1978 931 steering clutch compartment bottom plug part # needed

Could the hole be 3/4" female pipe thread? Over 50 years ago while trying to clean up an oil soaked dry steering clutch on an early RD7 I seem to remember using a 3/4" short nipple and gate valve on the drain hole for multiple 'flushings' (unsuccessfully) using various solvents.

Daron

I tried that first, it is a strange size that 3/4" and 1" wouldn't fit or thread properly. Thank you for the suggestion.

Part number is 8M3837 for the magnetic plug and 6K5551 for the gasket.
size 1.12 - 12

Edit: just looked at your picture.
That part number is for the drain plugs with the raised casting ring around them (5- used).
Could be a 6S8224 plug (6-used in various places)
I'm checking the size
The 6S8224 plugs are 0.875 - 9

Thank you OM, the part # 8M-3837 was not the correct plug. It was too large and had a magnet for catching shavings. I have ordered 1B-5170 after calling Cat Specialty help center - hopefully this is the correct plug.

1B5170 seems big at 1.25 - 11nptf.
Just realized I typed 0.775 - 9 instead of the correct 0.875 - 9 for the 6S8224.

[quote="Old Magnet"]1B5170 seems big at 1.25 - 11nptf.
Just realized I typed 0.775 - 9 instead of the correct 0.875 - 9 for the 6S8224.[/quote]

I thought the same thing on the sizing. But a 1" tap goes in freely to the holes, so maybe the 1.25" is the correct size. I have a single 1B5170 ordered and will report back if it is the correct part when it arrives.

The good news is that we finished the rebuild on the transmission and have reinstalled the engine & transmission without an injury. The old girl starts up quickly and just purrs. All three forward gears and reverse are good and the steering clutches and brakes all work very well.

Now to take off the tracks and repair the seals on both track tensioners and try to remove the rusty bolts holding the track frames onto the cross members. One of the bolts was so rusted out I pulled it straight out with my bare hand on the front track frame.

[quote="Old Magnet"]1B5170 seems big at 1.25 - 11nptf.
Just realized I typed 0.775 - 9 instead of the correct 0.875 - 9 for the 6S8224.[/quote]

I thought the same thing on the sizing. But a 1" tap goes in freely to the holes, so maybe the 1.25" is the correct size. I have a single 1B5170 ordered and will report back if it is the correct part when it arrives.

The good news is that we finished the rebuild on the transmission and have reinstalled the engine & transmission without an injury. The old girl starts up quickly and just purrs. All three forward gears and reverse are good and the steering clutches and brakes all work very well.

Now to take off the tracks and repair the seals on both track tensioners and try to remove the rusty bolts holding the track frames onto the cross members. One of the bolts was so rusted out I pulled it straight out with my bare hand on the front track frame.

Hello All
I don't think those plugs are metric as OM stated. Unless Cat have some weird way of measuring metric then the format for metric is M12 x 1.0 for example which is a 12mm diameter bolt with a 1mm pitch which is measured from one point on the thread to the same point on the next thread whereas the way you have written those threads is simply the decimal conversion of standard imperial sizes as below
1.12 - 12 is 1-1/8" UNF
0.875 - 9 is 7/8" UNC

As far as I know there is no such thing as a metric pipe thread that is in common usage. Even the Germans use BSP. Australian plumbers call the BSP threads by the metric equivalent but they are BSP.

Regards

Phil

I stand corrected. Even though the 931's are all built in Japan the various plugs are not in metric. I was somewhat lead astray buy some internet info and the described difficulty in getting a correct size. Thanks for the correction.