, which is what lets pressure in the system bleed back to the reservoir. If the pushrod holds the piston past that point, pressure has nowhere to go, and as the fluid warms and expands the brakes apply themselves harder.

This produces a characteristic pattern: the brakes are free when cold, drag progressively as the car is driven, and are worst after repeated braking. A car that binds tighter the longer it is driven is describing this fault.

What to do

• Check the pushrod adjustment between the pedal and the master cylinder, and the free play it should leave.
• Check the pedal returns fully to its stop, and that nothing is fouling it, including carpet, underlay or a badly fitted mat.
• Check the return spring.
• Confirm the diagnosis before adjusting anything: with the car raised and the brakes bound, slacken the bleed nipple at one wheel. If the wheel frees immediately, pressure was trapped in the system, which is consistent with this fault.
• Check the compensating port is not blocked by debris or by a swollen seal, which produces the same result with correct pedal adjustment.

Read further: Brake hydraulics and the servo

Finding

The servo, or the fluid itself

Why this follows. With correct pedal free play and all four brakes binding, the pressure is either being held by the servo, or every seal in the system has swollen at once, which points at what is in the system rather than at any one component.

The contamination case is worth understanding before you start replacing parts. If mineral oil, engine oil or the wrong fluid has ever been put into the system, every rubber seal and flexible hose in it swells. That is not a repair to one component. It means replacing the seals and hoses throughout, and flushing the metal pipework, because a single surviving contaminated part re-contaminates the rest.

What to do

• Check the servo is releasing. Disconnect its vacuum supply and see whether the binding changes.
• Check the servo's own air valve and return.
• Check the fluid. Note its colour, and whether it smells or looks unlike brake fluid. Look for a swollen or sticky reservoir cap seal, which is often the first thing contamination reaches.
• Establish the car's service history if you can. Contamination is usually a single past event rather than a gradual fault.
• Check whether the correct fluid specification for the car has been used consistently, and be aware that the archive has not established the factory's fluid specification by series and market, so confirm it against the workshop manual for the car.

Read further: Brake hydraulics and the servo, Brake and clutch reservoirs, and why replacements leak