NA6 Brake Rotor Wear

Wolfgang · Postby **Wolfgang** » Sat Sep 23, 2017 4:32 pm

I need the wisdom of people who know MX5's better than I do.

Now that twelve months worth of rust has been scrubbed off my rotors I'm concerned about the amount of area the pads are covering on the rear rotors and that it's different from one side of the car to the other. Is this a normal amount of coverage or am I worrying about nothing?

LiteIsRite · Postby **LiteIsRite** » Sat Sep 23, 2017 6:32 pm

Here's mine, FWIW. Brakes were professionally inspected recently, no issues reported. Welcome to the forum BTW!

Wolfgang · Postby **Wolfgang** » Sat Sep 23, 2017 9:17 pm

LiteIsRite wrote:Here's mine, FWIW. Brakes were professionally inspected recently, no issues reported. Welcome to the forum BTW!

Thanks

Hmmm... mine don't appear to be quite right, could explain why it doesn't really stop. I know they aren't as assisted as new cars but even from 50kmh it takes some effort to pull the car up. And they are shuddering when they get hot.

Sooo... What are the latest must have brake pads and rotors for street use?

Magpie · Postby **Magpie** » Sat Sep 23, 2017 9:43 pm

Is there a lip at the top of the rotor?

Grease the slider pins for a start. Make sure you adjust the rears correctly.

A good street pad at the A1RM's, however the Winmax W3's are another good choice.

Wolfgang · Postby **Wolfgang** » Wed Sep 27, 2017 10:28 pm

Magpie wrote:Is there a lip at the top of the rotor?

Grease the slider pins for a start. Make sure you adjust the rears correctly.

A good street pad at the A1RM's, however the Winmax W3's are another good choice.

No, there doesn't appear to be a lip around the outer edge. Apparently it had new pads and fluid not that long ago, not sure what pads they put in but me thinks they aren't very good.

93_Clubman · Postby **93_Clubman** » Thu Sep 28, 2017 10:59 am

MX5 rear calipers are also prone to internal corrosion, especially of the adjusters, & as Magpie has said, grease slider pins & adjust rears using the correct method.

Wolfgang · Postby **Wolfgang** » Sat Sep 30, 2017 9:35 am

93_Clubman wrote:MX5 rear calipers are also prone to internal corrosion, especially of the adjusters, & as Magpie has said, grease slider pins & adjust rears using the correct method.

Seeing as the car has sat unused outside in a coastal environment corrosion is almost a certainty. I'll suss it out this weekend.

Wolfgang · Postby **Wolfgang** » Sat Sep 30, 2017 2:57 pm

So I had a look at the rear brakes this morning. Pads are glazed, rubber seals are perishing, pistons corroded, lower slide pins pitted, and one upper pin has a strange wear pattern. Not looking pretty...

RS2000 · Postby **RS2000** » Sat Sep 30, 2017 3:49 pm

The corrosion on that part of the pistons is ok to just clean up, but you will have to pull them out & check the piston OD & cylinder bore. They could still be ok & just need a seal kit.
That pin looks like chrome is flaking off.

93_Clubman · Postby **93_Clubman** » Sat Sep 30, 2017 4:01 pm

And check for internal corrosion of the adjuster mechanism - it's located under a cap-like bolt on the opposite end of both the calipers to the piston, ie it's not obvious there's adjusters present.

Wolfgang · Postby **Wolfgang** » Sat Sep 30, 2017 9:01 pm

I had a feeling that corrosion on the outside wasn't a huge problem, but as said it could be corroded further back.

The outer adjuster on the more corroded side was harder to adjust and stayed in place, whereas on the other side it fell out when I removed the allen key.

I'm of the mind that if I'm going to remove the piston to inspect it I might as well refurbish the calipers. Annnd the snowball keeps rolling...

The thing I can't figure out is why the pads would glaze so quickly? Judging by the amount of material on them they are reasonably new and the previous owner only used the car for urban driving. I'll give them a sand and see how they go.

Got to say, this sure is a knowledgeable, helpful, and friendly community.

Magpie · Postby **Magpie** » Sun Oct 01, 2017 8:42 am

Pads can glaze due to overheating. This will result in the rotor looking like there is not pad material on it as well

In the rear this is almost always the hand brake adjuster lightly keeping the brakes on, resulting in drag and heat.

No need to sand, service the brakes and then bed them in properly or replace the pads.

93_Clubman · Postby **93_Clubman** » Sun Oct 01, 2017 11:07 am

Wolfgang wrote:The outer adjuster on the more corroded side was harder to adjust and stayed in place, whereas on the other side it fell out when I removed the allen key.

Yeah, as they corrode they become harder to loosen or adjust & that's when the threads can be stripped as people apply too much pressure to turn them either way. Btw, the more corroded side is usually the passenger side in a RHD MX5.

Magpie · Postby **Magpie** » Sun Oct 01, 2017 7:31 pm

Pick the old lower slider pin

Wolfgang · Postby **Wolfgang** » Sun Oct 01, 2017 8:20 pm

Magpie wrote:Pads can glaze due to overheating. This will result in the rotor looking like there is not pad material on it as well

In the rear this is almost always the hand brake adjuster lightly keeping the brakes on, resulting in drag and heat.

No need to sand, service the brakes and then bed them in properly or replace the pads.

Adjustment seemed to be alright, the pins did need a clean and regrease though. I will try another round of bedding in now the rust has been removed and see how I go.

93_Clubman wrote:Yeah, as they corrode they become harder to loosen or adjust & that's when the threads can be stripped as people apply too much pressure to turn them either way. Btw, the more corroded side is usually the passenger side in a RHD MX5.

I was mindful of not forcing it. I suspect the reason for the drivers side being worse is due to that side of the car being more exposed to salt laden winds while it sat unused.

Magpie wrote:Pick the old lower slider pin

Hmmm... this could be a trick question. The one on the right.

While we are at it, would the rotors be comprimised from being so heavily rusted all over? I can't get a definitive answer.