gearbox/shift issues - any suggestions?

[patrick911]

A few weeks ago I took the 1973 911T for an early morning drive, and just when the car was warmed up, i lost the use of 3rd and 4rd gear.
I managed to time the traffic lights (when I managed to finally get the car in 3rd for once) and got the car back home fortunately.
I played around a bit with the gear coupler, but when re-adjusting I could either engage 1 to 4 or 3, 4, 5th and reverse. Finding a way to use all gears did not work.

The play in the shift coupler seemed acceptable so I then ordered a new shift rod bracket & bushing (in tunnel) and figured, since I bought a Stomski paradigm shifter - stealth edition (as in: looks like your standard 915) for the RSR a while ago, to replace the whole lot.

Anyway, long story short, the shifter install & new bushings all worked fine, but re-aligning it with the shift-coupler does not.
I can get into 1 & 2, but it is extremely hard to get it into 3 and 4 but I can't reach the most right plane (5th & reverse) at all.
I have been trying various things, knowing this arrangement can be very fiddly, but i can't get it to work.
And there's a lot of resistance from the box, to the point where I fear I may be about to break stuff.

So what's next? I am starting to fear that the actual gearbox, or the shift rod coming out of the box, may be the issue.
The gearbox has been very noisy for the last few years, so maybe it is just time for a rebuild?
This is not something I think I can do myself, so where would you recommend I go for either to analyze this or for a gearbox-rebuild in Melbourne?

thanks,
Patrick

[Kane k]

A quick check you can do, before you go down the mechanic path, is check the shift fork.

Will involve a gearbox drain though, then obviously a refill, and if doesnt solve problem, then a total waste of money - your choice!

You will need to remove the shift fork per the photo below, 4 bolts and a new gasket for re-installation, order that first if you go ahead.

But the studs in shift fork do rattle free then the fork becomes loose.....hense bad shifting.

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You can see in photo below the stud has fallen out and the whole fitting was loose.

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I re-cut the bolt thread, got new bolts and faced them down, and to safety the bolts from further movement, i lockwired them. Job done.

Like i said this job will cost you time, a gasket and oil, and might not be the issue. It was a issue in my case, but who knows, just passing on information, best luck Patrick.

[Kane k]

Patrick I just looked through my assortment of sh*t, your lucky day.
Let me know if you need it can post to you, free of charge.


Mechanic wise i would recommend Darren at "Auto Coupe" in Eltham, he does gearbox rebuilds, you could ask him first, over the phone what he believes is going on, he is a great place to start.



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[Gus Carfi]

Nice work kane

[patrick911]

Apologies for not replying sooner.
Yes, thanks heaps Kane for taking the time to respond. I have spend another Saturday trying to get this done, but in the end I gave up. I reached out to Darren at Autocoupe and he'll take a look.
I know the coupler can be very fiddly to get right, but for some reason the shift - and always just the single plane - goes way too heavy so something's not right.
Let's hope Darren can fix it....

[Kane k]

Darren will get you sorted, no worries

[patrick911]

He sure has.
The car drives like a dream, shifting is so much more precise than the original 915 ever has done.

Ah and yes, it was a walk-of-shame as I had made two big mistakes; first to not clean out the cup so the new shifter bearing sat too high, second, the shift-bearing that sits just beyond the shifter in the tunnel was fixed - by me - incorrectly.
When I took the old one out, it must have slipped into the tunnel so I automatically assumed it was fixed under the tunnel-metal, not on top.

I think both these meant the alignment was completely off, causing the mechanism not to want to move at all.
There was also too much play at the shift-coupler, which Darren fixed, but yes, not my finest day in the garage....