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10-03-2013, 01:33 PM | #1 |
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Join Date: Sep 2012
Location: Queen Creek, AZ
Posts: 551
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Bad tranny leak! Seal with yoke/driveshaft?
Hey guys,
My TH400 has leaked since I bought it. and not a little bit, a pretty decent amount comes out where the transmission meets up to the driveshaft. I replaced the pan and governor seal when i first bought it and didnt help the problem at all. Is there a seal between the driveshaft and yoke when I goes in the transmission that I can replace? It seems to be stemming from that location. If so, easy at all? I'm still half noob... Any other thoughts would be great. Thanks! Posted via Mobile Device
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Weev- Life's tough...... It's even tougher when your stupid - John Wayne |
10-03-2013, 02:02 PM | #2 |
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Join Date: Aug 2013
Location: Fort Worth, TX
Posts: 309
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Re: Bad tranny leak! Seal with yoke/driveshaft?
Yes, the seal can be replaced by pulling out the drive shaft, prying out the seal in the end of the tail shaft, and installing a new seal. Hardest part is getting the old seal out. Buy a replacement seal and you will see how it installs.
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10-03-2013, 02:10 PM | #3 |
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Join Date: Jan 2012
Location: Whitesboro, Texas
Posts: 932
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Re: Bad tranny leak! Seal with yoke/driveshaft?
We had the same problem with our TH350 – after replacing the output shaft seal it still leaked. Turned out to be the yoke on the drive shaft – it had worn down enough over the last 40+ years so it wouldn’t seal properly.
Good luck!
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Cheers - Wayne Our Shop Build - http://67-72chevytrucks.com/vboard/s...d.php?t=620966 '55 Wagon Build - http://67-72chevytrucks.com/vboard/s...d.php?t=689157 1971 Cheyenne Super Ochre/White LWB 350 Auto - my son's truck "Nancy" 1972 GMC K2500 Custom 4X4 Olive LWB 400 SB 4-speed -"Greenie" - Restoration to begin after the '55 Nothing sucks more than that moment during an argument when you realize you're wrong. |
10-03-2013, 04:01 PM | #4 |
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Join Date: Jun 2010
Location: Upland Ca
Posts: 4,147
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Re: Bad tranny leak! Seal with yoke/driveshaft?
Yes, easy job. Clean the trans lip where the new seal goes very well and apply a "little" sealer to the metal lip of the seal before tapping in. Apply a assembly lube, cam lube or grease to the rubber part of the seal before installing yoke.
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
10-03-2013, 09:38 PM | #5 |
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Join Date: Sep 2012
Location: Queen Creek, AZ
Posts: 551
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Re: Bad tranny leak! Seal with yoke/driveshaft?
Thanks for the heads up guys. auto zone by my house said there is two different sizes of seals when I asked if they had one in stock, will have to measure when I pull it out. When I unbolt the u joint by the axle, when I go to pull out the yoke... Is there a pin or anything I need to remove? Googling online I read about some pin to pull... Just double checking.
Thanks again!
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Weev- Life's tough...... It's even tougher when your stupid - John Wayne |
10-04-2013, 09:48 AM | #6 |
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Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: Bad tranny leak! Seal with yoke/driveshaft?
The TH 400 has two different tailshafts which take different size yokes/bushings and seals. I am not sure when the changeover was made but up to 70 the transmission had the smaller yoke/seal. Spline size is the same but the yoke diameter where the seal/bushing fits is different. The larger yoke is 1.885 amd the smaller yoke is 1.685 approximately.
Check the fit of the bushing/yoke in case it is worn to the point where the seal won't work. If the yoke is loose then the bushing and/or yoke will need to be replaced. Jim
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1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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