915 Transmission jams in gear sometimes

[450knotOffice]

Guys, the transmission in my '84 hangs up in certain gears at times. It usually happens if I've been in a gear for a while and I've been pushing the car a bit. For example, when pushing the car fairly hard on Ortega while staying in third gear for an extended period of time, I've been almost unable to get the transmission out of third. It's like it's locked. A little bit of hard tugging always ends up freeing it but afterward the transmission will feel normal, sliding in and out of each gear with ease. Today, after some spirited passing on the freeway in fourth gear, I ran into the same issue. It's happened to me in fifth gear too. It always seems to happen after a bit of hard driving in one gear for an extended period, as opposed to simply cruising in one gear with no real load put on it.

What the heck might be causing this? There are times when I think the transmission won't come out of gear no matter how hard I tug on the lever. The bushings have all been replaced and the shifter is new (Porsche short-shift). This problem has been ongoing but seems to be getting worse lately.

[Nitrometano]

I have a 72 and that happened to my tranny in the 5fth gear. I replace the under shifter and rod bushings and the rear tunnel shift rod coupler bushings. And the problem was resolved.

[dentist90]

I got hung up in 5th gear this summer... one time only. Was goin' pretty good on a straight and at the end of it went to gear down and whoops! We're stuck in 5th. Clutched repeatedly and played with the throttle and it finally pulled out. Finished the rest of the drive avoiding 5th until I got close to home. It was fine next time and hasn't done it again, although I haven't been quite to that speed again. I first thought perhaps it was a loose bolt on the shifter fork or a worn shaft that was binding. I have since opened the transmission and found a bit of a ledge on the the 5-R slider hub. I was thinking this could be the cause if the slider gets caught on the tiny ledges as it tries to slide back.
I have only had this happen in the one gear, not any others. In 450knot's case I can only guess that the hubs/sliders are wearing a bit and the sliders are binding? Is it possible to pick up a small metal filing and have it jam under the slider? Time to change transmission oil? I replaced my shifter, all bushings and the coupler last year, so they're not worn or loose in my case.

[450knotOffice]

Thanks for the input guys.

After some research it seems that a few others have had this problem. Grady Clay has chimed in on this issue in the past and his intimate knowledge of the transmission is mind boggling. It seems that more often than not, assuming the linkages are good, the synchros and sliders are bad, causing an occasional hang-up.

One more thing to add to the list this winter (I think I need another credit card..)

[rob justice]

Sometimes sticking in gear is a 'charactor' of my car also. It only happens in 4th or 5th. First time it happeded I was pretty worried but its only occasional (very) that it happens.
I've found to get it out of a 'stuck' gear, don't try and force the car out of gear but move the lever as if you're selecting the gear it's stuck in again and it always pops out. It only takes a very slight touch of the lever and it's free again.
I don't think its a box problem rather than the shifter coupling needing a tweek but since it's not a constant problem, I've just learned to live with it.

[cstreit]

I had this happen on an almost new gear. Turns out that the stop-blocks and energizers were worn, the brake bands inside the syncro were getting wedged underneath the syncro and keeping the op.sleeve from pulling off.

[cashflyer]

I had this problem on my way up to the Dragon recently. Had been cruising in 5th, went to downshift for a merge and it wouldn't pull out of gear. After several clutch cycles and speed changes (trying to "rock" the gears) I finally ended up just strong-arming it.

No problems for the rest of the trip. weeeird

[Jim Richards]

Same here with 5th gear on my 73E. It seems to happen after cruising in 5th for a while. It's not a constant problem, but frequent enough to be annoying.

I also have the occasional problem getting INTO 3rd when downshifting from 4th or 5th. It only happens when I approach a hairpin turn after a high speed straight with cars around me. No pressure.

[450knotOffice]

Yea, I'll agree that the most common gear that jams up is 5th. It does happen with the other gears though (3 and 4).