Vibration between 25mph - 35mph

Hi all, need your input. I've had a shaking from the rear for a while now and can't seem to locate the issue.

It's most noticeable when I'm accelerating quickly. it's strongest right at 25mph and slowly goes away till I hit 35mph and is completely gone. It'll stop if I take my foot off the gas pedal. If I punch it after 35mph I don't have this vibration. Not as noticeable going down hill but I'm guessing cause I don't need to give it as much gas as going up hill.

*Asked a driveshaft shop and they said an out of balance driveshaft wouldn't cause a vibration at such a low speed and if my u joints were bad I'd feel it at higher speeds as well.
*I changed my tires and balanced so I'm writing off tire balance. *I removed my rear sway bar just to check and still shaking. *Checked engine and transmission mounts and they are good.

Sounds like grinding gears... GRRRRRRRRR when I punch it/when it vibrates. Gets noticeably louder in the cab during vibration. Not a death wobble but something isn't right and it's driving me crazy!

Before I move on to my next theory of it being my slip yoke, would like your opinions on this. Anyone had an issues like this before?

Thanks!

 

do you have a lift kit? if so, how much?

 

Yes, 2" in front about 1" in rear. Thought about lowering the center bearing but it's not much of a lift to cause issues I would think.

 

wheel bearing?

 

You just did your new lift, right?

Was this happening prior?

 

Thanks I'll look into it

Quick google search... and I may be wrong but the vibration and sound go away if I take my foot off the gas pedal. From what I read the wheel bearing would still make the grinding sound even when not accelerating.

 

Yes it was there before the new suspension as well...

 

Rear end / third member issues? LSD? Had a Blazer with LSD that would shudder if the fluid wasn't changed regularly. The friction modifiers needed refreshing every 15k. Also bearings in there and gears that could be out of whack.

 

Not sure what a third member is, will need to look into it but I don’t have LSD. Wish I did lol.
How would someone check if gears are out of wack?

 

I just went through this exercise (tires/balancing, carrier bearing, u-joints, drive shaft balance, etc.), and finally took it to the local shop where they identified the problem as the right front wheel bearing. And indeed it was!

 

DUDE!!!! My front wheel bearing had rust in the area where the axel connects to it. Only area with rust. Someone in another thread mentioned my bearing could be bad.

Where were you feeling the vibration?

 

I remember you asking about that rust on the splines. Could be you are on the something. Might have to tear her back down again.

 

Lol. Honestly Ill GLADLY take it apart again if it leads to getting rid of this vibration. Same side I had to take apart cause I missed the axel washer too. 3rd times the charm hopefully.

 

I’ll be replacing the bearings and hubs on both sides. Also rebuilding the driver axel as advised by a friend who’s a mechanic. I brought up the vibration to him and he said a sure indication of a bad bearing would be fine rust particles and when there are fine rust particles it usually means the housing is messed up too, “50/50”. I hadn’t even mentioned the rust to him. Well hopefully I’ll have a smooth ride soon enough.

 

Changed the bearings, hubs and everything else. Seems like not many places are willing to press the old bearings out. In the end the virbaration is gone but still feel a little something from the rear. I almost feel like my mind is playing tricks on me but it gets louder in the cab right around 25mph and seems like it’s coming from rear.

 

Have you drained and filled the rear diff and transfer case?

 

Just did the rear diff last week and transfer case was done about a year ago.

 

Greased all 9 zerk fittings on both front and rear driveshaft and the vibration is almost completely gone.

 

This suggests that one or more u-joints are bad. The grease temporarily compensated for some of the slop in the joint, masking the problem. Soon the grease will spin out and the problem will return

 

My thought as well

 

I went to the driveshaft shop today to have them check my Ujoints. Turns out I have some work to do tonight. My mechanic who I had take the slip yoke out to clean and re-grease about a year ago didn't put the yoke back in the correct spot. The driveshaft shop had placed arrows on the driveshaft when they balanced it and the yoke to driveshaft arrows are nowhere near each other. I've been driving around with an out of balance driveshaft. Hopefully this is the cause of the vibration.

 

That would do it...

 

Sucks, but at least you know what's wrong now.

 

Another Goofy Mechanic Blunder story.

 

My slip yoke... think there needs to be some grease in here.

Anyone know how much I need to torque tHe drive shaft bolts?

 

So besides my slip yoke having a hole in its rear where grease spills out, the driveshaft doesn’t line up with the differential connection when aligned correctly.

mechanic must’ve allowed the wheels to rotate when they took off the driveshaft.

 

Arrows aligned, no more vibration! I feel like I just got laid.

 

There ought to be a way to charge mechanics with malpractice...