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hi guys, im keen to get a timing belt kit and waterpump for a service on my na. anyone have any experience with ebay kits? if i was to piece something together what brands should i look out for?

any help would be great!

Gates belts and pulleys are as good as any around. GMB Japan water pumps are OEM quality. No one sells oil seals and gaskets for the front sprocket and cam covers as good as Mazda's. Get the genuines from Mazda or Amayama.

so if im building a kit:

belt: gates. (whats the difference between race and normal?)
tensioner and idler pulley: gates?
water pump: GMB (are the gaskets that come with it any good?)
crankshaft gasket, cam covers, cam gears: mazda/Amayama

anything else while im there? I have short nose wobble so will get bolt and keyway as well.

That's about it. Gates belt/pulley/camseal kits and GMB pump/gasket kits come off ebay. The seals and gaskets supplied in those are equal to OEM. It's only the front crank seal and cam cover gasket that are better Mazda branded.

I have never figured out how there's any difference between Gates standard belts and racing belts, apart from price. Maybe someone who builds full-race motors would know of some advantage in the racing belt.

As above, gates belts all the way.
The kit should come with new pulleys and tensioners.

Water pump, as above.


Don't cheap out on the timing belt, I had one out in by a mechanic wayy back at my 100k service, brand was "Racer"

Belt said "guaranteed 80,000km"...... Not great for something with a 100k interval.

I had to replace the belt at 60,000km when all the teeth stripped off it, looks like they were separate bits of rubber glued on as opposed to being a single moulded piece.

So yeah, don't cheap out.
Engine won't bend valves if it goes, but you're still stuck pushing the car regardless.

hks_kansei wrote:Engine won't bend valves if it goes, but you're still stuck pushing the car regardless.

Unless it has big cams, and perhaps non-standard cam timing. In stock form all NAs and NBs are non-interference I believe.

thanks all. I have a decent crank wobble so will change the lot before its first track session.

That's an entirely different problem. Changing timing belt won't fix that in itself. When you've got the front sprocket off you'll have to do some serious investigation looking for damage to the crankshaft nose, the key and the sprocket. At best you may get away with just a new key and sprocket (from Mazda/Amayama only) but there's also a strong chance that the crankshaft is FUBAR too. In which case you'll need a new crank or maybe another motor.

Just google "SNC" or "short nose crank" on miata.net.

In any case I wouldn't buy parts until I'm confident the engine is salvageable.

i am aware of the fix procedure, but had seen some pretty bad ones online fixed so i was just hoping i could fix it and do other maintenance while i was in there. i think you are right though. ill pull it apart first and check the damage before buying up big.

If you're going to take it to the track then it'd pay to replace all the water hoses too, including all the nasty little ones around the thermostat, throttle body, inlet manifold, oil filter and back of the head (whichever your motor has, they're all a bit different). Engine boiling, often with cylinder head destruction, is one of the most common DNFs for old cars which haven't been tracked before. That means you might as well take out the radiator first so you have room to work and see well around the crank nose.

Good luck with it. I suppose you already know about Carco MX5 in Canberra for backup and advice?