Bad synchro - replace trans - grinding gears

Could save money by replacing the Slave gear and range selector switch.


Don’t need replacement transmission.

 

Check the filter in the back of the transmission. It’s that coolie hat looking thing on the shift solenoid at the back of the transmission. You only have to have the input pressure to that solenoid drop by 1psi or so before it won’t shift right. A small air leak down there will do the same thing. You should pre-select range and splitter shifts on newer Eatons. The old ones, up to the 15 series I think, weren’t supposed to be pre-selected. You made the range or splitter shift when the main was in neutral, that ####s the new ones up. As @Judge said the shift solenoid itself may be bad. Lots to check down around the back of the transmission before changing it. In the end there may be damaged synchros back there, but that’s only in the auxiliary section. Those can be replaced without pulling the whole transmission out of the truck.

 

Wouldn’t hurt to change your transmission fluid/oil.

 

Eaton or Rockwell. Has to be one or the other, not both. The transmission in that truck may have been changed if the trans says different than the door decal on the truck. Doesn’t really change much, both transmissions work basically the same, and look similar at the back. Rockwell should have an air filter back there too.

 

And even if all the advice ^up there doesn't help, they make a kit to replace the range synchronizer. That's the usual mechanical cause of range shift grinding, no need to replace the tranny.

 

I’ve never had the auxiliary off a Rockwell. Only seen them on the floor but I’d imagine they’re similar to an Eaton as far as getting the auxiliary off it in the truck. He’s probably going to be into synchros. I aimed him at the air filter as that’s the root cause of a lot of tore up synchros and may have stopped it if they’re not badly damaged. Usually range shifts while coasting gets the rest, like pulling it out of 6th gear and punching that range selector down while they coast to a stop. That’s a big one on fleet tractors. Either way, I’d hate to see the guy into a transmission over auxiliary synchros, Eaton or Rockwell that should be an easy fix.