Installing drain plug in differential

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Apr 16, 2005 | 09:54 PM

Engage

Thread Starter

Racer

Joined: Oct 2001

Posts: 474

Likes: 64

From: Portage La Prairie Manitoba

Installing drain plug in differential

Has anyone drilled into and installed a drain plug on an 81 aluminum
differential or would that weaken the casing too much?

Barry

Apr 17, 2005 | 12:49 AM

flynhi

Le Mans Master

Joined: Aug 2000

Posts: 6,273

Likes: 14

From: Austin TX

My ace mechanic (who builds Open Road Race cars) recommends against this. In normal use, diff fluid seldom needs replacing. A leaking drain plug can waste your diff very quickly.

Apr 17, 2005 | 01:10 AM

MIKER

Melting Slicks

Joined: Oct 1999

Posts: 2,581

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From: Tolar Texas

Quote:

Originally Posted by Barry

Has anyone drilled into and installed a drain plug on an 81 aluminum
differential or would that weaken the casing too much?

Barry

When I performed the rebuild/gear swap on my '80, I installed a 1/4-20 NPT brass drain plug. It hasn't leaked a drop. I have no idea whether or not the installation of this drain plug weakened the casing.

Apr 17, 2005 | 09:19 AM

Engage

Thread Starter

Racer

Joined: Oct 2001

Posts: 474

Likes: 64

From: Portage La Prairie Manitoba

Thanks guys... anyone else have this done?

Apr 17, 2005 | 09:28 AM

GTR1999

Tech Contributor

Joined: Aug 1999

Posts: 15,175

Likes: 3,989

From: Connecticut, USA

I do them all the time in the earlier iron housing without a problem. what I did on Muncie aluminum cases is to drill and tap a 1/4 npt hole and use a 1/4 x 1/8 npt brass bushing with a 1/4 npt plug. The bushing is sealed into the aluminum and you don't wear the threads out because you use the 1/4 plug for the drain. I first did this 25 years ago and there have been no problems with it. I wouldn't drill into the housing though until it was accessible to clean out the chips.

Gary

Apr 17, 2005 | 09:47 AM

Engage

Thread Starter

Racer

Joined: Oct 2001

Posts: 474

Likes: 64

From: Portage La Prairie Manitoba

I was thinking of drilling and tapping a 1/2 inch magnetic plug into it while the differential was in the car. The 81 is a real pita to get at.

Barry

Apr 17, 2005 | 10:03 AM

ram82fire

Burning Brakes

Joined: May 2001

Posts: 1,102

Likes: 0

From: spring city pa

I have installed a drain plug in my 82 alloy housing ,,,,,,,, no leaks or problems . Send me an email and will send pics & info if needed.

Geo

Apr 17, 2005 | 10:09 AM

Mike Mercury

Team Owner

Joined: Apr 2001

Posts: 54,204

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From: S.W. Ohio. . . . . . NRA Life Member

In the Feb 2003 Corvette Fever magazine there was an indepth article detailing how to add a diff drain plug.

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Apr 17, 2005 | 10:59 AM

Engage

Thread Starter

Racer

Joined: Oct 2001

Posts: 474

Likes: 64

From: Portage La Prairie Manitoba

Mike,
Could you post or email me a copy of it?

Thank you.... b.bugera@shaw.ca

Apr 17, 2005 | 11:01 AM

#10

spikezz4

Pro

Joined: Apr 2000

Posts: 625

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From: The Villages FL

Diff Drain Plug

The shop I'm with puts together a kit for exactly that purpose for C3's and C4's. When the daily maintenance shop was running, practically everything that came in went out with a drain plug installed, if the owner planned on being a regular. If you can not find the kit in one of the catalogs, email me and I'll see if they can send a kit out to you.

Spike
spikels6@thevillages.net

Apr 17, 2005 | 12:01 PM

#11

Engage

Thread Starter

Racer

Joined: Oct 2001

Posts: 474

Likes: 64

From: Portage La Prairie Manitoba

Thank you Spike

Apr 17, 2005 | 01:22 PM

#12

Mike Mercury

Team Owner

Joined: Apr 2001

Posts: 54,204

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From: S.W. Ohio. . . . . . NRA Life Member

Barry, I looked on their web site but couldn't find it online. I do have copies from the magazine though. I'll see about scanning the pages... or possibly snail-mail copies to you.