want to drill and tap boss on np205

[14-Bolt]

Need to know how far apart the holes are, know there 5/8". But dont know distance apart center to center. Not using bracket now, bit have all guts torn out and want to tap now for possible future use. Pic from pirate.

This is mine

 

[76zimmer]

not following you here, if you have it torn apart, can't you measure the c/c distance, and why is that important if you are going to tap them?
I'd think they are already tapped.

 

[ryoken]

3 3/8" center to center on my case...

 

[4X4HIGH]

Not all 205's have the holes in the case already. He needs to know the spacing and how deep to drill and tap the holes.

 

[JDNobodi]

Not all 205's have the holes in the case already. He needs to know the spacing and how deep to drill and tap the holes.

True. I think it is something GM did in the mid 70's with the manual 4 speeds.
My 73 with a 4 speed came with frame bracket, but my brother's 77 with a 4 speed didn't and the holes on the side 205 weren't drilled and taped.

 

[ryoken]

my 77 4 spd 205 has em...

 

[76zimmer]

just got schooled, both my 205's have em, both used the strut rod to the bellhousing.

 

[14-Bolt]

Came from a 82 chevy, with syncromesh junk. The pic I got from pirate for example. On mine theres just a boss there, wouldn't be asking if the holes were already there, most late model cases didnt have them cuz they didnt run torque brace. If I want to buy something pre-fabbed in future it would be nice to have the correct hole spacing. Thanks for info

Yesterdays fun, es nice.

 

[blazinzuk]

Cool. My 86 has them it was behind a 4 speed, guess I am lucky

 

[mtnman]

my 77 4 spd 205 has em...

My 77 4spd 205 DOESN'T......

 

[ryoken]

I'm assuming it is a very random thing..... depending on if/what was being installed...

so some of these where used for the torque rods, and some for a frame mount, and some not at all? wonder what GM's policy was...

 

[mtnman]

wonder what GM's policy was...

Assuming they had one....

 

[14-Bolt]

noticed they machined off the boss on the inside during manufacture, does anyone else have this inside of case, shallow tapped holes? or are they deep and go all the way down into the inside boss. Think I'm going to say hell with it and drill and tap through case so I have nice deep threads.

 

[14-Bolt]

Latest, through hole tap where inside boss was machined off from factory. Blind tapped other hole.

 

[4X4HIGH]

Now don't forget to put sealer on the bolt that goes into the case otherwise you'll end up with a potential leak.

 

[TJ1978]

Bump for reference as I have to do his to mine. Still not clear what size hole he drilled or what size tap was used also the space apart the holes are...

Any help with exact info I'm after would help tremendously

 

[Bent77]

@ryoken said 3.375” on center

I’d bet someone has a case loose to check the threads

 

[TJ1978]

..

 

[Wes Harden]

5/8" x 11 tpi. Tap you by will determine the drill size. Am not home so can't go to shop and look. It is going to be 17/32" guessing

 

[Wes Harden]

Tapping threads this size needs a big tap handle. Bigger than most tap and die sets come with. I had to use a handle at work do some 18mm bolt threads. Then I decided I needed one in my tool set, haven't found any I'm willing to pay for. Might have to revisit this since I retired