Getrag syncro gumbo

[Sri Ram]

an update: over the weekend, I drained the oil in the trans--looked good, some sparkles, no shavings--pulled the pto covers, and had a look around. Everything looked fine on both sides. I pried at the gears, very little movment. Put it back together and overfilled by . 5 qt (all I could get in at the time).

Since I'm having trouble going up or down into third gear, I think it must be the 3-4 syncro. I've requested the manual pdf from jleonard, and have been taking notes on the recent getrag-related posts here. But, out of curiosity, anyone else have 3-4 syncro problems?

 

[1stgen4evr]

3-4 syncros. Yes, at about 350k miles my transmission would not shift normal. I drove it for some time using the experience of driving the Mack duplex transmissions from the 50s.



There should be NO forward and back movment in the gear set. It should have just a tad of preload. Same for the countershaft.



James

 

[Sri Ram]

There should be NO forward and back movment in the gear set.

Hmm…I only checked for up down movement. Still, you think it'll be drivable for a while? I've been driving it some, but it has to be coaxed into third. Do you think it will cause any damage to drive it in this condition?

 

[1stgen4evr]

Do you think it will cause any damage to drive it in this condition?



There are a thousand variables on how and where you drive/load etc, but if you didn't have any up and down movment, you probably don't have much end to end movement either. If you didn't have any bright metal in the lube, all is well. (You know to check the magnet?) The 3 - 4 syncros get the most use in normal service so no great surprise they go first. Certainly, every time I have pulled mine down there has been minor backlash. If you consider the manner that a tapered roller bearing carries its load, you will see that much end play allows the bearing to be loaded on a smaller portion of its surface.



And if the transmission isn't noisy, I expect all is well. At the time you do work on the transmission, keep in mind that too little preload is better than too much. I have done plenty of transmission repair and other things that require a rolling resistance for correct 'fit'. I use my hand and set the rolling resistance at a barely perceptable condition. In analogy, I liken this to buying new shoes. If you get them too tight, you will get a blister. And you can be sure that if you 'blister' the pocket bearing, you got trouble. Too loose and you will have the shoes floping and won't get much service either.



James

 

[Sri Ram]

I use my hand and set the rolling resistance at a barely perceptable condition.

As loose as possible with no play?

 

[1stgen4evr]

As loose as possible with no play?



I can live with that and so can the Getrag.



James