1963GrayGray

Has any one drilled the bottom of their differential housing to drain the gear oil. Hopefully someone can provide a drawing or measurements so that I can drill and tap the rear housing on my C4 autocross car.
Thanks in advance.
Dave

Aardwolf

There have been a lot of threads on that in the C4 section. I have not put a drain plug in since I still have to use a pump to put new fluid in. Getting the old fluid out doesn't take long, then I swap the hoses around on the pump and put new fluid back.

jabrun

I drilled, tapped and installed drain plugs on two of my C4's. I drilled about 1/2 inch ahead of the parting line where the rear cover bolts on bottom dead center between the exhaust pipes. I believe I used a 1/4 pipe plug.

1963GrayGray

Thanks for the responses. This will help, as I can't seem to get enough of the lube oil out with a suction pump.

MAC95 6SPD

Take a wire coat hanger and put it inside a hose for the siphon pump. Bend it into a hook. The wire holds the hose in place and it will allow you to insert the hose into the bottom of the case. Even if you dont get every last drop out you will get enough out for a good change.
Mat