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Driveline vibration advise please

curts97

NAXJA Forum User
Location
abq,nm
I just re-geared to 4.56 about 3 weeks ago and have about 300 miles on it with easy driving no high load. About the middle of last week I noticed a vibration around 30-35mph. It gets stronger as speed increases, but is not accel/deccel dependent(it is speed based not throttle based). I tossed it up as a bad u joint. I ended up replacing it this weekend. Now the vibration is worse. I did some searches and found a couple threads stating it could be the pinion nut has come loose. I have rechecked both pinions and they are nice and tight. I do not have a sye. I do have a tc drop though.

It is just weird that it would develop randomly when everything seemed fine.

Also I checked for axel wrap last night. There is little movement from the axel when power is applied forward and reverse. An motor & trans. mounts were replaced about 4 months ago. They do not have any cracks or tears in them either.


My plan of attack:
1. Remove front/rear ds to figure out which end it is coming from.
2. check u joints in front ds for play/slop
3. use gauge to check actual pinion angles.

Any other suggestions of what to check next or first?
 
If you find that it is coming from one of the driveshafts then get it balanced. The driveshaft is spinning mucch faster now and a small imbalance that was not apparant before will be noticable now.
 
Post a pic of pinion angles with DS on.
Any slop in the pinion yoke? You are 100% sure its not coming from the front DS?
 
I pulled the front drive shaft after work. On the way home I noticed that the vibration was nearly gone. However it was still there at about 50mph now but a lot less severe.

No play in pinnion either. An I will take a pic of the angle on my lunch break today.
 
So I rebuilt the drive shaft and reinstalled it. The vibes are still there. It looks like I have a little in and out play on the transfer case yoke. It's about an eighth of an inch could this bee the problem? And is it just a bad bearing or is the shaft damaged. I can see if it was up an down it being a bearing. But in and out?

What do you guys think?
 
Pics of rear angle...

IMAG1667_zpsaa7d45ce.jpg


IMAG1669_zpsedaaf7a1.jpg
.

I also noticed on the freeway after 65mph it vibrates from the rear but only while on the gas. This is without the front drive shaft in. With the front in. It still vibrates from 35mph up.
 
I just re-geared to 4.56
When I regeared, the front end developed a vib that was eventually tracked to the front axle pinionu-joint angle being over the FSM recommendation of less than 1 degree of angle. Adjusting the pinion angle to about 1/2 degree eliminated it. Regearing causes the driveshafts to spin faster at any given speed.

Have you measured the rear axle u-joint angles, calculated the proper rear axle shim and install shims to adjust the u-joints angles so they run at the same angle?
 
Front pinion angle. After I regeared I had the same issue for 3 years. Finally got the angle "good enough," however it still vibes a little. Part of the price for not having hubs.
 
Pics of rear angle...

IMAG1667_zpsaa7d45ce.jpg


IMAG1669_zpsedaaf7a1.jpg
.

I also noticed on the freeway after 65mph it vibrates from the rear but only while on the gas. This is without the front drive shaft in. With the front in. It still vibrates from 35mph up.

That angle looks good if you're running a cv shaft but, you said you are not
running a sye
I'm betting your pinion angle and out put yoke angle are pretty mis matched
and that's why you're getting a vibration
Hans
 
I do not have an SYE and had the same problems after lifting and re-gearing. I did not want to spend the money on the SYE as it would have been double the cost being I have the 242 T-case, nor did I want to do a hack-n-tap. What I did was call Tatton's driveline out of Utah and had a CV driveshaft made that still has the slip yoke end the goes into the T-case. This was about 2 years ago and about 270$ delivered to the door. couldn't be happier with it. I can still run the stock shaft if needed, no mods, just plug and play. If you run the SYE or hack-n-tap kit you still have to buy a shaft anyways. All I did was tell them what I wanted and gave them a measurement from center to center of my existing driveshaft and they did the rest perfectly...Definitely recommend this route. Not to mention all my wheelin buddies were P****d off when they found out how cheap I got off running a CV shaft and didn't spend any time or $ messing with the T-case. Very strong made shaft balanced perfectly and had it to my door in less than a week. Oh, and one more thing, all his in house built shafts carry a no B.S. warranty, you break it they replace it. Hope this helps.
 
How do you deal with getting home when you bust a rear driveshaft?
 
I can take along the stock shaft if I'm worried about it, or like most be stuck and have to be towed. Welcome to the offroad world where al things are variables and you cant control them all.
 
It's like going bear hunting with a stick...sometimes you get the bear, and sometimes the bear gets you. For instance you can take two spare tires with you and get 3 flats.
 
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