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TR2/3/3A TR3A overdrive question

Dick Burk

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I have a '59 TR3A with overdrive. The overdrive operates fine. In attached picture you see two electrical connections on the top of the transmission shell. One is the switch which activates the electric overdrive. I have no idea what the other is. A relay switch? Only one of the leads is attached to an electrical line. My TR show manual does not show more than one switch for an overdrive. Any ideas?
 

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My rebuilder wanted to be sure I understood...

s9ppvLd.jpg
 
The OD unit I have does not have the switch for OD in 2nd rebuilder thinks it is not wise to use, I am tending to agree but I've never had an OD found the rebuilt one and jumped on buying it. How often is the OD used in second anyway?

Second question is how do TR3 owners check transmission oil level and re fill the transmission if you've done the conversion? The TR3 had a nice access hole and dip stick the TR 4 OD unit fills on the opposite side and it seems like an awkward situation if you are doing the routine maintenance tasks. How do you deal with this situation?
 
I don't use 2nd OD every day certainly; but it does come in handy on occasion for things like driving hard on twisty mountain roads, or maximizing acceleration in a straight line. Sure, using the overdrive means it will wear out quicker; but that's true of the whole car. If you are looking to minimize your driving costs, I'm afraid you've got the wrong car. It's not about miles per gallon, it's about smiles per mile. The only problem I've had that I directly attribute to 2nd OD is that a previous rebuilder either didn't check the pressure or didn't get it high enough. But he never said he did it on purpose, just "Ok, bring it back and I'll fix it."

What I did was to transplant the shift rails and forks into my original top cover, so I could keep the dipstick. Others have drilled out the later casting for the dipstick.

But, you need to get under the car for routine maintenance anyway; so it's not that much more hassle to jack up and support both ends (to get it roughly level) and check the gearbox oil through the port on the side. Then you can grease the front suspension and check the rear axle oil (etc) all without having to move the car again. I try to go through all that at least once a year (or about 12,000 miles for me), but it doesn't always get done on time.

BTW, HF has their 6 ton jack stands priced at only $40/pair at the moment. Their 3 ton stands ($24/pair) will certainly do the job, but sometime I need the extra height.
 
I use 2nd od when I am trying to hold a certain speed and 1st is to high,3rd would lug.This is usually on some backroads along the area rivers scenic cruises.No way as necessary as 4od but I do use it.
I have tr3b od and had the earlier dipstick top fitted,then matched the dipstick to the level that the fill plug allowed.
Its nice to be able to fill from top while checking dipstick especially if you just want to check between change intervals but not necessary as I can pull and replace the fill(left side) and drain plugs without jacking up the car.
Tom
 
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