Crankshaft Pulley Repair on the Boosted Miata 

Hey Gimpy, yeah youtube skews very young although Mike the Miata King was one of the first guys posting videos about Miatas and he's no spring chicken either. Glad you'er enjoying them! I'll keep them coming the best I can.

Baithehuman thanks! I was using a Bluetooth serial adapter from EFI Analytics.

Thecharliejolly thanks man!

Honestly, I've never used loctite in the 3 or 4 rebuilds I've done over the years (on these bolts anyways) and never had a problem until this last time.

Yeah - you will need that.

HooverTuber thanks!!

lol your a doushe

MiataMods thanks.MM!

PB blaster penetrating solvent and or heat then press would be the last resort I suppose

I'd like to think too much power! But probably just not tight enough :)

lol wouldn't we all like to assume that the problem ;) Well good luck with your hand! Hopefully you can be back out driving soon! and I must also say...for a man older than me I am surprised you are up so late!

Afaik it's common for FI Miata motors putting out high torque to do this. There are aftermarket balancers that supposedly fix this available, but they are expensive. Probably best to do some research.

I was running 232whp 232ft/lbs and didn't have this problem, I never heard much about the pulley itself coming off in that fashion. More common is past 250whp its recommended to get a better harmonic balancer(not because they come off) to reduce vibrations and protect the oil pump.

Yeah - in my case I'm sure I didn't torque the screws enough. I did use blue loctite this time however so hopefully that helps. I do want the ATI super damper, but not at 400 bucks I don't! When I invest in a Boundary oil pump on my next build, I most likely will get the ATI to protect it.

Yeah, you should be able to remove the pulley with the trigger wheel and everything still attached after removing the main bolt. You probably need to drop the sway bar to have enough room though.

Thanks! More coming....

1.8 vvt

Yes 96 thru 05 use them.

Having a hard time finding one in Cali what would happen if I didn’t run one been looking through the forums but can’t seem to find anything I know it sounds like a dumb question but just wondering

vandieselcuuuz won’t run with out it

Thank you 🙏🏽 I know it’s a lot what I’m asking but any websites I can order one from I’ve tried treasure coast moss and I think I found one on eBay but feel weary about it

Thanks for taking the time to share this info, great stuff! - just a couple points. That pin that I replaced with a screw is just an alignment pin, so that the timing marks are correct. It's fairly snug and no it's not perfect, but it will work until I get a balanced damper installed soon. I agree the stock M6 hex washer head bolts are weak, but honestly I've never had any trouble until this episode and it likely due to me not snugging those m6 bolts down to spec. I know fasteners, sold them for 15 years to the military and aerospace. I would not use socket head cap screws in this application, mainly because the sockets strip - even on the hard alloys - it's all cheap imported crap, at least the stuff you can get per each at your local fastener distributors. The best solution are grade 8.8 or better hex washer heads, loctited (pick your poison - I'm staying with blue) and properly torqued to 90-100 in/lb -should be fine for most applications. But I agree, that pulley design is not great that why I'm replacing mine soon!.

This joint design by the folks at Mazda depends mostly on friction created by the clamping force from those M6 screws, jointed part location with anti-rotation provided by that single pin. Knowing metal is more rubber like than solid, the joint will move once a high enough shock load is applied by drive belt wind up and release, AC compressor clutch engagement and similar over comes the friction created by those three M6 screws. Once joint movement occurs, the road to failure is rapid. It is a joint design that will fail. What the design folks at Mazda did not account for is the real world shock loading involved with drive pulleys and belts that store and release energy, think pulling on a rubber band then letting it go. Good quality metric socket head cap screws are available from a number of on line suppliers that is not made in China junk. They are not that difficult to get (Bossard, Brighton Best, SPS, . www.unbrako.com/socket-screws As for socket head cap screws stripping out, that depends on the quality and tolerances of the internal hex of the screw and hex bit used to drive it. When high quality internal wrenching screws and hex bits are used, stripping out is usually not a problem. MS20004 to MS20024 series internal wrenching bolts don't have too many problems with their drives stripping out when driven by proper high quality tools. The older (now discontinued) NAS144 to NAS 158 series internal wrenching bolts used a larger internal hex size to reduce the potential stripping out problem. If this was a significant problem the current MS20002 -MS20024 series would have continued with the larger internal hex, but the aerospace folks did not and reduced the internal hex size. Ponder for a moment if this hub to pulley joint should ever need to come apart. Rational answer to the application is no, This implies using high strength loctite as being a non-issue or problem. Adding high strength loctite between the surfaces of this hub-pulley joint as an added means to reinforce this joint can be a good thing. The damage this hub-pulley can cause if they came apart under load at speed can be severe. Given the potential severity of what can happen if this joint failed, make this joint as inseparable as possible under all possible operating conditions. Breaking the loctite bond is just not difficult, heat the part to just over 300 degrees F and remove. This is what we do for flywheel and similar threaded joints.