Crank bolt keeps coming loose.

If you use a ARP bolt you don't want to use lock tight , you use ARP assemble lube .. With lock tight you will get a bad TQ reading ...The molly lube that comes with a ARP bolt will get you the right TQ number .. Just like you would not use lock tight on a rod bolt or head bolt you would not use it on a damper bolt ..

Bolt lost its stretch ,I would opt for an ARP version
and try again..

smokinzx14r said:

If you use a ARP bolt you don't want to use lock tight , you use ARP assemble lube .. With lock tight you will get a bad TQ reading ...The molly lube that comes with a ARP bolt will get you the right TQ number .. Just like you would not use lock tight on a rod bolt or head bolt you would not use it on a damper bolt ..

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There are write ups out there calling for loctite to be used.

http://www.powerperformancenews.com/features/ati-damper-install-2015-mustang-gt/

I install w damper and snout mating surfaces clean and dry.
Never oiled. The reason for the interference fit is to insure torque transfer to damper without shifting.
The keyway to key is a torsional clearance fit.
If you reduce torsion transfer by oiling the interference fit between snout and damper, you must increase torsion transfer via the key way. If your key way has any torsional clearance, then you will hammer the key way everytime torsional lash is taken up in either direct.

Short version, if the snout is oiled, torsional vibration can result in the crank hammering the keyway due to lash/play. Impacts lead to cracking.

When installing damper, I keep a strap wrench on the damper holding all the lash to the SC drive side of the keyway. If the ATI is cut way oversize, I peen inside in two places front and rear on non driveside of keyway to help force key to forge on drive side of damper key way.

sigintel said:

I install w damper and snout mating surfaces clean and dry.
Never oiled. The reason for the interference fit is to insure torque transfer to damper without shifting.
The keyway to key is a torsional clearance fit.
If you reduce torsion transfer by oiling the interference fit between snout and damper, you must increase torsion transfer via the key way. If your key way has any torsional clearance, then you will hammer the key way everytime torsional lash is taken up in either direct.

Short version, if the snout is oiled, torsional vibration can result in the crank hammering the keyway due to lash/play. Impacts lead to cracking.

When installing damper, I keep a strap wrench on the damper holding all the lash to the SC drive side of the keyway. If the ATI is cut way oversize, I peen inside in two places front and rear on non driveside of keyway to help force key to forge on drive side of damper key way.

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ATI install instructions specifically call for and highly recommend adding anti seize to the snout of the crank before installation.

Anti seize is typically grease, oil, wax or MDS based.
Wouldnt use it unless the first clean dry fit up required more than 120ftlb. I would stop and pull and reprep.
If it was almost on, I would use a bronze wire brush(gun kit utility size Otis, ProShot, BirchwoodCasey) by hand on damper and crank. This will transfer a very small amount of bronze to the metal surface grain and decrease friction very slightly. This will be less decrease than using Aluminum, Copper, Graphite in MDS(Moly) or parafin oil.
If still too tight, very light dressing with silver anti seize.
If still too tight, mic the crank for a couple minutes and spec a hone to ATI.

Slamdcoop0428 said:

ATI install instructions specifically call for and highly recommend adding anti seize to the snout of the crank before installation.

Click to expand...

Have discussed w ATI several cranks and am aware of that recommendation in some cases. Given your results, I suspect they may tell you to try clean and dry with silicon in keyway only.

Can you mic the crank and damper and call ATI with the results?
If you logged peak torque for each revolution pulling damper on theyll take that too.
Check the Ford OEM manual and a couple engine builders.

If you are going to do frequent tear downs for race service, then maybe grease, but also make sure that key and keyways are hand fit tight or pinned or tight double keyway.
For a one off service street car, its your call. I am not a professional engine builder so YMMV.
I make sure everything is clean and mic for galling and correct it.

Dont take my word, ask ATI. Evidently, Its an interference fit for a reason. Interference increases force transfer between parts, grease decreases it. You want as tight as possible without exceeding 105-120ftlb torque on bolt, like 10,000+lb linear force forging damper onto crank.

If you try installing clean and dry and are only seeing 5ftlbs needed to pull damper on, grease, oil or antiseize will make that worse.

Properly cleaned and any galling lightly corrected, I find ATI dry fit goes on without exceeding 70-100ftlb. I am putting an extra 150bhp load on snout to drive a Whipple, I am lucky it holds without hammering keyway or ratcheting the bolt loose ( slight turn of the bolt the extremely small angle that occurs due to keyway lash). Ratcheted loose bolt moves slow typically only with each complete torsional spike cycle, so could be 500-5000 miles to see a complete turn loose. If the bolt is backing down torque or backing out, possible either thermal cycling or ratcheting action are in play. No guarantees, just allow for the possibility your keyway is loose with insufficient torsional grip and friction fit between crank and damper. Think about how this could result in cracked keyways in the case of an extremely loose damper with a locktighted bolt.

If you cant increase the grip, I would considering a fresh damper hub and trying again crank polished clean and dry.

Crank and damper dims are very tightly controlled by both Ford and ATI.
If possible, try to measure your torque during install w a torque cell in addition to torque wrench.