Thread size on Transmission - Hydraulic pump drain cap ?

(quoted from post at 09:36:44 06/07/17) Does anybody know the thread size on the transmission - hydraulic pump drain plug . I have a few 8N's that have that plug on the transmission fill cap and I have a few with the twist on cap . The covers with the twist on caps have rusted so I am trying to find something with threads I could weld in place to use a screw on cap .

The OD of the threads are about 2" and my pitch gauge looked like a 13 teeth per inch thread . It is slightly bigger than the 1.9" threads on 1-1/2 pipe and smaller than 2" pipe .

Once I find the technical name I can search for a fitting to make work .

Thanks - Ken .

Click to expand...

(quoted from post at 09:16:27 06/07/17)

(quoted from post at 09:36:44 06/07/17) Does anybody know the thread size on the transmission - hydraulic pump drain plug . I have a few 8N's that have that plug on the transmission fill cap and I have a few with the twist on cap . The covers with the twist on caps have rusted so I am trying to find something with threads I could weld in place to use a screw on cap .

The OD of the threads are about 2" and my pitch gauge looked like a 13 teeth per inch thread . It is slightly bigger than the 1.9" threads on 1-1/2 pipe and smaller than 2" pipe .

Once I find the technical name I can search for a fitting to make work .

Thanks - Ken .

Click to expand...

The thread is 2-12 UN. For a rusted out twist-lock filler cap the easiest solution is a simple replacement cap. If the cover is rusted away I would suggest an ORB style port and plug. I have made quite a few of these. They could be welded on or fastened in place by removing the cover and using the locknut on the underside. You could also use a conventional bulkhead style hydraulic adapter of the appropriate size.

TOH

Click to expand...

(quoted from post at 12:16:56 06/07/17) I never cared much for that cap so about 10 years ago I changed it. The plug is a shortened 1 1/2" male pipe thread welded to a steel plate w/ hex head. I removed the top cover, enlarged the hole with a die grinder, cut a 3/4" piece off the end of a 1 1/2" black coupling , put it in and welded around it. Got a gasket on the plug too. Works great.

Click to expand...

(quoted from post at 12:19:29 06/07/17)

(quoted from post at 09:16:27 06/07/17)

(quoted from post at 09:36:44 06/07/17) Does anybody know the thread size on the transmission - hydraulic pump drain plug . I have a few 8N's that have that plug on the transmission fill cap and I have a few with the twist on cap . The covers with the twist on caps have rusted so I am trying to find something with threads I could weld in place to use a screw on cap .

The OD of the threads are about 2" and my pitch gauge looked like a 13 teeth per inch thread . It is slightly bigger than the 1.9" threads on 1-1/2 pipe and smaller than 2" pipe .

Once I find the technical name I can search for a fitting to make work .

Thanks - Ken .

Click to expand...

The thread is 2-12 UN. For a rusted out twist-lock filler cap the easiest solution is a simple replacement cap. If the cover is rusted away I would suggest an ORB style port and plug. I have made quite a few of these. They could be welded on or fastened in place by removing the cover and using the locknut on the underside. You could also use a conventional bulkhead style hydraulic adapter of the appropriate size.

TOH

Click to expand...

Thanks for the reply .

From comments on the board it is a common complaint that the top cover rusts and a good twist on cap will not fasten correctly . I was hoping to find a cheap steel fitting that could easily and cost effectively be tack welded underneath a slightly modified top cover so the later style screw on cap could be used and still look original .

From a quick search I did not find a 2-12 female thread fitting . I would say if the project gets to over $10 - 15 on a fitting it would not be worth repairing a damaged cover .

I'll look again this evening after work .

Thanks - Ken.

Click to expand...