• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

Overdrive drain plug

Share this page

M

Member 10617

Guest
Guest
Offline
Well... here I go. Tomorow I'm going to change the gearbox/OD oil in my 58 TR3. I've changed the engine oil several times since getting this car, but this will be the first time for the gearbox/OD.

I have an "Overdrive Drain Plug Spanner from Original Duplicates," so I think I'm equipped. But the tool came with the following statement: "It is often very difficult to remove since it seizes in the aluminum case. This tool is designed to engage one of the (6) notches and provides proper leverage for safe removal and replacement."

I can't tell if this is a WARNING (the plug is difficult to remove) or REASSURANCE (this tool can do the job).

Before I dive into this -- or rather dive UNDER the car to do this -- can anyone give me some pointers or tips from experience on how to go about removing the plug.

I do know that I need to replace the fiber gasket (which I have) and apply antiseize compound to the threads. But first, I have to get the thing off without stripping or breaking anything. (Intereesting how "delicate" these robust cars can be.

Sounds to me like one of those situations that Dr. John is very familiar with: brass seizing in aluminum casing.
 
Sorry, Ed, neither The Blue TR3 nor the TR3 racecar has/had overdrive, so I'm not familiar with the plug. I am, however, all too familar with dissimilar metal corrosion, now called galvanic corrosion, though.

Just remember the Holy Trinity (as appropriate):

The Hammer (maybe not in this case)

The Torch (mmmm....)

And the Aero Kroil.

Or PB Blaster or equivalent. Aero Kroil has the right number of words and syllables, though.

Why does the tool engage only one of the 6 notches. Would think the more, the merrier.
 
It IS sitting right at the bottom of the OD, covered by oil. Odds are actually pretty fair that it won't be that hard to remove. Mine never has been -- though I have the hex-head version -- 36mm, I think -- which is way easier to crank on, if need be.
 
My M.O. for something like that is to clean the area thoroughly and then put your favorite penetrant on affected area and leave for a day to soak in. Try the tool after that. If it loosens, fine. If not, propane torch-heat,cool-heat, cool and try again. Bonne Chance

Jim
 
The OD has been in the car for about a year, so hopefully the plug is not too solidly attached. Moreover, it is a source of an oil seep, so something has been flowing around the plug for nine months.

Why change the oil now... so soon ... you might ask. Well, I want to substitute RedLine 90 for what's in there now and I want to learn how to do this myself. Then I'll leave it alone for 8000 to 12000 miles, except occasional topping off.

I don't know anything about the hex head version of the tool, but couldn't use it because my plug is not hex-shaped. The tool I have, as you probably know, is the one recommended by Moss, and was purchased through Moss. It is long-handled and is a substantial piece of work (thick and heavy), so I should get some good leverage, as the accompanying literature promises.

Has anyone out there used one of these tools?

I'll proceed cautiously....

Wish me luck.
 
FWIW, British Tool Company sells a tool that will engage all 6 notches.

I had to pull my drain plug the other day, and couldn't find the tool I made before, so I just made another one. Took less than 45 minutes (not counting the time I spent searching for the other one). Just a heavy bar of steel (sold as concrete form stakes @ Home Depot) and a couple of 5/16 bolts, filed & ground to 1/4" squares.

Not entirely satisfactory, there really isn't room to swing it under the car (looks like the Moss tool would have the same problem), but it got the job done. And it at least engages two notches instead of just one.
 
Just curious, has anyone tried using the early plug (with the hex) in place of the later plug? I think you'd have to make a button to support the filter screen, but otherwise it should work ? I've already got a socket for the hex version ...
 
Hi, Randall,

I like the British Tool Company tool a lot. Wish I had seen it before purchasing the Moss tool. I'll have to think about switching to this one.
 
LexTR3 said:
I don't know anything about the hex head version of the tool, but couldn't use it because my plug is not hex-shaped.
Click to expand...
FWIW, the hex head plug was original on the TR2-4. The notched plug that Ed has was used on the later model overdrives, as fitted to TR4A IRS and later.

They can be interchanged to some extent, but there are other changes required to match (eg filter screen). The later plugs also came with magnets that, AFAIK, were not originally used with the hex plugs. However, there is room for one or two magnet rings with the early plug.
 
Well... I bit the bullet and attacked the (notched) overdrive filter drain plug today. My fears that perhaps it would be difficult to remove were entirely unnecessary. The plug was so loose that I was able to remove it with my fingers! That explains why it has been leaking. (Give that guy a cigar!)

I will install a new fiber gasket, apply some antiseize, and replace the plug and tighten it "snug" and then fill the transmission with Red Line 90. Red Line has gotten great reviews from practically everyone in this Forum who has responded to my questions.

Then my routine will be to top off the trany every now and then, but not drain and refill for 8,000 miles. I know that the manual says 12,000, and some even say 15,000 miles (or more), but (a) since it is easy for me to do, and (b) the car sits idle several months of the winter, 8,000 miles won't hurt. There are even some sources that say it should be changed annually, but I suspect they are talking about these cars that are or were driven daily, and hard.

So for, so good.
 
TR3driver said:
FWIW, the hex head plug was original on the TR2-4. The notched plug that Ed has was used on the later model overdrives, as fitted to TR4A IRS and later.

They can be interchanged to some extent, but there are other changes required to match (eg filter screen). The later plugs also came with magnets that, AFAIK, were not originally used with the hex plugs. However, there is room for one or two magnet rings with the early plug.
Click to expand...

Just fyi, but I don't think the changeover occured at the TR4A. I suspect all TR4's had the notched plug (both mine did), and probably late TR3A's also.

For the overdrive I just went through on the 3A project I converted to the hex style. I didn't notice a difference in the filter screen, but one big difference is that it is attached via a screw and spacer to the lower nut that is part of the oil pump. I was able to fit a couple of those magnets in there for good measure.
 
TR4nut said:
Just fyi, but I don't think the changeover occured at the TR4A. I suspect all TR4's had the notched plug (both mine did), and probably late TR3A's also.
Click to expand...
Interesting. I was mostly going by the factory parts books, plus an old Moss catalog. Even the 4A parts book still shows the same part number for the plug, plus the bolt, spacer and washer that retains the screen with the hex plug.

Did you happen to notice, was the plug in the pump drilled and tapped for the bolt to hold the screen? If so, the big plug may have been changed at some point after the OD was manufactured.
 
TR3driver said:
Did you happen to notice, was the plug in the pump drilled and tapped for the bolt to hold the screen? If so, the big plug may have been changed at some point after the OD was manufactured.
Click to expand...

Both od's with the notched plug had pump plugs with no extra tapping to accomodate the older style. I picked up the earlier style from a donor Healey box which had all the little bits I needed, along with a 28% reduction sungear setup.

Thinking about it, I can't say late 3A's and all 4's had the notched style - my experience base starts around the CT30000 ish point, 1964, for what I own. I did pick up a TR3 box with the notch od setup, but that arguably could have been a hodgepodge of old and new parts.
 
Well, it certainly wouldn't be the first time that something changed and the factory neglected to note it. For example, the front cover on the gearbox definitely got shorter for the diaphragm clutch, but the P/N listed didn't change. And since the OD was made by Laycock, I'd guess the chances of undocumented changes would be even higher.

I didn't check the part numbers, but ISTR that the later screen has a larger grommet (hole) in the bottom, to fit over the post in the middle of the plug. I could be mistaken, though, it's been awhile.
 
TR3driver said:
I didn't check the part numbers, but ISTR that the later screen has a larger grommet (hole) in the bottom, to fit over the post in the middle of the plug. I could be mistaken, though, it's been awhile.
Click to expand...

That very well could be - when I compared the screens I was just worried about their overall size. The hex plug doesn't have that post so I think either screen might work provided the earlier style holding screw arrangement is wide enough.
 
Well, I'm going to have the parts in my hands in a few days, so I'll take a look. Apparently I've busted a thrust washer again.
 
My screen, a little basket-like affair, sits on a magnet ring that sits on top of the drain-plug. There is a small hole in the bottom of the screen that fits over a very shallow stud on the plug, but nothing holds the screen secure except whatever is above it when the plug is screwed in.
 
Randy and Randall,

Like Randy, the TR3 o/d transmission that I bought and originally installed in my TR4A also had the notched plug.

Scott
 
Back
Top