Eaton Fuller FRO-15210c will not go into neutral or reverse

[ivanuke]

Hey guys I'm having an issue with my 2001 CH613, its got an Eaton fuller FRO-15210c that does not go into neutral or reverse gear. I can go into any other gear. Here is a bit of troubleshooting info:

Air tanks take a long time to build pressure, and leak off within 5 minutes but cant hear any air leaks.

I have to start the truck with the clutch engaged or else it moves forward.

The shifter is physically in the neutral position but still has the last gear engaged

The range selector will shift from high to low gear even when gear is engaged. The shift sounds very weak (Maybe air module?)

I somehow got the truck into neutral one time and idling without holding down the clutch, but as soon as I lifted the splitter, a gear engaged and jerked the truck forward. Can no longer go into neutral and i cant repeat this behavior. 

I can clutch and shift into any of the low or high gears no problem using the splitter, i verified its going into all other gears because i creep forward at different speeds.

Truck does not engage reverse switch so no siren or reverse lights (cant go into the gear so this is probably a given)

The transmission has a plug where the neutral switch is (I guess its not needed for this model?)

Any help or advice is appreciated!

Edited November 14, 2019 by ivanuke
added more troubleshooting info

[david wild]

FUBAR

[Truck Shop]

On the early FRO's the shift fork in the rear section was held in place with a snap ring, those are known to break. You will have to remove the transmission and remove the top cover/shift bar housing. You will be able to see the shift fork

and shift bar. Snap ring goes on end of shift bar. It's a simple fix. I have repaired several for that problem.

[ivanuke]

17 minutes ago, Truck Shop said:

On the early FRO's the shift fork in the rear section was held in place with a snap ring, those are known to break. You will have to remove the transmission and remove the top cover/shift bar housing. You will be able to see the shift fork

and shift bar. Snap ring goes on end of shift bar. It's a simple fix. I have repaired several for that problem.

Thank you for that information. I looked at the manual and it looks like the shift fork for the reverse is also for first gear, but my first gear engages fine and im able to shift into another gear fine as well. Would this still be likely cause of a fail snap ring for the 1st/reverse shift fork?

[JoeH]

&##@$&&& Fuller transmissions!! Pull it and put a Mack trans in!!!! 

Just kidding, figured I finally got a chance to critique one of David Wild's beloved transmissions.

Another thing to check: pull shifter off transmission, make sure all shifters are actually in neutral. My 8ll shifter jumped out from shifter rail pattern a few times when we first got it, then could only make a big circle with the shifter. There's an o ring and a metal cupped washer in the shift lever ball socket, and the o ring deteriorated, causing the shifter to sit up higher, thus allowing it to pop out of the shift pattern if you weren't careful. But that shouldn't cause massive air leaks.

[david wild]

HAHA

[Mack Technician]

If hate’in on Mack transmissions was in style Dave would be Coco Chanel.

[ivanuke]

Update: I had to leave town but had a mechanic take a look at it. He said the forks had too much play and sold me a "refurbished" shift bar housing with all forks and everything ready to drop in for $550, and charged me $250 labor and took my old housing as a core. I am a bit suspicious about this as I wasn't able to verify, but word from the shop is the truck is working fine now. I just find it strange all three shift forks are now "too loose". Hopefully he didn't pull a fast one on me because I wasn't able to verify, but did have someone there less mechanically inclined witness what was going on. In either case that fixed the issue, take with a grain of salt. I had the air module tested and the o-rings replaced on the range selector piston, that didn't solve the issue beforehand.

Edited November 17, 2019 by ivanuke