The brakes were working pretty well until recently when I noticed the car would pull to the right on braking. Hitting the brakes at speed is now really scary! Fairly new pads, replaced the flex hoses, opened and cleaned each cylinder (both sides even though I suspect the problem is on the left). I notice the inside pad on the left moves away from the disc when the brakes are released whereas the other three (one left, both right) stay touching the disc enough to cause a slight resistance (fairly easy to rotate the hub by hand). How much should the pad release? Is the one that releases working correctly and the other three dragging? Thoughts?
Visible gap between one pad and disc when brake pedal released - other is touching the disc.
I had the same problem, I took the front brakes apart and double checked everything and put them back together, still did it, I think a tiny bit of oil got on one of the rears. It can pull from the front or the rear brakes not working properly. I fixed it by dragging them a while to get the brakes good and hot and ever since then it’s been fine.
This is an indication that you have more braking force from one caliper than the other.
The car will pull away from the weaker side. So your problem is on the left.
The likely problem is that you have a sticking piston. Contamination on the discs can cause this problem but the contaminants burn off quickly and the problem stops.
Pads sit very close to the disc with the brakes off. You shouldn’t be able to see a gap.
Agreed - even a small gap can cause a delay in that pad operating which will cause a noticeable yaw. I found this the hard way many years ago when I deliberately had all pads pushed back from the discs while doing some high speed testing, to avoid any possibility of any minute amount of drag. All good till I braked hard at the end of the measured section, when the car dived violently towards the infield. There’s a large comment in the project notebook “DON’T DO THAT AGAIN”!
I did a complete rebuild of the brakes (front and rear), new pistons, pads, rotors, pipes, flex hoses and guess what. The car still pulls to the right on hard braking! Nothing changed! This morning I inspected the front suspension again. The only thing I found was one of the shocks (left) is ‘sticky’ by comparison. I say ‘sticky’ as extending (manually) it grabs/binds in places and is not smooth like the righthand side. Question to consider is could this ‘sticky’ shock be enough to cause the suspension to ‘steer’ itself on braking? Has anyone experienced something simliar. Thoughts?
Centering the caliper should make NO difference at all. If it’s off-center, after the first stop the pistons will pull back, leaving one further out than the other, eliminating any possible problem. So, messing with centering is pointless. I don’t even understand wht the factory bothered with it.
If one pad is retracting more than the other (and I don’t see how that can be happening), it may cause pulling on gentle stops, but on a fast, hard stop, where you stomp the pedal and the pressure increases almost instantly, this won’t matter. You may get a short jerk to one side, and then braking pressure will equalize.
If you get pulling on both gentle and hard stops, then something is either binding, or fluid pressure is not being released properly. The ONLY thing I can see that would explain pulling on the Dunlop system is a failed left flex hose, or undue friction in the left piston or pad. Anything else would affect BOTH front brakes.
I’d be looking at how much force it takes to move each piston. One may have an over-size seal or dust boot, or a rough surface on the cylinder, or a pad that is too wide, and rubbing on the sides of the slot in the caliper that it rides in. Those faces should be smooth, and the pads should have a small clearance so they slide easily.
I would also sand the pads, just to ensure no contamination on the active surface. Also throroughly clean the rotor faces with brake cleaner and a Scotchbrite pad.
Seems pretty unlikely to me, but swapping them round could probably be done in a few minutes (they aren’t loaded when the car is on the ground), so you could always try that to see…
Thanks all. I tend to agree it is unlikely a ‘sticky’ shock would cause such an extreme pulling to one side but as suggested I swapped them this afternoon and will test when the roads dry tomorrow.
On light braking the pulling is barelynoticeable but stomping is scary.
I made sure the rotors were clean after assembly and pads slide freely. I would have thought any residual contamination would burn off pretty quickly during the road test. I applied a light pressure to the brake pedal this afternoon and with front wheels off the ground rotated each wheel - same friction both sides and they both release ok.
I love it when someone thinks outside the box. As Wiggles said, check your left rear trailing arm mount. Braking puts tension on the trailing arms, and if the left one shifts backwards then the rear suspension will be steering the back of the car to the left, which points the front of the car to the right.
My car used to pull to the left under hard acceleration. I spoke to Terry of Terry’s Jaguar Parts, now gone but he told me the front ball joints could cause that for a similar reason, lift the front and apply torque and things move. I replaced them, it was the ball joint.
pauls
If the problem is in the front brakes/suspension, you will feel the steering wheel will pull to the left when you hit the brakes I would not expect that to happen if the problem is actually in the rear.
Colin, when you say it pulls to the right on hard braking, does it make a quick dive to the right and then center, or does it continue to pull to the right until stopped? IMO, this can be different symptoms.
Others have mentioned, but be specific. You said you checked the front suspension. Does that mean we should assume the ball joints, tie rod ends, control arm bushings, steering rack mounts, wheel bearings, etc. are all in good condition?
Tom
Colin, did you notice what brand is the sticky one? If you decide to replace it I’d be interested to scoop up and dismember it as part of our study of dampers and their internals.
