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Discussion Starter #1 (Edited)
Hi Guys,

while changing the rear seal today of my C4 i noticed some radial movements with the driveshaft installed.

Should it sit tight or is a bit of movement (2-3 mm) ok?

Thanks a lot in advance!

Martin
 

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Hi Guys,

i am looking for a torsion rod for the trunk lid in my 67 Mustang Fastback.

Please let me know, if you have one and are willing to send it to germany.

I am also looking for the 67 Radio Knobs for my 8-track w/ console

Hints are very welcome here as well. Thanks a lot in advance!

Martin
mo,
You should post your want ads (WTB) here:
Classic Mustang Wanted Ads - Vintage Mustang Forums

Paul
 

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I could not find a spec in my shop manual for that runout but 2-3mm radial play (.080 - .120) seems excessive. Perhaps the tailshaft bushing is worn out.

Paul
 

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67 coupe, 69 Sportsroof, 86 hatchback
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Generally if play is excessive you will also get a fluid drip as the seal can only do so much. I don't know of a spec, during a transmission rebuild the tail bushing is usually just inspected and replaced if there is any doubt about its health. Kind of a judgement call, much like deciding how much play is too much.
Without actually seeing it in person my vote is that it's OK but keep an eye on it for leaking. Leaking=not OK.
 

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Generally if play is excessive you will also get a fluid drip as the seal can only do so much. I don't know of a spec, during a transmission rebuild the tail bushing is usually just inspected and replaced if there is any doubt about its health. Kind of a judgement call, much like deciding how much play is too much.
Without actually seeing it in person my vote is that it's OK but keep an eye on it for leaking. Leaking=not OK.
^^^

Hypothetically speaking, you could pull the yoke & tailhousing and mike the unworn surface and compare it to the ID of the bushing....
 

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That would be more work than simply replacing the bushing, which does NOT require removing the housing. With correct tools, 2 hour job.
 

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67 coupe, 69 Sportsroof, 86 hatchback
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Not hypothetical at all, that's of course THE correct way to determine the existing clearance, bartl. But we don't have a specification that I know of to compare that measurement to that I'm aware of. I have the old Ford shop manual section about a C4 and a somewhat newer Ford service manual for the C5 and neither has any specifications of any kind related to clearances of ANY of the bushings. Some business about the special tools to replace them and that's about it. Kind of implied that the technician is to judge whether the bushings need replacing. Or maybe an assumption that the rebuilder will just replace them all anyway? They don't really say. At least in the manuals I have.
Now I'm wondering if there is a default sort of spec for such automatic transmission bushing clearances out there, kind of like that rule of thumb .008" clearance per friction when you don't know the actual spec for a clutch drum. Hmmm.
 

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Discussion Starter #10
Thanks guys, much appreciated!

I replaced the seal because it was dripping. Then i inspected the transmission shaft, slip yoke and radial play.

Without the driveshaft installed i can move the transmission shaft 1cm in every direction.

With the driveshaft installed, i can move the whole thing just 2-3 mm. But it is noticeable play and i wondered, how long the new seal will survive that.

I can also spin the whole driveshaft 1cm with the transmission in P, which is giving me a loud "clong" when i shift a gear.

The shop manual is not giving any hints on that unfortunately.

I will test drive everything. If the new seal is leaking sooner, i will change the bushing and seal.

Hope its not too much gynecology with the exhaust installed.

Martin
 

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67 coupe, 69 Sportsroof, 86 hatchback
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Without the yoke in the transmission the tailshaft has no support at the end and so flops around a LOT.
Rotating the driveshaft a bit with everything installed is normal when "cold". If you tried that just after getting in from an hour long drive on the freeway you'd find almost all that play had disappeared. Because of heat expansion in the rear end which is why that play exists.
The only thing in this thread so far that would concern me is if the new seal takes care of the drip. If not then a new bushing is in order AND the yoke bears careful inspection as they can wear too.
 
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Yep, you can't be concerned about movement with the yoke inserted. If the seal solves the problem, no problem there. It is continues to drip and you can't stand it, you need a new bushing.
 
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