Aggressive unidentifiable shake.

[Quinlan_C-E]

Rear shaft appears to be phased correctly. I ran a pattern on the diff and it looked OK but has an extreme amount of backlash. I pulled the diff to get a better look at the bearings and whatnot and looks like maybe someone replaced the diff with a junkyard one and left the original pinion in. I see there's some random numbers and letters on both but they don't match. Did they typically have matching codes of some sort?

 

[XOLATEM]

Is the rear driveshaft phased correctly?

That was my question...can you take a couple of pics of the rear driveshaft assy. and post it up...?

Those puppies need to be aligned a certain way...

On the diff gears...lets see what numbers you are talking about and how much backlash you have...do you measure it with a mic or just take a s.w.a.g. at it..?

One other thing...with the front wheels pointing straight forward...measure your wheel base...each side...center-of-axle to center-of-axle.

process of elimination...

 

[Black dawg]

I am not sure what in the diff could cause a vibration that could be felt, other than a bent pinion causing the yoke to run crooked.....

By your description of the problem, this sounds like an out of phase, or incorrect angles type vibration. Pictures would be nice if possible.

 

[Quinlan_C-E]

Ok thanks ill be sure to try all the above mentioned and get some pictures this evening. I didnt measure the backlash and to be honest im not sure what the spec even is but i had a mechanic family member turn it by hand and said it's way too much. Will focus on the driveshaft for now.

 

[Quinlan_C-E]

Wheel base I'm measuring 156" on both sides. I'm not sure the best way to check phase but with a bubble level it says good and a cheap inclinometer phone app says within half a degree. Here's some pics as requested of driveline angle, the driveshaft, and different numbers regarding the crown and pinion.

 

[Quinlan_C-E]

Angle between pinion and shaft

 

[Kdo58]

You can get a action camera for cheap, I would mount one underneath and see what's shaking

 

[DougBoy66]

I am pretty sure your problem is that Red T-Bird. I could hold on to that for ya to see if that help with the truck vibration.

 

[K-nite]

The drive shaft angles look off to me. Could be the picture. The carrier bearing looks low or is it missing the axle blocks. Drive shaft usually has downward slope the whole way and not a straight line. Front half down a couple degrees and back half down more dramatically. The pinion should be pointed down slightly, looks up from picture. Do a web search about drive line angles, might help you.

 

[Quinlan_C-E]

Camera is a good idea for sure. The Thunderbird is my Grandfather's unfortunately so you'll have to talk to him. It does take up an awful lot of space in the shop, I wouldn't be disappointed to see it gone.

The angle does look aggressive I thought too and the pinion is also pointed up slightly. but both axle blocks are in it and the carrier bearing is as high as it can possibly go.

 

[Kdo58]

Looks like your yoke coming out of the transmission is leaking bad, have you replaced the bushing in the tailshaft housing?

 

[XOLATEM]

Angle between pinion and shaft

That end of the driveshaft looks pretty beat up to me...as if that end vibrated out and lost a u-joint at some time...or...someone had a hard time installing the u-joint...

On the rear gears...(I am no expert, here...) but the numbers look normal for a 4.10 gearset...E5TW DA is part of the ring gear number...it has 41 teeth and the pinion has 10 teeth. That is the numbers you see on the ring gear...
other stuff on the pinion may have to do with the shift at which it was manufactured and a partial part no# D3TE A...and in my opinion if the pattern looks good then the backlash is fine.

Sometimes folks will grab the yoke and twist it from left-to-right and call that slack the backlash...not entirely true...to get a backlash figure you have to immobilize the pinion and move the ring gear up and down with a dial indicator attached to the housing and the plunger against the gear.

Unless you have a lot of wear on the pinion yoke from a previously loose and/or tossed u-joint...I would not blame the rear...

Concentrate on finding the imbalance in the driveshaft assembly...check the slip yokes, wear in the TFC extension housing bushing, whether the driveshaft was welded together straight to begin with, method of balancing, ...that sort of thing is what I would be eyeballing closely...

Just my .02

 

[DaveBen]

One more thing to check; the pinon shaft and the tranny output shaft should be at the same angle (approximately). Shim the axle up or down using wedge shims.

 

[Black dawg]

One more thing to check; the pinon shaft and the tranny output shaft should be at the same angle (approximately). Shim the axle up or down using wedge shims.

This is only true with a one piece shaft, with 2 u joints, 1 at each end.

 

[Black dawg]

Wheel base I'm measuring 156" on both sides. I'm not sure the best way to check phase but with a bubble level it says good and a cheap inclinometer phone app says within half a degree. Here's some pics as requested of driveline angle, the driveshaft, and different numbers regarding the crown and pinion.

The angles do look wierd to me, but had a low mile unmolested supercab in not to long ago that looked similar. There are ford manuals that list angles for all models if you can find one. Two piece driveshaft angles can be difficult to make work. Any signs of mods, trans swap, rear end swap/re welded on perches? Does the part the carrier bearing bolt to look modified?