vibration in drivetrain at low rpm in 4th and 5th gear

dirtmover · **Posted:** Sun Nov 30, 2008 8:30 pm

My U-joint felt like the rumble strip at the side of the highway but only on deceleration below 40km/h and intensifying until I reached a stop. When I checked underneath I could see that the seals had popped.

bigugly · **Posted:** Sun Nov 30, 2008 8:36 pm

I have the suncoast TC so it better not be that. I paid enough for the thing. Didn't have this vibration before my OEM TC bombed so I doubt it is the TC.

FastRob let me know if the new U joint fixes the vibration. For less than $200 not a big deal if it solves the problem.

retmil46 · **Posted:** Mon Dec 01, 2008 3:26 am

Had same symptoms, "rumble strip" effect under varying conditions. New set of u-joints cured the problem, also got rid of annoying clunk going between Park/Reverse/Drive and smoother on highway.

If you really want to get fancy, Google "Tom Woods Custom Drive Shafts", and get a set of the Gold Seal greaseable units - if they ever fail, he'll not only replace the u-joints but your whole driveshaft as well.

chadhargis · **Posted:** Mon Dec 01, 2008 10:49 am

I only have the issue in 4th and 5th gear, lightly accelerating. I don't have any clunks or other issues except ever so often, the transmission will suddenly downshift. Sometimes violently enough to skid the rear tires. It's not fun.

It's almost like the TCM is rebooting or something. My guess is that I have a fudged up TCM. Wish I could get my hands on another one.

retmil46 · **Posted:** Mon Dec 01, 2008 12:19 pm

chadhargis wrote:

I only have the issue in 4th and 5th gear, lightly accelerating. I don't have any clunks or other issues except ever so often, the transmission will suddenly downshift. Sometimes violently enough to skid the rear tires. It's not fun.

It's almost like the TCM is rebooting or something. My guess is that I have a fudged up TCM. Wish I could get my hands on another one.

Chad, as far as the tranny downshifting on it's own - if you've still got your Scangauge II plugged in as per your sig - hate to say this but you need to get rid of it. I had the same problem while using the Scangauge - since I removed it nearly a year ago the problem hasn't reocurred since - my tranny guru concurred, he checked out my tranny and TCM forwards and backwards - he found a buried trouble code that won't trigger the CEL on the dash, the code basically meant the TCM had lost communication with the rest of the bus and rebooted itself - since this had only ocurred since I installed the Scangauge, we theorized that the Scangauge was adding in enough noise on the data bus to cause the TCM to occasionally lose comms and reboot itself - only thing I know is, since I unhooked the Scangauge the problem has went away.

Yeah, I know, it sucks to buy a $150 piece of gear that turns out to be worthless for your vehicle. :evil:

ATXKJ · **Posted:** Mon Dec 01, 2008 12:25 pm

I plug my scangauge in a startup for a few minutes and then unplug it
definitely never have it plugged in while on cruise control - overloads the bus and kicks it out of OD - not nice
(happened several times when I had the scangauge connected - never with it disconnected)

chadhargis · **Posted:** Mon Dec 01, 2008 1:33 pm

Humm....well...I just may have to unhook that sucker then.

The only thing I use it for is to reset the CEL due to the ORM.

I'd love to do an SEGR, but in all honesty, I simply don't want to risk fouling up my wiring harness trying to hook it up. If I knew someone who lived nearby who could help me install it, then I'd do it. I just don't want to fumble around trying to figure out how to do it by myself.

The downshift thing doesn't happen often (it's rare actually), but the shudder happens almost every time I drive the vehicle fast enough to get into 4th gear. I live in Tennessee, and it's hilly. So if I go up a hill at more than 50mph and don't remember to either stop accelerating, or mash the pedal to kick down the tranny, then I get the shudder.

retmil46 · **Posted:** Mon Dec 01, 2008 2:21 pm

chadhargis wrote:

The downshift thing doesn't happen often (it's rare actually), but the shudder happens almost every time I drive the vehicle fast enough to get into 4th gear. I live in Tennessee, and it's hilly. So if I go up a hill at more than 50mph and don't remember to either stop accelerating, or mash the pedal to kick down the tranny, then I get the shudder.

Close to the same conditions I'd get the "rumble strip" effect, as far as gearing, speed, and engine rpm, also while mashing down the pedal to accelerate and/or kick down the tranny. New u-joints a few months back, and so far it hasn't reoccurred.

And I was seeing this effect both prior to and after the Suncoast install - I just chalked it up to an oddity of our vehicles - until the first thread about u-joints popped up several months back, and several other people also described the rumble strip effect.

As far as the Scangauge, no problem having it plugged in for a few minutes when starting up to clear the CEL - I just wouldn't leave it plugged in when driving on the highway. It was fairly intermittent with me as well - maybe 5 times in 3000 miles, no rhyme, reason, or pattern. But when it happens at 70 mph on a crowded interstate 1600 miles from home and the tranny drops completely out of gear for a few seconds, it certainly gets your attention (and nearly puts a wet spot on the seat!). I decided I'd rather eat $150 for the Scangauge than 2 or 3 grand for a tranny rebuild, especially after just spending a good chunk to put in the Suncoast.

chadhargis · **Posted:** Mon Dec 01, 2008 4:44 pm

So, how does one go about getting the U-Joints replaced?

Is thing something a local transmission shop can do?

I'm not taking it to the dealer if at all possible.

retmil46 · **Posted:** Tue Dec 02, 2008 2:49 am

chadhargis wrote:

So, how does one go about getting the U-Joints replaced?

Is thing something a local transmission shop can do?

I'm not taking it to the dealer if at all possible.

Local tranny shop should be able to do it in less than 2 hours tops. My tranny guy did mine, plus replacing a ball joint boot on one of my Moogs the original installer had screwed up, and the whole deal took about 2 hours. May even take as little as one hour if they're not busy and know what they're doing.

Even if you go for some top end u-joints like the Tom Woods Gold Seal greaseable I got, you're talking 20 bucks each or less. If I remember correctly, my tranny guy said he preferred some high quality greaseable units from NAPA if the customer didn't already have replacements in hand.

fastRob · **Posted:** Tue Dec 02, 2008 10:36 am

I have trouble thinking of the installation.
When I pulled mine apart to do the T/C, the shafts went together like a ball in socket with cap screws.
A peculiar setup in my mind's eye, to say the least: constant velocity joints.[/b]

CRDMiller · **Posted:** Tue Dec 02, 2008 10:56 am

I have been beating the crap out of my crd for a while now ~16k miles in 5 months. And i have NEVER experienced this vibration.

Yesterday at 2 pm i got my ecu back from inmotion tuning.

As soon as i get on it in 4 or 5'th gear, all the way from 1800 to 2100 or so it feels like i am driving over rumble strips! Particularly when i am in 5'th at 60 (via slowing down from 65, i often cruise like this in 55 mph zones)

And it is most defiantly the tc slipping.

Pre tune, 19.5 psi or so was max boost ~1800 rpm pulls from 4'th and 5'th
Now i'm in the neighborhood of 23 psi. As soon as i break over 19 or so it shudders (it feel like a portable drill with a slipping clutch, you know like setting a dewalt to like 5 when your screwing into plastic or something)

It is defiantly a hell of alot faster though.

Although I sure wonder how effective it is once you get to that point.

Cowcatcher · **Posted:** Tue Dec 02, 2008 11:00 am

Definately U joints in my book. I thought it was TC too since I have never had my original recall one replaced. I took it too the dealer...got scolded...then an apology when he found it was U joints. At the time I posted it here and many were finding failure at around 40K miles. I swear there was always slop in my driveline on startup, just another "Jeep thing", but with the new U joints it is smooth as butter. Any monkey could replace them for $75 to $150 including parts but it is not something the dealer could screw up if that is your fear. Mine was still under warranty so it didn't cost me anything.

CRDMiller · **Posted:** Tue Dec 02, 2008 3:13 pm

Thanks, will investigate u-joints, is there a write up on here osmehwere? also, part numbers for the greasable joints?

Dawgbyte1975 · **Posted:** Tue Dec 02, 2008 4:57 pm

you can find the u-joints on the napa website under jeep liberty, there is a greasable one listed

dirtmover · **Posted:** Tue Dec 02, 2008 7:59 pm

chadhargis wrote:

So, how does one go about getting the U-Joints replaced?

Is thing something a local transmission shop can do?

I'm not taking it to the dealer if at all possible.

You don't need a transmission shop, any mechanic can do it. Heck you could do it yourself! I had the dealer do mine only because it was under warranty. It took him about 30 minutes including before and after test drives.

bigugly · **Posted:** Tue Dec 02, 2008 9:54 pm

thanks everyone for the posts. I will get the U joints replaced. I am glad I posted this question because it looks like there are others that got some help out of this as well.

Thanks again.

kb61751 · **Posted:** Wed Dec 03, 2008 2:25 pm

I just have a hard time accepting that its the u-joints causing the problem. Drive shaft load and speed would be the same (or greater)at other load\transmission ranges. I feel it may have something to do with the engine load at that speed (1600-1800 rpm), which is only held there under load for any long time when the transmission is in TC lockup. I vote for a fuel issue (air, overloaded, etc). The other is that the TC is slipping when locked up, but at 2000 rpm where the most torque is developed it does not make that noise, so I don't think its that.

robotmind · **Posted:** Wed Dec 03, 2008 4:32 pm

CRDMiller wrote:

I have been beating the crap out of my crd for a while now ~16k miles in 5 months. And i have NEVER experienced this vibration.

Yesterday at 2 pm i got my ecu back from inmotion tuning.

As soon as i get on it in 4 or 5'th gear, all the way from 1800 to 2100 or so it feels like i am driving over rumble strips! Particularly when i am in 5'th at 60 (via slowing down from 65, i often cruise like this in 55 mph zones)

And it is most defiantly the tc slipping.

Pre tune, 19.5 psi or so was max boost ~1800 rpm pulls from 4'th and 5'th
Now i'm in the neighborhood of 23 psi. As soon as i break over 19 or so it shudders (it feel like a portable drill with a slipping clutch, you know like setting a dewalt to like 5 when your screwing into plastic or something)

It is defiantly a hell of alot faster though.

Although I sure wonder how effective it is once you get to that point.

I experienced the same thing with the inmotion tune. I have just recently had my u-joints replaced with Spicer grease-able u-joints in a attempt to solve the problem, but to no avail. New trans fluid and both filters with AMSOIL synthetic ATF. AMSOIL fluids in the front and rear diffs as well as the crank case. I also have the ORM ; ) as well as a provent. I have a facet lift pump (4106 I think???) hooked into the factory wiring. I have the CAT fuel filter mod with the CAT 1R - 0750 high efficiency filter. Its been about 10k miles since replacing the fuel filter and I ordered 2 new ones. Hoping that it may make a difference. I do run homebrewed bio from time to time... maybe my filter is a bit clogged. It this doesn't work I guess 'll get the Suncoast and TransGo shift kit. I just don't know what to do anymore... :roll:

Cowcatcher · **Posted:** Wed Dec 03, 2008 6:29 pm

kb61751 wrote:

I just have a hard time accepting that its the u-joints causing the problem. Drive shaft load and speed would be the same (or greater)at other load\transmission ranges. I feel it may have something to do with the engine load at that speed (1600-1800 rpm), which is only held there under load for any long time when the transmission is in TC lockup. I vote for a fuel issue (air, overloaded, etc). The other is that the TC is slipping when locked up, but at 2000 rpm where the most torque is developed it does not make that noise, so I don't think its that.

That was my opinion too. I even went to my tire guy and had him pull all the tires thinking it was a balance or bad tire issue. Finally decided it was the TC and by that time it was getting worse, it was starting to happen at different speeds, under different situations and in all gears to some extent or another. It was also worse in the mornings after sitting all night. U joints. :lol:

vibration in drivetrain at low rpm in 4th and 5th gear

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