Pontiac - Race The next Level

          
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  #1  
Old 10-06-2025, 10:00 PM
dv657172's Avatar
dv657172 dv657172 is offline
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Default Transmission Slip Yoke insertion depth

65 GTO drag car - TH400

My current Spicer slip yoke (casting #C3-3-319) looks to have an approximately 3" long shaft with approximately 1.5" outside the transmission with car at rest leaving 1.5" in the transmission.

I have seen a recommendation that there should be more like 3" in the trans and 0.75" - 1.0" of the shaft outside the transmission.

Do I need a slip yoke with a longer shaft?
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1965 GTO Cameo White, Red Interior - 389, ST300 numbers matching
1965 GTO Black, Black Interior "Post" car - 389, M-20 numbers matching
1965 GTO Silver, Black Interior 100% dedicated drag car w/1968 400(461), 16x Heads, TH400, 3.90 9" Rear 1.656 60' 7.566 90.057 (1/8th)
1971 GTO Black (orig. Quezal Gold), Gold Interior - 400, TH400 numbers matching
1972 GTO Cardinal Red, Black Interior - 455, TH400 almost numbers matching
  #2  
Old 10-07-2025, 03:41 AM
Dragncar Dragncar is offline
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How long is your tailshaft ? I was having a problem with a T400 out of a Olds station wagon. Rear section of the transmission is 9 1/2".
I ran the stock one that came with trans with adapter U joint for years with no issues. But I wanted to upgrade with the new engine's greater power. Tried to get a long one from Summit, they are long and all but the splines were not full length inside, so it stuck way out. Did not like it. Sent it back.
I tried the standard length ones and it just went past the rear bushing kinda like yours. Made a couple passes, not liking it.
What I did was call Inland Empire Driveline and sent them my factory one from the station wagon. They custom made one just like it with full splines but for 1350 U joint. Made from 4340.
Cost over 200$ but it was worth it.

  #3  
Old 10-07-2025, 08:18 AM
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dv657172 dv657172 is offline
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Dragncar - Tailhousing looks to be 4" long
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__________________
1965 GTO Cameo White, Red Interior - 389, ST300 numbers matching
1965 GTO Black, Black Interior "Post" car - 389, M-20 numbers matching
1965 GTO Silver, Black Interior 100% dedicated drag car w/1968 400(461), 16x Heads, TH400, 3.90 9" Rear 1.656 60' 7.566 90.057 (1/8th)
1971 GTO Black (orig. Quezal Gold), Gold Interior - 400, TH400 numbers matching
1972 GTO Cardinal Red, Black Interior - 455, TH400 almost numbers matching
  #4  
Old 10-07-2025, 10:17 PM
Dragncar Dragncar is offline
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Get a new yoke. If you are racing I would not want a "casting". Forged or billet only.

  #5  
Old 10-11-2025, 11:04 AM
dv657172's Avatar
dv657172 dv657172 is offline
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Location: Maryville, TN
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Thanks Dragncar for the advice, especially since I just installed a higher stall converter. Will upgrade over the winter.

Any recommendations in terms of brand?

__________________
1965 GTO Cameo White, Red Interior - 389, ST300 numbers matching
1965 GTO Black, Black Interior "Post" car - 389, M-20 numbers matching
1965 GTO Silver, Black Interior 100% dedicated drag car w/1968 400(461), 16x Heads, TH400, 3.90 9" Rear 1.656 60' 7.566 90.057 (1/8th)
1971 GTO Black (orig. Quezal Gold), Gold Interior - 400, TH400 numbers matching
1972 GTO Cardinal Red, Black Interior - 455, TH400 almost numbers matching
  #6  
Old 10-12-2025, 02:01 PM
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73LeMans 73LeMans is offline
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Strange

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Who needs nice and pretty, when you can have mean and nasty?
KRE Aluminum headed 463CID 73 LeMans. Used to run 10.6x @ 124.55. 3700lbs
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So much for 2020...shootin for 9s in 2021...and in 2022 apparently.....and 2023....and 2024.....and 2025.....who am I kidding? there will be no 9s with this engine!
>>My 73 Build thread
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