420A Popping Out of Every Gear

[BLACK'98DSM]

Looking for ideas as to why my NVT-350 is now popping out of every gear (besides reverse, which it will not shift into.)

Backstory: I was out tonight to do a test run. From a dead stop, I did a hard launch (started slipping clutch at 4500 rpm, she was hooking so I quickly engaged). Everything was great until 7k when she popped out of 1st and quickly over revved. I thought I broke 1st gear until I realized it was just thrown back to neutral. I slowed down a bit and put it back in 1st to verify functionality, 1st held up until I started accelerating then popped back out. Decided to shift into 2nd and take her home. Quickly popped out of 2nd and then 3rd after. Any medium to heavy throttle pops it out of every gear, verified on the highway. Was able to drive home very gently with still an occasional pop out. Once I made it home I traced out the entire shifter cable assemblies to make sure there was no issue with them. They appear perfectly fine, everything still tightly secured and undamaged. It's only been a couple of years since I installed new OEM ones anyway. Next I checked for fluid leaks, possibly from a broken belhousing. But everything is still clean and she's still full. Soon I'm planning to drain the trans fluid and hopefully see the degree of the damage (will post findings). I have very much doubt that all of the synchronizers became shot at once. Something with the gear shafts must be out of line.

Looking for suggestions and thoughts. I've battled many trans issues in the past but never had this one. Seems like a strange issue especially for a freshly rebuilt transmission that supposedly holds up nicely in turbo cars.

 

[motomattx]

How are your motor mounts? excessive driveline movement can yank it out of gear.

 

[1990TSIAWDTALON]

Its possible the entire gearset is shifting under load and popping it out. If you get a chance, check for in/out play on the main shaft. Sorry to hear about the crappy luck.

 

[97egl]

Based off every gear having the same issue I would guess that one of the input/main shaft bearings has probably failed as Marty mentioned.

Draining the transmission may not show you much. If the magnet did its job it will have caught the ball bearing and bearing cage pieces. I wouldn't drive it until you figure out the issue tho. If there are ball bearings floating around in the transmission and they get between two gears it wouldn't end pretty.

Also check for fluid behind the inspection cover inside the bell housing. If the front input shaft bearing goes bad it will wreck the input shaft seal and you may see some fluid leakage.

 

[CKOPOCT]

Not a tranny expert by any means, but what about the End Nuts? Similar issue was just discussed, though that person was also experiencing grinding. Just trying to float ideas.

 

[BLACK'98DSM]

Not a tranny expert by any means, but what about the End Nuts?

The NVT350 does not have end nuts like the Mitsubishi transmissions. Instead it has press fit bearings held onto the shafts by snap rings.

 

[BLACK'98DSM]

Based off every gear having the same issue I would guess that one of the input/main shaft bearings has probably failed as Marty mentioned.

Draining the transmission may not show you much. If the magnet did its job it will have caught the ball bearing and bearing cage pieces. I wouldn't drive it until you figure out the issue tho. If there are ball bearings floating around in the transmission and they get between two gears it wouldn't end pretty.

Also check for fluid behind the inspection cover inside the bell housing. If the front input shaft bearing goes bad it will wreck the input shaft seal and you may see some fluid leakage.

Pulled the inspection cover and everything is still clean and dry inside. You're right about the magnet catching some damage but I also have a magnetic drain plug installed that caught quite a bit of material the last time my cage came apart on one of the shaft bearings so I'm confident I'll see some wear from there if there's a major issue. Not to mention all of the aluminum/brass shavings that could possibly be present and are not magnetic.

It's only been 2 months since I installed all new bearings (yes ALL of them new). As much as I'll hate to pull my trans again it sounds like I need to. I may just go ahead and pick up another one, build it right, and keep my current one for spare parts. There's plenty of goodies inside worth holding onto.

 

[CKOPOCT]

The NVT350 does not have end nuts like the Mitsu transmissions. Instead it has press fit bearings held onto the shafts by snap rings.

Ah, good to know. More nuggets to file away. That's why I love this site. Always an education, and respectful too. Much appreciated.

 

[BLACK'98DSM]

These are the remains of the input shaft snap ring. It was completely shredded and damaged the bearing cover as well. Getting a new snap ring and bearing cover was no issue at all. I'm still unsure of the cause though. Perhaps it was stretched and did not fit as tightly as it used to. I wouldn't have thought it would cause destruction though.

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