C-1 Differential Drain Plug

[Daniel K.]

Stripped out the threads on this differential housing drain plug. 1/2-20 replacement will not work. What size will fix it?

Thanks & Happy Holidays,

Dan K.

[Richard P.]

Re: C-1 Differential Drain Plug

I had a similar problem on oil pan. Purchased oversized self tapping plugs at pep boys. Still holding 5 years later.

[Edward J.]

Re: C-1 Differential Drain Plug

Stripped out the threads on this differential housing drain plug. 1/2-20 replacement will not work. What size will fix it?

Thanks & Happy Holidays,

Dan K.

Dan, I am not sure if they make a heil coil that size, But maybe worth looking into. pretty sure there pipe threads. maybe a oversized oil drain plug as Rich says.

Dan, looked on line they do make a 1/2x20 threads heil coil kit, the tool warehouse sells a kit for about 36.00 and comes with everything you'll need.

[John F.]

Re: C-1 Differential Drain Plug

What is a heil coil kit??

[Robert S.]

Re: C-1 Differential Drain Plug

A typo. Should be heli-coil. Drill a larger hole, tap with the included tap, and screw in some stainless steel replacement threads in the 1/2 x 20 size you need. Reinstall your plug and live happily ever after.

[Mike M.]

Re: C-1 Differential Drain Plug

agree with heli-coil but would add that i'd be sure and use a good loctite -type sealer between the heli-coil and the rear axle housing and also coat the drain plug when installing it in the heli-coil

[Tom P.]

Re: C-1 Differential Drain Plug

Several of the above approaches will (or may) work. This is the FOR SURE way that I fixed it on the 60 axle housing that is in the 56.
Screwed in the drain plug, put a nut on the threads coming through the bottom, spot welded the nut in a few places, removed the drain plug and drilled a couple of holes in the nut to allow the oil to drain a little more.
Uh ya--------------------you gotta remove the axles/center section to do this one. DUH!

[Mike M.]

Re: C-1 Differential Drain Plug

tom: i've used your' welding a backup nut or nut plate" when repairing leaking sbc oil pans. i'd suggest you or anyone taking your approach to not spot weld the nut/plate but rather run a continuous 360 degree bead around the nut. that slippry oil may get by a spot welded nut/plate. regards and merry christmas,mike

[John F.]

Re: C-1 Differential Drain Plug

Mike, I think it is the gasket that makes the seal not the nut.

John

[Tom P.]

Re: C-1 Differential Drain Plug

Mike, I think it is the gasket that makes the seal not the nut.

John

Correct! But I didn't want to be the first to say that.

[Daniel K.]

Re: C-1 Differential Drain Plug

Thanks guys. I already have the pig in along with axles. I may look at a self-taping plug and see if that works. If not and if I don't like the 3.36 just installed, I'll go the welded nut route. Housing has seen some action too. 4.11 posi was a professional rebuild with no burn outs or power shifting or grabbing gears and only at 2k miles. Even when new, the differential would clunk when starting out and going around corners from a stop, but the corner thing is normal I've been told.

[Tom P.]

Re: C-1 Differential Drain Plug

It is not normal for a rearend (either posi or non-posi) to clunk from a dead stop. BUT, it is not uncommon for a posi rear to clunk, chatter, whatever, either when going around a corner, or after going around a corner and then returning to straight ahead as the clutch pack unloads--------------ESPECIALLY with the 57-62 style posi rears.