2laneblacktop

Hi all, hope everyone is staying safe and healthy during this pandemic.

Tonight I took my mostly stock Zenki S14 out on the highway for an Italian tune-up - I drove it hard in 2nd, 3rd, and 4th, backing off as I upshifted to 5th and decelerated. No shifts were missed, and no grinds.

At my turnaround exit, the trans would not shift out of 5th. I stopped, turned off the engine, and still the trans was stuck - I applied force but backed off not wanting to break something. Clutch operation was normal, fully disengaging the engine from the trans when pressed.

I was in a high-crime neighborhood, so I started the car and managed to limp it home in 5th gear all the way, and only had to run 3 red lights (thankfully it was 1 AM and no traffic). I tried several times to downshift on the way, to no avail. It only let go of 5th gear when I hit a hard bump in the road, jarring the whole car and stalling the engine. After that I started the car, it shifted into first normally and I got home.

Any ideas for this? I'm running Redline Lightweight Shockproof Gear Oil, which does a great job eliminating the grinds I used to have. The slave cylinder is fresh as is the clutch fluid, and yes I bled the system. The clutch did not seem to be the issue, the shifter or gearbox did not want to let go of 5th. Thanks...

Kingtal0n

Is this on an sr20det transmission made from 1989-1995

Some of those years have a synchronized reverse, and some do not. I think the ones without have an easy-to-break fork for 5th gear. It loses a leg and then grinds going into 5th. Or gets stuck.

Its the only thing that comes to mind immediately. 5th is really weird to lose. Its tied to reverse. I would suggest you find a spare trans immediately, and,

when u get time swap them out. then pull the bellhousing off this trans and just look for anything obviously wrong with it (they are pretty simply, just using eyes and turning the parts can tell alot)

If you are not using a stock shifter that could be an issue
Also make sure you have a new nismo slave and new clutch master and a braided hose. Those parts are all cheap no excuses.

jr_ss

That transmission is toast. I had the exact same thing happen to me after a pull. It was stuck in 5th. I strong armed it out and only had 1st and 2nd after that. Time for a new transmission.

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97nismo

When mine stuck in 5th I found out the clutch was in pieces and I still had pressure when I pressed the clutch...

But honestly the stock trans are not all that great.

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2laneblacktop

Thanks everyone for your input and information; here's an epilogue: I had a transmission shop do a rebuild, and this a paraphrasing of their diagnosis. The shift fork and collar for 5th gear were damaged when the gear was engaged at high speed, due to excessive movement of the tail end of the transmission, leading to the collar getting pushed too far and getting stuck. The (badly dry-rotted) transmission mount at the rear of the trans was implicated in the trans failure, there was excessive play and the shifter was very sloppy, wagging like a dog's tail at speed. The driveshaft yoke was also damaged, and I ended up replacing it when I had the trans rebuilt. The sad thing was I had a new trans mount on order when this all happened, because I was going to install it along with a short shifter kit. Does this explanation jibe with your experiences with S chassis transmissions? It makes sense to me, though I'm surprised that it was possible to break a trans this way.

jr_ss

Sounds like a crock of shit to me... You ragged on a weak transmission. It said to hell with your 250-300ftlbs of torque.

Tail shaft wagging like a dog my ass.

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My SR20VET