Differential grease????

[Craig -1965]

Hello Guys,

I've been thinking of replacing the differential grease, but noticed there is only a add hole but NO "drain" hole. I checked my Corvette shop manual and they have no comment. The vet is 41 years old and to my knowlege this could be the original stuff from the factory. Now I'm a mechanical engineer and designing a differential with only a fill hole and no drain seems like a oxy moron. I intend to replace the old grease, so do I suck it out or is there something I'm missing????????

[jims427400]

Craig,
you guessed rite.. just us something to suck it out..
I used a large syringe that I got from a hospital and attached a short section of tubing.
You could use one of those drill powered pumps for changing oil through a dip stick.. just a thought..
Good luck.. Jim

[JimVette]

When I had my '66 I changed the fluid a couple of times in the 20 years I owned it. Remember to add the additive. The original additive was produced from whale oil and it worked fine. When they changed to something else (save the whales) it took two bottles of GM additive to work for me. This was of course for a positraction rear end.

[Craig -1965]

Thanks guys, that big sucking sound that you here is the differencial grease being extracted. Good point about the additive, the posi will not last should the magic stuff not be used.

[MARGUGLP]

Doesn't the rear have a housing cover?

Originally Posted by Craig -1965

Hello Guys,

I've been thinking of replacing the differential grease, but noticed there is only a add hole but NO "drain" hole. I checked my Corvette shop manual and they have no comment. The vet is 41 years old and to my knowlege this could be the original stuff from the factory. Now I'm a mechanical engineer and designing a differential with only a fill hole and no drain seems like a oxy moron. I intend to replace the old grease, so do I suck it out or is there something I'm missing????????

[JimVette]

Yes it does. But in order to remove it you have to remove the spring.

[LVMYVT76]

there was an article in corvette fever showing how to add a drain plug to the c-3s. Don't know if that would work on your diff or not.

[Craig -1965]

I will Add a drain hole should the day come the differential requires removal. Do you happen to know the month or issue the of the drain hole article?

[LVMYVT76]

I'd have to look, it seems it was this year, but time goes by so fast now.

[jims427400]

Craig,
Corvette central has a drain plug kit listed in their C3 catalog..part#582267..$64.95..I think it should work on a C2..
Someone else will know for sure.. Good luck.

Jim

[jims427400]

I also rebuilt my differential last winter,added a fiberglass spring(i recommend that)and new SS emergency brake cable set, and added a heavy duty differential cover.. but didnt think of your idea of a drain hole..oh well,maybe in a couple years when its time to change again..

[Craig -1965]

Thanks again guys, there is some good information here and by all means "Have a great Thanksgiving"!!!!!!!!!!!!