mx5 nbfl spongy brakes

[Loafers92]

Hi all,

My mx5 svt has recently developped weird braking. Around 10k miles ago I replaced the ebc greenstuff pads that came with the car with a full set of Roddinsons pads and replaced the fluid with rbf600. The car already has stainless steel brake lines. After the change of pads, I felt that the car braked really really well, never showing any fade in heavy downhill mountain driving for example. It developped a leak in the right rear caliper but it was fixed.

Recently though, I've been feeling the brake pedal going from having a firm feeling to a spongy feeling with more travel than usual, and less braking power. I went for a run yesterday and felt the brakes taking longer to stop the car as well has having to press the pedal further down than usual, and a smell of pad as well.

Any ideas what this could be? Should I look at rebuilding all calipers? Or maybe its somehow related to the pads (still plenty of life left though). I'm a bit puzzled with this!

Thanks

[Nickp82]

Probably slider pin stuck/seized in to carrier

[Loafers92]

Nickp82 said:

Probably slider pin stuck/seized in to carrier

Sorry, I'm a bit of a mechanical numpty - I thought the slider pins are just there to hold the caliper in place right? Why does a seized pin have such an effect on the braking of the car?

[Nickp82]

I’m no tech genius but the slider pin whilst holding the caliper in position, also allows the necessary movement of the caliper for effective braking.
A seized pin will usually mean one side of the brakes is too close/rubbing (hence pad smell) and the other is too far away (loss of braking efficiency)

Better explanations welcomed!

[Colin RedGriff]

There is only one piston in the caliper. When you press the pedal, the piston only presses the pad on that side of the disk. The caliper body is mounted on sliding pins so as the pressure is applied the caliper body can move and pull the pad on the opposite side of the disk against it with equal pressure.

Here's a link to an Edd China video that explains how it works and how to service it (it;s a Ford but the principle is the same),

YouTube

[Loafers92]

Cheers guys, I get it now - I had no idea that the mx5 was running a floating caliper setup (shame on me!)

It all make perfect sense, I just need to figure out which caliper to take apart (front left was letting off a strong brake smell so might start there) but honestly it doesn't seem too complicated to do them all

[griffdude]

Autolink sell caliper pistons, seal kits & slider pins.

If you look on YouTube, Bofi has a how to rebuild your caliper video.