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I had one wear out, and the main problem I noticed was the grinding noise, and the vibration that got worse with speed. I thought it was u-joints, but when I pulled the driveshaft, I noticed the excessive play in the bushing.
 

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If you drive it that way for long/hard, things wear prematurely.
Worn rear case bushing, chatter marks around the planetary bearings and loose output shaft to planetary hub are common in my experience.
 

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Discussion Starter #4
I am trying to track down a vibration that is definetely speed related. It is not noticable to most at speeds under 70 but I have driven this car 125,000 miles and I know its there. At 90 you know it is not smooth.

I put in a new 3:73 Pumpkin from Ford and then later put in a Mark VIII shaft from Ford. That shaft was so bad that I could not drive over 65 with out the car shaking violently. I put the stocker back in for a while and now I have a Metal Matrix shaft from Dennis. The vibration seems to have started after I removed the Mark shaft and is still there with the MM. I think something was damaged by the Mark shaft but what?

Tony
 

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Discussion Starter #5
Rich,

Can this be changed with out pulling the transmission out of the car.

Tony


Rich95XR7 said:
I had one wear out, and the main problem I noticed was the grinding noise, and the vibration that got worse with speed. I thought it was u-joints, but when I pulled the driveshaft, I noticed the excessive play in the bushing.
 

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WOnder if that's been my problem. I'll have to check it when I replace the tailshaft seal. Like TMcColl asked, can this be changed with the tranny still in the car or does it have to be removed???


Later.
Slowride
 

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You only have to remove the tailshaft housing from the transmission to have a new bushing pressed in at the local machine shop, or on your own press if you have one.
Of course, the rear mount and driveshaft will have to come off first, and lots of fluid will come out if you don't drain the transmission first. If the rear case bushing is worn as well, the transmission has to come out and completely dissasembled. This can happen from extended/hard driving with a worn tailshaft bushing.

FWIW
 

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I was told by Ford that the bushing is cast into the extension housing and them
machined so you have to replace the entire extension housing if the bushing is worn.
That's what they said, I haven't look closely to see for myself.
 

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News to me - Every '93 later 4R70W I have seen has a replaceable bushing.
Just replaced one on a virgin 94 last week.
Maybe it was the AOD (DOA!) he was referring to??
 

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Discussion Starter #11
Greg,

I just checked the yoke on my old DS and there appears to be some rub marks and actually a small flat spot has been worn in on on side. Is this what you see with a bad bushing?

If you read my earlier posts you can see what I have done so far.

Thanks for the info.

Tony
 

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I'm not sure what you mean by 'a flat spot', but there should be no flat spots on the bearing surface of the yoke. (The shiny part that inserts into the transmission.)

The simplest way to check it is to grab the driveshaft at the tranny end, while installed, and shake it up and down. Most of the time, the bushing wears on the top front, due to the weight of the driveshaft tilting it that way. I don't have any fixed figures in mind, but I'd say any more than about 1/4" of movement is too much.

If the shaft is out, just look into the bushing bore with a flashlight, or feel it with your fingers. It should be smooth and not be damaged. Worn bushings generally have radial scratchmarks around a portion of their periphery - again, at the top towards the front of the car. If it's totally wiped out, it's could be much worse.

If you have an inside micrometer or snap gauges, just measure it around the circumference.

A new bushing is about $2.00.
 

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Greg,

I would imagine if it moved 1/4 inch (more or less) it would be very worn out. I believe it was you and I that had a discussion when I was installing my driveshaft about how the driveshaft yoke, when installed on the output shaft, supports the rear end of the output shaft, via the tailshaft bushing.

I would say anything on the order of .010-.020 inch would be just about the limit. That's only about 1/64 inch.

The reason I say this (other than being a tool and die maker, before I was a tool and die designer, before I was an engineer) is that if the yoke were moving that much, you would have a big-time tranny flud leak past the tailshaft seal. Over time, if the bushing wore that much, the seal would wear with it.

The leak would be aggrevated by the fact that with the added bushing clearance, more fluid would seep past the bushing, and the worn out seal wouldn't be able to hold it in at all!

Plus, I'm sure there would be a terrible clunking noise while driving while the driveshaft yoke bounces around in the worn bushing.

Am I making any sense?

When I finally got my yoke on the splines of the output shaft, I could feel no discernable movement. Granted, I didn't use a dial indicator to check it out, but over the years I developed a feel for clearances based on movement. I'll bet I didn't have more than .005 inch movement...if that....
 

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Discussion Starter #14
Greg,

We are talking about the same piece. The one that goes into the back of the tranny.

It has some wear marks but is not grooved except that in one spot about 1/4 inch square it is worn flat. Cant explain why it would not go all the way around the circumference.

Do you by any chance know the part number?

When I get home I am going under and see if there is play.

Tony
 

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rustyul,

That figure was off the top of my head. It is probably not correct, as I generally go by feel myself - never actually stuck a dial indicator on one. I've seen them worse than that, however! But even with an average new bore clearance of .005", the bushing's short length combined with rocking the tailshaft diagonally through that clearance would add up to a cumulative movement of much more than that at the driveshaft yoke - probably around .025".

The seal is not pressurized, and the fluid leaks out rather slowly, even with a fair amount of clearance - that long-lip seal does a pretty good job - until you reach the limit of the lip.

As for the clearances, etc. Yea, I know about 1/8" = .125" and such.
I am the proud owner of many starrett micrometers, depth micrometers, snap gauges, etc. :D

However, I just spent the morning trying to convince the woman at the local transmission shop that .10" was thicker than .067" - sheeeese.... :zbash:
 

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Tell you guys something.........I'm so happy I read this post out of couriosity. I've been searching a vibration in for about a year---give or take a few months. Anyways, lately, I just chalked it up to the rear end---the original was worn out, and the new 3:73's.

Well, I'm right in the middle of a motor rebuild right now. When I removed the driveshaft, I checked the tailshaft to see if the bushing was bad. When I checked, the output shaft moved all over, more towards the top, but it was really loose. WEll, at least with the motor out, won't be such a pain to pull the tranny to fix! *LOL*


Just wanted to say thanx for wonderfull info. Gotta a question though, is there a way to check the rear case bushing without tearing down the entire tranny???

Thanx again guys!!!!!!!!!!

SLowride
 

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Slowride said:
Tell you guys something.........I'm so happy I read this post out of couriosity.
...
Well, at least with the motor out, won't be such a pain to pull the tranny to fix!
...
Just wanted to say thanx for wonderfull info. Gotta a question though, is there a way to check the rear case bushing without tearing down the entire tranny???

Thanx again guys!!!!!!!!!!

SLowride
Glad you enjoyed it! :D

You don't have to pull the transmission to replace the tailshaft bushing, however, just the rear housing (6 bolts) - Although in your case, it's no big deal.

When you have the tailshaft housing off, rock the output shaft around, there should be minimal play - meaning .006-.008" clearance AT the bushing. With that long tailshaft, however, the movement at the END of the shaft would be....
...maybe... 1/4" - 3/8" at the end of the shaft.

I just put one of these together yesterday, with new bushings, and I don't remember exactly how much movement there was at the end of the shaft. I just go by feel and experience. (After checking all the parts during assembly with a micrometer and snap gauge...)

If you go into the transmission, you should probably update all the frictions (and the mech diode if you drive hard) while you are in there, and make certain your end play is .006-.015" or so to reduce stator shaft sealing ring wear. There is a color coded selective washer behind the pump housing that is used to set this. They come in .017" progressions. The RED one will usually tighten up the unit properly, I have noticed that the stock (generally neutral colored) washer allows too much clearance - Ford calls for .005 - .044", but this is too much. One piece teflon seals on the input shaft and output shaft, instead of the scarfed seals, are a good idea as well. Etc., Etc., Etc.... There is a long list of things to check/update for a long life job. ;)

Check the work in progress section for some observations I have made while working these trannys.
 

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Thanks again Greg. I'll probably start the tranny repairs this weekend, after I finish getting my block torn down and out to the machine shop for inspection. So, after removing the tailshaft housing....that's how I check. Basically, I should know if there's too much play or not. I'm no expert....but from my years of wrenching....I'm pretty good at telling if something is too loose or not.

Thanx again for the info. Good thing I don't have to worry about the other tranny stuff. I did the "J-Spec" rebuild just over 2 years ago. It wasn't the full rebuild....but I did add the extra friction and seperator plates that could be added before the machining work had to be done on the pistons. The only thing I'm not sure of is if the solid teflon seals were put in or not. I couldn't find them........but my tranny guy said he did and put them in.


Later
Slowride
 

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Slowride said:
... The only thing I'm not sure of is if the solid teflon seals were put in or not. I couldn't find them........but my tranny guy said he did and put them in....
I went through the same grief concerning those solid seals, until I found a supplier in my area. APD couldn't get them, Ford doesn't sell them. Finally I found that Transtar carries them - but they are 20 miles across town! Anyway, should anyone else needs a source for these, the numbers are:

TRANSTAR http://www.transtarindustries.com
Output Shaft/Direct Clutch Solid Teflon - 53224S
Input Shaft Solid Teflon - 53233S

Good Luck!
 
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