924Board.org

[Mitch Matherly]

Hey all,

So i recently finished an engine rebuild on my 79 924, and the cars running great. It was accompanied by a rebuild of the rear rtansaxle, where i had Kevin from Catellus Engineering replace the synchros on gear one. He did an excellent job, no compaints from me.

But when i put everything back together, i had one horribly frustrating flaw. The car refuses to engage first gear.

When i have the rear end raised in the air, it will turn the wheels if i sort of hold the shifter in place (it still does not fully engage). But when it's on the ground, the shifter just "bounces" in my hand, like it's refusing to mesh somehow. It does *start* to send power to the wheels, but it's not engaging at all so I don't try to get it moving that way because i don't want to break things. By "bouncing," i mean if i hold it into position, it forces my hand forward and then falls back again, over and over.

It even does this "bouncing" behavior with the clutch pressed in. I replaced all of the shift linkage bushings, to ensure that that wasn't the issue either.

Y'all think this is maybe just me doing something wrong on the rebuild? i'm really hoping there's something i can do without dropping the trans axle again, or that this is a known issue of some kind.

If any of you veterans on here have any advice, i'd apprciate your input.

[chuck21401]

I'm not an expert but recently installed a rebuilt G31 dog leg transaxle into my 931.

I believe that the 79 924 also has a dog leg transaxle, so I think they are similar...and have the same two rod shift mechanism.

I wonder if the problem could be related to adjustments in the shift rods, coupling and/or angular joint.

With my car it was tricky to connect the shift rod coupler to the transaxle. I remember having trouble tightening the conical screw (#16 below)- tight quarters. I'm not sure if it's possible to get that wrong...the screw should line up with the depression on the shift rod on on transaxle? Maybe something to check?

I replaced the angular joint (#11) below. Did you replace that one? There is some adjustment there in terms of screwing on the joint to the shift rod. In addition I think the shifter needs to be centered as that is installed and/or adjusted.

Are you able to get it into reverse?

Here's another thread to check out:
https://www.924board.org/viewtopic.php?t=22871



Here's the old and new angular joint. I marked the new part and moved the nut over. It took some convincing to get the joint on to the ball mount...but in the end shifting was much improved.




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1981 Porsche 931 w/S1 engine & euro g31 transaxle. Water-cooled intercooler

[Mitch Matherly]

Yeah, i did replace the angular joint. In my car i believe it was just a bushing that i replaced, but it really firmed up my shifting into every other gear. (i actually suspect this was my primary issue and that i did not need to disassemble the transaxle in the first place... whoops.)

But i can get into reverse just fine, and every other gear is smooth and firm as well. The two shift rod mechanism is a nightmare though, defintly worth a second look and something i didn't think to dedicate more troubleshooting time too. It would make sense, especially since the transmission went easily into first on the bench before i installed it in the car.

[Cedric]

Did they only change synchros or any other parts?
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1980 924 Turbo
www.instagram.com/garagecedric/

[Mitch Matherly]

Yeah, it was just the synchros. Rest of the parts are all original.