TH 400 output bushing
Thread Starter
Intermediate
Joined: Oct 2005
Posts: 46
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From: Vikersund
TH 400 output bushing
Hi!
I have changed the rear oil sealing on my stock TH 400.
First now I see that the Yoke has some radial clearance, maybe 1/2 mm up and down. The seal was not leaking before. I've only chnged the seal because i already was changing the u-joints. The yoke has only a bit wear around the outer lip.
How much clearance is allowed here?
How hard is it to change the output bearing? Are there some mauals for this job in the net?
I have changed the rear oil sealing on my stock TH 400.
First now I see that the Yoke has some radial clearance, maybe 1/2 mm up and down. The seal was not leaking before. I've only chnged the seal because i already was changing the u-joints. The yoke has only a bit wear around the outer lip.
How much clearance is allowed here?
How hard is it to change the output bearing? Are there some mauals for this job in the net?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I'm not positive, but I believe that the snapring on the end of the output shaft is 'trapped' in the extension housing so that it can't be removed without disassembling the whole transmission.
But, that shouldn't prevent you from removing the old oil seal to take a look in there. If you can get room enough to dislodge and remove that snapring from the output shaft (and the 6 bolts on the extension case), that housing will come right off. You will need to support the back of the tranny, since you will be removing the rear support piece. With housing and seal removed, you can press (or carefully drive) out the old bushing and install a new one. Where you get a new bushing without buying a whole rebuild kit, I don't know. But, that's how its done. (...IF you can get that snapring off...)
The overall end clearance of the transmission is set with the gasket thickness (and shims) for that extension housing. So, make sure the new gasket (when compressed) is nearly the same thickness as the old one you remove. Otherwise, the tranny end clearance will be different.
But, that shouldn't prevent you from removing the old oil seal to take a look in there. If you can get room enough to dislodge and remove that snapring from the output shaft (and the 6 bolts on the extension case), that housing will come right off. You will need to support the back of the tranny, since you will be removing the rear support piece. With housing and seal removed, you can press (or carefully drive) out the old bushing and install a new one. Where you get a new bushing without buying a whole rebuild kit, I don't know. But, that's how its done. (...IF you can get that snapring off...)
The overall end clearance of the transmission is set with the gasket thickness (and shims) for that extension housing. So, make sure the new gasket (when compressed) is nearly the same thickness as the old one you remove. Otherwise, the tranny end clearance will be different.
Melting Slicks
Joined: Mar 2009
Posts: 3,126
Likes: 15
On my th400 when you remove the drive shaft you can wiggle the output shaft. The bushing that 7T1vette mentioned is in the tailshaft housing. How it works is when the driveshaft is installed the outside of the yoke rides in the bushing and the output shaft is supported by the splines inside of yoke. Mike...
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
The typical clearance spec in the TH400 for bushings is .008" so there should be very little clearance between the trans yoke and the tail shaft bushing. There is no thrust bushing in the tail housing, so it may be R&R'd while the trans is in the car if you can get enough room. Replace the yoke bushing and seal in the tail housing with the proper tools when it is removed.
The freeplay of the transmission output shaft is set by the output-shaft-to-case thrust washer which is not disturbed when the tail housing is removed. Further, the gasket for the tail housing is standard and does not have a thickness requirement.
The freeplay of the transmission output shaft is set by the output-shaft-to-case thrust washer which is not disturbed when the tail housing is removed. Further, the gasket for the tail housing is standard and does not have a thickness requirement.
Last edited by larrywalk; Apr 21, 2011 at 03:54 PM.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Try Transtar Industries for parts (314-344-3300).
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
larrywalk is correct... There is no snapring in there. It's been too long since working on a 400, I guess. I checked the exploded cross-section in the Overhaul manual and mistook the [sectioned] seal casing for a snapring. There should be no difficulty removing the tail housing with the 6 retaining bolts.
