skpyle

Hello Gentlemen,

While releasing 2mm of flexplate preload on the Red Witch, I inspected the front torque tube bearing. And found that it is only approximately 3-3/4" from the back of the bellhousing.

I believe this bearing has migrated forward.





Front bearing appears to be OK.






That is not 11". I could twist my hand and reach in and touch the outer rim of the bearing insert.





I understand that the only proper fix is to completely remove the automatic transmission/differential assembly and torque tube, then replace all the bearings.

Unfortunately, that is not going to happen any time soon. The WYAIT would crush me. I am already in too far on engine and engine bay work.

I am going to reach in with a brass drift and a hammer and try to work the front bearing back down the torque tube.

Therein lies my problem. I don't know how far back to go. I have been unable to find a specific reference for stock bearings. Dwayne's excellent write up is for the installation of Constantine's Super Bearings. I will do those. Someday...

I have seen a couple of references to a distance of 11" as a good distance.
I have done searches for 'torque bearings', 'drive shaft bearings', 'shaft bearings', and 'tube bearings.'
I have not found a cold hard value. The WSM just tells me to replace the central tube as individual components are not supported.

So here is what I am asking: can anyone tell me how far back to drive the front torque tube bearing? Or like a thread or threads that would help me?


Thanks for your time and efforts!

OTR18WHEELER

Seth, I am sure the front bearing is supposed to be near 4 inches from the face of flange , as in most TT inner pics, you can see the travel Marks of the bearing as it migrates rearward.
If you can find a former thread of mine, I documented my observations with pics.
....it's 4 inches, I'm sure.
Most failures show the front bearing at near 12" rearward., the harmonics of the shaft move the bearings toward the center.
I'm sure your ok at 3.75" from the face of the flange.

FredR

Seth,

I have seen a couple of Dwayne's references regarding the position he found the front bearings located- one being 10 inches the other being 11.25 inches.

However, one should note that he was not doing this exercise just for the fun of writing his excellent pictorials [his TT refurb thread is an epic]. Thus what he saw may reflect a degraded situation and you should take note of what others have experienced, preferably with strength in numbers before you resort to hammering the thing into what may be a false position.

If all else fails send Constantine a PM asking his opinion- if anyone knows for sure he is likely your man. I am sure he would chime in if he sees the thread but I suspect he is an occasional visitor these days

Rgds

Fred

skpyle

Thanks, Farris! I have found the thread you were referencing, I think. He had 4" on his bearing.


Fred, I am not going to jump to a knee jerk reaction. As I have yet to find a diagram showing the proper location of the bearings, or any kind of consensus on location, I am going to leave well enough alone.

In the future, if I learn different, it is not that big a deal to drop the lower bellhousing cover. I will deal with it then.

I have not yet reached out to Constantine, but I will do so.


Thanks!

Constantine

Hi Seth,

The front bearing should be 8 to 10 inches from the front opening.

As you figured out, we would advise to leave well enough alone at the present time. Suggest you check its location at every oil change to make sure it isn't continuing to migrate forward.

A sign that it came out of the TT would be pronounced drive line vibrations during driving.

Cheers

FredR

Seth,

Without wishing to initiate the 100th nervous breakdown, I rather feel Constantine's input might be a bit of a game changer here. Assuming your torque tube is the original it is now 31 years old. I rather suspected Constantine would tell you that the front bearing had migrated because my memory of that bearing is that it was not sat 4 inches from the front when I last saw mine.

Now the questions are why did it migrate and where is the rear one sat? One presumes the reason for migration is that the rubber on the bearing carrier is not as rubbery as it was originally and therefore is on the march. Will the rear one be in any better condition?- doubt it.

If nothing else, for the front bearing I would be inclined to drill a hole in the outer tube and insert a grub screw protruding about 6mm inside the tube to arrest any further forward movement of the carrier. If the rear one is where it should be then perhaps leave well alone or do the same.

On the other hand, perhaps it is time to consider whether to fit a set of super bearings and have done with it. Appreciate how deep you are into this but given where you are already I suspect it would be relatively easy to move the motor forward a bit to permit removal of the torque tube without touching the transaxle. If that is correct then removal will hopefully be very easy and take little time to achieve.

Trust the above constructive input.

Rgds

Fred

alex70

Here is an old thread re: TT/bearing etc. Maybe you can glean some info from it. Never had to do bearing work on my two 928's.

https://rennlist.com/forums/928-foru...-bearings.html

skpyle

Thank you for replying, Constantine! I very much appreciate your advice and perspective.
I will take your advice and inspect the front torque tube bearing at each oil change.




Hi Fred!
You bring up really good points. I am going to assume age is the culprit for the migration of the bearing(s). If I am really lucky, the damper is banging around in there as well.

However...I have to draw the line here. It will never end. I am in a deep hole financially that I must climb out of before there can be any more major repairs. Then there's the time aspect. I am uncomfortably close to having the Red Witch off the road for a year. That hurts. I bought her to drive.

You are correct, it would be relatively easy to inch the engine forward to remove the torqe tube and upper bellhousing. However, that will take alot of time. More importantly, right now, I don't have the $1000+ it will take for a set of SuperBearings, a SuperClamp, and the torqe converter bearings. Not to mention whatever else WYAIT creeps up. I've got to keep this managable, and not continue to spiral out of control.

From what I have learned in taking all this apart now, is that I can do it again in the future. And I will.

I am going forward with what Constantine has suggested, monitor the bearing. I am trying to read between the lines and infer that it will be OK for awhile longer. I hope.

Thanks!





alex70, thanks for the link! That was some good reading. There was another link within that was just as good.




For the moment, I'm going to hold what I've got and keep an eye on the bearing.
It will be dealt with in due time.

Chalkboss

FWIW, I measured roughly the same on my 87 for the front bearing. And it was a rebuilt TT from a very reputable source with about 20K miles since replacement. I have no vibrations, runs smooth as silk. I am keeping an eye on it as well...

Good luck!