Author Topic: Manual transmission, Lost 3rd and 4th Gears  (Read 274 times)

Offline Brian

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Manual transmission, Lost 3rd and 4th Gears
« on: February 10, 2018, 06:22:20 PM »
Hi guys, It's been a while since I've browsed RPA.

I just lost 3rd and 4th gears in my N50 xterra. 1/2, 5/6, and reverse all work fine. The gearbox has not displayed any problems up until this point. Clutch works normally.

The gear select simply won't push up or down into 3rd or 4th, as if the gates disappeared. It happened suddenly with no warning, no grinding, clunking, or rattling that I noticed. Went to slide it into 3rd while accelerating from a stop and there was no gate. I've applied some moderate force on the lever and it doesn't budge. It doesn't seem wise to force it with all my might. Same symptoms when moving, stopped, ect.

I'm thinking that the 3/4 fork or rail is bound up or stuck for some reason. I'm inclined to think some "E"clip or spring pin wiggled itself loose  ::). It's clear the transmission will have to be removed. It doesn't really seem to be a Nissan problem, just a manual gearbox in general problem.

Any insight?
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Offline 93Rubie

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Re: Manual transmission, Lost 3rd and 4th Gears
« Reply #1 on: February 11, 2018, 07:05:15 PM »
When I first started reading this I was thinking automatic transmission. I've never seen a manual box fail in a Xterra or a Frontier (same driveline). How many miles?

FYI, Nissan dealer technician for about 5+ years total.

With no noises, I would be inclined to think a shift fork, pin, or other mechanism has failed. Gear failure or syncro failure is unlikely. I'll honest I don't even know if individual parts are available for these boxes. We don't see many and most are trouble free. I've done a couple clutches in them but that was all.

I can find out about individual parts in the AM.
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Offline Masher Manufacturing

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Re: Manual transmission, Lost 3rd and 4th Gears
« Reply #2 on: February 11, 2018, 07:27:20 PM »
Congratulations, you have now found the GM patented skip shift feature. 

Before taking the trans out, see if you can remove the shift cover or even the shifter and have a look inside.  I don't know these trans specifically but I'd guess a roll pin on the fork or other end at the shifter worked out and bound the rail. 

For a used trans , have a look a look at car-part.com , they are in the $ 500 range around the PGH area.  Don't bother e mailing the salvage yards as most never reply so calling is best.





Offline 93Rubie

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Re: Manual transmission, Lost 3rd and 4th Gears
« Reply #3 on: February 12, 2018, 06:35:19 PM »
Individual parts are available from Nissan
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Offline Brian

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Re: Manual transmission, Lost 3rd and 4th Gears
« Reply #4 on: February 14, 2018, 08:42:23 PM »
More or less echoing my thoughts.

It's getting old driving through 80 traffic signals a day on 20 miles of rt-30 misery, heh heh.

I'm back on the road for about a month next week so the truck will just sit. By the time I return the weather should break and I can drive the M3. Then I'll pull it in the garage and see if I can fix it. If that doesn't work out then yes, the gearbox is readily available as salvage in the $400-$600 range.

It has 150k on it, and it would have needed the transmission removed to put a clutch in sooner or later regardless (Although it's holding strong). If memory serves I have some access to the shift rails from the top. I vaguely recall pouring gear oil in through the console instead of using a pump when I changed it several years back.

I've never actually disassembled a manual gearbox before so I'm kinda looking forward to that, but the counterpoint is that it's gotten awfully rusty under there so it might be an unpleasant time removing it from the block. It does have a lot more access room than the e36 I last yanked a transmission out of a few times.

Definitely an unusual problem. Modern manual boxes are usually all but bulletproof in unmodified cars. Something about fluky transmission problems. My last one was the flywheel/pressure plate dowel pin that dislodged itself in the M3.
Neo: Why do my eyes hurt?
Morpheus: You've never used them before.

Offline Masher Manufacturing

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Re: Manual transmission, Lost 3rd and 4th Gears
« Reply #5 on: February 15, 2018, 08:46:21 PM »
If our guy 93 could post a exploded view ( or link to ) of the trans it would be helpful.