1930 A crank threads

L

Lucasville30A

Junior Member
The threads in my crankshaft for the ratchet bolt are stripped out. Not exactly sure how it happened but I noticed the bolt was loose and that the threads in the crank were basically non existent. Is there a helicoil that I could use to fix this and retain the original ratchet bolt?
 
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Stripped out threads in this location may result from using a ratchet bolt that is too long in the threaded portion. I have several - probably from 1930's era V8 applications - that are a bit to long for the drilling in the Model A or B crankshafts. Check bolt length before torquing that sucker down.
 
If you have a lathe you can make an internally threaded sleeve to press into the end of the crankshaft after boring it out a bit. Chill the sleeve in liquid nitrogen before inserting it.
 
I have heli-coiled a Model B crankshaft with very good success. I discovered the problem when building the engine, right before I was ready to install the crankshaft so the process was relatively easy because I could get it in the lathe to drill and tap the hole.

In my opinion, a heli-coil done correctly is a permanent repair.

My experience,

Chris W.
 
nkaminar said:
If you have a lathe you can make an internally threaded sleeve to press into the end of the crankshaft after boring it out a bit. Chill the sleeve in liquid nitrogen before inserting it.
Click to expand...

I'm curious, where do folks get liquid nitrogen? And I mean like as a consumer, not "I have access through my job."
 
My 2 blade original fan came apart last week, dented the hood and I found the blade on top of the throttle linkage , I replace it with a new cast aluminum blade new water pump, belt, upper radiator hose was cut and leaking and the crank pulley was warped also, The original blade showed no signs of cracking prior so just an FYI change out the old blades out of precaution as someone could have been hurt or killed,
Peter
 
alexiskai said:
I'm curious, where do folks get liquid nitrogen? And I mean like as a consumer, not "I have access through my job."
Click to expand...

I get dry ice from my local Safeway. Not quite as effective as LN, but quite a bit better than the home freezer.

Home freezer: 28F
Dry ice: -109F
Liquid Nitrogen: -320F

LN is available around me from most industrial/welding gas suppliers, as it can be hooked up to supply large quantities of inert gas for heat treating ovens. The big kicker with LN is that it requires a special (aka expensive) thermos (“dewar”) to store it.

And I would not use a LN-enhanced press fit for this repair, as suggested by nkaminar (as much as it pains me to disagree with you, NK!). Press fits should not be used where there is a torque loading. Better to use a threaded repair such as a Helicoil or internal/external threaded sleeve.

My $0.02, and likely of equal value.
 
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