patdaly

See, that's what is bugging me. The front gear, on the input shaft drives the countershaft, which then gives you 1rst,2nd,3rd,5th and reverse.

4th is direct drive, which is the Input shaft being directly coupled to the mainshaft. For you to lose 4th, the only way I can see is for either the shift forks to be off of the rail, or the dogs to be gone in either the slider or the input shaft. There just really isn't any other way, short of perhaps the main shaft being broken behind the 3rd gear, but man, I would expect carnage if that happened. When they tear it down, have them pull the input shaft first, and see if the 3rd gear falls off with the shaft.......

weiercd

Sounds like a plan. I agree that damage should be much more significant If mainshaft damage was the problem. I was completely on board with your conclusion of a shift fork, as there was no grinding, 1,2,5,R work flawlessly which seems so strange. What If the shaft wasn't broken, but the 3rd gear splines were toast where it meets the shaft. Would this create the same situation?

weiercd

The feeling while driving was similar to rounding a nut with a wrench. You could feel all of the built up force as the truck loaded when shifted into third then it simply let go. Same as how the force feels when the wrench rounds out the nut, not a sudden snap or crack.

patdaly

3rd gear splines would explain 3rd, but nothing other than a mainshaft really explains 4th.................

The more I go over the power path, the more I am convinced your mainshaft snapped behind 3rd gear.

If so, then you are a lucky man, my luck with unsupported gears always ended up with shrapnel through the case.........

weiercd

Sounds good to me. When I have these guys rebuild the tranny, aside from the broken parts, I plan to have them replace the synchros and do a bearing kit. Is there anything else you think I should do while I have it out?

patdaly

Nah, the NV4500 is a pretty stout trans, if they have to replace the mainshaft, I would get the good fully splined one.

weiercd

Any particular brand?

patdaly

Not sure, I have never had to buy one, Torque-King used to be the setup, but they don't make them anymore, Infidel might hop in and let us know the best current shaft.

weiercd

Just dropped it off at the tranny shop this morning. Waiting for them to tear it down and give me a reply.

patdaly

Any word yet?

weiercd

No not yet they didn't give me an estimate on time as I am out of town for two weeks. Plan to call them tomorrow anyways and check things out.

weiercd

Well I called today. They have the tranny apart. Still figuring out the pricing for parts. Was a short conversation but I believe be said it was a broken main countershaft. Will have a more clear understanding tomorrow. Will post pics once I receive everything again.

weiercd

Was quoted 1300 for a total rebuild, all new bearings, seals, synchros, and replaced broken parts. Sounded reasonable to me. He ordered the parts today. Said the work will take approx a week. Should have the beast up and running for summer time.

patdaly

Yep, not bad for a broken mainshaft. You must live right, because if it were me, it would have chucked gears through the case.

weiercd

Lol oh I know what you mean I think this is probably one of the only times ive caught a break. Although I'm not sure how much of a break it is since its our main vehicle with a family of 6 to be down for months lol. Either way a wins a win