Popping Out of 5th Gear (sideshifter), really don't want to rebuild the trans...need ideas Options

[rcrgyrl]

Working through issues with this new to me car. Took it for a great drive today.

But...I'm having issues with 5th gear.

Symptoms -
Popping out of 5th Gear when I lift, especially during downhill stretches when you don't need the throttle. Generally won't pop out when I'm on the throttle.
Harder to get into gear when going down hill as well.
Usually can get it back into 5th when it pops out if I match the rpms
Can sometimes hold it in 5th but not always and I'm afraid trying to do so is doing awful things to the inside of the tranny
With car in the air, when I put the shifter in 5th, I can push on the linkage at the trans and feel it pop into gear (I think)
Reverse and 1-4 all work nicely

What I have done -
Replaced the firewall bushing and both bushings at the end of the shift rod linkage at the tranny.
Inspected shift lever and linkage and rod and see no points of failure

I'm hesitant to try and adjust the linkage because the other gears are all working quite well.

Any thoughts, or am I just going to have to pull the tranny and have it rebuilt?

Thanks in advance!

Rcrgrl
'75 1.8 Dual Carbs

[Gary]

Check the motor mounts (attach motor to engine crossbar), and transmission mounts (below trunk). They are rubber and deteriorate over time allowing the engine/trans assembly to move forward and back.

[ChrisFoley]

Seems more like its not an internal problem. As suggested, loose/broken engine or transmission rubber mounts are a good place to start looking.
When you were replacing bushings, did you also replace the cup bushing inside the shift rod head where it couples with the dongle on the transmission?

[mlindner]

You might have the shift rod a little farther onto the shift console fitting. That would reduce the throw into 3rd and 5th. Best, Mark

[rcrgyrl]

Thanks all - I did replace the cup bushing (more accurately I installed the cup bushing as it was missing completely). The PO had this engine installed in 2019 so I didn't think about mounts, but will check them today.

[rhodyguy]

Is the front to back shifter free play the same, engine not running, in 4th and 5th?

[rcrgyrl]

Is the front to back shifter free play the same, engine not running, in 4th and 5th?

A little less free play in 4th and a little more in 5th.

Engine mounts look good. Tranny mounts are older but don't look cracked or busted. Probably will replace them just because they are old and it doesn't hurt but I don't see that as the issue.

Thanks

[Morrie]

I have first hand experience with this, from troubleshooting to root cause.... the hard way (is there another??)

75 914 1.8 project. Got it running. Grinding bad into 2nd gear, popped out of 3rd gear. The rest was good. I have taken apart and repaired a few 901 transmissions so went after it, after checking all the bushings, and adjustments.

Inside, found some general wear, badly aligned shift forks, and a thrashed syncro ring on 2nd. All the gears clicked into place manually so I inspected everything, replaced the syncro ring, a couple dog teeth that were worn, and swapped the sliders from 2-3 / 4-5. Put it back together and back in the car.

Next thing I know, I have a great 1-2-3-4 experience now, but pops out of 5th instead of 3rd. Even though I inspected the slider and adjusted everything properly, the issue moved with the slider location and orientation. To make sure (you can do this now) it was the slider and not the linkage, you can do the following. Preferably on a lift but can be done CAREFULLY on securely placed jackstands.

First, pull the cover off of the shift rod at the side shift plate to expose the actual connection. Next, have a friend click it into the gear you are having issues keeping. carefully mark the location. now pop off the ball cup from the ball and see if the location changes... meaning the linkage is keeping the trans from fully going into that gear. If everything looks good, manually shift the trans into 5th with the ball disconnected, clutch in. Start the car (safely elevated.... I can't emphasize safety enough here) and let the clutch out gently. Even if 5th, off the ground it should start the wheels turning. Now lift off. If the trans pops out of gear like this, you most likely need to go in and replace parts. My advice there is to get a good used slider and just replace it, rather than doing what I did, thinking I had inspected well enough. In mine, the groove must be worn just enough to not be able to manage the torque and keep the gear locked/ engaged.

I am no expert at all, but I can tell you that if you have some patience, Dr. Evil's videos can help walk you through an inspection and repair of yours for probably $500 bucks including parts, video, and patience. I have a bunch of bits here, so let me know if you need anything. I've scrapped a couple tail shifters for goodies.

Best of luck- and if you want real help, reach out to Mike (Dr. Evil). He is the absolute best and will take care of you with a rebuild if you want to go that route, and it will be done well and fairly.

[rcrgyrl]

Thanks for the suggestions. Since I don't have a lift available for this car and am not comfortable with it running on jackstands I modified Morrie's suggestion a bit as follows

Put the driver's side rear up so the tire is not on the ground, but kept passenger side on the ground. (yes using jackstand - always jackstands)

Disconnect shift linkage.

Put car in 5th gear. Now, in theory, I should be able to turn the driver's side tire with the car in 5th and if properly engaged the engine will turn (like when adjusting valves). As soon as I tried this, the tranny popped out of 5th. I figure if no shift linkage is hooked up and it comes out of 5th when I turn by hand its gotta be inside the tranny. So I'm pulling it in the next few weeks and taking it to be rebuilt.

Will let you all know what we find out, just for grins & giggles.