Keyway damage - what caused it, what prevents it ?
 

Built motor – crank was last at machine shop getting balanced and then installed by me. New keyway, new bolt, new Supermiata damper – torque wrenched on. Car ran great for about 20,000kms. I’d like to note that I had rev limit settings based on what I found on here. She did like to shoot a flame or 4 and a beautiful staccato sound that was especially nice in tunnels and when playing in the snow and on a few city 2nd gear corners etc etc. Keep the rev limiter in mind for later on.
Started to hear some sounds on start up – maybe rod or cams or VVT ?? Pulled the VVT plug and it sounded better – must be VVT. Car didn’t run as good – down on bottom end power and overall power but I attributed this to the VVT issues. . Sound came back a bit. Decided to pull motor to put in FM Stage 2 clutch (ACT HD slipping at 20psi) and I had a front main or oil pan leak and I wanted to get the sound sorted. Cam timing looked spot on, but at TDC the timing marks were about a cm or more off. Interesting. Pulled the damper and oh no!

What caused this? What can prevent it? Could the violent action of the rev limiter and the mass of a dampers sudden retardation start to work the keyway ?

BTW - I found a 90,000km 1.8 short block so I’m going to take that crank probably. Rather that than weld and machine the old keyway.

Insufficient or overtorqued crank bolt.

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My guess is not enough torque, not enough red loc tite. The ATI damper presses onto the snout, makes for a much less-prone-to-stripping-or-vibrating-loose keyway interface.

So does the supermiata damper.

Landrew did you use loctite?

i can't tell by the pics if the key way in the crank itself is worn but I would doubt it as the key itself is usally what wears as yours shows. I would do as mentioned above, new key and crank gear. What could have been the problem is the key itself design. I have built several motors and I grind the inner end of the key to match the curve machined into the crank. This does two things IMO. It gives the key a little more sitting in the crank key way groove but more importantly it gives the key a better chance of not binding the dampener when sliding on. The stock square end on the oem key design well not slide back down forward if it is too high by just a little which can give a false torque reading. Then when you run the motor it can vibrate forward and down in the crank grove and let the torgus value on the crank bolt loosen If the key is formed more to the grove in the crankshaft if it is say a little high in the crank at the rear it well tend ti slide down and forward in the crank as the dampener is installed if that makes sense. I have done this to several motors I have built and never had a problem and this is the way a lot of keys are in cranks on other manufacturers as they use the half moon design keys. I install the key with some rtv in the crank grove and let it set and then never seize the crank and key and the hub inside before pressing on. I use a old crank bolt to install the dampener and then install a different one that has never been used to install the dampener. I personally use ARP lube to get a truer torque reading on the threads and under the head of the crank bolt and when torqued to the 125 ft lbs if I remember the recommended specs correctly have never had a issue and mine gets tortured. As stated above it is important to shape that key to matche crank grove and allow it to be able to slide down level as the dampener is installed so you don't have the key bind.

I have never once in my life used red loctite on the crank bolt. What I do use is the proper OEM torque spec, and 100ft.lbs is not it. (99-05 Engine FSM specs 116-122ft.lbs, I use 120ft.lbs). Blue loctite is the appropriate compound.

That whole area looks really impressively terrible for 20,000km.

Also, how's the torque wrench. They lose calibration over time and especially if handled roughly. The ones in our factory are on an annual recalibration cycle. Critical fasteners like head bolts/nuts and this one should be torqued with your golden wrench, not the one you use for quick wheel lug checks at the track.

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Just to clarify: You're mad because he stated the OEM torque specification and proper loctite?

Red loctite can cause stripped threads and broken bolts when removed without heat. And heating the nose of my crankshaft is not my favorite thing to do if I'm doing a timing belt job.

Blue loctite and FSM spec is the way to go.

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Its not closed minded. You listed an incorrect value. On a bolt with a specified torque. He was just correcting it.

Incorrect information doesnt help anyone.

Wadded panties don't either.

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Are you done crying?
Red loctite seems fine until you need to remove that bolt later.

Bigass impact wrench turned to setting #3.

:scratch:

:spit:

What?

Why y'all looking at me like that?




j/k

I don't have time to sugar coat it for you. 100ft.lbs is wrong. The FSM says 116-122. You don't need any experience at all to read the FSM and use the right torque spec. Red loctite is wrong. It's a serviceable fastener which must be removed every ~60k miles for timing belt service. Red loctite is designed for permanent applications. "Remove every 6 years" is not permanent.

This has nothing to do with popularity or your perception of my ego or anything else. Torque specs are not subjective. You published incorrect info, I corrected you. I'm not going to waste my time tip-toeing around your feelings because you think that you deserve a participation trophy for your new ideas. If you don't like being told off for being wrong, be wrong less.

I've always used red loc tite, 272 I think, didn't know blue was the OEM spec. Either way never had a problem taking a bolt out, never used heat either. I use red on that bolt, the flywheel bolts, and converter bolts as I don't ever want those vibrating loose. Not surprised that OEM spec is not Red loc tite but ther'es plenty of non-OEM things folks do to engines when building them for high performance/racing.

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