55 F100 U Joints

[tommyleea]

Replaced the U joints in my pickup. The U Joint at the yoke end is very close to the yoke end cap. It hardly rotates at all, because of the minimal clearance between the yoke and u joint. It does rotate the opposite way. I have never seen this situation before. I am wondering if I should take it apart and do something with the yoke cap, or if it needs to move during operation will the cap just deform as required? Thanks

[Mac VP]

The original u-joint had an offset to the cross that allowed the plug to clear. The replacement u-joints have a symmetrical cross that bumps into the original plug, as you found out. The solution is to take it back apart and drive the original plug out. Replace it with an expansion plug (slightly convex -dished shaped). They are set by hitting them in the center with a blunt brass punch and heavy hammer. If you can’t get it to seat tightly you can tack weld the plug. I don’t have the size for the plug handy so you’ll have to check that.

[tommyleea]

Originally Posted by Mac VP

The original u-joint had an offset to the cross that allowed the plug to clear. The replacement u-joints have a symmetrical cross that bumps into the original plug, as you found out. The solution is to take it back apart and drive the original plug out. Replace it with an expansion plug (slightly convex -dished shaped). They are set by hitting them in the center with a blunt brass punch and heavy hammer. If you can’t get it to seat tightly you can tack weld the plug. I don’t have the size for the plug handy so you’ll have to check that.

Thanks for that info..How solid is that plug, and do you think operating it as is, the u joint would deform the plug into shape, or would it just destroy the u joint? What does that plug do anyway?

[Ole Don]

Originally Posted by tommyleea

Thanks for that info..How solid is that plug, and do you think operating it as is, the u joint would deform the plug into shape, or would it just destroy the u joint? What does that plug do anyway?

The plug is there to prevent trans lube from running out along the splines.

[Mac VP]

The original plug is a pressed steel part and can be driven out from within the splined part of the yoke. Of course , you’ll need to remove it from the transmission and remove the u-joint as well before you hammer the plug out. You can also push it out with a hydraulic press if you have one.

[tommyleea]

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Originally Posted by Mac VP

The original plug is a pressed steel part and can be driven out from within the splined part of the yoke. Of course , you’ll need to remove it from the transmission and remove the u-joint as well before you hammer the plug out. You can also push it out with a hydraulic press if you have one.

Copy..Thanks..I do have a press, and haven't installed the driveshaft yet, so not a big deal..

[tommyleea]

Originally Posted by Mac VP

The original plug is a pressed steel part and can be driven out from within the splined part of the yoke. Of course , you’ll need to remove it from the transmission and remove the u-joint as well before you hammer the plug out. You can also push it out with a hydraulic press if you have one.

First step accomplished. U joint removved, and plug pressed out.

[Daves55Sedan]

Bear in mind, the splined output shaft of your transmission should be thoroughly greased, because that yoke will slide back and forth on the shaft as you go over bumps or load down the bed of the truck.
If that metal plug is gone, you will fairly quickly push the grease out thru the hole you just made. That plug, keeps the grease in.

[tommyleea]

Originally Posted by Daves55Sedan

Bear in mind, the splined output shaft of your transmission should be thoroughly greased, because that yoke will slide back and forth on the shaft as you go over bumps or load down the bed of the truck.
If that metal plug is gone, you will fairly quickly push the grease out thru the hole you just made. That plug, keeps the grease in.

Grease or tranny fluid? Thanks..I plan on installing a new plug, maybe a freeze plug of the proper size. Thanks

[tommyleea]

Just an update..I used a 1 5/16 concave freeze plug to replace the old plug. It worked like a champ, fit just right. Used a press and some sealant. Thanks for all the help.

[tommyleea]

Here is the clearance with the new plug installed. Big difference.