Rumpity Rump

Sure would like to drain my own differential fluid . I once saw a picture of a drain plug that was put thru the undercarriage support and directly into the bottom of the Rear End housing. Im wondering how much distance there is from the housing to the internals of the Rear End ?? Has anyone done this ?

Thanks, RR

GTR1999

I've rebuilt a couple of C3's and drilled and tapped a drain in the housing, not the cover. I did this with the differential apart so chips weren't an issue. There was a Corvette article about drilling and tapping the bottom of the cover while still on the car a while back. I don't like this approach because you can't be certain chips don't get into the oil and then mixed in with the bearings. The shop in the article offered a "kit" to do this but all you need is the correct drill and pipe tap. If you don't have any other issues with the differential I'd leave it alone until you do. A suction gun will get most of the oil out for a change.
Gary

bence13_33

I agree. I could drill and tap the cover myself however, why take the chance of getting metal chips into your rear end? When it comes time to change the rear end oil I'll probably just get a syringe and some vacuum hose and start sucking it out of the rear end.

Dalannex

I agree. Stick with a suction gun until you have the diff apart. That's how I do mine.

-Justin

norvalwilhelm

I drilled and taped a hole in my rearend years ago. I did it when the rearend was apart. If you drilled one now and stayed towards the drivers side I think you would be fine. The crown gear is offset towards the passengers side. Even if you drilled and hit the crown gear you might scratch a gear tooth but take the chance.
As stated there is a possiblility of leaving metal chips behind but you could flush the case a few times with varsol. They drill oil pans and tap it for oil return lines on turbo's and superchargers and don't overly worry.
If you are like me I jack on my rearend so watch where you put the plug so it doesn't interfer.
|You only need a pipe tap, say 1/4 npt and a 7/16 th drill bit. Drill a smaller hole first then enlarge it with the 7/16 th drill. Any pipe plug will work.

Juliet

One thing to think about - if you're going to have your car judged by NCRS and the judges notice it, a drain plug will earn you a point deduction. :D ~Juliet