Transfer Case Bolts

[BC98]

Does anyone happen to know the length and thread pitch for the bolts to attach the transfer case to the transmission adapter? I've got a 1990 NP241C that I'm attaching to a 4L80E and I lost the original bolts & washers.

Thanks!

 

[kennyw]

Does anyone happen to know the length and thread pitch for the bolts to attach the transfer case to the transmission adapter? I've got a 1990 NP241C that I'm attaching to a 4L80E and I lost the original bolts & washers.

Thanks!

It is probably listed in the parts illustration manuals posted in the tech manual section.

 

[tarussell]

As best as I can tell from an ATS manual it should be (M10 X 1.5 × 30.0) but verify the length just in case the adapter flange thickness varies.

 

[BC98]

Forgot to update this before. I ended up picking up some new grade 8 hardware a from a local farm store after taking measurements.

I used 3/8”-16 x 1.5” bolts.

 

[tarussell]

Forgot to update this before. I ended up picking up some new grade 8 hardware a from a local farm store after taking measurements.

I used 3/8”-16 x 1.5” bolts.

That case is drilled for metric thread size and pitch - SAE is close but no cigar…

 

[BC98]

Would it be close enough that they thread in by hand?

 

[tarussell]

3/8” & 10mm ( .375 v/s .394 ) are very close in diameter and the thread pitch will allow threading but not correct contact for complete torque values securing the fastener's.
It may work for a while but I would not recommend trusting it - especially considering what is attached to those bolts.

 

[Wes Harden]

Normally 3/8 will eventually bind in a 10mm 1.5tpi hole, but it will wiggle a lot. If you got them in and the bolt is not wiggling they are probably correct. Try a tap of ea size in the t case hole. Just for piece of mind.

 

[kennyw]

M10 x1.5 x 35 LG Grade 10.9

 

[BC98]

Well, crap. It looks like I'll need to get some different fasteners....

 

[obijuank5]

Do yourself a favor and get studs. It’s much easier to install IMO.

 

[tarussell]

Do yourself a favor and get studs. It’s much easier to install IMO.

And better - two sets of threads sharing the tension loads.

 

[kennyw]

And better - two sets of threads sharing the tension loads.

Add to that the process of tightening the nut on a stud has a much lower risk of stripping than a bolt torqued in an aluminum tapped hole.

 

[obijuank5]

Look at y’all big brained guys

 

[BC98]

Weird update…

The transfer case is definitely threaded for 3/8-16 bolts. I picked up some M10x1.5 fasteners and they completely bound up after BARELY threading in. Double checked and all threads were clean.

I was not expecting that. At least I have some spare metric bolts that will get lost in my garage now!

 

[tarussell]

Weird update…

The transfer case is definitely threaded for 3/8-16 bolts. I picked up some M10x1.5 fasteners and they completely bound up after BARELY threading in. Double checked and all threads were clean.

I was not expecting that. At least I have some spare metric bolts that will get lost in my garage now!

T-case ? You were asking about the bolts that went through the adapter and threaded into the tail end of the transmission case - or did I miss something ?

Also, threads that have already had wrong pitch/size fasteners inserted and torqued/tightened will be compromised for any form of hand threading.

Note: Since the 4L80E came about being designed in the late eighties for a ‘91 model year introduction it was set with metric hardware from the start.

Just try’n to help keep ya’ all set and good with your hardware.