Check the tail shaft bushing. If it's worn the seal will pull down causing a leak. Just a thought.
How do I fix this leaky TH350
I have a TH350 that came in my 69 Vert. The previous owner bought it from Jegs, it's probably got less than 2000 miles on it since it was bought.
I fixed the first 2 issues present when I bought the car pretty easily, the pan gasket leaked (overtightened bolts and a cork gasket) and the rooster comb was loose on the shift shaft. Since then it has functioned perfectly.
The trans has always leaked out of the output seal. I replaced the seal and the slip yoke (with a used but unscored yoke) first, then replaced the seal again when I installed a Denny's driveshaft (with a brand new slip yoke) fabricated to work with the QP 9" rear I installed last year. It still leaks quite a bit of ATF past the slip yoke when sitting. It've very annoying.
The engine is being replaced with an LS1 in a few months so I'm gonna pull the trans at the same time. It would be great to resolve the leaky tailshaft once and for all.
Any suggestions?
Thanks
Joe
I fixed the first 2 issues present when I bought the car pretty easily, the pan gasket leaked (overtightened bolts and a cork gasket) and the rooster comb was loose on the shift shaft. Since then it has functioned perfectly.
The trans has always leaked out of the output seal. I replaced the seal and the slip yoke (with a used but unscored yoke) first, then replaced the seal again when I installed a Denny's driveshaft (with a brand new slip yoke) fabricated to work with the QP 9" rear I installed last year. It still leaks quite a bit of ATF past the slip yoke when sitting. It've very annoying.
The engine is being replaced with an LS1 in a few months so I'm gonna pull the trans at the same time. It would be great to resolve the leaky tailshaft once and for all.
Any suggestions?
Thanks
Joe
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I considered that the bushing might be canted.
It certainly shouldn't be worn out, allegedly the trans was rebuilt.
Being as the "rooster comb" was loose when it arrived from Jegs, the entire assembly is suspect IMHO. Maybe it was a Friday afternoon unit. I guess I'll find out when I pull it.
Thanks.
It certainly shouldn't be worn out, allegedly the trans was rebuilt.
Being as the "rooster comb" was loose when it arrived from Jegs, the entire assembly is suspect IMHO. Maybe it was a Friday afternoon unit. I guess I'll find out when I pull it.
Thanks.
I agree with the above with the bushing.
Does it have any up and down play ?
Another though is, how far in is the slip yoke ?
Just thinking if not in far enough and allowing the yoke to move out too far and causing premature wear ?
Does it have any up and down play ?
Another though is, how far in is the slip yoke ?
Just thinking if not in far enough and allowing the yoke to move out too far and causing premature wear ?
Custom driveshaft. The yoke is buried in the tailshaft housing. Never noticed if there was play in the bushing, I'll have to inspect when I pull the trans.
Still about 1/2-3/4" of shaft showing ?Custom driveshaft. The yoke is buried in the tailshaft housing. Never noticed if there was play in the bushing, I'll have to inspect when I pull the trans.
Please excuse my ignorance but what exactly is a "rooster comb"? Had several TH350 and TH400 cars, built my own TH400 a few years back, but unfamiliar with this term. Just curious. Thanks.
Maybe I'm using the wrong terminology. The plate attached to the shift shaft inside the trans has notches for a spring that create the detents for the gear positions. I heard it called a roster comb.
Please excuse my ignorance but what exactly is a "rooster comb"? Had several TH350 and TH400 cars, built my own TH400 a few years back, but unfamiliar with this term. Just curious. Thanks.
Nope, that is what it is. Rooster comb.Maybe I'm using the wrong terminology. The plate attached to the shift shaft inside the trans has notches for a spring that create the detents for the gear positions. I heard it called a roster comb.
Scudzuki & Doug, thank you guys for the reply & helping me learn something new! I googled it and it the pics of chicken/rooster combs came up. Perfect term for this part, looks just like the the animal. My uncle that farms would be disappointed in me for not knowing. Always curious, had to ask or miss a chance to learn something. Nice 69 Scudzuki by the way!
That yellow arm in the pic is what you hear click when shifting gears and sometimes the bolt that holds it comes loose and if your car ever drifts when in park and you hear that dreaded click, click, click...this is whats wrong and is an easy fix as Scudzuki found.Scudzuki & Doug, thank you guys for the reply & helping me learn something new! I googled it and it the pics of chicken/rooster combs came up. Perfect term for this part, looks just like the the animal. My uncle that farms would be disappointed in me for not knowing. Always curious, had to ask or miss a chance to learn something. Nice 69 Scudzuki by the way!
The seal leaked with the original driveshaft with 2 different yokes (the first of which was scored right where the oil seal contacted) so I know the yokes were properly engaged.
When I bought the car, it was difficult getting the car into the forward gears. To get it in any gear, the new reproduction console shifter had to be pulled back to the 1st gear position then forward to the desired gear. It could not be manually shifted into 1st gear at all. It took all of a minute under the car to figure out that whatever the shift shaft connected to inside the trans was loose on the shaft, or the trans was totally effed. A local-ish transmission expert I talked to suggested the rooster comb was loose. I was armed with a new 2 piece RMS, a new Melling high volume oil pump, a new pan gasket, and a new trans pan gasket when I got the car back on the lift. Replacing the RMS revealed a scored rear main bearing and journal but I installed the new RMS and reinstalled the bearing cap anyway then replaced the oil pump and pan gasket and pan. I pulled the trans pan, tightened the loose nut on the shift shaft, fixed the deformed pan flange using a ball peen hammer and a socket (as an anvil) to "tent" slightly each bolt hole towards the bottom of the pan, replaced the cork gasket with a silicone one, reinstalled the pan without torquing the living $hit out of the pan bolts, readjusted the shift cable, filled the engine with 20w-60 synthetic oil and topped off the tranny fluid. It's been a pleasure to drive ever since but the oil pressure is still low as soon as the engine is up to temp and I know it needs some bottom end maintanence. The trans fluid leak bothers me too. The RMS no longer leaks, at least.
It's what I always referred to as the "parking pawl". But it will be a rooster comb going forward to me, explains it perfectly! I really welcome opportunities to keep learning & that led to ask the question. Appreciate you guys helping me out.That yellow arm in the pic is what you hear click when shifting gears and sometimes the bolt that holds it comes loose and if your car ever drifts when in park and you hear that dreaded click, click, click...this is whats wrong and is an easy fix as Scudzuki found.
The rooster comb is the gear selector actuator, it's not the parking pawl. If it comes loose on its shaft, it results in an inability to precisely control what gear the trans is in (and thus whether or not the parking pawl is fully engaged) via external inputs (the rotation of the shift shaft and the shifter position) but the comb and the pawl are not the same component.
Not an economical fix for the leak....replace it with a 200R4! Hey honey, my trans has a small leak, looks like I'll for sure need a new trans...forum guys all agree so must be the ONLY possible solution! Yea, that should work. 
On my original TH350 trans inside the trans right behind the speedo gear is a can with an O ring on it that the yoke slides into. The yole has a vent hole in the center that will drip fluid if the can is missing.
Jeff
Jeff
I have this same leak on my 350. I am planning to replace the o-rings as well. I'd like to go 200r4 also but haven't found any locally to rebuild.Not an economical fix for the leak....replace it with a 200R4! Hey honey, my trans has a small leak, looks like I'll for sure need a new trans...forum guys all agree so must be the ONLY possible solution! Yea, that should work.
I finally pulled the motor and trans yesterday and removed the TH350 tailshaft housing.
This is a Jegs performance trans with a few thousand at most miles on it. The tailshaft housing is intact. The vent on top of the trans is not occluded. I don't see any indication the fluid is leaking anywhere other than the yoke/seal interface (even when the car sits).
I measured the bushing and yoke and there's .006" clearance (1.508" bore, 1.502" journal) which I think might be enough to allow sufficient deflection of the yoke to create a gap in the seal. I ordered a new bushing and seal. This will be the 4th new seal and the yoke is new.
I've also been eyeing up the sleeve and o-ring that is available. Not sure if I should install one of those as well. I can't see where the o-ring would seal being as the output shaft is splined right up to where the speedo drive gear mounts. From what I can tell, the sleeve is used in vented tailshaft housing applications, and my tailshaft is not vented.
Again, any insight is appreciated, thanks.
Next stop, LS swap! Woo hoo!
Joe
This is a Jegs performance trans with a few thousand at most miles on it. The tailshaft housing is intact. The vent on top of the trans is not occluded. I don't see any indication the fluid is leaking anywhere other than the yoke/seal interface (even when the car sits).
I measured the bushing and yoke and there's .006" clearance (1.508" bore, 1.502" journal) which I think might be enough to allow sufficient deflection of the yoke to create a gap in the seal. I ordered a new bushing and seal. This will be the 4th new seal and the yoke is new.
I've also been eyeing up the sleeve and o-ring that is available. Not sure if I should install one of those as well. I can't see where the o-ring would seal being as the output shaft is splined right up to where the speedo drive gear mounts. From what I can tell, the sleeve is used in vented tailshaft housing applications, and my tailshaft is not vented.
Again, any insight is appreciated, thanks.
Next stop, LS swap! Woo hoo!
Joe
The correct sleeve mounts under the speedo gear and the o ring seals around the yolk. The purpose of the sleeve and o ring is to prevent t fluid from getting down the splines and leaking out the vent hole in the yoke. In my short time working at AAMCO back in the 70s I saw this a few times.I've also been eyeing up the sleeve and o-ring that is available. Not sure if I should install one of those as well. I can't see where the o-ring would seal being as the output shaft is splined right up to where the speedo drive gear mounts. From what I can tell, the sleeve is used in vented tailshaft housing applications, and my tailshaft is not vented.
Joe
Jeff
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