So the slip yoke In my aod trans is slowly dripping. I've pulled the nose and replaced the output seal and bushing and the drip is still present. It appears as if the middle of the yoke itself is the origin of the leak. I fingered some RTF sealant between the U-joint and the yoke and the leak stopped temporarily. I searched and it appears that some yokes have a hole in the center. Mine Definetly does not. I asked my mechanic why the slip yoke would leak and his response was that he has no idea but the the nose of the trans shouldn't have fluid in it anyway. That the trans must be shot if any fluid was down in the output shaft area. I reminded him about the grooves in the output bushing which are meant to circulate fluid but he assured me I was mistaken. Two questions. 1. Is he out of his mind? 2. Do slip yokes go bad? Mine appears to be two different types of metal pressed together. The main body and the splines look to be pressed in. This seam is where I suspect it is leaking from. Thoughts?
My thoughts, replace the slip yoke and find a new mechanic. If there is no fluid at the output shaft of the trany, why would there be a seal?
Yeppers, definitely the slip yoke. You may not see it, but there has to be some hole or relief somehwhere otherwise you'd never get the thing in or out due to trapped air and suction. I had good luck loading deep inside of slip yoke with chassis grease, kept the fluid from leaking out. This was on an S10 t5 yoke though. Mopars ran the relief along the splines into the inside of the tailshaft so there shouldn't be a leak ever. Never ran a Ford drivetrain...
The splines in the yoke or on the output shaft may be worn more than normal. That is a vent hole so it won't build up pressure between the end of the shaft and the inside of the yoke. Is the trans fluid at the correct level? Does it have the correct dipstick and dipstick tube ? Do you by chance park it on a steep driveway on a regular basis? Any of those might cause it to leak some. The tail shaft seal doesn't have any effect on the leak you are experiencing, the bushing however might hold the yoke a bit steadier and not let it move around if it had a loose bushing in it.
Fluid level was correct with what I assume is the original tube and dipstick. They were swapped into my 55 Plymouth with early 302 and aod 4 speed trans. The car is always parked inside my garage nice and level. After the sealer was applied to the yoke it didn't leak for a week. Then today I noticed a huge puddle under the car. Guess I'll pull the yoke and try a new one. Would I be able to feel the excessive wear on the output shaft and the yoke fitment? Or are we talking microscopic wear? The odd thing is, the mehanic is supposedly extremely well know. He has done suspension and exhaust on many many show cars including 2 riddler cars. To figure. Thank you gentleman.
There better be fluid in the tailshaft or everything will wear out. You can't run the bushing dry for very long. As to the necessity of venting the tailshaft, unless the precision of the splines has increased greatly, they aren't air tight or fluid tight. Often, one spline will be flattened to allow fluid to get into the splines to lubricate them.
You didn't say specifically what trans and yoke you have but if the yoke has a hole in it then either it has a groove machined in the smooth part of the yoke or output shaft for an oring or like some that have a sleeve that goes over the od of the yoke and is sealed onto the output shaft. Go to an older trans shop that might be able to help or someone in that brand dealership parts that may help. If the ykr and trans applications aren't compatable, make sure there is no seal inside, remove trans tailhousing and make sure it has no seal or sleeve. Weld up the hole, grind one spline on the output shaft about half off to allow pressure to bleed out of the yoke.
Check the slip yoke itself! I had a "Pommy" Ford Cortina that leaked oil down the center of the yoke. It had a type of "freeze plug" in the center that leaked. I was to blame because I fitted a driveshaft that was too long and bottomed out . Most slip yokes slide inside an external bush [in the tail housing ] which locates it.
........this may be a dumb suggestion, but is the yoke OD that the seal contacts scratched or grooved?
We had one in my shop a few years back that leaked out the center - but IIRC it was a Chevy. Cure? New Yoke! And his statement "the nose of the trans shouldn't have fluid in it anyway" scares me that he works on peoples cars - Of course there is oil in the tailshaft (WTF is a Nose?) or the damn thing would seize up. Ever noticed that if you pull the drive shaft fluid comes out?
On TH350s there' were 2 different types, 1 had an O ring on the output shaft and the other didn't. The one with the O ring had a yoke with a hole in it, the other had a sealed yoke.....BTW there is some fluid back there, but not full pressure.
Pull the yoke out and look at the splines. If you have splines to the end, there will be no o-ring on the output shaft. If the the splines start about 1-1 1/2 inches from the end of the yoke then your output shaft takes an o-ring that seals on the inside of the yoke, on that 1-1 1/2 inches that is smooth before the splines start. Those o-rings get hard over time and will cause leaks.
Greetings! In the absence of pictures, I'd say yoke. The "freeze plug" at the end of the yoke is leaking.
It does sound like the plug at the end of the splines . Install new plug with a little RTV around it . Find new shop to deal with !!!
i have same problem with my 727 and seems like when making or raparing trans some put a0.09 hole in yoke .i spot welded it an no problem now
Perhaps Kerrynzl is on the right track, as he is the first to suggest the "freeze plug", all I can add to the mystery, is perhaps since this is a retro fitted drivetrain, the length of the driveshaft might not be exactly perfect. Something had to upset the apple cart for this problem to develop. If the ds is slightly too long, then on extreme rear suspension compression, it could try and force the yoke forward against the output shaft, thus disrupting the plug.
Sorry guys just got back to working on the car. I was forced to move last minute to a 500sqft studio apartment with a 3 car garage I pulled the slip yoke from the car, flipped it vertical, and filled it with water. It pissed right out the center of the yoke on the u-joint side. How do I go about checking if the drive shaft needs to be shortened? I would imagine I can just reassemble a new yoke/ drive shaft and put the rear suspension under compression with my trans jack on the pumpkin all the way to the trunk and make sure the read tires still spin in neutral? As for finding a new yoke. I guess my best bet would be taking the trans serial number to the ford dealer and having them tell me what it came out of? Sorry guys, should have mentioned. I'm a young buck. Learning this all as I go.
Take this from an old tranny man, there is nothing wrong with the trans. There is a soft plug in the slip yoke, and that is leaking. This happens quite often, and it is not a serious problem. Just replace the slip yoke and be done with the problem
Maybe not....why is the plug leaking? The yoke should push all the way into the tranny then pull out 1 1/2 inches when the driveshaft is hooked up. Any less, the yoke gets slammed up against the tailshaft, pounding out the plug. Driveshaft too long is common among hot rod guys, see what caused the leak before buying more parts.
Good point, the previous owner claimed to daily drive the car for years and then within two months of me having it the yoke was leaking. I didn't do anything to the driveline except for put new shocks in the rear that was it. I planned to lower the rear with blocks but haven't attempted it yet. How do I go about testing for enough play in the driveshaft length? I understand the concept and need for the proper length but how do I determine if I have it? Is this 1.5" of play needed when the rear suspension is fully compressed or with zero load on it? I would imagine when fully compressed with the pumpkin to the trunk right?
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