Do I need a new crankshaft?
 

Just took off my crank pulley because it was wobbling.


Can I still use this crank or is it time for a new one? I'm guessing the crankshaft bolt wasn't properly torqued since I had to remove it a bunch of times recently.

I have a good pulley boss/pulley/woodruff key. But does the crank need to be replaced as well?

You can click pics for 3000x2000 res.
https://www.miataturbo.net/attachmen...ine=1340761244
https://www.miataturbo.net/attachmen...ine=1340761244
https://www.miataturbo.net/attachmen...ine=1340761244

The damage to the crank nose doesn't look all that horrible. I'd certainly attempt the repair first. Worst-case scenario is you wind up having to replace the crank anyway. Best-case is it lasts for another half light-second or more.

i'd wait for someone else to chime in; take my opinion with a grain of salt...
but the crank looks fine.
a new pulley boss looks to be in order.

Yeah I have a new everything except the crank. I even have a crank that I gave away to a friend.

I figure the same way - worst case scenario it starts wobbling again I'll just put in another crank.

Reinstalled everything using my old 1.6 pulley boss. Once the thinner boss arrives (cause I need it for toothed wheel) I'll redo it. For now, no wobble.

https://www.miataturbo.net/attachmen...ine=1340766880

Crank is fine....I'd loctite it and be done. I recently did this and my crank was much worse than this and have had no problems since

With loctite fix you basically loctite crank + key + timing belt sprocket into 1 solid piece, correct?

Yes basically fill in the key way on the crank with Loctite....set the woodruff key in ..and slide the crank gear/pulley over key. The excess loctite will fill in the gaps. note this is Loctite 660 aka quick metal...for me not the easiest stuff to find an cost about 15$ for small tube.
I also used regular blue Loctite on the crank bolt..torque to a little over 90ftlbs

I'd think he could get a full light-second out of it, the keyway might be a little loose at the end, but the keyway doesn't appear displaced at all, as shown in the m.net locticte repair how-to. A new pulley is definitely in order though.

I posted in the other thread: crank good, pulley shot. JB Weld or the Loctite fix if you think the key is too loose. Otherwise, go for it.

You know what's funny, is that after I posted that, it sort of hit me that the speed of light is actually not all that fast.

I mean, it is fast. We all know that. Faster than a leopard, for instance, or a lotto vendor on welfare-check day. But it's not incomprehensibly fast. My own car has traveled just over 1.149 light-seconds in only 22 years, which easily falls into the range of "things that I can actually wrap my head around," especially since it was parked for the majority of that time.

Damn, my chassis is right around 1 light second. The crank... was in 4 different cars at this point.

I have two cranks you could have.

My keyway is worse than yours with most of the damage toward the last 1/4 of the outter portion of the nose. I have over 100k on it with multiple teardowns and no Locktite, just torqued to factory specs, and it looks no worse now than it did 100k miles ago.

:makeout:

100k miles turbo?

Non turbo. Built 1.9L, lightened crank, 11:1 compression. Lots of autocrossing/high rpm before and after the re-build (100+ events). The last 30k+ the engine has seen numerous trips to 8000 rpm.

When I bought the engine, the damage had already been done. I bought a new pulley boss and key. The key fits snugly in the keyway.