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I put new pads in the front of my car yesterday, and as I was pushing the piston back into the caliper back on the driver's side there was a little "pfffff" and then some watery oily crap (brake fluid one assumes) came out of the rubber seal.

Now, I don't know the consistency of healthy brake fluid (haven't changed it on a car I own yet) but it didn't seem viscous enough. It may have been water and goop inside the seal, it may have been brake fluid.

The same seal on the opposing caliper has bits missing, so it's not even a seal.

Add in to that the pads had very different wear levels (non-leaking caliper used nearly all of the pads, the leaking side used about 50%) I didn't put the old pads in, but assume (hope) P.O changed them in pairs at least, I did also clean and lube the slider pins.

So, do I rebuild the existing calipers (is there a kit?), get new NA6 ones, or look around for a bigger brake kit altogether? My initial plan was to put pads in and see if that helped the sometimes uninspiring stopping, but I'm not sure it will now.

I would have them rebuilt, including the proportioning valve, master and new fluid. The rears can be a bit expensive to rebuild because of the hand brake adjuster built into the caliper. Contact Automotive Plus (Dave) for some kits or MX5 Mania. I can post a link if you want to DIY the rebuild.

What is the cars primary use?

Replace / upgrade. Personally I'd upgrade.

You can get na8/NB stuff for a couple hundred these days. Sure they might need rebuilding in a couple of years but atleast they will be the bigger units and potentially significantly newer.

Na6 brakes will cost you the same to rebuild but if you want to upgrade later will be worth nothing.

Master cyclinder etc don't touch them unless the are leaking. Just flush really well.

IF the brakes are still uninspiring after the swap then you can't start looking at other things.


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I agree/disagree with you Sailaholic

Yes upgrade would probably be the best path, however rebuilding the master/proportioning valve will fix any issues with residual pressure allowing the brakes to drag. Based on what I know now I would recommend the rebuild of the master etc.

I was thinking of rebuilding the calipers, how does the pressure get equalised left/right? I just assumed it was a T piece, if one side was stiff, the other would pump up harder.

Doing the master and a prop valve at this point might be getting carried away ;)

I do like the idea of NB brakes, I'll see if I can get some of those on the cheap, rebuild, install and hopefully have no trouble for the next bunch of years of the car's life.

Otherwise it'll be a caliper rebuild for a start.

Magpie can I trouble you for the link to see what's involved in the DIY'n? Please

Rear brake operation http://www.miata.net/garage/ebrake/index.html or http://fastcraft.biz/blog/?p=725

Front caliper http://mazdaroadster.net/showthread.php?1859-Front-Caliper-Rebuild

There are a few more DIY guides on the internet if you need more.

Cheers Sir!

I'd actually found the front caliper rebuild howto in my explorations of the internet, I remember the red caliper photos.

I've emailed the usual suspects about rebuilt "kits" and/or NB calipers & brackets, I'll know soon if I'm rebuilding or upgrading - rebuild kits are available from the UK for about AUD$80 per caliper so it's just a matter of waiting to see what the locals come back with.

Let us know which way you jump / costs. I've been holding off on a rebuild till I moved house but will soon be doing the full job front and rear.


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Well, here is what I've put together so far.

Background:
I'm starting from a fully-stock NA6 brake setup, and was about to go to braided lines anyway. I had "brake upgrade" on my mind already. I tend to price cheapest, most expensive, and somewhere in the middle (then I usually pick the middle price). I'll round up to the nearest dollar, five or ten, depending on the value of the thing, this builds some buffer into the price in case the dollar shits itself again, if not, you've got beer money already in the budget. Doing all of the work myself I've not included time as a cost. "ELF Fluid" is what I picked for a pricier brake fluid, I've done no research on the value of this fluid yet. Likewise, you can get cheaper rotors and pads than listed here, I've picked these rotors because they look good, and the pads because they're middle of the price-field.

Option A: All NB8B Calipers + Slotted Rotors + Braided Lines + 'good' Pads:
NB8B Calipers (ebay): $660
NB8B F Rotors (DBA 4545, ebay): $340/pr
NB8B R Rotors (DBA 4534, ebay): $260/pr <-- these are actually NB8A rear rotors, so add a few dollars for the correct ones.
Braided lines (HEL): $190
F+R Pads (Mania): $400
Brake Fluid (ELF, Mania): $42
Total: $1892


Option B: Front NB8A Calipers + Rotors + Lines + Pads:
NB8A Calipers (ebay): $200 (ish)
NB8A Front rotors (DBA 538S, ebay): $260
Braided Lines (HEL): $190
F Pads (Mania): $200
Brake Fluid (ELF, Mania): $42
Total: $892



Option C: Rebuild: (this section is all over the place)
$50/pair for rubber seals (6 seals, so both sides) - rear kits have "more bits" and are $43 per side.
A+ gave me a kit number: (they have none in stock) "pbr front caliper rebuild kit k2423s"; which on ebay is $13 - I can't find a parts list though, so don't know what you get, a local pbr stockist can probably tell us.)

AutoPlus will do exchange rebuilds for $220ish, which includes being sent off to be machined (magpie's link above indicates the same machining can be done at home with a hone tool)

Or the Ebay-UK rebuild kits average out around $100 + $25 shipping - there's a few different kits with pistons and rubber, much more complete than the local kits. None of the options seem to have the replacement slider pins, they're about $25/each from the UK.

http://www.mx5parts.co.uk/ have a wonderful shop you can look at all the different bits and see what you need. Their prices may not be terribly competitive once you include shipping though.

So for me to rebuild and replace my lines and fluid it'll be about $250 (kits) + $100(pins) + $42 (fluid) + $190 (lines) + $200 (new pads, fluid on one) = $782


Conclusion:
So, if you already have the calipers you want, you can do a full rebuild for about $125 an end, plus your time. If you want a rubber-only rebuild it's cheaper. If you don't have a missus to oversee your spending, new racecar-looking brakes will be just shy of $2k Actual racecar brakes are double that again. (and won't fit my car)

So if you're on the fence about upgrading your brakes, it's time to get off the fence and just upgrade them.

Well, good news for me, Mania happened to have an NB8B brake set that'd just rolled into the shop which they let go for much less than their website lists. They told me next week, and still managed to get them sent today. It makes me a very happy camper indeed!

Also, in the "DBA Rotor Comparison" thread (viewtopic.php?f=30&t=52072) the suggestion that using cheaper brake rotors and replacing them more often works out to be roughly cost neutral with running expensive rotors and changing them less frequently, and the type of pad will affect the life of the rotors as well.

In light of these new bits of information, I did a quick "ebay look" and the numbers come down a long way, you're looking at about $400 for new pads and rotors instead of about $1000

Thus concludes the rambling for today.