Transmission died 1st Gen

Heck, i'm not sure of nuttin. Tried shifter from another tranny that looked "ok" and there was no change. what else is one to do on a Monday but lay on a concrete floor under a greasy truck

 

Well, Clutch is about done but not down to rivets or showing loss of material.

Gotta decide what next! Have a spare tranny but wish I knew how good it is.

 

That sucks, guessing that means the synchros are shot?

 

Don't know what's in there but I would guess more than syncs. It went into gear just fine - wouldn't move.

Gotta figure out what I unbolt to see the "pieces"

 

R154s have this problem sometimes (very similar to r151 box internally in your taco assuming you have the v6 manual), 4th gear syncro breaks/sticks or shift interlock or something like that.
Better off replacing the whole trans unless you are good at rebuilding stuff, even if you are the R series parts are hard to find new and expensive these days.

 

Replacement will be rebuild or used. Have a used one now but trying to figure out if l'll chance it. Been looking for explanation on how to get it apart. Guess I can remove all bolts and see what happens - seems to be trash anyway.

 

Most transmissions the top will unbolt allowing one to pull the top off. Putting it back in can be a pain as the shifting forks must be aligned right. Following this as has me wondering how it could shift into other gears and not move while will shift into 4th and have it stall. I am thinking maybe a sheared pin on 1 and 2 shifting fork and maybe a bent fork on 3 and 4. Just a guesstimation though.

 

Im still thinking its a bearing. I'm in the same spot with my whining trans. every gear except 4th. And i have a spare trans just don't know its history.

 

This sounds like main input shaft bearing. I guess the OP could be dealing with same

 

Yeah that's what my thought was too. after i do the swap i'm going to have it rebuilt.

 

Yeah keep us updated on what they find. That's the symptoms I had when I damaged that bearing towing a lil uhaul trailer and full truck, 1994 Nissan Hardbody 2.4L MT 4x4, from Washington to Utah. I towed in 5th gear. Didn't know any better. Expensive lesson to learn. But I drove it for at least 6 months with that bearing whining. Never got worse and so saved the cash and then had it done. This was 01- 02 or so? And I didn't pull the tranny, they did and I wanna say it was like 750 bucks or so? Been too long but yeah. Noisy whine while accelerating in all gears except for 4th, which apparently 4th gear doesn't use the input shaft? Is that right? That's how it was explained to me but I am definitely no manual trans expert, or even slightly experienced with repairing them. Just always swapped trannys.

 

yeah I'm no expert either when it comes to the transmissions that's why I'm just swapping it. I hope the new ones better than this one is, they have about the same mileage on them. Everything I've read and research says it's an input shaft bearing as well. So once I swap these guys out I'll have the shop take a look at it. I feel like @Malpais82e has the same issues but his just seized up. I've been driving mine 11 months now like this granted I've only put about three thousand miles on it.

 

I had similar a thought about his as well

 

Tough to explain in words but 4th gear is just the shift collar locking the two half’s of the main shaft up 1:1. All other gears use the countershaft to mostly (R, 1/2/3rd) underdrive or overdrive (5th) the back half (driveshaft output) of the main shaft. If you have a whine in all gears but 4th, there is a problem with the countershaft bearings

 

^^ This. 4th gear on this trans (1:1) is basically locking the input shaft to the output shaft (the 2 halves of the main shaft), which definitely uses the input shaft.
On another note, I don't even think you can have a manual transmission where a gear does not use the input shaft and the output shaft.

Any other gears (not 1:1) usually involve the countershaft, where the gear on the input turns the countershaft, which turns a gear on the output at the desired rate (under drive or over drive).
So I would agree with Snowy, if your issue goes away only in 4th, it does not have to do with the input or output, and is an issue going on with the countershaft (bearing etc..)

 

Yeah that makes a lot of sense being countershaft bearing.

 

Now that you explain that to 40 year old me and I have a few more years under my belt that makes much more sense than when the dude explained it to 21 year old me back then. Sounds like what I had going on. He said I likely damaged it towing in 5th gear and it left whine in all but 4th. So what you say makes sense

 

Ha, I didn’t understand it until I took a transmission apart and got to see how all the shift forks work so you’re ahead of me by understanding my jibberish explanation of a trans

 

Exactly, now that I've seen insides and pics and images whatever, that makes sense

 

@OP: I'm sorry to hear that your truck is having transmission/clutch issues and am glad that you're able to haul it home. It looks like that you're trying to service it yourself. I hope that you're able to fix it correctly with the correct transmission & parts on your truck. If you can't figure it out, I might suggest to bring the truck into a transmission repair shop that will diagnose & repair the transmission to get your truck running again.

That being said, I've driven my truck on its original clutch for 19 years. The clutch went out last year while I was driving home. I had to call AAA, got towed home, then towed to the repair shop the next day. I'm not as mechanically inclined or experienced on servicing transmissions as some of the forum members on this forum so I had my master mechanic perform the repairs. I had the clutch & carrier bearing replaced and both differentials serviced. It wasn't a cheap repair, but I have peace of mind knowing that I can travel with no mechanical failure and won't be stranded off the side of the road.

1st generation trucks are considered old vehicles, most have been purchased as used (if they're not scrapped due to frame rust issues), and as such will suffer from worn out truck parts in need of replacement, driver abuse, and lack of /poor maintenance.