1.8 crank pulley two pieces, right?

[riefdaddy]

I'm in the middle of a timebelt/waterpump/cam seal/water hose replacement job on my Miata. Everything is going well except for the crank pulley. I have damage to the pulley surface that contacts the drive belts and I am replacing the pulley. The new to me part is supposed to be delivered by Friday, or Monday. Apparently you can find 1.6 pulleys all day, but 1.8 are as rare as hens teeth. I opted for an OBX underdrive pulley, so we'll see how that works out. Anyone use one before?

Here is my issue and main question. I pulled the pulley with no issue, but everything appears fused together (lots of rust). I just want to make sure that there are indeed multiple parts to the crank pulley on the 1.8. Correct me if I am wrong, but there should be a spacer, then the pulley and then the inner portion that actually fits onto the crankshaft. Is that correct? I want to be sure before I use the BFH to "delicately" persuade the pieces apart. This would be after letting it soak in PB Blaster to help things progress.

[riefdaddy]

I decided what the hell and beat it into submission. It is the three pieces that I thought it should be. So that mystery is solved.

Anyone use an underdrive pulley? I know it is lighter that the stock pulley and less drag, but anyone have insight into the OBX pulley? I researched as best I could and all I find is from mnet. They are clueless as they somehow believe the pulley on a Miata is a harmonic balancer, when in reality a Miata is internally balanced on the crank. I have to replace mine as it is cracked in a few spots and is so rusted I can't find any timing marks if I need them.

[—RotorNutFD3S—]

They're not incorrect, the OE Miata crank pulley IS a harmonic balancer. A harmonic balancer has nothing to do with weight, it reduces torsional vibrations/resonance, which can cause things to crack and/or break.

You can possibly get away with an underdrive crank pulley on a naturally aspirated Miata but definitely not on one that is boosted. Would I use one? Absolutely not, I've seen too many oil pump failures posted in mostly stock Miatas to trust them.

[riefdaddy]

RotorNut, thank you for the reply. You got two items in one, I didn't say that a harmonic balancer had anything to do with weight. I said the new pulley was lighter than the stock pulley. My pulley was very rusty, I mean so rusty the pulley boss and the pulley had become one. I do now see the layer of rubber for the dampening effect of a harmonic balancer, but only after I cut my old one in half. I'm not going with boost and I don't really go above 5k rpm, so I'm not so worried regarding the oil pump catastrophes I've read about on the turbo sites. I'll definitely be on the lookout for any unexplained NVH.

[— kung fu jesus —]

It isn't just F/I Miatas that have issues with those aftermarket crank pulleys. I have seen failures in other models that use them in FWD BP applications too. I would replace with OE or a SuperDamper ($$0, regardless of how fast you spin the the motor. You won't FEEL any unexplained NVH, remember the motor sits on flexible engine mounts.

[riefdaddy]

True, true. I'll take a look at the stock replacement from Rosenthal.

[riefdaddy]

Just ordered a new one from Rosenthal. Thanks RotorNut and KFJ!