drilling the d44 for a drain plug
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,680
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From: NEwhere Ohio
drilling the d44 for a drain plug
I got a recommendation here to drill a hole in my d44 to drain the fluid.
I'm having a hard time stomaching this idea.
Where exactly do I drill the hole? I surely want to drill at its lowest spot, but where is that?
How do I keep the hole from leaking?
Also, how do I keep shavings from the drill from getting into the case...
The original plan was to stick a tube in thru the fill hole and pump/ suck out all the fluid......
I'm tempted to just do that.
Any advice
I'm having a hard time stomaching this idea.
Where exactly do I drill the hole? I surely want to drill at its lowest spot, but where is that?
How do I keep the hole from leaking?
Also, how do I keep shavings from the drill from getting into the case...
The original plan was to stick a tube in thru the fill hole and pump/ suck out all the fluid......
I'm tempted to just do that.
Any advice
Drifting
Joined: Aug 2010
Posts: 1,704
Likes: 8
here ya go,on the left of center bolt (driver side)
http://forums.corvetteforum.com/c4-t...4-pumpkin.html
http://forums.corvetteforum.com/c4-t...4-pumpkin.html
Last edited by tunedport85inject; Mar 12, 2013 at 08:01 AM.
Team Owner
Joined: Sep 2003
Posts: 25,394
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I got a recommendation here to drill a hole in my d44 to drain the fluid.
I'm having a hard time stomaching this idea.
Where exactly do I drill the hole? I surely want to drill at its lowest spot, but where is that?
How do I keep the hole from leaking?
Also, how do I keep shavings from the drill from getting into the case...
The original plan was to stick a tube in thru the fill hole and pump/ suck out all the fluid......
I'm tempted to just do that.
Any advice
I'm having a hard time stomaching this idea.
Where exactly do I drill the hole? I surely want to drill at its lowest spot, but where is that?
How do I keep the hole from leaking?
Also, how do I keep shavings from the drill from getting into the case...
The original plan was to stick a tube in thru the fill hole and pump/ suck out all the fluid......
I'm tempted to just do that.
Any advice
http://forums.corvetteforum.com/1566195484-post8.html
Le Mans Master
Joined: Oct 2007
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From: Akron Ohio
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Just to the left underneath the middle cover bolt, just like in the pictures, is where I put mine.
Drifting
Joined: Jul 2004
Posts: 1,356
Likes: 291
From: MA
I did this on mine as well. Same location as above picture.
Just a suggestion: do not run the tap all the way through the hole you are going to drill. I ran the tap about 3/4 into the drilled aluminum case. Then run some pipe sealer around the threads of the plug.
Mine has never leaked and it has been 5 years!
As far as the aluminum drill filings getting into the case, put wheel bearing or marine grease on the drill bit when drilling.
The run some gear lube (I used ATF as it is thinner and flows better) into the fill hole and let it drain out the new hole you just drilled. This will flush the remaining filings out of the case.
Just a suggestion: do not run the tap all the way through the hole you are going to drill. I ran the tap about 3/4 into the drilled aluminum case. Then run some pipe sealer around the threads of the plug.
Mine has never leaked and it has been 5 years!
As far as the aluminum drill filings getting into the case, put wheel bearing or marine grease on the drill bit when drilling.
The run some gear lube (I used ATF as it is thinner and flows better) into the fill hole and let it drain out the new hole you just drilled. This will flush the remaining filings out of the case.
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
The guys at Corvette Clinic in Florida have a kit for this upgrade complete with drill bit and template. Check it out:
84-96 Diff kit:
All necessary items are included drill bit and tap along with a drain plug, template and instructions. Template provided to insure accurate placement of drain. Stops are welded to drill bit and pipe tap to prevent internal differential damage. Differential fluid flows out as drilling is performed flushing out any chips that come loose.
We typically ship the same day payment is received. Send $59.50 money order or check (No Credit Cards) to:
• Corvette Clinic Inc
5224 West State Road 46 #336
Sanford, Fl 32771
84-96 Diff kit:
All necessary items are included drill bit and tap along with a drain plug, template and instructions. Template provided to insure accurate placement of drain. Stops are welded to drill bit and pipe tap to prevent internal differential damage. Differential fluid flows out as drilling is performed flushing out any chips that come loose.
We typically ship the same day payment is received. Send $59.50 money order or check (No Credit Cards) to:
• Corvette Clinic Inc
5224 West State Road 46 #336
Sanford, Fl 32771
Team Owner
Joined: Sep 2003
Posts: 25,394
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Generally a tapered pipe thread is used for this type of drain plug. There's not a machined surface already present to accommodate a gasket or o-ring. Could you? I'd suppose so but why?
An AN/JIC type plug generally has a gap from the last thread to the hex - are you suggesting to use the o-ring seal there?
Some actually use the center rear cover bolt as a drain and just drill from the inside to the back of the threaded bore. If you used this procedure I would think you could use a copper brake washer or something similar. You have a machined surface for it to seal against.
Last edited by WVZR-1; Mar 13, 2013 at 06:11 PM.
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From: Kingman AZ
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The Corvette Clinic is run by Chris Petris of former Eckler's fame and Corvette Fever, Corvette Enthusiast, Corvette Central fame. I think his shop moved to Tennessee though.
I was at a C4 class he put on and he talked about this procedure. He claims that as the gear oil flows out it takes any shavings with it.
I just wonder about all that stuff flowing down into the drill motor, down your arm etc. I guess you could suction most of the oil out before you did this so it would not be so bad.
I was at a C4 class he put on and he talked about this procedure. He claims that as the gear oil flows out it takes any shavings with it.
I just wonder about all that stuff flowing down into the drill motor, down your arm etc. I guess you could suction most of the oil out before you did this so it would not be so bad.
Team Owner
Joined: Aug 2005
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From: Riverside County Southern California
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The D44's right side is higher than the left.
On the D36 I did it on the right, but on mt D44 did it on the right. Why? I couldn't tell.
Melting Slicks
Joined: Sep 2010
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Ok now that is clear.. the other pic reference. Must have been the D36 & the case was even!!
I still prefer a -AN fitting and yes the O-ring goes on the machined shoulder. Use a counter sink to make the seal fit. I do not like pipe thread.
I still prefer a -AN fitting and yes the O-ring goes on the machined shoulder. Use a counter sink to make the seal fit. I do not like pipe thread.
Team Owner
Joined: Aug 2005
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From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
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An O-ring will work. I've done this trick on all three C4s. I use teflon tape and I have NEVER has a leak.
Slingshot
Joined: Dec 2001
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From: Charlotte NC
http://petrisenterprises.com/store/#...ry=0&id=373075
Melting Slicks
Joined: Jan 2009
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From: folsom california
if you are concerned with chips going upward into the differential case; remove the differential "cover" bolts, these are what mount the differential to the batwing; split the batwing from the differential, and all the fluid will drain out, plus now you can flush and clean everything from the differential casing.
when I did mine, it was in conjuncrtion with removing the batwing completely to allow installation of polyurethane bushings in the batwing mounting ears, so there was no issue at all regarding possible contaminants in the differential housing.
I drilled and tapped my differential for a 1/8th inch National Pipe plug; when these threads are sealed with teflon tape there is absolutely no chance of leakage.
one hint: use a pipe plug designed to accept an allen head wrench, a long allen wrench makes subsequent removal and installation of the plug much easier than trying to manuever an open end or crescent wrench between the bottom of the differential and the exhaust system.
when I did mine, it was in conjuncrtion with removing the batwing completely to allow installation of polyurethane bushings in the batwing mounting ears, so there was no issue at all regarding possible contaminants in the differential housing.
I drilled and tapped my differential for a 1/8th inch National Pipe plug; when these threads are sealed with teflon tape there is absolutely no chance of leakage.
one hint: use a pipe plug designed to accept an allen head wrench, a long allen wrench makes subsequent removal and installation of the plug much easier than trying to manuever an open end or crescent wrench between the bottom of the differential and the exhaust system.
Safety Car
Joined: Jun 2006
Posts: 3,629
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From: FL
here ya go,on the left of center bolt (driver side)
http://forums.corvetteforum.com/c4-t...4-pumpkin.html
http://forums.corvetteforum.com/c4-t...4-pumpkin.html
Team Owner
Joined: Dec 2000
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From: Phila., PA burbs
I'll mention a method I read about on here years ago that several members had tried, although I'm not sure I'd advocate it. They removed the bottom center, rear cover bolt and drilled an angled hole, through the bolt hole, into the cavity. They did it in such a manner that once drained, they would simply re-install the cover bolt. The drain hole was concealed inside the bolt hole. They claimed it worked without any problems or leakage, but I think I'd be a little leery. I tried finding the original thread, without success, although it was probably 10 years ago.