I've noticed while checking everything in search of a vibration in my car that the drive shaft slip yoke feels a bit loose to me. It's held by this bushing in the tailshaft, number 48 below.

And although I have all the factory manuals, (note photo is from the GM unit repair manual.) yet I can't seem to find a spec on the fit of this bushing. The seal is not leaking. But the yoke feels very loose to me. How tight is this bushing supposed to be??
My gut says I need a new one.
But purchasing a part, putting it in and finding the fit just as loose could be soul crushing. Wish I could find a fitment spec. All I can seem to find is if the seal leaks replace the bushing.
Also, finding this part in Australia seems to be an issue. Is this the same bushing as other transmission tailshafts? And if so, which ones as this could help me find the correct parts.

 

They definitely wear out. I had that issue on my 86. Thankfully it was an automatic and the tailshaft removal was easy. Try reaching out to forum member @5speeds , he is in the business and knows everything about these trannies. I once purchased a rebuild kit from him many years ago and it was top notch.

 

The slip yoke should be checked for wear on the OD, if you see it gouged then the bushing is probably the same. You can see Paul's videos where he is showing a yoke fit, they should slide in but really not rock in the bushing. The bushing should be available over there, but you would know better than me. If you have the snap-on tool you can pull the bushing with the trans in the car, otherwise you have to remove the trans.

 

There's a lot of latitude here as far as clearance and I haven't really known of a written statement of a clearance spec., as if it were truly critical it would be more common to be having the bushing honed to size post installation in the housing by a machine shop. Rather a familiar mechanic with experience acquires a "feel" for when the clearance sum may be beyond what is generally deemed acceptable. Generally by the time a clearance sum is so great as to create a notable vibration the oscillation (cause of the vibration) will induce a failure of the fluid sealing function; unless of course the fluid level is exceedingly low in the transmission. Measurement of the bushing for dimension is not possible (accurately) unless the tail-shaft housing were removed so, and as stated previously by another, removal of the slip-yoke for its' inspection will generally indicate whether the bushing is bad as the tube will generally (those of O.E.M. production) show excessive wear and seems to pretty much to mimic what one would find in the bushing in the way of wear & tear.

I don't care for the idea of replacing the bushing "in-the-vehicle" as the idea of hammering-in (some of the old time "mech-a-necs" would simply drive a new bushing in having it displace the old and just leave it floating on the shaft!) a new bushing just doesn't appeal to me as the correct process. Rather pressing--out the old bushing, with the ability to clean-up the bore of sludge or perhaps any damage to the housing bore, then pressing-in the bushing without the hammering which does collapse the trailing edge (some), and then the ability to engage the slip-yoke into the bore and establish reasonable fitment, which is not really possible if also having to engage the transmissions' out-put spline simultaneously.

Scott.

 

should wiggle a little bit and that's it, those bushing wear out all the time especially on units that run low on fluid a lot ,

 

This thread may help you
https://www.corvetteforum.com/forums...ng-please.html



also road force balance tires

 

Thanks for the replies guys. I'm off to work now but this evening I'll get under and have another look. Thinking I need to replace however.
anyone know if this is the same bushing as one that goes in a Muncie or a Auto trans?
I should probably add that my trans is a Borg Warner Super T10. 1977. Seems to be a hard to look up transmission here in Australia.

 

I just did this to my '71 C3 this week. Replaced the Muncie bushing, seal, & slip yoke. Got all the parts from Paul C. at 5speeds.com.

I removed the old bushing by narrowing a hacksaw blade, fitting it in a single hand-held handle, and 'sawed' the bushing out. The new bushing was pressed in using something like a large socket to guide it in evenly (I think most Folks use a small stub of PVC pipe as a driver). The new seal was then tapped in with a hammer.

I was skeptical of this method, but it worked exceptionally well. No more leaks.

Good luck!

 

Well it's evening here now. Got back under the car and checked the situation a lot closer armed with the information I gathered here.
So, slid yoke into the approximate running position. Checked for rock, as I really have no other spec. And I still feel that the rocking is excessive. But then if I slide it outward a half inch and check again. The rocking is very minimal. Then if I push it inwards just past the normal running position, again the rock is minimal. Then out to normal running position. And it rocks. Out comes the yoke.
yup. Wear on the yoke it's self. But the bushing actually seems OK.

Note the nasty grove about 2/3rds down from the end. And a minor grove about 1/3rd of the way from the end.
new yoke is definitely in order. But the bushing when you place this yoke off the wear groves feels fine.
note this gear box has never had a leak. Has never been low on oil. And unlike so many cars. This car has actually had it's gear oil changed more than almost any car on the road. This is one truly over maintained car. And still, look at this yoke. And absolutely no leaks.

 

That should be the same yoke as a TH400. Another option I used over the years was spray welding and turning to size to save the original yoke. A lot of the places that did this are gone around here now but if you have an electric motor rebuild shop near you they might have a spray welder.

 

Interesting idea. Not clear on electric motor rebuilders around here. I can get one out of the states but I'm looking at 400 bucks. Might have a line on one in Melbourne. It's a maybe, I'll know more in the morning, 10 PM here. But it won't be cheap either.

 

I do realize that I'm here, not there, and without the parts in hand, but, based on my observation of the photos and your description, I wouldn't put a new slip-yoke on that old bushing. Although it would without a doubt tighten things up, I feel that there is probably sufficient damage done to the bushing that the service lifespan of the appreciated effect will be lost in an unappreciated short span of time. Realize that although both the slip-yoke and the bushing bore start out as consistent diameters in their length, with the as in-service period increases they both will become hour glass shaped generally somewhat commensurate with one another in material loss: aka. when one is "wore-out" so goes the other. The wear surfaces, even with the loss of material, should still represent relatively smooth and somewhat polished appearance under normal service conditions; the rather coarse grooving and including the couple of really notable surface irregularities presented seems to indicate lubricant displacement and the two surfaces really working one another, with free particulate being afloat between the two?

Scott.

 

I was wondering how long it would take for someone to point out that bushing isn't perfect as well. I'm still hunting for one. Even Zip Corvette doesn't list it.

 

go to a transmission supplier not a reseller.

 

I have a the GM bushing part number you may be able to cross...GM #3978765 P&I Catalog says 71-79
About the spray metal repair,
Another idea do you have a shop that repairs Hydraulic Cylinders in your area?
They should be able to build that shaft up with hard chrome if you give them the specifications...

 

Does anyone have dimensions for this tail shaft bushing?
PLEASE!
I went to a old school transmission shop today. TWICE. The old guy there said he thinks years ago he cut down a bushing from a TH400 to fit a Super T10.
He "Thinks".
We know the I.D. of the TH400 bushing is the same.
We don't know if the OD is the same and we know the 400 bushing is longer.
He has in hand a bushing for a TH400.
I pulled the seal out of my tail housing tonight. Got a good look at the bushing. It looks thicker to me. And definitely shorter. I don't want to cut it and destroy it only to find this one won't work.
Sooo.
Anyone have dimensions for the tailshaft bushing in a Super T10?

 

Measure the tail bore and make a slight press fit.

 

Trans Star and Capitol Core just to name two supplier's for bushings and they could probably tell you the size difference if any at all, I would replace the yoke and bushing , based on the yoke I can't imagine the bushing being fine

 

the one from my thread posted earlier.. for vibration mine was not worn but out of balance.. it had about 30k miles on the shaft below.. have assembly balanced

 

Just a random thought: didn’t Holdens of the same vintage share some parts with Chevrolets? Maybe you could find one that way?