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Discussion Starter #1
So my truck was driving smooth up until a couple days ago and I haven't been able to find any write ups that had similar issues as me. First off my truck leaks transmission fluid, but it has been leaking since the day after i got it rebuilt so I don't think that's what is causing the issue. Anyways, my symptoms are hard vibration felt in the stick as soon as i hit 50 mph and above, but only feel the whole truck vibrating hard when in neutral going 50 mph and above. If i'm going under 50, there is no vibration felt in the truck or stick at all. If the truck is in gear going over 50 the vibration ranges from very light to non existent besides the stick itself vibrating, but again very hard vibration if in neutral going over 50. Has anyone had similar problems, and what did they do to fix it?
 

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So many possibilities, if you fell no vibration in the seat I would rule out driveline and rearend. I would prolly start with checking the trans oil for metal, maybe a bearing or synchro. Or throughout bearing, pilot bearing

Sent from my super awesome outdated Samsung phone while waiting for masakimms# 500mA overdraw draw to catch fire which turd will be blamed for and we will be sitting on dustybumpers tailgate watching the fire and plotting against yommy.
 

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I had a similar vibration and found that nut on the output yoke had fallen off and the universal joint kept it from being pitched away .


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I had a similar vibration and found that nut on the output yoke had fallen off and the universal joint kept it from being pitched away .
I had the same thing happen on my 94's 2wd ZF5-42. Just for information the output shaft yoke nut is a one-time only use nut (if you take it off you have to replace it). With the nut falling off, there was also a nice leak at the output shaft seal. The part I got was Ford part F81Z-7045-CA (about $5.83 online, list is $8.83) if anyone needs it. Cheers!
 

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I had the same thing happen on my 94's 2wd ZF5-42. Just for information the output shaft yoke nut is a one-time only use nut (if you take it off you have to replace it). With the nut falling off, there was also a nice leak at the output shaft seal. The part I got was Ford part F81Z-7045-CA (about $5.83 online, list is $8.83) if anyone needs it. Cheers!


Yeah I ended up cleaning the nut and threads real well applied blue loctite and slapped it back on there .
Anyway it’s worth looking at for sure


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Discussion Starter #6
So many possibilities, if you fell no vibration in the seat I would rule out driveline and rearend. I would prolly start with checking the trans oil for metal, maybe a bearing or synchro. Or throughout bearing, pilot bearing

Sent from my super awesome outdated Samsung phone while waiting for masakimms# 500mA overdraw draw to catch fire which turd will be blamed for and we will be sitting on dustybumpers tailgate watching the fire and plotting against yommy.
I'll make sure to do that. I just bought fast coolers manual transmission cooler kit so I'll look at the old fluid when I install those.
 

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Discussion Starter #7
I had a similar vibration and found that nut on the output yoke had fallen off and the universal joint kept it from being pitched away .


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Where should I be looking for that nut? Is it where the rear driveshaft connects to the transfer case?
 

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If it's 2wd it should just be on the differential side of the drive line, the transmission side will slip in and out. Speaking of that I've seen a few slip yolks (transmission side) get sloppy and cause a vibration.

Sent from my super awesome outdated Samsung phone while waiting for masakimms# 500mA overdraw draw to catch fire which turd will be blamed for and we will be sitting on dustybumpers tailgate watching the fire and plotting against yommy.
 

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Discussion Starter #9
Well I've noticed another weird driving characteristic. When I'm going 50+ and let off the accelerator, all vibration stops including the vibration felt in the stick, which I normally feel going 50+. Any thoughts?
 

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Check rear pinion nut on driveline.
 

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Discussion Starter #11
So I did some research and saw that bad driveshaft u joints can cause vibration driving at high speed. Could this possibly be the issue if the pinion nut doesn't fix my vibration, or is what I previously described not characteristic of bad u joints? Also, wouldn't tightening down the pinion nut mess up the preload?
 

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So I did some research and saw that bad driveshaft u joints can cause vibration driving at high speed. Could this possibly be the issue if the pinion nut doesn't fix my vibration, or is what I previously described not characteristic of bad u joints? Also, wouldn't tightening down the pinion nut mess up the preload?


Yes a bad universal joint will (could)cause the vibration you describe .
Tightening down the pinion nut will cause the preload to change however , if the nut is loose then there is NO preload . You could snug it up if it’s loose and see if that corrects your vibration.
On my trucks I remove the crush sleeve and install a spacer and shims to achieve the correct preload . Then I don’t have to worry about that crush sleeve and the nut backing off . A spacer and shims for a ford 9” pinion will work on the 10.25 rear .


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Discussion Starter #13
Yes a bad universal joint will (could)cause the vibration you describe .
Tightening down the pinion nut will cause the preload to change however , if the nut is loose then there is NO preload . You could snug it up if it’s loose and see if that corrects your vibration.
On my trucks I remove the crush sleeve and install a spacer and shims to achieve the correct preload . Then I don’t have to worry about that crush sleeve and the nut backing off . A spacer and shims for a ford 9” pinion will work on the 10.25 rear .


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Thanks for the advice! I turned the radio down (for once) and listened to the truck during take off from a stand still and noticed a consistent grinding/scraping/popping noise at low speeds that disappeared as the the truck sped up so I'm becoming more and more convinced it's a u joint issue. I'm thinking I will go down to NAPA this weekend and pick up some new u joints, anybody got any advice on high quality u joints? I think I'll also check my pinion nut for looseness while I have the driveshaft off. Should I also replace the front driveshaft u joints and axle u joints while I'm at it?
 
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