Advice on how to drill/tap output shaft(nissan)

sharksanddanger

sharksanddanger

Well-Known Member
Joined
Apr 18, 2005
Location
Reidsville
Well my friend has a SYE to go on the back off his t-case and they recommend using a cobalt bit, drilling a pilot hole, then drilling immediately to 27/64". I assumed we just step up a couple sizes here and there to get to the 27/64" size. Well the problem is the shaft is very HARD and it makes it quite difficult to cut into it with the bit and a lot of cutting oil. After we get it drilled we still need to tap it. Any suggestions on what to do with this, any machine shop in the area willing to tackle this for a small fee?
 
The output shaft is more than likely hardened on the outside. When I attempted to drill and tap an NP231 I ran into this.

What I ended up doing was taking a torch to it to "anneal" (not sure if that is the correct term) the metal then I was able to drill into and tap it much easier.
 
When I did my H&T we drilled a pilot hole... then just kept stepping it up until we were at the size we needed.. Took awhile and some sore arms (laying under the jeep).. but it worked and hasn't failed yet...
 
I thought of the torch idea but wasn't sure about it.

The problem with this one is we can't get the pilot hole started, the material is much harder than the jeeps that I have messed with in the past.
 
Use a new bit and more pressure. If you use a good bit, a hack and tap should only take a pilot hole then the final hole. I also wouldn't anneal the output shaft, or take a torch to it and the output seal.
 
grind the end of the shaft a little bit to get thru the hardened area then drill away
 
are you using a low-speed drill?
 
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