Miata brake rattle

When going over slightly rough, washboard roads my Miata makes a really annoying noise. It sorta sounds like rocks in a can. It's fairly faint so its most noticable when the top is up.

Eventually I realized the noise went away when I touched the brakes so I focused my efforts there. The brakes worked fine, and looked fine too except it was missing all four of the "W" clips on the rear pads. Hoping to fix it once and for all I replaced all the clips and springs front and rear with a kit I got from Rockauto.

After installing them the noise went away and all was well for awhile. But that was this spring and now the noise is back.

Any idea's short of replacing all the clips and springs again? They're not expensive but I'd hate to have to do this every few months to keep them quiet.

It's a '94 Miata, OEM calipers and Brembo blank rotors. Mazda value pads up front, Axxis Ultimate pads in the back.

Thanks! Jason

Adjust the rear calipers per the manual. You do realize that you are running a better pad on the rear than on the front and may have an imbalance going on.

In reply to fastmiata:

You mean the pre-load for the parking brake? If that is the problem then why did the noise go away with the new clips/springs?

The parking brake works pretty good. Well the passenger side at least. The cable on the driver side seems to be seized up so that side doesn't work despite it being adjusted properly.

Yeah, the rear pads are more aggressive but that's intentional. It's a common trick among us autocrossers to help neutralize the heavy front brake bias the Miata seems to have. Since we can't install a proportioning valve in many classes the pad compound is all we have to work with.

There is adjusting screw on the back of the caliper. You should use it to move the caliper to install pads and also to tighten the pads. Frozen calipers and E-brake cables are quite common and you may need to replace some of your hardware.
Funny about your pad choice. I run stock pads on the rear on my SM to stay away from rear steer under braking.

I doubt the adjuster has anything to do with the noise.

I'd try R&Ring the springs. At least inspect them. I've run without those in the past and they do make a noise, but even running just one per wheel seems to be enough to shut them up. I don't know what the Rockauto ones are like, never tried 'em.

By the way, different Miatas have different stock proportioning valves. 2001 "Sport" cars with ABS actually have an empty one that delivers 100% pressure to the rear wheels. But they all look the same from the outside. Just sayin'.

Another thing to check: sometimes aftermarket pads have more clearance than OE's. I've seen aftermarkets 'click' when first braking even though all the antirattle stuff is in place.

Thanks Keith. I really didn't think the adjuster had anything to do with it either.

I'll pull the wheels and see what they're like. FWIW the Rockauto clips and springs looked just like the presumably OEM ones that were on the car, just shinier. I guess there could be some variation in material thickness not obvious to the naked eye though.

Probably not a good idea to deliver 100% braking to the rear though . Flatspotted rear tires are just as bad as front ones plus I hear you can get moving backwards in a hurry that way.

Jensenman - I'll see if I still have my Mazda "value" rear pads to compare against the Axxis ones. If so I'll stick a caliper on them and measure that notch which holds them in the retainer.

Some Miatas do seem to need 100% rear pressure - at least, that's what our customers buying our adjustable valves tell us. It's all going to depend on your cg, tire traction, brake pad choice and surface. A Spec Miata on hot RA-1s on a racetrack is going to want more front bias than an autocrosser on cool tires and a dusty parking lot, I expect. Lots more weight transfer going on.

Just in case anyone's interested, here's how the factory proportioning changed over the years. I suspect a 1.6 Miata would benefit from, say, a 1994 ABS valve.

is there supposed to be a link in there?

don't the abs proportioning valves run wide open because the abs is used to maintain the f/r brake bias?

I left the link out as a reading comprehension exercise. Congrats Strizzo, you passed!

http://flyinmiata.com/tech/stock_bpv.php

Yes, the 2001+ cars with Sport brakes and ABS let the ABS take care of proportioning. Same with all the 2006+ ABS cars, which is pretty much all of them.

Ok, so this morning I pulled all four wheels off to look around. Nothing seemed amiss so I pulled the caliper and pads and they also looked fine. All springs & clips present and in good shape.

I put it all back together and no surprise but the noise is till there. Any more ideas?

Did you check to see if you still have the pieces the pads slide on installed?

The things that aren't springs in this link: http://shop.oreillyauto.com/ProductDetail.aspx?MfrCode=BHH&MfrPartNumber=13306&PartType=354&PTSet=A

I lost those on my car a while ago and it was shockingly loud. Definitely louder than the noise you're describing but it can't hurt to check any way.

Yes, all clips, springs, and shims are present.

Front:

8 - pad clip things (4 per side)

4 - V shaped springs (2 per side)

Rear:

4 - rear pad clips (2 per side)

4 - W shaped rear springs (2 per side)

All of them are only a few months old too. I replaced them all with new parts this past spring.

What I find interesting is that you replaced them, the problem went away and now it's back. Did you use any anti-squeal goo on the pads that may have washed off? What's changed? If the springs aren't expensive, try installing a new set just to find out if the noise goes away again. If not, then you're looking at the wrong area and it might be something totally different like a loose sway bar end link. If so, then something's changing with those springs.

In reply to Keith:

Yeah, that's my next step. Order some new OEM springs/clips from Mazda and see if the noise goes away again. The swaybar endlinks (OEM) look fine and the noise does go away when you apply the brakes even very slightly.

No goo or anything else on the brakes. Other than lubing the slider pins I avoid any kind of extra "stuff" on my brakes. Especally after seeing how 1. It didnt solve the squeeling brakes on my brothers RX8 when the dealer used it. 2. It gets on to everything once the brakes heat up enough to make it run.