TR2/3/3A TR3 Transmission oil

[Penni]

Where do I look for the transmission oil stick?
I see the regular oil stick.
Thanks, Penni

 

[TR3driver]

Assuming your car is early enough to have a dipstick for the transmission, there should be a large rubber plug in the transmission tunnel (inside the car) roughly at the same level as the handbrake grip and 8-10 inches forward of it. The dipstick is under that plug.

However for cars after TS50000 (or earlier cars with a later gearbox installed), there is no dipstick. Instead there is a fill plug on the side of the gearbox (under the car) and you simply fill until oil runs back out of the hole.

Sorry I don't have a decent photo handy, maybe someone else does. But there is a photo in Practical Hints if you have the edition appropriate to your car.

 

[Geo Hahn]

Here is where that hole is that has the rubber plug on pre-TS50000 cars:

No need to remove lots of carpet, usually I just peel back the front end passenger's side of the tunnel carpet enough to get at the plug. The dipstick is a tight friction fit in the hole in the top of the gearbox so you may need to twist it a bit as you pull up.

If yours is a later (post-50000) then, as noted, you'll be under the car checking the level at the fill plug shown here:

You will probably need to stick something in there to see if the oil is up to the bottom lip of the hole -- a bent length of wire may work though the oil usually stays pretty clean and may be hard to see.

If as original, that fill plug is 7/16" square head (same as engine oil pan) and best removed with an 8-point socket or a purpose-made tool for that size plug.

 

[TR3driver]

Thanks, Geo.

Note that the gearbox shown above is a TR4-onwards 4-synchro unit with overdrive, which looks somewhat different than a TR3A 3-synchro. IIRC the plug is slightly farther back on the 3-synchro box (but still in the same general location) and doesn't have that rounded bulge next to it.

Good tip about the 8-point socket! I can't count how many of those plugs I have seen mangled by folks trying to use first an open end wrench, and then usually Vice-Grips (which mess it up even further). Sears or any decent tool store should have the 7/16" 8-point socket (which is also useful for the drain plug).

 

[Member 10617]

Sore subject with me... I had no idea that I would lose the dipstick when my transmission was "upgraded" to an overdrive. Not only that, but filling the transmission also used to be through the dipstick hole! a very simple and logical procedure. Now it's under the car.

The procedure for checking the transmission level without the dipstick, though relatively simple, is tedious, especially if you don't have a lift for the car:

1. Jack up the side of the car where the transmission fill hole is located.

2. Crawl under the car and take the plug out (be sure to use jack stands!).

3. Pump some transmission oil in the hole.

4. Position a pan under the transmission fill hole.

5. Remove the jack stands. Lower the car. If you have put sufficient oil in, any excess oil will come out the hole when you lower the car until the transmission oil level reaches the proper level. If not, you have to go through the procedure again. Remember that the car will be at an angle when one side is jacked up, so putting a stick or something in the hole is not going to give you an accurate reading.

6. Raise the car again. Replace the jack stands(!)

7. Crawl under the car. Replace the plug, clean up, remove the jack stands, and lower the car again.

8. Finished. Fortunately, if you don't have a major leaking problem, you don't have to do this very often.

9. The same procedure applies when you drain the transmission and the OD: up, down, up, down.


Some will recommend that you drill a new dipstick hole.

 

[titanic]

I missed the convenience of the dipstick when I got a TR6. I was inspired to cut an access hole opposite the fill plug so trans oil level could be checked without jacking up the car. You might also consider get a hex head plug (3/8"npt) to replace the square headed one. The opening can be cut to accommendate a rubber plug like the one use for the jack opening in the floor pan. Another alternative might be to use the top cover from the earlier trans., but I am not sure if it would fit.
Berry

 

[Perrymip]

Alternatively, if you do have a garden variety leaking issue, you'll train yourself in a short time to reach under, lying beside the car, remove the plug, fill using an oil can with a flexible extension, then clean up the spillage after it fills and begins to flow down your arm.

 

[TR3driver]

Another alternative might be to use the top cover from the earlier trans., but I am not sure if it would fit.

It can be done, but you have to disassemble both top covers and swap the 1/2 and reverse rails & shift forks from the TR6 cover to the TR3 cover. Here's a shot of mine, where you can just see the dipstick head sticking up between the two OD switches.

Probably easier to drill the TR6 cover for the dipstick, but I'm not certain offhand if all of them still have that part of the casting.

FWIW, I prefer hex socket plugs (rather than hex head), and I use a magnetic version for the drain plug. Both are available from McMaster-Carr or any good plumbing supply house.

 

[titanic]

Randall-Good point, I didn't consider swapping the rails&forks. AFIK, the boss for the dipstick remained to the end of production. Probably because the same casting was used. I thought about trying to use the dipstick on the TR6, but decided there wasn't enough room under the dash and too much other stuff in the way.
Berry

 

[CJD]

My tranny cover has a plug on the left that lines up with the fill plug...do not all covers have that?

John

 

[Crankshaft]

No. I did as titanic. I used the original plug and bought an eight point socket at sears.

Crank

 

[Geo Hahn]

My tranny cover has a plug on the left that lines up with the fill plug...do not all covers have that?...

Nope. some thoughtful PO did that for you. On my TR4 I added a hold for the fill + one to service the OD solenoid:

 

[Don Elliott]

I know a TR4 owner who put a gearbox + overdrive in it which had come from a TR 250. He saw the dip-stick on my 1958 TR3A and drilled through the boss on top of the gear stick assembly and fabbed a dip stick like mine.

On a late TR3a I restored, I put a rubber floor plug for access to filling the oil as shown in the photo above.

On my TR3A I also added a hole and rubber plugs for easier access to the overdrive solenoid.

 

[CJD]

My tranny cover has a plug on the left that lines up with the fill plug...do not all covers have that?...

Nope. some thoughtful PO did that for you. On my TR4 I added a hold for the fill + one to service the OD solenoid:

I assure you it's from the factory...unless the PO found a way to stamp it cleanly and then repaint the entire cover with the original color paint, both under and over the hole, and without getting overspray on tranny or frame! Plus I see the rubber plug listed in the moss catalogue.

John