TR2/3/3A Gearbox/OD oil

[BobbyO]

The shop manual suggest 30W oil for the gearbox w/overdrive in the UK and 50W overseas at temps above 70 degrees. After checking past post I see people using Redline MT-90 and GL4 which states it's a gear oil similar to 5W40/10W40 viscosity engine oil. Some time ago I replaced the oil in the gearbox using 30W engine oil but did not check the OD operation until yesterday and it did not work. It did work prior to the oil change but I'm not sure how long prior the change. Could the oil be causing the problem or should I look elsewhere? Checked gearbox oil level a few days ago and it was correct. Actually, my first inclination is to check electrical connections. Any suggestions?

 

[M_Pied_Lourd]

Check elsewhere. 30W non detergent won't be your issue.

Cheers
Tush

 

[TR3driver]

No, can't blame the oil for that one. I would definitely start with the electrical stuff.

Triumph did actually change their recommendation for oil to GL4 somewhere around 1958-1960.


Doesn't make much (if any) difference to OD operation; but helps the countershaft bearings last longer in the main gearbox. The MT-90 again doesn't make much difference to the OD, but improves shifting in the main box.

The overdrive has a pressure regulation system built into it, so it's pressure and operation are relatively unaffected by the viscosity of the oil.

PS, there are several other changes that only showed up in "Practical Hints" (basically the owner's manual). It was revised at least 5 different times with additional or corrected information. I strongly suggest that you get a copy, and check it first. Here's a PDF, or you can buy a paper reprint from the usual suspects.
https://drive.google.com/open?id=0B2H2NJt34OffNjQ4MTkyNjItZTVmYi00M2U2LWJhYWUtMjEyZDgxMzUyNzUw

 

[TFB]

The shop manual suggest 30W oil for the gearbox w/overdrive in the UK and 50W overseas at temps above 70 degrees. After checking past post I see people using Redline MT-90 and GL4 which states it's a gear oil similar to 5W40/10W40 viscosity engine oil. Some time ago I replaced the oil in the gearbox using 30W engine oil but did not check the OD operation until yesterday and it did not work. It did work prior to the oil change but I'm not sure how long prior the change. Could the oil be causing the problem or should I look elsewhere? Checked gearbox oil level a few days ago and it was correct. Actually, my first inclination is to check electrical connections. Any suggestions?

My first check would be sit in car ign on engine off,gearshift in 2,3or 4 and toggle od switch.You should hear the relay click and putting your ear down under the rocker hear the solenoid pull in.If that checks out mechanical adjustments need to be checked.My only issue so far has been the adjustable lever slipping on the shaft.

Tom

 

[Geo Hahn]

I used 30wt for years before switch to redline. So yeah, not an oil issue.

...Actually, my first inclination is to check electrical connections...

Mine too. For years I shied away from having an OD because of the number of threads that appeared about problems with them. Then I started reading the threads and it was mostly the electrics that were causing the problems. Well d'oh -- that was when I decided to wait no longer.

 

[BobbyO]

Chased some electrics today and confirmed the on/off switch is good and there is power to the relay although the wire colors are not per diagrams. Doesn't surprise me. Have power to what I think is W1 and W2 and through the switch. Also power to what must be C1 but relay does not click. Didn't go from on/off switch to ground, bypassing the transmission interlock switches. Guess that would tell me if the relay is any good and point to the interlock switches as bad. Correct? Any other ideas?

 

[DavidApp]

The overdrive solenoid has 2 coils. 1 to pull it in and the second to hold it in. So if you have continuity through the solenoid it could be just hold in coil that is carrying the load. Not sure if you can open the solenoid to check the internal switch.

David

 

[DavidApp]

You may already have this link.

https://www.buckeyetriumphs.org/technical/AOD/AOD1/AOD1.htm

 

[TR3driver]

Chased some electrics today and confirmed the on/off switch is good and there is power to the relay although the wire colors are not per diagrams. Doesn't surprise me. Have power to what I think is W1 and W2

There are (at least) two different ways to wire the OD relay. The way shown in the AAW diagrams and the workshop manual is NOT the way the factory wired TS39781LO; nor the way shown in Practical Hints. You may need to do some research to find out just how your car is wired. This diagram is close to what I found on TS39781LO (with factory overdrive), except it doesn't show the 2nd isolator switch.


Put the gearbox in 2nd, 3rd or 4th, turn on the ignition and the dash switch; then either W1 or W2 should be grounded. If not, you've got a problem with one of the switches or the wiring to them. Try the other gears while you're at it. (There are only two isolator switches, but it's marginally possible for the 3-4 switch to work in one gear and not in the other. Mine became intermittent in 4th gear but almost always worked in 3rd.)

If there is 12v across W1 and W2 (one is ground and the other not), but C1 and C2 are different, then the relay is bad. If you have 12v on both C1 and C2, then it's probably the solenoid, or some mechanical problem. Time to pull the cover for further investigation.

 

[BobbyO]

Investigated some more today but, still no luck. The terminals on this relay are not marked so I don't know which are which. And it's not like any relays drawn (or pictured). Viewed from the bottom, there are two spades at one end, another about 3/4th of the way up and slightly to the side with the last being in the middle at the other end. So nothing really lines up. With everything in the ON position and all wires connected, one of the bottom spades has a brown wire and reads 11.86v. The other one has a white (could be very faded yellow) wire and 0v. Checked and its not ground. The middle one has a yellow wire and reads 11.86v while the one at the other end has a yellow w/green stripe wire and reads 12.25v. The relay does not click but if I remove the wire from the 12.25v connection and ground it, the relay clicks. Really don't know where to go from here. All suggestions will be greatly appreciated.

 

[TR3driver]

Any chance of a photo? Maybe check the voltages at the two wires to the dash switch? (Come to think of it, did you try with that switch in both positions? The original configuration has "on" = "down", but mine has been installed upside down for so many years that I leave it that way.)

My only other suggestion is to start tracing wires, find out where they go. One way to get more information would be to check at the relay with the various switches turned off.

 

[glemon]

When I rebuilt the gearbox in my Healey the O/D did not work after, the guy who did the rebuild, a semi-retired foreign car mechanic who has been working on thesecars since MGAs and TR3s were new, suggested I jack the car up as high as possible in front and top up the oil a bit. It worked. May or may not be your problem, but easy enough to try.

 

[Got_All_4]

glemon may have something there. I purchased a Jtype over drive tranny that was rebuilt by a hack. He used RTV silicone everywhere and a lot between the main case and the adapter case. So much that the inlet hole below the mail bearing that lets the oil travel to the overdrive unit was plugged. If something like that occurred to yours oil may not be getting to the OD unit so it can't build pressure to engage the unit.
If you recall how much oil you installed in your tranny and compare that to what the manual capacity says for a OD tranny that would tell you your low on oil and raising the car may work. By raising the car you would essentially be raising the oil level in the tranny and over filling the case and letting the oil run into the OD unit through the rear main bearing filling the OD. However you would never know if it's at the correct level and also the OD unit would never get any oil circulation because of the plugged hole.