|06-13-2014 07:47 PM|
yep - new ujoints solved 98% of the vibration. still a tiny little bit left that I CAN believe is due to the driveshaft angle, but hugely improved.
moral of the story - sometimes a bad ujoint (or impending bad ujoint) may be difficult to diagnose as such. at least for a knucklehead like me. hopefully this thread can help someone else.
|06-12-2014 11:35 AM|
you'll be comforted by the fact that i DID inspect the shaft back then and thought it was ok, and then begrudgingly accept the explanation (by you) that the vibration was due to the u-joint/pinion angle and that it was perfectly reasonable given the 4" lift.
the 2 years sound ludriciously long, however the total miles driven since then has probably been much less than 5k (semi daily local driver for my teenage son).
|06-11-2014 09:16 PM|
|Jerry Bransford||A bad u-joint was suggested immediately after your first post back in 2012. It seldom pays to ignore suggestions, especially when made several times by different experienced people.|
|06-11-2014 08:49 PM|
ok, so this is kinda funny... I've been chasing this issue for quite a while (note my first post, which was my FIRST post). Now that the Jeep is for sale, and although we've lived with the issue for two years, prospective buyers are not particularly impressed with the vibration I discovered 2 years ago and never sorted.
so, I decided to finally figure it out. [Funny how like when you sell your house you fix EVERYTHING so it's more appealing for the next guy, instead of fixing from the getgo so YOU can enjoy it the whole time] Anyways, I pulled the rear driveshaft and tested in 4wd hi, and low-and-behold, vibration GONE.
and the best part, I noticed slop in the Ujoints. Turns out one of them was toast, missing all the needles and very worn. I'll post the results after reinstalling the new joints tomorrow, but thought this pretty ironic!
|05-27-2013 05:44 PM|
|Jerry Bransford||Glad you found it. I stopped using clip-on weights due to how easily they can be scraped off & converted to stick-on weights that sit further into the wheel's inner surface so they can't get scraped off.|
|05-27-2013 05:09 PM|
Idk if you can see well, this is the INNERWALL of my tire. Sure enough if you look at where the rim and the tire just meet there's a indent in the tire where the weight must of rubbed.
So glad I joined this forum!!!
I do like my Automatic. It's my friends I hang with that rag on me about it lmao.
|05-27-2013 08:38 AM|
Perhaps mud or sand collected in a wheel, or a wheel weight was lost, throwing a wheel out of balance. Neither of those are uncommon. Shocks wouldn't cause that problem and it's doubtful your transmission was harmed since 2002 and newer automatics have remoted vent openings that are effective at keeping water out.
Don't be bummed your Rubicon has an automatic. Automatics are superb offroad, most hard-core wheelers run automatics. I converted my '97 TJ from its original 5-speed manual transmission to an automatic and after that rig was stolen, insured my replacement rig, an '04 Rubicon, had an automatic. Not to mention that automatic transmissions can give up to 2-3X more low-end torque than manual transmissions. Thank the magic of your automatic's torque converter for that.
|05-27-2013 12:11 AM|
Okay so I have read everything above. I understand this post is a weee bit old, but thanks to google it steered me to this thread. I now have a 06 LJ Rubicon (Auto sadly) Now my quick story starts about 2 days ago... My truck was fine, took it threw some trails with a buddy (in 4H), everything seemed okay. Just yesterday the beach opened up, we were allowed to purchase a permit. I did, and decided to take my truck on the beach. NOTICED while in sand my truck was reving at 2k going about 7-10mph in (4H)... I didn't think something was right... but i haven't taken a vehicle on the beach in a while. While on the road (back in 2H) i have noticed a weird Vibration feeling at 30mph.. Then again at 50-60mph with a noisy drone/hum at this speed. I have thought it could be one of the following..
Tires missing a weight.
My shocks are bad.
Or a Transmission problem.
after reading this, i suppose a rear U-joint could be a suspect as well now... any ideas? Does my problem sound like it fits in this thread?
|11-26-2012 07:11 PM|
|11-26-2012 06:40 PM|
so i decided to pop the rear diff cover off for a peek and this is what i found. ring gear looks perfect, and pinion too. but the spiders look AWFUL - heavy worn and pitted. i also noticed the fit between the spiders, cross pin, and housing is pretty sloppy - i'd estimate about 0.005" (they are visibly wobbly).
could this be responsible for the growl/drone, or is it pretty normal (yikes!)? how tricky a job to replace?
|11-05-2012 10:57 PM|
|Coljag||I have found it! The rear universal joint on my rear driveshaft had siezed. I was unable to find any play because there wasn't any play. Replaced u/j and problem fixed, yay! Might be your problem?|
|11-04-2012 11:07 PM|
I seem to have a similar vibration? I noticed it last week and it became really bad when I had three people in the Jeep. It seems that with one extra adult in the back seat the vibration increased substantially for some reason? Anyhow I have a 2" Suspension lift and a transfer case drop. The Jeep has been fine for the last 12 months but suddenly this vibration has come about. Still searching for the source? Drive shaft universal joints appear tight. If the driveshaft angle was bad I would expect the problem from the day the lift went in?
I am sorry I can't offer any help here but others may have similar experience and located the cause? Thank goodness for more knowledgable helpful people on this forum that might be able to enlighten us all.
|11-04-2012 02:19 PM|
|Jerry Bransford||If getting rid of that type of vibration was as easy as simply changing the rear pinion angle by adjusting control arm lengths, we wouldn't be paying $$$ to buy and install SYEs and CV driveshafts once we get to 4" and taller suspension lifts.|
|11-04-2012 01:41 PM|
success, mostly. replacing the broken trans mount definitely improved the severity of the vibration, but (as i was warned by everyone!) there is still a fairly pronounced vibration under power. while i was under the jeep i took some measurements, and then started playing with a spreadsheet to see the effect of various angles.
so here's a few conclusions:
* any driveshaft angle at all creates cyclic speed fluctuations in the DRIVESHAFT. the greater the angle, the greater the fluctuations. some folks claim this is the source of the vibration (it is in fact, vibrating, albeit torsionally). theoretically if you take anything with mass and accelerate it and decelerate it rapidly (ie, vibration) then those forces will be felt. basically, its a F=ma type thing. However, my contention is it's NOT the primary source of vibration, since removal of torque transfer (lifting throttle) reduces virtually all the vibration i'm feeling, and that shouldnt have anything to do with this type of vibration since neither 'm' nor 'a' have changed.
* any misalignment between the transmission/t-case and axle will result in speed fluctuations at the AXLE. in my case, it's significant due to the 4" lift which rotated the axle pinion upwards. if the tcase and axle are aligned/parallel then the speed variations are cancelled out and the axle rotates at the exact same speed as the tcase. due to my misalignment there is a ±2% speed variation which is felt as a pulsing sensation. i think that when you chop the throttle, there is enough slop/lash in the drivetrain that those vibrations disappear.
so, rather than CVs, i wonder if longer LCAs in the back would realign things enough and remove the drone...
(btw, i'll share the spreadsheet but cant figure out how to upload)
|11-02-2012 10:36 AM|
Can you post a pic of the rear driveshaft, and rear axle showing pinion angle?
Another question: was there any damage to the transfer case as a result of the front end damage? Many times in a frontal collision, the front drive shaft will be forced back into the tcase and cause internal damage, which potentially could result in the symptoms you described.
|11-02-2012 10:23 AM|
|11-02-2012 09:35 AM|
|11-02-2012 01:59 AM|
The first thing you need to do before replacing anything is to determine if the slip yoke on the rear shaft has been eliminated and replaced by an SYE and CV shaft or whether there is a transfer case drop.
Like Jerry said it is unlikely that you will be able to reduce the driveline angle enough with only a transfer case drop so a SYE and CV shaft is the only realistic solution for vibration when you have a 4" lift.
If you don't have this, this IS the cause of your vibration. We are not guessing. It takes but merly a minute to check if you have the correct rear shaft setup. Why not check?
|11-01-2012 08:23 PM|
...not be argumentative, but it makes the damn rear-view mirror blurry and my ass numb!!! that's a shit load of vibration!
anyways, ujoints were fine but i think i found the culprit: a broken/sheared transmission cross-member mount. I cant exactly rationalize how that would translate to this type of vibration, but as soon as i can replace and road test i'll post back. thanks for the help guys.
|11-01-2012 03:58 PM|
|11-01-2012 03:55 PM|
|11-01-2012 03:34 PM|
fwiw, its a 5-spd 4.0L.
i wouldn't have thought the 4" lift would have compromised the joint angle THAT much, lots of jeeps with that amount of lift. i mean the level of vibration is unsettling... i drove to the inspection station this morning no faster than 45 mph (80 mile RT) cause i thought i was either slowly destroying something or it would suddenly gernade/seize.
i'll check the joints tonight.
|11-01-2012 12:58 PM|
|Rolf||Is it a 4sp auto?|
|11-01-2012 12:09 PM|
|jrussblues||Sounds like you need to lower your transfer case skid or add a slip yoke eliminator and a new rear drive shaft. The 2nd suggestion is the better but more costly way of correcting the problem. When you add lift it increases you factory rear drive shaft angle past a point that it can properly function at.|
|11-01-2012 12:08 PM|
|Jerry Bransford||Drivetrain vibrations that only occur during acceleration are usually caused by the rear driveshaft u-joints vibrating from either an excessively high pinion angle (when modifications have been made to allow that) or a bad u-joint in the driveshaft. Both of those would be my immediate first suspects. But that you have a 4" suspension lift makes me think that your u-joint angles are simply excessive. Fixing those excessive angles is best done with a SYE kit and aftermarket CV driveshaft. Dropping the t-case via spacers can also reduce the excess angles but I doubt you could drop it enough within reason to cure the vibrations from such a tall suspension lift. With a 4" lift, installing a SYE (slip yoke eliminator) kit into the transfer case and aftermarket CV driveshaft is the right solution. Good luck with it.|
|11-01-2012 12:08 PM|
|Dextreme||Very well could be a Driveline U-joints. I had that same accelleration vibration on a different vehicle (1 ton truck) and it was the U-joints...they had no extra play in them, just shot.|
|11-01-2012 12:01 PM|
vibration on acceleration (first post!)
Just bought a 2003 as a salvage project: needed a front suspension including axle, lower control arms, and shocks due to a front end collision (exact circumstances unknown). All done, and successfully inspected, however whenever applying throttle there is a very distinct drone/rumble/vibration/growl that permeates through the entire vehicle.
* occurs ONLY under accel; as soon as you lift the throttle it goes away
* begins almost immediately as the vehicle starts to roll
* the severity of the vibration is proportional to the throttle (worse with more throttle)
* overall excellent condition
* new ball joints, shocks, LCAs
* brand new tires (33" BFG mud terrains)
* frame professionally trued and measured
* aligned, with caster set at mid-spec
* 4" lift
* u-joints SEEM ok, but not thoroughly inspected
* rear axle untouched
It seems to me that it's goign to be driveline related, but short of putting a stethoscope on the rear axle while on stands, or pulling the cover, not sure what the usual suspects might be. Hopefully someone on this board can point me in the right direction. Thanks!