Fawndeuce

Hi,
I have a drivetrain vibration that is especially noticeable at about 50 MPH.
I pulled the driveshaft, I had noticed quite a bit of play at the slip yoke.
As you can see in the vid there is a lot of movement at the output shaft of my '62 powerglide, this can't be normal?
If not, how do I fix it, I know very little about these transmissions?

Thanks,

Paul

1955 copper

That's part of the planetary gear and may be broken or a bushing is worn. R&R the trans.

Fawndeuce

Thanks Roy.
The transmission otherwise works fine, how much play would there be normally? Does the shaft or the yoke fit in the bushing?



Paul

larrywalk

The transmission output yoke (not present in your video), which locates the output shaft, rides in a bushing in the tail-shaft housing and normally runs with a clearance of ~.008". If the trans was working fine, re-install the output yoke and re-do your check. If the movement is negligible, you're fine.

If you find more than ~.015" of movement with the yoke in place, mic the output yoke for wear. If none is found, then the extra freeplay is most likely in the output bushing which should be replaced.

Fawndeuce

Thanks Larry. There is more than .015 of play with the yoke installed, I don't have a micrometer, but do have a vernier caliper, could that work to check the yoke?
Can I change the bushing with the transmission in the car?
We are supposed to be taking the car on a 250 mile trip this weekend, but the vibration is quite noticeable especially at about 50MPH, stops if I shift to neutral.



Paul

larrywalk

Yes, check the yoke along its length with the caliper - if where the bushing rides you discover that it has reduced diameter, that's the wear. However, your picture does not appear to show any necking, but it may have been ground down to eliminate signs of previous wear. I just measured a good yoke - the OD is 1.502"

larrywalk

BTW, when you shift to neutral at 50 mph, the output yoke and driveshaft will still be rotating. Have you checked for the vibration at the same rpm in neutral while stopped?

Fawndeuce

I just measured 1.501 the full length with my digital vernier Larry, no difference at the area where the bushing makes contact.
I'm also going to replace the U-joints anyway while the driveshaft is out, but the play was between the yoke and tranny.
The vibration follows like a sine pattern, a continuous and even cycles of strong to weak to strong to weak, about two seconds between peaks @ 50MPH, intensity is speed depend and and it's been getting worse over time. It is really present under load, if I lift off or go to neutral it goes away or is greatly diminished.
Can I change the bushing without pulling the tranny? The motor was rebuilt during the resto about 10K miles ago, and by the looks of it, the yoke probably changed, but the PO may never have opened the tranny?



Paul

JohnZ

Snap-On makes a tool to remove/install the bushing with the trans in the car; otherwise the taillhousing has to come off to change it.

larrywalk

Yeah, it sounds like the bushing is worn. It may be less costly to unbolt the tailshaft housing and have a shop press in a new bushing - Snap On is not cheap, but I like their tools!

Fawndeuce

I put the driveshaft back on to to check the yoke deflection. I get about .030~.040 total from max push up to max pull down, or about .015~.020 per side.
Local trans shop said to bring him the tailhousing, he said he does not have, nor can he get all early tailhouse bushings?
Is it safe to drive a couple of hundred miles as is? Hate to miss our weekend trip...





Paul

larrywalk

Try a different shop. According to my Transtar catalog, the extension housing bushing is the same part number for the PG, Muncie (with 27 spline shaft), and the TH350. This is a very common bushing.

Fawndeuce

Many thanks Larry for all of your help.
I have a friend with a shop who has the tool to pull the old one with the tranny in the car (maybe same tool that John showed?).
Now that I know that the bushing is available, I'll get a new bushing and seal and have him do it for me so that I make the weekend trip.



Paul