Countershaft play

[my123ca]

There is about a 8mm play on the countershaft of a g76/27-5 transmission. Is it suppose to be that way? If not, How do I fix it? This is the first time I opened up a transmission, are the front and rear countershaft bearings sliding in and out of the housing?

[Robert Squires]

* Are we talking about a 716.005 manual 4-speed transmission? What year and model car?
* Are you sure you mean 8mm and not 0.8mm? It's been a while since I did some manual transmissions but a 0.8mm endplay on the countershaft is quite a bit. An endplay of 0.25mm sounds a lot closer, particularly given the lighter oils used in the later gearboxes.
* Why are you going through this gearbox? The only things that ever went wrong with the '70s, '80s Mercedes manual gearboxes were seal leaks and maybe synchro ring wear, particularly 2nd gear synchronizer ring. The symptom for this was gear grinding on the downshift from 3rd to 2nd, even with good clutch action. Even if half the oil leaks out of one of them, they'll run quite a while before giving much of an indication.
* On high mileage manual gearboxes, mainshaft and countershaft end bearings typically move easily in the case bore. Just make sure that the endplay shims are all there when you reassemble. You don't want a preload, just close to zero endfloat. Be sure to count for the gasket.

[Chas H]

The countershaft is located by its' front bearing. If you have the front transmission cover removed, that bearing can move somewhat freely in the main housing. That's probably the play you are observing.

[my123ca]

The transmission looks similar to a 717.0 manual 5 speed. Its from a 280 se coupe 111.025 according to EPC. I only have the transmission.

"If you have the front transmission cover removed, that bearing can move somewhat freely in the main housing. That's probably the play you are observing."

This is the one im seeing. Theres about an 8mm play on it. Is that normal? There is more play in the countershaft than in the main shaft. I have not installed the shims yet. I measured from the top of the rear countershaft bearing to casing with no gasket - max. play. The gears on the countershaft will grind against the gears on the main shaft because of the play. I was going to install new gaskets thats why I opened it up.

[Chas H]

Check the endplay with a dry fit of the cover installed. Make sure the shims go back to the original place. I really think you have no problems.