Mpuig94

I'm getting a bad vibration from under my truck. I get it when i'm coasting and just hitting the gas just a bit. I can feel it if i grab the bed through the rear window as i'm driving. I've searched the forums and did some of the stuff i've read. i have a 94 pick up 4x4 with a 22re. i started getting the noise when i put 3" lift springs in the back. i've corrected the angles and changed the u-joints and i'm still getting the noise. It's not as loud as it used to be but still there. Changed the read axle bearings and still geting noise. When i took the drive shaft out to do the u-joints i checked the two flanges that it mounts to and i can rotate the pinion flange a bit. It feels a little sloppy. The one at the transfer case feels good. Could the bearing be bad or the pinion preload not right? I'm getting a little oil at the flange of the 3rd member so i'm going to replace the seal but i'd like to know if i should change the bearing and check the preload.

Thanks

4Crawler

iTrader: (3)

Sounds like a loose pinion flange, I'll usually feel a little vibration in mine under light load when just getting on or off the gas. Probably was shaken loose before you corrected the shaft angles. Snug up the pinion nut a little, I unstake the nut and take it up to 90 ft.lbs. or so and re-stake it:
- http://www.4crawler.com/4x4/CheapTri...eal/index.html

Mpuig94

OK i'll give it a try and see what happens.

Mpuig94

well it's not the 3rd mamber. the vibration has got to be coming from the transfer case. i tryed to see if i can feel the vibrations any where else in the truck and i can feel it when i touch the 4x4 shifter. could it be bad a bad bearing or the chain?

Duffdog

dumb question, but when you changed the u-joints, did you mark the driveline yokes to be sure that they are in "phase"? I had this problem for about a year, until I figured out that the driveline was exactly 180degrees reversed from where it should be. Once I spun the rear yoke around, vibration was gone.

Mpuig94

yea it's in phase. i checked it again today and it's good. i tourqed the nut at the 3rd member and no change. this week end i'm going to try to tourqe the nut at the transfer case to see if that helps.

vasinvictor

iTrader: (3)

Welcome to the vibration club. I've spent lots of $$$ chasing mine. It's very faint now, but still there none the less. Pull the rear DS, lock hubs and put in 4wd and see how it drives.

Mpuig94

that's the first thing i'm going to do tomorow. i'm also going to put the truck on jack stands and run the truck to see if i can hear it better.

ok, took the rear ds out and ran it in 4 wheel drive. i got NO noise NO vibration at all. so it has to be eather the DS or the 3rd member or both.

Duffdog

Another option could be a bad 3rd member or something gone wrong inside of it. Had that problem with my last 4r, pinion bearings were pitted and pinion turned rough.

also, I noted that the rear output shaft from the back of the transfer case was not very tight at all. I could move the driveline up and down about 1/8". That contributed to some vibration also.

highway

mine was doing that and i greased the slip yoke really good and it is almost gone .

Mpuig94

i'm leaning towards the 3rd member. so i;m going to have that looked at first but i also want to have the DS balanced. i'll update as soon as i have it checked

Mpuig94

well had the DS balanced and i'm still getting a vibration. i did find some metal panels that are loose. so i'm going to remove them and see what happens.

vasinvictor

iTrader: (3)

I hope you find the source of yours, but I've replaced nearly everything on mine, including 3rd member, and it still vibrates while light on/off the gas or coasting in neutral. The only things that are left are the transmission and transfer case... Things that helped the most are when I had my transfer case output shaft bearing replaced, and then tightened the flange nut on both ends. I am just learning to be friends with my vibration. That, and the new 33x12.5 BFG A/Ts help drown it out a little. I've thrown in the towel on finding mine, but good luck. If you do give up, you are in good company.

InternetRoadkill

Vibrations while coasting are usually traced to the pinion bearings. They are either worn or have the wrong pre-load on them.

I got the same problem, but I haven't had a chance to take it apart to fix it.

Mpuig94

well i swaped out the 3rd member and no change.
so far i've done new drums and shoes, 3rd member,u-joints and balanced drive shaft, rear axle bearings and seals and still a vibration. i've checked my angles many times and looked to make sure the the driveshaft was phased correctly. if i take the drive shaft out and drive in 4x4 there is no vibration. there is no play if i try moving the flange at the transfer case. i'm thinking the the angles from transfer case to driveshaft and drive shaft to pinion are to large. could this be what's make everything vibrate? from what i've been reading they say that 3° is the perfect angle at eather end of the driveshaft. when i measure my angles i'm seeing 12° at each end of the drive shaft. could this be my problem?

4Crawler

iTrader: (3)

Yep, 12* is getting up there in the angle range of the u-joints. I found mine no longer ran smooth once I hit 12*-15* and had to swap to a CV shaft. Reason being is the the u-joints don't quite cancel out each other and that mis-match gets bigger the bigger the angle:
http://www.4crawler.com/4x4/CheapTri...n-Measurements

BlackBox

Sounds like it very well could be the angle of your u-joints. I chased the source of my runner's vibes for years until i finally found a competent shop to check out my driveshaft (I'd had it balanced, got new u-joints, new gears done right, etc). For me it turned out to be that the splines inside the shaft were all chewed up. May be worth it to pull the shaft apart and see if the splines are still in good shape.

Mpuig94

Well after a lot of searching and looking. i think i have found the problem. the 3" lift springs are pushing the rear back by about 1.5 inches. which is the amount the slip splines in the drive shaft is pulled out. when i bought the springs they said direct fit but i think the spring perches had to be relocated. i just ordered new stock spring to go with my 4" lift kit i just got. as soon as i install everything I'll let you all know what happens.

Mpuig94

OK I'm stumped. Here is what I've done.
1. Took drive shaft out and driven in FWD vibe/noise stopped.
2. Had drive shaft balanced and u-joints replaced. vibe/noise still there.
3. Changed out 3rd member and rear bearings and seals. vibe/noise still there.
4. Put in new trans mount. old one was broken. vibe/noise still there.
5. Put new stock leaf springs. vibe/noise still there.
6. Added 1.5 inch drive shaft spacer to put slip splines into right engagement. vibe/noise still there but not as loud as before.

Anyone have any thoughts on this?
I guess the next thing i should look at is the transfer case.

4Crawler

iTrader: (3)

Didn't mention if you had checked the drive shaft alignment and phasing:
- http://www.4crawler.com/4x4/CheapTri...l#Measurements
- http://www.4crawler.com/4x4/CheapTri....shtml#Phasing

And you might try different positions of the shaft on the t-case and/or pinion flanges. Sometimes one position will run smoother than another. Just unbolt the shaft, spin the flange around 90* or 180* and reattach the shaft.