G54 fourth gear goes kaplowee.

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Oct 19, 2004
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Ok, when I installed the 3L diesel with the turbo, it prompty stripped the crap out of the anemic stock L50 transmission. Didn't really feel like hunting down a diesel bellhousing (clutch release fork on opposite side) for a W, G, or R transmission (because they are like hen's teeth). And on top of that possibly having to relocate the crossmember and/or messing with the driveshaft length. Marlin Crawler had the perfect solution, bore out the existing L50 to accomodate a G54 gearset and bearings. Great, plug-and-play.

30,000 miles later I get a wee bit of clash going up or down into fourth gear. Start with the simple stuff, change the fluid. A little dark, but no chunks brass or otherwise. Clash deminishes, until today. Shift up into fourth, and nothing. 1, 2, 3, 5 and reverse work fine.

Take the scenic route back to the mechanic's shop. They drop the transmission, get the top cover off and everything looks fine. Then start spinning each individual gear by hand. Fourth gear (closest to the front) the little ring-gear bit that lines up with the synchronizer is spinning independently of the actual gear. How could this have broken?

Got someone from Marlin on the phone and their reaction was "whaaa? really?", They want pictures of the broken bit to make sure they are sending the right stuff to fix the unit. Personally, I don't see the point of pictures. It looks like I need a new input shaft which has fouth gear on it. And maybe the input bearing and seal.

Anyone ever break their transmission in such a manner?
 
Like i said, just a wee bit of clash that went away after changing the oil. The last transmission (stock L50) I burned out third and fifth went, howling like a banshee. I think I just won the Irish sweepstakes with an input shaft that was defective in the first place.
 
Sorry I didn't get back to you today Kevin. (I'm the "guy") I needed pictures as I have never heard of that one. When I told Marlin about it he was shocked as well as he's never heard of the splines on the gear stripping at the input. They are pressed together so there is no room for shock loading between the 2. I do have the part for you sitting on my desk and I'll be calling you in the morning.
 
Oh, hey man.
Thanks, "guy".
The mechanic who dropped the transmission was also a bit gobsmacked. He had worked on many Toyota truck transmissions back in the day, and he said he's seen a lot of things smashed to hell from neglect/abuse/misuse, but that was a new one for him.

btw, wasn't intending to be disparaging of your shop, you guys seem to be on the ball and make a good product. Like I said, just luck of the draw I got a goofy input shaft.







...great, one more person on here who knows who I am.
:flipoff2:
 
:hhmm:I drive by you all the time....maybe I need to hunt you down?:D
Oh, hey man.
Thanks, "guy".
The mechanic who dropped the transmission was also a bit gobsmacked. He had worked on many Toyota truck transmissions back in the day, and he said he's seen a lot of things smashed to hell from neglect/abuse/misuse, but that was a new one for him.

btw, wasn't intending to be disparaging of your shop, you guys seem to be on the ball and make a good product. Like I said, just luck of the draw I got a goofy input shaft.







...great, one more person on here who knows who I am.
:flipoff2:
 
A picture or three.
Damn thing is still clashing into fourth with the new input. Let it run in a bit, wait and see. But I have this sinking feeling that something is up with the synchronizer. If it was a fork or a shifting hub, one would think one would get trouble with two gears and not just one.
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