Hey guys.
So over the last year or so Ive noticed a slight shake or shimmy at crusing throttle around 44-46 mph and again around 70-75. It only happens at these speeds and there is no shake if under acceleration, only while just maintaining cruising throttle %.

My buddy just cracked his trans case and the shop that built it for him said vibrations from bad U jounts may have caused it. Obviously something I dont want happening to me.

Ive had about 5 rotations and balances on my tires so Im pretty sure its not them.
How can you tell if your U joints are on there way out?

Any ideas will be appreciated.
Ian

 

look for rust near the joint cups if any u-joint is toast.
remove drv shaft and rotate joint by hand thru its range of motion if its tight/sticks/or rough it requires replacement.

for what its worth the U-joint should cause the most vibration when under load/acceleration

 

HMMMI have a similar issue but mine only does the shake between 30-35 mph which is the same speed you balance a tire at. I was going to just get the tires balanced again thinkin maybe that was the issue, but now this post is makin me second guess

 

At 168K on my truck I was trying to figure out why my fuel mileage had been down, had replaced IAT, MAP sensor and was looking at replacing the injectors. Was only getting 17 to 18 mpg, truck historically had gotten 18 to 19 just driving around, and 19 to 20+ on all interstate. Replaced all rear u-joints and the middle bearing because I heard a clicking when going through an underpass with a load. Since the new u-joints mileage is back up to where it had been historically and I was REALLY SUPRISED how much smoother the truck ran on the interstate. I think I was lucky that I did not knock out a pinion bearing or tailshaft bearing on the transfer case because of vibrations.

DuaneW.

 

huh thats strange, Mine only does it at cruising or just light acceleration. If im givin it even just a little extra, it wont shake at all.

Maybe that will have to be the next weekend project, Take the drive line off and replace anything needed.

Feel free to chime in anyone else, not quite sure if U joints are the cause yet.

 

I brought this up last night to one of my buddys thats been drivin a cummins for a few more years then me now, he said he had a problem very much the same.

He got a harmonic balancer put on his drive line and the shake at those speeds went away. I cant find anything on line about it really but this is the place he told me to go and where he got his done.
http://www.sixstates.com/products/products.jsp

Think a outa wack driveline could be givin me this shaking at ONLY the previously mentioned speeds?

 

Bump, Anyone?

 

I had a very similar vibration in mine. I also noticed a little surge or bucking when pulling away from a stop (standard trans). This was especially bad when towing. My fix was the driveshaft carrier (or support) bearing. The old bearing portion was fine but the rubber between the bearing and housing was getting weak.

 

So it Did end up being a drive shaft related issue in your case.

Alright, looks like ill give then a call and see whats up. Thanks for the info guys.
Ian

 

Replacing the Ujoints is not a big deal, if you are unsure take driveshaft off and check/replace them, it will take a sat morning to do it, and if you really want do the center bearing also, but you will need a press or a shop to take it out.

You won't believe how smooth it will be later, and you'll know joints are new for a long time.

 

I've been having a very similar problem recently. The vibration is there at all speeds and obviously worse the faster I go. It sometimes feels more like a wobble though than a vibration. I've had new tires put on and had them rebalanced 4 times thinking this was the culprit. At a stop, when I go to take off there is a thump, axle rotates from being under load and then the thump/pop occurs. I can visually see the leaf springs jump and feel the whole truck hit/pop when this occurs. It will not be back until I come to the next complete stop. The ujoints seem very good to me. I've replaced the tranny, rear end, leaf springs, shocks, stabilizer links, carrier bearing, and had it to the shop probably 6 times and they can not figure out where it is coming from. They thought it might be the bushings on the leaf springs. Even though the u joints seemd fine can they still cause something like this? My fuel mileage has dropped down to 14-16mpg from 118-20 since doing all this. Need Help!

 

Well mine's not that bad, good luck to you luckyrogue thats a drag, ope you can track it down.

Ill see what sixstates says and might even just replace the u joints regardless. Wouldnt hurt to have new ones after 75k miles anyway right

 

Yeah, I sure hope I can figure it out one of these days. All I really have left to do is change the u-joints, replace the bushings on the leaf springs, and I guess I could rebuild the t-case but I highly doubt that is the culprit! Good luck with yours and let us know if you solve the problem.

Luke