So about 8 months ago I had Long field heat treat and cryo my front d30 5:13s. I am finally getting them installed and my installer told me to verify that heat treated gears would be okay in a daily driver and not wear excessively.

Long field stated when I had them done up front would be okay however I spoke to some lady who seemed confused about the process in general. Now long field was bought out... New company has no clue on the process and no longer does it.....

What are your guys opinion on the gears being heat treated then cryo'ed.

 

Heat treatment is actually a broad term for many different processes, such as annealing, solution annealing, normalizing stress relieving, quenching just to name a few. Without knowing the exact metal composition of the original component, whether it was work hardened or had some previous treatment along with the new heat treatment method you could not hope to know what kind of grain structure you might come up with. There are many other variables for each of the processes that can have a major effect on the grain structure such as the ramp up and ramp down times / speed along with the soak time and if it is taken to the lower transformation temperature or above. The best you could hope for now is to get some hardness readings done on the gears to see if they are in an acceptable range. The company that did the heat treatment should have supplied documentation on the treatment performed and the results with hardness readings within a predetermined range.

 

I received nothing regarding the process. all I did was shipped out the gears and a week Or 2 later they we're back at my house. the gears are now a golden color. is there anyway I can tell if they will be ok?

 

About the only thing you could do would be to take some harness readings at the edge of the gear face and on the back of the gear. The gear face should have localized hardening while the rest of the gear should have lower readings indicating a more ductile structure. You would need to know the ASTM material grade of the gears to know what the hardness range should be. There are some engineering books on the subject such as "Heat Treatment of Gears: A Practical Guide for Engineers" that has harness ranging ( Rockwell C) for the different materials. It is a pretty complicated process heat treating gears being that you are doing multiply treatments including localized to obtain different grain structures for increased hardness for the face of the gear and ductility and toughness for the rest. For all practical purposes it really is a crap shoot not knowing what they did.