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want to drill and tap boss on np205

I can always once it's gutted take it to a machine shop and have it done to the size I need. I may not even need to empty the case for the them to do it. It will just be heavier.

Just need exact specs I venture
 
Might be cheaper, tap handles I was shopping for were $80-100+ pre COVID. Plus still need the tap and drill bit, probably @ $40 together

Don't cheap out on taps, get good ones. If you snap a tap it is total pita to get out.
 
TJ1978 said:
I can always once it's gutted take it to a machine shop and have it done to the size I need. I may not even need to empty the case for the them to do it. It will just be heavier.

Just need exact specs I venture
Click to expand...
Wes’s thread size is spot on for the holes in any of my drilled cases.

Ya’ might not want to take a partially assembled case to a shop and have it drilled - metal shavings everywhere and the guy doing the work is not gonna be happy about the added nut-sack drop factor. Bare case would be the way to do it.
 
Wes Harden said:
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
Click to expand...
When I take it the shop I ask them to drill this size hole and tap it to 17/32?

How deep all the way through or 1 1/4 deep? And how far apart the holes? How I get that measurement
 
No not all the way through. I think 3/4" deep is plenty. I am not sure how thick the casting is there. I will later this week. Mine is drilled and tapped and no torque rod yet. I need to fab my own.
 
As Paul mentions earlier in the thread…3-3/8 c/c for the holes. 5/8-11 thread size.
My old support rod has elongated holes

D99B5BBE-E9EB-4D7A-B680-F80D68A36ABF.jpeg
 
I would not do any drilling on your case until you have mocked up the torque bar to your tranny. Still if it were me I would be looking for another Np205 that has the holes.
 
TJ1978 said:
@Wes Harden @tarussell

To tap/drill etc?

www.homedepot.com

Drill America 5/8 in. - 11 High Speed Steel Tap and 17/32 in. x 1/2 in. Shank Drill Bit Set (2-Piece) POU5/8-11 - The Home Depot

Make fine bore holes and accomplish your nailing works effortlessly with the help of this exclusive Drill America Speed Steel Tap and Shank Drill Bit Set.
www.homedepot.com
Click to expand...
An industry standard ( they are variables and exceptions ) is 1-1/2 thread depth engagement of the diameter of the retaining hardware ;but you are working with a limited amount of material until you possibly make it a through hole instead of a blind one ( blind hole is what you want but I think there is enough material there to keep ya safe ).
You can mark off the proper dimension on your drill bit with tape as a guide to keep you from drilling to deep.
Also keep in mind that the tap you have there is not a bottom/finishing tap and the very bottom of your engagement will not have proper threads - but if you have enough hole depth to drill a little deeper than what thread depth is needed all will be well.

Keep in mind that a machinist shop can do this for most likely less money than acquiring another drilled case plus freight charges ( you had mentioned this in one of these post lately ).

Also don’t let this give ya’ a headache - if you are not wheeling hard where sudden high traction and plenty of frame flex is the plan than this bar is not a 100% necessary.
That being said I am a fan of these bars in any 4WD but on the average user most cases it wouldn’t matter if they were there or not. I think they are good insurance and effective but don’t be afraid of light wheeling without one.
 
I think the torque bars first appeared in 1978. In 1972 was the side braces. From 1973-1977 did GM have any transfer case brace?
 
My 77 was missing all the braces, and had the wrong type case transmission in it when I got it.
So many times lazy mechanics leave out important items just because it's inconvenient
 
wazzabie said:
I think the torque bars first appeared in 1978. In 1972 was the side braces. From 1973-1977 did GM have any transfer case brace?
Click to expand...
I think you are right about 78 possibly being the first year of the torque bar brace on some applications.

I did have a 74 K/20 with a side torque mount ( early Energy Suspension catalogs showed it was listed up to 75 but that doesn’t prove or disprove anything ).

The GM trucks I’ve worked on with iron T-cases go along with 69~75 having the side mounts and never saw any brace or mounts ( stick or auto ) from 76 & 77 and 78 the brace started showing up on auto trans trucks and stick trucks by 1980 but that seems to be hit and miss through the 80’s.

Also had a 77 K/10 350/465/205 with no brace and no drilled holes in the case.
Had a 83 GMC K-3500 Crew Cab 454/465/205 with the side brace and the lower bell housing to motor mount plate bars.
Parts trucks - a 79 K/30 Crew Cab 292/TH400/203 with a brace and bell bars ; and a 78 K/30 Cab Chassis Wrecker 292/465/205 with no brace , no bell bars and not drilled case .
Friends 78 K/5 350/TH350/203 no brace and not drilled.
Friends 78 K/10 400/TH350/203 with brace but no bell bars.
A 77 K/15 parts truck 400/TH350/203 no brace and not drilled.
Another 77 K/10 parts truck 350/465/205 no brace and not drilled.
And my current 83 K-30 454/TH400/205 has the brace and bell bars as well.
Used a shop truck a 78 K/20 292/456/205 no braces and not drilled.
Local fire support truck 81 K-30 350/TH400/205 had the brace and bell bars.
IIRC NVRENU’F’s old 91 V-3500 350/4L80E/205 had brace and bell bars.
John’s buddy with a 80 K/25 400/TH400/205 had the brace and bell bars.
Local body shop tow truck 81 K-30 454/465/205 had the brace and bell bars.
Knew a guy with an 88 V-3500 350/465/205 came with the brace and bell bars.
A friends 85 K-30 454/TH400/205 had brace and bell bars.

Never saw any mention in the books of the brace before 78 or anything about the side mounts after 74/75-ish.

Seems like the mid to late 70’s three pedaled trucks didn’t get the brace….anybody know for certain if they ever saw an original equipment brace on any 76 & 77 trucks or 78 & 79 465/205 trucks ?
 
@tarussell I bought a spare 4spd/205 assembly once, the tag on the 205 said ‘79 and it was not drilled on the side. I always thought it was strange that case wasn’t drilled but my ‘80 K10’s 205 is drilled (it’s in my Blazer).
 
nvrenuf said:
@tarussell I bought a spare 4spd/205 assembly once, the tag on the 205 said ‘79 and it was not drilled on the side. I always thought it was strange that case wasn’t drilled but my ‘80 K10’s 205 is drilled (it’s in my Blazer).
Click to expand...
What about that 84 K-30 Cab Chassis that ya’ got your first front D60 out of ?
 
tarussell said:
What about that 84 K-30 Cab Chassis that ya’ got your first front D60 out of ?
Click to expand...

I don’t remember. It was a 4spd/205 but I don’t even remember what happened to that combo.
 
nvrenuf said:
I don’t remember. It was a 4spd/205 but I don’t even remember what happened to that combo.
Click to expand...
Wasn’t that the one with the 10-spline coupler slap smooth worn out ?
That truck was worked real hard all it’s life!
 
On the 78 K5 that I own I know for a fact that it was built from the factory with a brace for the NP203-th350.

It is interesting that GM progressed thru three iterations (side frame brace->no brace->torque rod w/bell bars). Logic would be that the best design is what GM ended up with. I sure wish we had some context to why GM made these changes.
 
tarussell said:
An industry standard ( they are variables and exceptions ) is 1-1/2 thread depth engagement of the diameter of the retaining hardware ;but you are working with a limited amount of material until you possibly make it a through hole instead of a blind one ( blind hole is what you want but I think there is enough material there to keep ya safe ).
You can mark off the proper dimension on your drill bit with tape as a guide to keep you from drilling to deep.
Also keep in mind that the tap you have there is not a bottom/finishing tap and the very bottom of your engagement will not have proper threads - but if you have enough hole depth to drill a little deeper than what thread depth is needed all will be well.

Keep in mind that a machinist shop can do this for most likely less money than acquiring another drilled case plus freight charges ( you had mentioned this in one of these post lately ).

Also don’t let this give ya’ a headache - if you are not wheeling hard where sudden high traction and plenty of frame flex is the plan than this bar is not a 100% necessary.
That being said I am a fan of these bars in any 4WD but on the average user most cases it wouldn’t matter if they were there or not. I think they are good insurance and effective but don’t be afraid of light wheeling without one.
Click to expand...
I've seen a few posts where guys just drilled through and then use thread sealer on the bolts...

Im may just try and drill and tap it. If I mess up a shop can do it im sure. We'll see. Seems you can only really drill an inch or so anyway, wes was saying 3/4 bolt length.

Im pretty's sure on my 203 the bolt is longer than 3/4 length I may take one out and just verify.
 
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