727 output shaft leaking

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smokinnjokin

smokinnjokin

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Whats missing here? I have taken the car to 2 separate shops to put a new seal in, but its still leaking like a sieve.
It seems to me like a seal is missing. 727 in a 67 satellite. Swap from unknown donor.
B96A6F54-D0CB-4ECC-B7D5-AF313EAAEB60.jpeg
 
Looks like the correct seal on there, and its brand new. Is there an inner o-ring that could be missing or damaged on install?
480734B9-1F04-4596-9052-83A55235BF6A.jpeg
 
Are they replacing the tail shaft bushing or oil seal only? If the bushing is worn not supporting the shaft/yoke the seal will leak.
 
Looks like the yoke is hanging out too far, which could cause the yoke to spin in a larger circle wearing out the seal much quicker.
 
Dicer said:
Looks like the yoke is hanging out too far, which could cause the yoke to spin in a larger circle wearing out the seal much quicker.
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This is a swap, 360/727/8-3/4 into 318 car. Do I need a longer driveshaft? That would explain the problem. Right when seal is replaced it is good, but leaks again within few hundred miles.
 
727 does have a longer bushing than 904 but yes the yoke needs to be at least close to correct depth. Yoke travels in and out as rear axle moves up and down. So without knowing vehicles stance when pic was taken, we can't know for sure where the yoke actually runs.
 
That is sitting on the ground with full tank and no driver. So about that’s as far out as the yoke travels, other than going over bumps. I will dump the air shocks and take another pic of it all the way in.
 
With that seal the boot should be back as far as the clean part. The driveshaft is too short. Probably need a new yoke also. I would replace the bushing also. Kim
 
smokinnjokin said:
That is sitting on the ground with full tank and no driver. So about that’s as far out as the yoke travels, other than going over bumps. I will dump the air shocks and take another pic of it all the way in.
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If you want to see the driveshaft all the way in, support the frame rail and let the rear suspension droop fully. The rearend pivots on the front leaf mount. As the rear suspension droops, the rear moves slightly forward. It's not much though - about 1/8" on my 66. Most people think the driveshaft pulls out as the suspension droops, but that's just not true.

I'd disconnect the driveshaft at the rearend and insert it completely in the trans then pull it out and connect it with the rearend (at ride height), and see how much it pulls out from all the way in. It should be about 3/4"-1". It looks pretty far out to me in the photo (driveshaft is too short).
 
Yoke and bushing are probably worn. Can you shake that yoke? Driveshaft way too short. Imagine how far in that yoke could go if that wasn't a booted seal. Might be able to reuse a worn yoke if it rides in an unworn section after the driveshaft is stretched a bit.. But I bet that tail bushing is shot.
 
Well that explains why this thing is eating tail bushings. Now to find the proper length driveshaft.
 
Thanks all for the tips. Going to do a tf-2 shift kit, add part throttle kickdown, replace the bushing and rear seal on trans, and get a longer driveshaft. I talked to a guy at a Nashville d-shaft shop, and he said that he might not be able to lengthen the one I had, and that he thought it next to impossible to junkyard-pick one. Between FABO and FBBO, I'm hoping to be able to find one.
Based on my crude measurements, my current shaft is 51" from center of u-joint to center.
With my suspension going through full range of travel, I need a 52-52.5" shaft to keep 1" of spacing between slip yoke and bushing. Any idea what car had that d-shaft? 727 slip yoke on one end, 8-3/4 on the other.
 
smokinnjokin said:
Thanks all for the tips. Going to do a tf-2 shift kit, add part throttle kickdown, replace the bushing and rear seal on trans, and get a longer driveshaft. I talked to a guy at a Nashville d-shaft shop, and he said that he might not be able to lengthen the one I had, and that he thought it next to impossible to junkyard-pick one. Between FABO and FBBO, I'm hoping to be able to find one.
Based on my crude measurements, my current shaft is 51" from center of u-joint to center.
With my suspension going through full range of travel, I need a 52-52.5" shaft to keep 1" of spacing between slip yoke and bushing. Any idea what car had that d-shaft? 727 slip yoke on one end, 8-3/4 on the other.
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boy, there`s some bullshit and wrong thinking in this thread !
 
smokinnjokin said:
Care to enlighten me? I'm listening.
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I have had 4 diff driveshafts built , 2 chevies , a hemi , and this currant 440/505 wedge barracuda .
By two diff. driveline shops/specialists , both said to measure the center to center distance w/ the car setting in the static position . They then took an inch off the measurement for the length , never had a problem , 10 ;20 and 10 ; 40 cars ------------
 
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