Hi everyone,

I depowered my rack last week, and my buddy noticed that my crank pulley has a wobble to it.

My best attempt to explain the wobble:
There is 1.5-2 mm dfference between the lowest and highest points around the circumference of the crank pulley at idle.

I read the articles about the weak crank keyways on the 90-91.5 miata on miata.net, but mines is a 93. I also verified that I have the long-nose crank. Is there still a chance that my keyway is busted?

I will check torques on the bolt tomorrow. Is there anything else I should look into?

 

I think you got it down. Just be careful when you check those bolts. Because the head snap off easy. My neighbor snapped two of those bolts while trying to torque them to spec.
*Its a lot of fun drilling them out*

 

The long nose crank is also susceptable to "crank wobble". I've seen two and repaired one with the locktite fix. See MNet garage for details.

 

I had the same problem with my 92 (also a long nose). I repaired it according to the locktite instructions and it has been fine for a year now and mine was pretty bad.



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Did you hear a metallic rattle noise at idle?

 

that's what min looks like, but mine makes deadly bird chirping noises.

 

Cant recall it making any noises. It was a year ago.
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I've seen 1.8s with pulley wobble. Also check the 4 bolts that hold the pulleys together. I've seen thoes little ******* shear right off.

 

Is it possible to check the key just by removing the big 21mm Bolt?

I may be able to see the keyway / key, to see any damages, using a dental mirror.

 

i noticed this on a 99 my buddy was looking to purchase a few months ago.

as far as i know the car is still for sale and about $2000 less than when we went to look at it.

 

My crank pulley fell off on the way home from work a few weeks ago,it was my own fault as i had done a key way/wood ruff key repair a week or so before and although had used a thread lock when torquing up the crank bolt i had failed to fit a new crank bolt and i believe the old bolt had stretched.

 

yeah i'm under the impression that no matter what car/engine you're working on the crank pulley bolt is one time use. even if not it's worth the extra few dollars in that "while you're in there" kind of way.

 

I had 2 bolts shear off randomly a couple years ago, definitely made the pulley wobble.

 

Keyway struck in my 00. About 1/8" play at front of keyway and the keyway on the inside of the cam pulley was also worn so replaced cam pully, welded keyway gap on the crank (to fill the excessive room) and ground it back to spec, new key fits nice and tight and I will be locktighting the whole thing tomorrow thoroughly. I too had a strange noise coming from the crank and I suspect it was this play in the bottom cam pulley. Yes I know welding your crank is not ideal since it anneals the metal etc (but the motor has 145K on it so I'm not too worried, by the time it's a problem I'll be into a new motor). Welding fix is a PITA (mostly all the sanding and grinding after the fact) but at least you know you will never have to do it again .... ever.