1969 driveshaft
Thread Starter
Racer
Joined: Aug 2001
Posts: 401
Likes: 22
From: SF CA
1969 driveshaft
Hi,
Everyday it is something new. I brought my driveshaft in to be balanced today and the man immediately said it was from a small block Vette and claimed to be an authority on them because he Dad owned many of them. My driveshaft holds "1310" U joints. He claimed that the big block driveshafts held larger "1350" U joints.
I called one of my sources and he checked, called me back and said, "All 68-70 4 speeds had the same driveshaft which I have and all of the automatics used a driveshaft with larger ends and called for a larger transmission yoke."
Opinions please?
Thanks
Everyday it is something new. I brought my driveshaft in to be balanced today and the man immediately said it was from a small block Vette and claimed to be an authority on them because he Dad owned many of them. My driveshaft holds "1310" U joints. He claimed that the big block driveshafts held larger "1350" U joints.
I called one of my sources and he checked, called me back and said, "All 68-70 4 speeds had the same driveshaft which I have and all of the automatics used a driveshaft with larger ends and called for a larger transmission yoke."
Opinions please?
Thanks
Safety Car
Joined: Jul 2001
Posts: 4,456
Likes: 6
From: Spicewood, Texas, USA TX-Texas
Re: 1969 driveshaft (BAD-L88)
Jay, your second source is correct.
From 68-70, all four speed transmission driveshafts are the same, GM PN 3957056. This shaft is 29 7/8" long center to center, and is 2" in diameter. All THM transmission driveshafts are PN 3921675, and are 29 1/2" in length and 2 1/4" in diameter. In 71-72, all transmissions used the 3921675 driveshaft previously used only for the automatic transmission cars. After 72, I have no information, but I suspect they continued to use the 3921675 driveshaft until the aluminum driveshafts began, or until the differential redesign, whichever came first.
The difference in 68-70 SB and BB universal joints is NOT in size, but in configuration: BB and LT-1s use bolted cap attachment to the corresponding yokes, all other small blocks use special U-bolts to secure the universal joint caps to the yokes.
You should tell your driveshaft mechanic that relying on his memory will become increasingly hazardous with advancing age. He is probably thinking his old man used to have a big block Corvette with a four speed, when if fact, he had one with a THM transmission. :D :D :D
[Modified by Chuck Sangerhausen, 7:30 AM 2/26/2002]
[Modified by Chuck Sangerhausen, 7:42 AM 2/26/2002]
From 68-70, all four speed transmission driveshafts are the same, GM PN 3957056. This shaft is 29 7/8" long center to center, and is 2" in diameter. All THM transmission driveshafts are PN 3921675, and are 29 1/2" in length and 2 1/4" in diameter. In 71-72, all transmissions used the 3921675 driveshaft previously used only for the automatic transmission cars. After 72, I have no information, but I suspect they continued to use the 3921675 driveshaft until the aluminum driveshafts began, or until the differential redesign, whichever came first.
The difference in 68-70 SB and BB universal joints is NOT in size, but in configuration: BB and LT-1s use bolted cap attachment to the corresponding yokes, all other small blocks use special U-bolts to secure the universal joint caps to the yokes.
You should tell your driveshaft mechanic that relying on his memory will become increasingly hazardous with advancing age. He is probably thinking his old man used to have a big block Corvette with a four speed, when if fact, he had one with a THM transmission. :D :D :D
[Modified by Chuck Sangerhausen, 7:30 AM 2/26/2002]
[Modified by Chuck Sangerhausen, 7:42 AM 2/26/2002]
Thread Starter
Racer
Joined: Aug 2001
Posts: 401
Likes: 22
From: SF CA
Re: 1969 driveshaft (Chuck Sangerhausen)
Chuck, thanks for confirming for me.
Are you sure about the yokes vs the U bolts? I know I have yokes on my half shafts but I think I have U bolts on my driveshaft,
Are you sure about the yokes vs the U bolts? I know I have yokes on my half shafts but I think I have U bolts on my driveshaft,
Safety Car
Joined: Jul 2001
Posts: 4,456
Likes: 6
From: Spicewood, Texas, USA TX-Texas
Re: 1969 driveshaft (BAD-L88)
Are you sure about the yokes vs the U bolts? I know I have yokes on my half shafts but I think I have U bolts on my driveshaft,
Jerry, I didn't mention that part about the grease fittings because I thought EVERBODY knew that! How about putting your mind and mouth to good use, and help BAD-L88 answer his question about the driveshaft universal joints since you have owned many big block Corvettes. :D :D
[Modified by Chuck Sangerhausen, 7:43 AM 2/28/2002]
Safety Car
Joined: Jul 2001
Posts: 4,456
Likes: 6
From: Spicewood, Texas, USA TX-Texas
Re: 1969 driveshaft (3X2-427)
Strange, I thought EVERYBODY knew DRIVESHAFTS had "U" bolts and not caps.
Sweetpea, I don't care what Howard thinks of you, you're tops in my book. I just think some people don't understand you. :cheers: :lol: :lol: :lol:
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Advanced
Joined: May 2019
Posts: 78
Likes: 5
From: Bellingham WA
Just to confirm, I have a factory big block and it used u bolts going into the differential and caps bolted on the half shafts. I changed the differential housing out with one that had come out of an automatic car and the flanges for the driveshaft hold a wider Universal joint. It also look like the yoke is a little longer in length so I would either need to shorten my driveshaft or put the old yoke back on. I didn't really want to mess with the crush sleeve but think getting a new crush sleeve and using my other yoke make the most sense.
