I scanned the post too quickly....
Drain plug
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,481
Likes: 2,190
From: Loveland
Drain plug
68 327/350 hp. 4 speed. Wanting to change the trans oil. I already tried to suck it out. Very hard to get it all out. The trany doesn't have a drain plug,,, DOH! What's the good, bad, and the ugly in tapping a new drain plug hole in the trans? I already orderd the 1/2 inch NPT plug, 1/2 inch NPT tap and 23/32 drill. I know it isn't "STOCK" but think it's a great upgrade
Last edited by kodpkd; Oct 29, 2019 at 02:23 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
No drain plugs in C3's (or any other GM car of that vintage). Drop the pan. Leave 2-3 bolts in loose, remove the others then tip the pan by backing off the bolt at one end. Allow most of the oil to drain off, then hold pan up in place and remove the other bolts.
Now, you can drill a hole in the pan and install a drain plug (assembly....NAPA about $8) so that future oil changes will be easier. Make sure you cut the hole in a place where the drain plug has clearance (on the inside).
Now, you can drill a hole in the pan and install a drain plug (assembly....NAPA about $8) so that future oil changes will be easier. Make sure you cut the hole in a place where the drain plug has clearance (on the inside).
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
You can also drill & tap just forward of the rear seal ... for a Zerk grease fitting serving tailshaft bushing ...
... an endurance race thing ... overkill if mostly street.
... an endurance race thing ... overkill if mostly street.
Is my vette stock?? HAHA
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From: Im not allowed to tell you
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Its eay if it's out of the car. Pull off the side cover. Stuff a rag in there to contain the aluminium filings. Drill the hole then run the tap in half way. If you tap it to the top of the tap then the plug will go in too far and possibly not seal. While you're in there pop out the round magnet that's glued to the bottom of the case. When I touched mine it fell out. If it pops loose while you're driving bad things happen.
Then make sure the new plug has a magnet built into it.
Easy peasy
Then make sure the new plug has a magnet built into it.
Easy peasy
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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If you look in the bottom of the case you can see the donut magnet
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Thread Starter
Le Mans Master
Joined: Jun 2019
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From: Loveland
I wish the trans was out of the car. Not going to happen. I'm going to leave the oil in the trans as I drill the hole. When the drill breaks through to the inside, the oil will carry the shavings out. I also plan to flush with clean oil. I figure a few aluminum shavings wont hurt the steel gears.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
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I wish the trans was out of the car. Not going to happen. I'm going to leave the oil in the trans as I drill the hole. When the drill breaks through to the inside, the oil will carry the shavings out. I also plan to flush with clean oil. I figure a few aluminum shavings wont hurt the steel gears.
Le Mans Master
Joined: Aug 2005
Posts: 6,541
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From: Temple Terrace Florida
If you wanted to be extra careful, you could add some thick grease to the flutes of the drill to catch any shavings. You could also do the same with the tap as it will cut the aluminum threads as well. Jerry
Le Mans Master
Joined: Aug 2017
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From: Cool Northern Michigan
I vote BAD IDEA. No one in the right mind would shove metal shavings through the fill hole, would they? But that's exactly what you want to do to make a drain hole.
Pump out as much fluid as you can with a vacuum pump. Refill, enjoy. Wait until the day comes that the tranny is on the work bench, disassembled, before drilling on it.
No magnet is going to help you here and a good fluid flush is only do-able with tranny laying on its side.
And if just one of the dozens of metal shavings or burrs works its way back to the tail-shaft seal, there WILL be another problem!
Just wait.
Pump out as much fluid as you can with a vacuum pump. Refill, enjoy. Wait until the day comes that the tranny is on the work bench, disassembled, before drilling on it.
No magnet is going to help you here and a good fluid flush is only do-able with tranny laying on its side.
And if just one of the dozens of metal shavings or burrs works its way back to the tail-shaft seal, there WILL be another problem!
Just wait.
Last edited by HeadsU.P.; Nov 1, 2019 at 08:36 AM.
Le Mans Master
Joined: Oct 2002
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From: Las Vegas - Just stop perpetuating myths please.
You got the trans type wrong also Ken - it's a manual and no pan.
Well I have to mention after decades of working in power plants yes, using the greased drill sometimes is the difference between a 1 hour job and removing a piece of equipment in the millions of dollars value. Now on an aluminum case using magnets won't help catch aluminum chips but it will if a steel case. Also a good flowing vacuum can be located where it is effective. Once the hole gets deep back out and clean then regrease and breakthrough on thin metal.
But I reads like the OP already has a liquid capable vacuum and it's a little work to pop the side cover much much less than removing the trans.
Just some alternative here.
Well I have to mention after decades of working in power plants yes, using the greased drill sometimes is the difference between a 1 hour job and removing a piece of equipment in the millions of dollars value. Now on an aluminum case using magnets won't help catch aluminum chips but it will if a steel case. Also a good flowing vacuum can be located where it is effective. Once the hole gets deep back out and clean then regrease and breakthrough on thin metal.
But I reads like the OP already has a liquid capable vacuum and it's a little work to pop the side cover much much less than removing the trans.
Just some alternative here.
Drifting
Joined: Dec 2017
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From: PA
I never did this on my vette, but I did do it on and old Delta 88 that was occasionally a little batty on it's shifting even after changing he filter. I disconnected the tranny fluid line going to the radiator, put a piece of rubber line on it and put the other end of the rubber line into a bucket. Then I started the car for a few seconds and shut it off. I checked the bucket to see how fast it was pumping fluid out to it. Based on that, I ran it for a few more seconds and there was a reasonable amount of fluid in the bucket. So I measured how much, added that amount of fresh fluid to the tranny, and repeated the process. After a few rounds the fluid coming out was pretty clean, so I buttoned it all up and quit for the day. Engine quit due to jumping timing (damned plastic coated metal timing gears) before the tranny gave up.
Obviously, make sure you when you pull the one of the two lines going into the radiator that you have the one sending fluid to the radiator as opposed to the one taking it from the radiator back to the tranny.
Obviously, make sure you when you pull the one of the two lines going into the radiator that you have the one sending fluid to the radiator as opposed to the one taking it from the radiator back to the tranny.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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The magnets are in the case for the metal gears........not drilling aluminum.
the grease is a good idea.
the grease is a good idea.
Race Director
Joined: Mar 2017
Posts: 11,949
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From: Virginia
Pull out what you can with the vacuum pump. I have one of these, and it's great on the differential, too.
OTC Oil Suction Gun
I also have a B&W 4-speed with a drain plug
. If you want to drill and tap a hole, I think you'd want to remove the side panel first, at which point you wouldn't need to drill and tap a hole.
OTC Oil Suction Gun
I also have a B&W 4-speed with a drain plug
. If you want to drill and tap a hole, I think you'd want to remove the side panel first, at which point you wouldn't need to drill and tap a hole.Last edited by Bikespace; Oct 30, 2019 at 06:08 PM.
Burning Brakes
Joined: Sep 2009
Posts: 1,124
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From: Western New York
If anyone uses the hand vacuum pump, as I do, I came up with a little trick to keep the fluid you suck up from running out the end of the hose and on the floor or down your arm and into your armpit. I bought a cheap brake bleeder hose that has the one way valve for one man operation. Seeing as it didn't work and I bought a Motive, I took the valve out of the hose and put it in the suction gun hose. Just make sure you have it in the right way. Works great.
Duane
Duane