T19 hard downshift 3rd to 2nd only when cold
 

Hi,
My T19 has problems when shifting down from 3rd to 2nd when outside temps drop to and below freezing point. You can´t get 2nd gear in unless you wait till the rpms drop and the gears align. You clearly can feel this alignment with your hand on the shifter. The issue is cured after a few miles when the fluids get warm. Then shifting is smooth. I replaced the oil with 80W90 GL4 gear oil two years ago when I got the truck.

Synchros worn?
Or change to lighter 75W90?

Tranny has to be pulled soon to change the flywheel (several teeth missing), so changing synchros would be easy.
Thanks

I believe your 2nd gear synchro is a little worn. You never used that synchro unless downshifting, because you always start out in 2nd correct? I bet it would help if you changed the fluid to a synthetic gear oil. I am impressed if you think changing the synchros in the trans is easy.

Hi,
no, I always start out in 1st gear (Diesel truck).
I too thought about changing the oil first, then judging if this cures the ill. Also read about the GL-4 EPs eating on synchros just these days. Now I´m worried, of course that I speed synchro wear by use of the wrong oil.
I´ll change the oil and use my engine 15W40 dino oil, since I have enough around. This sould be better than the GL-4. If it works out I´ll do another change later and use straight SAE 50 engine oil without additives.

Never meant the synchro job to be easy, but to have the tranny pulled only once. According to the T19 rebuild tutorials and youtube videos I watched it doesn´t look that difficult, btw. I´m all ears if it ain´t.

The gear oil recommended by my local Ford Dealer Parts Dept for the T-19 is Motorcraft 80W-90 Premium Rear Axle Lubricant, API Service GL-5.

I also see on this link that they say the same weight and API rating:

The Novak Guide to the Borg-Warner T18 & T19 Transmissions

Once on that page scroll down to where they talk about gear oil, or better yet use the find feature on your browser and search gear oil, takes you right there.

They do mention the use of 50W but caution if you live in a warm place it might not be adequate. I don't think you should use 15W-40 in it. I'm sticking to 80W-90 in mine.

BB2

Yeah, saw that on their site.

My shop guy also didn´t recommend 15W40 (too thinn in summer), but said to stick with the dino GL-4 80W90, that´s in there right now. He also said that it´s probably a slightly worn synchro with them sticking when cold.
I used Addinol dino 80W-90 GL-4. Addinol is a german brand and the GL-4 I picked is approved for synchronized manual transmissions. In contrast to the widespread automatic transmissions over at yours, the majority of our cars and trucks have manual transmissions, so I hope our guys know what oils they are developing.

I´ll probably use a Novak master rebuild kit and overhaul the gear box when it´s out of the truck one day I´m attending the worn flywheel.

I know it's expensive, but I think to avoid any tranny rebuilding, you should try a synthetic gear oil. It's main claim to fame is the viscosity when cold, which is what your main problem is. I would not try those other oils. I have tried other oils in another truck project I have, straight 30w, 10w-30, etc. and they were all too thick in the winter and caused hard shifting.

GL-4 or GL-5 will be ok in a T-19. The GL-5 rating is for extreme pressure and high velocity applications. From what I can gather GL-5 superseded GL-4 and for the past 20 years or so has been used in manual transmissions with no degradation of yellow metals. Additional sulpher in the GL-5 formulations is used to protect the gears better than GL-4. Some people are saying that sulpher is attracted to the synchros and can damage them. Others say that yes the sulpher is attracted but does not damage the synchros, there may be some color change but it wont damage the yellow metals. Damage to synchros is more likely caused from hard shifting and improper clutch operation.

Because of the controversy over the possible damage to synchros from GL-5, some oil companies have come out with a GL-4 product that has been reformulated for use specifically in manual transmissions. This is more of a marketing tactic than a big deal for synchro wear. These reformulated GL-4 lubes for transmissions are probably good.

I like the idea of extra gear protection offered by the GL-5. I don't think it will eat the synchros. May change the color as the sulpher adheres to the yellow metals but wearing them out has not been a problem you can trace to the lube.

Thanks for the answers.
Talked to my tractor repairman who did a lot of trannies during his lifetime. He confirmed that the wear on the synchros rather come from age and hard/wrong shifting then from chemical reaction of the sulphur.

I´ll buy a GL-5/Gl-4 75W-90 full synth and change the fuild. That should do the trick. If it ain´t then I know to rebuild the tranny when it´s out.
Would it make sense to pull the carpet and cover, then remove the top with the forks and have a look?

I wouldn't pull the top unless you want to make it easier to pour the new fluid in. You won't see much. If you could see something visually wrong with the trans you would have way more problems than you do now.

Allright, saves a lot of time :-)

Ordered 4 liters of 75W90 synthetic oil and will change as soon as it gets here.
Thank you guys

Don't think you will save time by taking the top apart. Get your lube in squeeze bottles and put it in through the fill plug hole. You know you will have the right lube level that way. Pouring through the top it may take a while to level out to the fill hole. You don't want to over fill.

Of course. I meant NOT taking off the top cover will save time. I´ll just do like you said, except for the squeeze bottle. I have an electric pump to o the work.

Even better :-X22 Let us know how you like the synthetic gear oil and if your shifting smooths out.

Well, I´ve changed the fluid to 75W90 full synth. It shifts smoother but the issue is not cured. However untill a smooth downshifting to 2nd gear is achieved it doesn´t take that long anymore. Can´t imagine the T19 was built that way (hard downshift whith cold tranny fluid). I think it did shift smooth up and down when new.

That trans has a 1st gear synchro correct? I have had transmissions that were like yours, and what I would do is go to pull it down in 2nd, but instead of forcing it into 2nd I would lightly push it up in 1st for a second. I do not go into 1st, it will not go. But putting a little pressure in 1st will help spin up the trans rpm a little bit, and then for me it would drop right into second.