70 mph vibration and trans slip yolk leak fixed

[Wikano]

There were two problems that seemed to be getting worse and worse after driveshaft install: 70 mph vibrations at all 4 driveshaft positions and a constant leak from the back of the trans.

Originally my old drive shaft had a worn out slip yolk that had some slop, causing some vibration on deceleration and trans fluid leakage. However with the new drive shaft the leakage reduced substantially but it was still leaking. I thought "Ok, must be some pressure build up. Let's install a breather." A fun little project for my 5speed but ultimately fruitless. Vibes and leakage seemed to get worse over time.

After rotating my driveshaft to all 4 positions, there seemed to be a 70 mph vibration that would taper off at higher speeds. So after spending some time underneath, I noticed there was a little bit of oil coming from the diff seal...

Problem: Elocker diff studs had come a little loose, which wasn't a surprise when the torque spec was only 19 Ft lbs!. This was in combination with the ultragrey gasket maker and no Locktight. These had loosen over time causing a wobble in the driveshaft that would cause a fluid leak from the transmission.

Solution: After cranking with some hand wrenches with moderate strength (maybe 33 ft lbs), the diff seemed to be locked down better. Bingo! No more vibrations and leakage! I would recommend a little more torque on those nuts if you reinstall your elocker or retighten them once the gasket has had enough time to fully cure.

 

[Devbot]

Hmmm... interesting. I'm lacking and elocker and getting a very similar vibration, but it starts at 35, and like a light switch too. After replacing all 3 U Joints, didn't happen beforehand or after taking it out the first time. Is it an oscillating sound, and feels kinda like someone driving next to you with bumping subs?
I assumed it was because I installed the slip yoke 180*, but I flipped it around and it was profoundly worse and constant, along with getting worse at 35+, so I chalked it up to some of the metal removed from the cardan yokes after galling the metal trying to fit the new bearings (didn't watch Tim's video :redbrick

 

[Wikano]

Hmmm... interesting. I'm lacking and elocker and getting a very similar vibration, but it starts at 35, and like a light switch too. After replacing all 3 U Joints, didn't happen beforehand or after taking it out the first time. Is it an oscillating sound, and feels kinda like someone driving next to you with bumping subs?
I assumed it was because I installed the slip yoke 180*, but I flipped it around and it was profoundly worse and constant, along with getting worse at 35+, so I chalked it up to some of the metal removed from the cardan yokes after galling the metal trying to fit the new bearings (didn't watch Tim's video :redbrick

Mine has been a long journey: original 2wd rubber rear bushing/slipjoint worn out=vibes, junk yard drive shaft was not balanced (balancing helped) and front slip yolk had slack= vibes, new driveshaft but took out elocker to adjust backlash=few vibes but got worse over time.

So 3 things to consider: slip yolk should not have any play, ujoints should not have play, drive shaft should be balanced and in phase (rotate 180 to see if vibes get better), and in my case the rear differential had some nuts loosen over time. I don't have a cardan joint in my set up so you may have a whole other can of worms.

If i get vibes from the drive shaft or the rear end I tend to feel my love handles or ass shake from the vibes. Front end vibes from brakes, flywheel, or unbalanced tires tend to make my feet/toes vibrate on the petals. I think the seat amplifies the lower frequency vibes from the rear of the vehicle.

I haven't had may vibrations at 35mph but my rear bearing going bad and loose lug nuts caused some lower speed vibrations. The vibrations from my differential seemed to "turn on" at 70mph and then quickly taper off until 77 mph but it was annoying when driving on the freeway and hovering around those speeds.