Need help diagnosing A833 tranny failure.

[turbo36]

Hey all, I have a failure of the tailshaft bushing in a rebuilt A833 tranny with only 500 miles on it. I developed a severe vibration so I started checking the typical problems (tire balance, bent axle, etc. etc.), upon checking the drive shaft to see if I threw a balancing weight I discovered that the slip yoke was very loose, so loose that if you wiggled it up and down it moved so much it makes a "clunking" sound.


The car has stock locations for the engine and rear so I doubt a driveline alignment issue. Everything in the driveline is either new or rebuilt with all new parts.

What would cause this to wear out so quickly?

1965 Belvedere II, 383 , A833 4 speed O/D

thanks, Bob

 

[benno440]

did you rebuild the gearbox? i cant see how the problem could be the gearbox unless, the rollers werent all put in or the alignment bushings were forgotten, possible bearing failure in the driveshaft, causing it to be loose in the tailshaft, the yoke is supposed to slide over the splined shaft in the box so i cant see how it could be loose unless the wrong yoke was used or the spline inside the driveshaft was stripped due to inproper alignment

sort of thinking out loud here as i have rebuilt 2 of these boxes and cant see how they could be the problem, hope you figure it out.

 

[turbo36]

did you rebuild the gearbox? i cant see how the problem could be the gearbox unless, the rollers werent all put in or the alignment bushings were forgotten, possible bearing failure in the driveshaft, causing it to be loose in the tailshaft, the yoke is supposed to slide over the splined shaft in the box so i cant see how it could be loose unless the wrong yoke was used or the spline inside the driveshaft was stripped due to inproper alignment

sort of thinking out loud here as i have rebuilt 2 of these boxes and cant see how they could be the problem, hope you figure it out.

The tranny was rebuilt by a well known company and the new drive shaft was built by a very good local company. I'm not naming anyone because I really don't know what happened yet and I don't want to start a fight.

 

[mmomike]

833

How was your oil level? I would have say you may have more going on in that trans than just a output bushing. Benno 440 is on the right track in thinking they is a issue in the main shaft of the trans. Or even in the drive shaft spider. How is you slip? Do you have any in the drive shaft? If nothing jumps out at you being wrong. I would definitely call the trans rebuilder and tell them your dilemma. They need to be on board with you in your time of need. Hopefully you deal with a honest shop. Could be just parts warranty in the trans which you still pay.... Better yet a labor Warranty in the trans! In that case they should eat it all parts and labor. Good luck Turbo!

Regards, Mike


69 Road Runner 383 A833

68 Charger 383 727

 

[Meep-Meep]

I'm having a very similar problem with my car and about ready to pull everything apart. I have some up and down movement in the slip yoke but not completely convinced that's the problem. One thing I will look at is the rear end. It's a Dana 60 and the pinion seal is starting to leak so I'm not going to ignore the pinion bearings. To back up this seemingly ridiculous claim, my 67 Ranchero (390, top loader) had a strange vibration around 45 MPH and when I rebuilt the rear end it went away. When I started to disassemble the third member I found the pinion bearings were loose as if there was no preload. Once back together correctly no more vibration. My Dana does not feel loose so it makes me wonder if it's really a problem, but I might pull the cover to see what's going on.

As far as causing a tail shaft housing bushing to wear out there isn't really that much I can think of. The obvious worn yoke will help take out the bushing and so will no oil. Those bushings have a hole in them that lines up with a cast in Vee notch in the housing. If it was installed incorrectly you may not get enough oil to the bushing followed by possible failure. A drive shaft that isn't balanced and/or bent may also contribute heavily to bushing wear. I'm starting to believe there may be forces acting on the bushing that we haven't yet considered.

Vibrations and why they happen is very fascinating and is the cause of a lot of mechanical failures. Keep in mind that a drive shaft can be balanced at test speed but may be out of balance in real time. The obvious reason is the length to diameter ratio but the not so obvious is the the strength of the material. Even a correctly designed tube that was too thin or compromised somehow will probably hit the first mode fairly quickly.

 

[chignikred]

i reread your post. Confirm if it is an OD trans, long shaft. Was the slip yoke engaged onto the splines of shaft properly, ie about 3/4 of an inch of the yoke exposed beyond the trans boot? Does the main shaft wiggle much at all , with yoke out and trans still together?
Two internal errors could be a reason;1- the snap ring hold any gear on the shaft may have been missing causing shift, 2- the needle bearings in the drive gear may be missing, causing extreme wobble of mainshaft. 3 - the rear main bushing may have been loose and pushed into the tailhousing upon insertion of the yoke. This may seem rare but just 2 weeks ago I dis assembled an 833 and this was the case. First time Ive seen it happen.

Red