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4R70W Tailshaft Leak

August 5 2005 at 3:16 PM

  (Login 69convert)
from IP address 67.164.193.53

 
I recently swapped a 4R70W into my '69 Mustang. The transmission works great with the Baumann controls, but I have a fairly bad leak from the rear. Is this most likely just the output seal/bushing? What else might cause that? Also, what all is involved in replacing both - do I just pull the housing off and do it, or can it be done with the housing in place?

Thanks!

EDIT: Probably wishful thinking, but is there anyway an overfull case can lead to a output seal leak? I think I may have overfilled the transmission quite a bit initially since I had a broken dipstick -

'69 Mustang Convertible


    
This message has been edited by 69convert from IP address 67.164.193.53 on Aug 5, 2005 3:42 PM


 
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allenman
(no login)
67.166.233.138

Re: 4R70W Tailshaft Leak

August 6 2005, 12:30 AM 

The rear 'seal' is a dust seal -- not a pressure seal so you are probably just overfull. Drain it down a bit and then check back in.

It's easiest to pull the tailshaft off (jack the tranny, remove x-member, driveshaft, unbolt tailshaft...) and replace the seal off the car.

 
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(Login 69convert)
67.164.193.53

Re: 4R70W Tailshaft Leak

August 7 2005, 1:11 PM 

Thanks Allenman - so if the case is overfull, it can leak out of that rear seal?

I'm using a dipstick and assy from a standard AOD - the tube sealed fine, but I'm wondering if the stick dips too low or something, and I'm full before it says I am. Any sure ways to confirm it?

'69 Mustang Convertible

 
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(Login 69convert)
67.177.29.35

Finally Getting Around to This

September 7 2005, 9:38 AM 

I've been on the road most of this month so I haven't tackled this yet. Before I go and buy parts, is the "rear seal" more than just the rubber boot on the back of the transmission? If it's just that rubber boot, that couldn't really be the source of my leak, could it?

'69 Mustang Convertible

 
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Silverfox
(no login)
208.178.240.12

Re: 4R70W Tailshaft Leak

August 8 2005, 12:25 PM 

Just to let you know, the c4/AOD 28 spline drivline YOLK is a smaller diameter than the 4R and should not be used. (I don't know if that is what you are using, just a guess if you didn't do the yolk swap also) If you do use it will not seal and it will not LUBE or turn inside the ext. housing bushing and cause serious vibration and eventual failure of the rear case bearing and case.

TWO SOLUTIONS to the issue mentione above.
1) Swap the C4/AOD yolk for the 4R yolk
2) Swap the Ext Housing for the approopriate length AOD housing that fits the yolk

Otherwise if all that is cool, just take out the 6 bolts and the VSS, pull it down, beat out the tail seal and swap it our for a LARG FLANG seal for extra longetivity.

 
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(Login 69convert)
67.164.193.53

Re: 4R70W Tailshaft Leak

August 9 2005, 5:16 PM 

Thanks - I do have the right yoke on it, and it was stable in the bushing, so I think (hope) it's just that seal! I haven't pulled it off to fix it yet, because I'm not convinced that I'm not just overfull, and it seems to be leaking a little less every day. At least there's less to clean up on the garage floor!

'69 Mustang Convertible


    
This message has been edited by 69convert from IP address 67.164.193.53 on Aug 9, 2005 5:25 PM
This message has been edited by 69convert from IP address 67.164.193.53 on Aug 9, 2005 5:25 PM


 
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(Login stuart40a)
Forum Moderator
24.66.94.141

Re: 4R70W Tailshaft Leak

August 8 2005, 3:35 PM 

Is there a possbility of it leaking from the plug in the back of the yoke?

 
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(Login 69convert)
67.164.193.53

Can "too full" make it leak?

August 9 2005, 5:23 PM 

I'm not sure I know where you mean - is there a plug somewhere between the yoke collar and the u-joint? I'll take a look right at it and see.

The leak flows pretty consistently when I'm driving, and then in fairly steady drips (ever 30 seconds or so) once it's parked for a while. It comes from the rubber boot on the back of the tailshaft, through the little vent hole in it. It seems to me it's just dripping out the rear seal and into the boot, collecting in there, and then running out.

I'd replace the seal, but I'm still not clear on whether a "too full" situation could, by itself, cause a leak around there? I definitely seems to be leaking less, but it could just be that I'm too LOW now. I'm using a DS and tube assembly from an AOD, I'm not sure if it's even giving me accurate readings? Thanks for all the help from everyone!

'69 Mustang Convertible


    
This message has been edited by 69convert from IP address 67.164.193.53 on Aug 9, 2005 6:16 PM
This message has been edited by 69convert from IP address 67.164.193.53 on Aug 9, 2005 5:28 PM


 
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(Login stuart40a)
Forum Moderator
24.66.94.141

Re: Can "too full" make it leak?

August 9 2005, 8:11 PM 

If it is leaking out of the hole in the seal it is either worn out or badly abused.

The plug I am speaking of is in the back of the yoke.
On some vehicles there is a hole in them to allow for air to be expelled when the yoke "slips" in the transmission.

Remove the drive shaft, extension housing and replace the seal, bushing and check the sealing surface of the yoke.

 
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(Login 69convert)
67.164.193.53

Thanks Stuart, One Last Question

August 10 2005, 9:26 PM 

Just wanted to confirm that it's a good idea to replace the bushing at the same time?

Not sure how the seal could have been damaged as the trans is fairly new, but I did slide a standard AOD yoke in there at one point and checked to see how much play was in it before getting the 4R70W yoke. Didn't drive it or anything, but I guess it's possible I bent it?

'69 Mustang Convertible

 
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(Login stuart40a)
Forum Moderator
24.66.94.141

Re: Thanks Stuart, One Last Question

August 10 2005, 10:00 PM 

It is wise to replace the bushing while you are doing the seal.
Perhaps it was a POS seal.

 
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(Login 69convert)
67.177.29.35

Finally Getting Around to This

September 7 2005, 9:40 AM 

I've been on the road most of this month so I haven't tackled this yet. Before I go and buy parts, is the "rear seal" more than just the rubber boot on the back of the transmission? If it's just that rubber boot, that couldn't really be the source of my leak, could it?

'69 Mustang Convertible


'69 Mustang Convertible

 
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(Login stuart40a)
Forum Moderator
24.66.94.141

Re: Finally Getting Around to This

September 7 2005, 11:11 AM 

The rubber boot is a dust seal. It is part of the actual seal.
The oil seal portion is in farther.

 
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(Login 69convert)
67.177.29.35

Re: Finally Getting Around to This

September 7 2005, 6:20 PM 

Thanks Stuart - got the part this afternoon - looks just like a rear end housing seal inside. I'm pretty sure I'll find that I damaged the old one when I stuck the smaller yoke in there and wiggled it around -

'69 Mustang Convertible

 
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(Login 69convert)
67.177.29.35

Output Shaft Play

September 7 2005, 7:24 PM 

Okay, I finally got under there again today. I haven't removed the tailshaft housing, but there is a ton of play in the output shaft. I can wiggle it a good 1/8" or so either way. Is that most likely a bad bushing, or could something else be wrong? What would cause the bushing to go bad like that? I didn't have any driveline vibration, so I don't think it's out of balance.

'69 Mustang Convertible

 
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(Login stuart40a)
Forum Moderator
24.66.94.141

Re: Output Shaft Play

September 7 2005, 8:27 PM 

Is the wiggle with the drive shaft removed?
if so, no problem.
If there is lots of movement with the shaft in either the bushing, yoke or both are worn.

 
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(Login 69convert)
67.177.29.35

Re: Output Shaft Play

September 7 2005, 10:01 PM 

It only wiggles with the driveshaft out - when it's in, it's a solid fit. You'll definitely make my day if you tell me the shaft should have some play without the yoke in there!

'69 Mustang Convertible

 
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(Login 69convert)
67.177.29.35

Problem Solved - thanks guys

September 8 2005, 4:03 PM 

 



    
This message has been edited by 69convert from IP address 67.177.29.35 on Sep 9, 2005 6:23 PM
This message has been edited by 69convert from IP address 67.177.29.35 on Sep 8, 2005 4:19 PM
This message has been edited by 69convert from IP address 67.177.29.35 on Sep 8, 2005 4:19 PM


 
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