Pops out of 5th gear

[Larrybrook]

This just started happening yesterday. Car runs great, shifts into 5th no problem; but when I ease up on the throttle it pops out of 5th and into neutral. Transmission was rebuilt about 2000 miles ago. I do have new motor and transmission mounts that I have yet to install...mine are original to the car...could that be it? Also I would like to swap out the transmission fluid. I hear Swepco 201 is very good? How much do I need? Last time I used a large syringe and clear tubing to fill the tranny...got any better ideas?

Thanks in advance.

[fintstone]

Sounds like adjustment or your linkage (bushings) to me. Probably the bushings on the shift coupler if they were not replaced recently. Certainly not the fluid. Nice looking car!

[Larrybrook]

Bushings in the shift linkage have all been replaced, maybe just needs a little more adjustment? I've followed the recommended procedure from this forum.

I will get around to replacing the transmission and motor mounts one of these days...I promise...

[fintstone]

I would bet on the additional small adjustment if you have replaced the shift coupler bushings already. I have seen the exact same thing happen...coincidentally, also on a '74. It only takes a millimeter off to do this...either by a sloppy coupler that results in a slight adjustment error (or simply just an actual tiny bit of adjustment is needed).

[rwest]

Agree on needing adjustment if bushings are all good. 5th doesn’t usually go bad as you never downshift into it!

[Schulisco]

Shift linkage adjustment!
Had the same issue while readjusting the shift linkage after replacing the bushings ... When properly adjusted no more an issue.

Thomas

[proporsche]

Originally Posted by Larrybrook

This just started happening yesterday. Car runs great, shifts into 5th no problem; but when I ease up on the throttle it pops out of 5th and into neutral. Transmission was rebuilt about 2000 miles ago. I do have new motor and transmission mounts that I have yet to install...mine are original to the car...could that be it? Also I would like to swap out the transmission fluid. I hear Swepco 201 is very good? How much do I need? Last time I used a large syringe and clear tubing to fill the tranny...got any better ideas?

Thanks in advance.

To fill the transmission use the gravity-it takes 3+1/2 liters..take the tunnel cover off and let us see your shift coupler...
Cover in the middle behind the seats.

Ivan

[Larrybrook]

Here's a photo of the coupler and the shift lever in neutral. Maybe try to get the lever closer to 90 degrees?

[Schulisco]

Originally Posted by Larrybrook

Here's a photo of the coupler and the shift lever in neutral. Maybe try to get the lever closer to 90 degrees?

No measurements for this, just a feeling. That means: take the necessary wrenches for the shift coupler and do a test drive to warm up the gearbox oil (at least 15mls/25km) and then stop at the side of the road, adjust the shift coupler, drive a bit to test it, then stop again and readjust it if necessary. Keep doing this until the adjustment is perfect. Caution: Do not tug wildly on the gear stick and do not make large adjustment steps, otherwise you could end up with two gears engaged at the same time...
All gears must engage quietly and as smoothly as possible in a 915 gearbox.

https://www.youtube.com/watch?v=b3nPONBAaZM

https://www.youtube.com/watch?v=2xwpwKu2jb8

Thomas

[Larrybrook]

I think its wise for me to replace the transmission and motor mount first, since they are original to my 50 year old car...and I have them in the garage already. I just haven't got to it yet. I'll do that and report back after the weekend.

Thanks for your help

[pmax]

I would do the easiest stuff first.

Readjust the shift coupler, get that vertical, the last few times I simply adjusted it in the garage, checked by "feel" that the throws to each gear are somewhat balanced when engaging them, that's all. There's enough slop in the factory setup it's likely OK to do so.

One more thing, that set screw is a PITA to tighten sufficiently, check it.

[proporsche]

Originally Posted by Larrybrook

Here's a photo of the coupler and the shift lever in neutral. Maybe try to get the lever closer to 90 degrees?

looks like it is off the adjustment..look at the 1st video boy from Germany posted..
That is all it would take

Ivan

[Larrybrook]

I replaced the engine and transmission mounts, and adjusted the shift linkage. It sure feels better, I'll report back if it pops out of 5th ever again. I replaced the old gear oil with new Swepco 201, and discovered I was about 1/2 litre low...I wonder it that was a contributing factor?

[yelcab1]

Originally Posted by Larrybrook

..., and discovered I was about 1/2 litre low...I wonder it that was a contributing factor?

No it's not the cause. I know a lot of people on here are fanboys of Swepco but I am not one of them. Lubrication technology of 40 years ago do not impress me.

[Schulisco]

I see it differently. To me the oil matters definitively on a 915. Yes - todaysoils are way better than everything from 30years ago. But: Todays high sophisticated oils don't improve a 915. These old gearboxes require those old fashioned oils to make the synchros work: The secret is "drag torque" these old mineral oils provide. The 915 implements the old Porsche synchronization which urgently required the drag torque. The later G50 with their Borg-Warner synchros is another story.
https://nineelevenophilia.wordpress.com/tag/borg-warner/

Thomas

[fintstone]

Either way, the fluid does not make a tranny pop out of 5th, the alignment does (whether misaligned or bushing wear.

[Fixer]

The rubber bellows seal under the inspection plate can bunch up and pop them into N.