Vibration after gear swap to 4.11

[stansfield187]

(This is a 2wd 4.7 2012 quad cab street truck by the way) As the thread subject says, after I did a gear swap I have a vibration and oscillation sound under hard acceleration. The sound is like rotating mass spinning - kind of like big 4x4 tires, even though I have low profile street tires. It's not very smooth. The shop installed 4.11 gears and posi track - yes the gears are 4.11. I changed out my tires, had other shops check the drive shaft and other possible problem areas. So, I took it back to the original gear swap shop (1 year later - had the truck in storage) and asked what could be the issue. The guy drove it and said it's more than likely a drive line issue. That possibly the angle of my drive shaft has to be adjusted or I have to have a new drive shaft fabricated because now the drive shaft is spinning at a faster rate with the new gears. That was his first impression.

It does make sense but that's more money for me to bring the truck in. HOWEVER, I don't think I have read about other people having this issue doing gear swaps. I'm not sure where the gears came from or the Posi track. I'm not the most vehicle tech savvy guy. I paid money and just told him to get the gear install done. The guy is definitely smart and has a good google rating for his business.

Has anyone else come across this problem?

 

[metalchewy]

Could the driveshaft be out of phase when the shop reinstalled it?

Driveshaft UJ To Rear Diff Yoke Alignment

I replaced the rear diff pinion seal on my Ram 1500 this afternoon. Prior to disassembly I marked everything up incl. the pinion nut itself so it all goes back exactly the same. However, whilst cleaning I managed to remove most of the marking I drew between the differential housing and yoke...

www.ramforum.com

 

[stansfield187]

That is a good recommendation. I wonder if I can do this myself without putting it on a rack. I read the thread and one poster mentioned special tools. I'm going to have to read more into this.

 

[metalchewy]

Look under it and see if yours matches the pic at the top. There are 4 bolts at the rear end to drop the back of the driveline.

If you notice that this problem exists by looking at it, I suspect the person you are talking to from the shop will fix it, as that would be their mistake

 

[stansfield187]

I took some photos - I guess this would mean my drive shaft is out of phase? My truck is lowered so I had to go to each side to capture front and then rear of the drive shaft U at different sides of the truck.

 

[GTyankee]

Is there a drive shaft shop in your area ?

I know that the drive shaft can not be be directly straight with either the differential or transmission.
It should be between 1 to 5 degrees off of straight
It can't be Zero & it can't be 6 degrees
If it is, you will have a vibration or even binding

The shop can use a simple inclinometer to measure it

 

[stansfield187]

Thanks! The shop that did the original gear swap is a performance transmission shop. I'll have to look around on google but there aren't very man specialty shops where I live.

 

[stansfield187]

I spoke to the transmission shop that installed my gears and showed them the pictures. I'm not mechanically efficient enough to verify this. This is what they had to say:

Shop
"The drive shaft itself is phased. We only unbolted it from the yoke at diff. The 4 bolts"

"We didn't change the phase of the shaft. Your drive is one piece and the yokes are welded on."

"If it was a 2 piece drive shaft and it came apart, completely possible"