| Trans Fluid in Final Drive [message #371428] |
Sun, 02 July 2023 22:42  |
Jess Bressi Cortez
Messages: 16
Registered: February 2014
Location: Orange County, CA
Karma: 0
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Junior Member |
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Greetings all,
First some background: I have a recently rebuilt Turbo 425 that works perfectly, about 5,000 miles since the rebuild. I've used 100% full synthetic Valvoline MaxLife ATF in the transmission since the rebuild. The label on the jug says it is recommended for use in vehicles that use DEXTRON II, III and VI. Valvoline's website says it is backwardly compatible with DEXTRON. My final drive is a 3.70 from Applied. It has about 25,000 miles on it. After about 5,000 miles, I changed the Final Drive from Dino gear lube to full Synthetic Mobile 1 gear lube. The issue: I am leaking a little transmission fluid. It looks like it may be coming from the Final Drive. It doesn't appear to be coming from the Final Drive Vent nor the axles. I drained the Final Drive today and rather than draining the 4 pints/2 quarts I expected, I drained almost 6 pints/3 quarts and it has a decidedly red tint to it. When I installed the rebuilt transmission a year ago, I also re-did all of the seals in the Final Drive, including the expensive double pinion drive seals. Is it possible that the final Drive Pinion seals just can't keep fully synthetic tranny fluid out of the Final Drive? I'm thinking I should try old school Dino/Kerosene-based ATF and see if the problem resolves. Anyone hear of this problem before? Thoughts?
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets
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| Re: Trans Fluid in Final Drive [message #371430 is a reply to message #371428] |
Mon, 03 July 2023 07:00  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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For trans fluid to get into thge final drive, would it not have to get past both the trans output shaft seal and the diff input shaft seal?
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Trans Fluid in Final Drive [message #371434 is a reply to message #371428] |
Mon, 03 July 2023 10:45 |
Jess Bressi Cortez
Messages: 16
Registered: February 2014
Location: Orange County, CA
Karma: 0
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Junior Member |
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Thanks for the prompt responses.
First, my understanding is that the surfaces between the transmission output and final drive are "wet" so the output shaft seal on the transmission (I don't know if there is one there or not, I'll look at the trans manual to confirm) isn't the only possible source of fluid into the final drive.
Second, I installed the new seals exactly in the orientation I took the old "Applied" ones out and my recollection is that they were oriented as in the photos.
I guess I'll pull the final drive and re-seal it once again. One thing I didn't include in my prior post was that this was also happening a year ago before I replaced the transmission (a completely new core was used) and re-sealed the final drive. It didn't recur for a year and 5,000 miles.
Change any views? TIA, Jess
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets
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| Re: Trans Fluid in Final Drive [message #371436 is a reply to message #371428] |
Mon, 03 July 2023 12:11 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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If you're gonna remove the final drive, check it and the trans output for sideplay.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Trans Fluid in Final Drive [message #371439 is a reply to message #371434] |
Tue, 04 July 2023 22:35 |
dsmithy
Messages: 210
Registered: July 2012
Location: Lincoln Nebraska
Karma: 0
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Senior Member |
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Jess,
Listen to Larry W. He was the Blacklister that rescued me when my transmission went south due to low fluid (which exited through the 3:70 final drive that I had installed that spring). Another Blacklister, John Biwersi who knows final drives, identified incorrectly installed seals at the input side. To his everlasting credit, JimK shipped me a new final drive at no cost to me. It's now 40K miles down the road with no problems from the transmission or drive. Those seals are fussy and matter.
Douglas & Virginia Smith,
dsmithy18 at gmail,
Lincoln Nebraska,
’73 “Sequoia” since ‘95: "Wanabizo";
Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy wheels/Sundry other
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