Proper servicing of overdrive

[Member 10617]

Since I acquired my 58TR3 about a year ago, I have changed the transmission fluid myself. No problem.

But recently I had overdrive added to the car, and that has changed everything. Not only is the transmission fill hole in a different place, but -- as you know -- there is an overdrive drain to deal with.

Next time I drain the transmission to add new fluid, I assume I will also need to drain the overdrive (and, as I understand it, check a screen at the drain for any clogging).

Do you have some tips you can give me on how to do all of this properly? Once I have it down, I should be good to go, but this will be another first for me.

 

[Geo Hahn]

One additional thing about that big plug... I think you'll find a stack of magnetic rings in there to capture any iron bits.

Indeed, replacing the regular drain plug with a magnetic one is also a good idea IMO though I thought the magnet in the one I got from a well-known vendor was pretty wimpy so I removed their magnet and JBWelded a molybdenum magnet in its place.

Perhaps I am paranoid about metal migrating in the gearbox as a friend had his TR3A gearbox grenade at speed when a (apparently long-ago) broken tooth found its way into a bad place.

The fill hole is, of course, a function of what top cover you have. You could use your old top cover on the 'new' gearbox but that would necessitate driling & tapping for the cut-out switches. Some (okay me) cut a hole in the gearbox tunnel to allow easy access to that fill plug on the side of the box.

I suppose the other question is what lube to put in it -- lots of prior dicussions are in the archives with no one clear choice emerging.

 

[Member 10617]

The old fill hole has been replaced by electronics for the overdrive, so filling and draining of the transmission for me is now through a hole in the side of the transmission case itself. The drain hole is beneath, and further down, of course is the overdrive drain.

What I am wondering is pretty basic:

(1) Do I drain the overdrive each time I drain the transmission? (Although I realize that the lubricant for the transmission also serves the overdrive).

(2) Is there any trick to draining the overdrive and accessing the screens?

George: I agree with you about a magnetic drain plug, and will add one the next time I change the lubricant. Also the same for my engine sump.

 

[simpson]

Ed, On the A type OD the screen sits atop the big drain plug ontop of the 3 plastic like magnet washers, so it will just drop out when you undo the plug.

 

[TR4nut]

If you have an early A-type, which has a plug with a hex nut design for removal you may not have the magnets. Also, the filter cage is screwed into the overdrive in that case as opposed to the later style where it will just fall out.

 

[angelfj1]

The old fill hole has been replaced by electronics for the overdrive, so filling and draining of the transmission for me is now through a hole in the side of the transmission case itself. The drain hole is beneath, and further down, of course is the overdrive drain.

What I am wondering is pretty basic:

(1) Do I drain the overdrive each time I drain the transmission? (Although I realize that the lubricant for the transmission also serves the overdrive).
<span style="color: #FF0000">
<span style="font-style: italic">There really isn't a reason to 'regularly" drain and refill the gearbox/OD. Checking the level and topping up is the normal routine.</span></span>

(2) Is there any trick to draining the overdrive and accessing the screens?

<span style="color: #FF0000"><span style="font-style: italic">Trick? No, there's no trick. To completely drain a TR gearbox equipped with a 'A'-Type OD, you need to open both drains, the gearbox drain and the large OD drain.
</span>
</span>George: I agree with you about a magnetic drain plug, and will add one the next time I change the lubricant. Also the same for my engine sump.

 

[TR3driver]

The old fill hole has been replaced by electronics for the overdrive, so filling and draining of the transmission for me is now through a hole in the side of the transmission case itself.

Actually, I think you'll find that you now have a later model gearbox, and that the place where the dipstick was is just a blank, smooth casting. The switches for the OD go somewhat over to the left of the dipstick hole.

It is quite possible to have both, in fact if you look carefully at this photo, you can see the head of the dipstick over beyond the OD switches
https://s258.photobucket.com/albums/hh260/TR3driver/TS13571L/?action=view&current=DSCF0023.jpg

<div class="ubbcode-block"><div class="ubbcode-header">Quote:](1) Do I drain the overdrive each time I drain the transmission?[/QUOTE]
I do.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:](2) Is there any trick to draining the overdrive and accessing the screens?[/QUOTE]I think the others have pretty well covered this. If you have the early setup, there is a big socket required to remove the plug, and as noted, a screw that you remove in order to remove the screen. That setup did not originally have the magnetic washers, but there is room to add just one or two of them between the plug and the screen.

The later setup has the notches in the outer edge of the OD plug, and it's best to find or make a tool that will engage at least two of the notches at once. Lots of folks just use a punch & hammer on one of the notches, which works sorta maybe, but has very good odds of distorting the plug until it will not seal properly. My "tool" is a length of flat iron from Home Depot, with a couple of strategically located bolts that have been ground smooth. But I've been kind of keeping my eyes open for a large socket that I could cut to fit all 6 notches at the same time.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]George: I agree with you about a magnetic drain plug, and will add one the next time I change the lubricant. Also the same for my engine sump. [/QUOTE]
Good for you. FWIW, I prefer the "hex socket" magentic plugs, which are readily available from MMC . Of course you'll also need the Allen wrench to turn the plug. With nothing sticking out, the plug can't get beat up from road debris, and since they are hardened (instead of being made of old cheese), they are much less apt to round off.

 

[Member 10617]

As usual, manky thanks for all the great information and guidance.

I kinda guessed that draining the transmission often was not really necessary, so I will just check the level and drain and change the lubricant at reasonable intervals.

As for the the overdrive (a rebuilt one) that was added to my car, the dipstick at the old filler hole is gone (I regret to say), and in its place is a bunch of wires and other electrical elements. It certainly was a lot easier pre-overdrive to check the transmission level and to top it off, but I guess this is the price I pay for having the overdrive. I wish I still had the dipstick.

Frankly speaking, I believe that adding the overdrive was unnecessary as I (a) normally drive back roads at 45 mph and (b) like the feel of the engine in normal 4th gear. But I was having the transmission rebuilt and figured it was a logical time to add the overdrive. Does anyone else feel this way? (Adding Xenon lights was the only other unnecessary "upgrade" or mistake I have made on this car.)

Randall: I will get one of those special tools from Moss to remove the OD plug. I don't trust myself to bang away at it with a punch.

 

[Geo Hahn]

...Frankly speaking, I believe that adding the overdrive was unnecessary...

Send me that pesky OD and I'll set you up with a nice 4-speed.

That special tool is only for (later?) ODs that have the notched plug... if yours is just a big brass hex then all you'll need is a wrench of suitable size.

 

[Member 10617]

Hi, George,

The OD I have has a notched plug... and it appears to be brass.

If I could take the OD out, I'd send it to you. But I think it is in to stay. My thinking was that although I didn't need the OD, someone in the future might want to have one in the car.

 

[TR3driver]

<span style="color: #FF0000">
<span style="font-style: italic">There really isn't a reason to 'regularly" drain and refill the gearbox/OD. Checking the level and topping up is the normal routine.</span></span>

Perhaps not, but some of us think following the factory recommended service intervals might be a good idea ...

 

[Member 10617]

Randall: I check the oil level whenever it is convenient (about every 4000 miles), but I have the 12,000 mile figure in mind for draining and replenishing the oil. I just didn't know if there were some other schedule when an overdrive is present. Page 51 is not too helpful in this regard.

 

[GilsTR]

What oil is best for the tranny / overdrive? Gil NoCal

 

[sail]

A search will find as many threads as opinions. Here is one:
Tran and Diff Oil
I had some problems with syncro action and found Redline MT-90 helped noticeably. Not cheap nor at the corner parts store.

 

[TR3driver]

Page 51 is not too helpful in this regard.

Yeah, it could be a bit more explicit. But I took it to mean that the schedule with OD was the same as without OD.

On the advice of several west coast gurus, I used Valvoline 20W50 racing (motor) oil in my A-type gearbox for many years. Ken Gillanders & Herman van den Akker did a 5 year test in Ken's ex-racing TR2, and after 5 years there was no detectable wear or discoloration to either the gearbox or the OD. It is formulated with ZDDP instead of the "active sulfur" additive that is a concern with some gear oils. And in my experience, it was certainly adequate and inexpensive.

However, I switched to Redline MT-90 a few years ago (in both A and J types), and at least so far it seems clearly superior to the 20W50. OD operation remains much the same (or at least I think the improvement in the A-type was probably due to my adjusting the pressure at the same time). But it really does seem to improve synchronizer operation; shifts are noticeably more quick and sure now, hot or cold. I feel it's worth the extra cost.

 

[Member 10617]

Redline MT-90 consistently gets good reviews and recommendations in a number of these postings. I have some now and will use it when I next drain and refill my transmission and OD. Thanks again for all the good advice.