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TOPIC: Internal Transmission Failure

Internal Transmission Failure 03 Dec 2009 16:50 #43


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My '78 5-speed - with a 4.7L engine - just experienced what the transmission specialist calls "internal transmission failure." I'm in San Antonio, Texas, and what prompted the trip to my general mechanic was that 1st gear started getting harder and harder to engage, and then the shifter started slipping out of 3rd.

I'd appreciate the following:

1. Any insight into what transmission horror awaits me;
2. A trustworthy 928 transmission specialist in San Antonio, Austin, or Houston (or somewhere in between).
3. Resources for rebuild parts, a rebuilt unit, etc.

Thanks.
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Internal Transmission Failure 03 Dec 2009 17:16 #44


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Obviously, you need new synchronizers. Other than that, there is really no telling until you get more details.

I would check out 928intl.com and 928gt.com first for replacement parts. By the way, your car should have the 4.5L and not the 4.7L engine.
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Internal Transmission Failure 04 Dec 2009 18:30 #45


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Well, this '78 is kind of a "frankenporsche". It's a ROW/German spec, with a the first 4.7L S engine swapped in about 5 years ago by the previous owner. When he bought it, the original tan/pascha interior had been redone in red & white and "authorized" by Porsche. The dash & gauges were replaced, so the only German originals are the indicator light display and the speed control stalk. It also has an "S" whale-tail spoiler.

I checked 928Intl.com, and found a rebuilt tranny and syncro's; I'm wondering whether the tranny failed partly because of increased torque from the larger engine, and if it can/should be replaced by a later year tranny to match the "S" engne.
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Internal Transmission Failure 04 Dec 2009 19:06 #47

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I am not aware of any differences in the transmission, but 928 Intl will know for sure. I had the transmission for my '80 Euro S rebuilt by them, and was VERY happy with the work, and results.

If you haven't considered it, now is a good time to consider an LSD upgrade if you don't already have one as well.

Synchros are a very weak point on the older transmissions. There was an improvement in '85 (if I recall correctly) that made a big difference. You could consider swapping in a newer transmission as well. Again 928 Intl will have the answers for you.
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Internal Transmission Failure 10 Dec 2009 00:01 #56


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Thanks. That's the kind of feedback I was looking for. I'll check with 928intl to see if a rebuild with all "new" synchro's is sufficient, or if it's possible/prudent to swap for an '85 tranny. The LSD upgrade suggestion is duly noted, and while I'm at it, I plan to swap in a short-throw shifter; while I'm not trying to create a track monster, I am looking to optimize performance and durability whenever possible.
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Internal Transmission Failure 10 Dec 2009 07:08 #57

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928 Int'l process at the time was to rebuild the entire transmission, replacing what was needed. They might have one to swap for you, in my case at the time they did not, so had my transmission rebuilt.

Just an fyi: The short shifter is nice, I have it in both of my cars (track and street), it is a simple upgrade and pretty much separate from any transmission work.
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Internal Transmission Failure 27 Jan 2010 17:32 #94


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:DGreat news on the old girl! It was shift linkages; all were replaced by Jones Autowerks in San Antonio for a reasonable sum. Thanks for everyone's help.:D

Fitz
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