1998 tj automatic transmission. I am feeling a slight vibration on even slight acceleration. It smooths out when I take my foot off the gas.
Vibration on acceleration
- Thread starter 1998 TJ
- Start date
Was good before and then got worse on its own, or did you do something to it before this happened.
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I would check the condition of the rear driveshaft U joints; especially the one near the transfer case.
Look for signs of rust particles where the trunion inserts into the U joint cup.
While you are down there; it couldn't hurt to check the rubber part of the transmission mount for tears and/or separation.
Look for signs of rust particles where the trunion inserts into the U joint cup.
While you are down there; it couldn't hurt to check the rubber part of the transmission mount for tears and/or separation.
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Give better details or did your wife lose her vibrator and the Harbor Freight batteries are going dead?
I see....
Keep your foot off the gas pedal and stop accelerating, it will smooth out.
That will be $499, cash or card?
Brianj5600
TJ Expert
Lots of good folks here who can help you pin down and resolve the issue (unless you are just stopping by to tell us about your vibration), but we'll all need more information.
1) Did you make any changes to your rig recently?
2) Can you take pictures of your rear driveshaft and where it enters the rear differential at the pinion. Upload them by posting here and clicking the "Attach files" button on the lower right side of your post. jpg format. You can do it from your phone.
3) Do you have a suspension lift? If so, how much suspension lift? Please measure your coil springs. Guessing doesn't help. What the advertiser who sold the coils said it will give doesn't help. We need to know the actual amount of lift. Stock front coils are 12" and stock rear coils are 8". Get a tape measure out and go measure. Whatever is above that number is the amount of lift you have front and rear. They are not always the same amount front and rear, so tell us both.
4) Did you recently hit your rear driveshaft while driving offroad so it might be out of balance and cause vibration under load
5) Tell us anything else you can think of that might help diagnose.
I have the same/similar symptoms as the OP. When accelerating I feel vibration and when I lift off the accelerator the vibration goes away. The Jeep is new to me, I've only driven it about 150 miles around town; I'm just now starting to notice some of these things. At 40+ miles an hour, it's very noticeable when I lift off the accelerator and coast. I am looking for some direction on what I can/should do to remedy the vibration, I'm assuming that it's attributed to the current drivetrain angles.
The Jeep is a 2006 LJR, it has an as advertised 4.5" Rubicon Express long-arm lift on 33" tires. The lift was professionally installed at 4West in California in 2008. To my knowledge, the entire drivetrain is otherwise stock. I have a good deal of documentation on the Jeep from the previous owner, my grandfather, but unfortunately he passed about 6 years ago. From the time of his passing until I acquired the it, the Jeep was infrequently used. What I know of the Jeep is from documentation and a family friend that wheeled with my grandfather; he shared a brief but concise list of known issues/maintenance objectives for the Jeep.
Per @JMT's direction, I'll try to go by the numbers here.
1) Did you make any changes to your rig recently?
Not anything that would have a material impact on the vibration I'm experiencing. I changed the valve cover gasket, oil pan gasket, replaced the RMS, and washed it. Oli leak may not be 100% fixed but it's 90+% improved.
2) Can you take pictures of your rear driveshaft and where it enters the rear differential at the pinion. Upload them by posting here and clicking the "Attach files" button on the lower right side of your post. jpg format. You can do it from your phone.
Yes - shown below
3) Do you have a suspension lift? If so, how much suspension lift? Please measure your coil springs. Guessing doesn't help. What the advertiser who sold the coils said it will give doesn't help. We need to know the actual amount of lift. Stock front coils are 12" and stock rear coils are 8". Get a tape measure out and go measure. Whatever is above that number is the amount of lift you have front and rear. They are not always the same amount front and rear, so tell us both.
Lift, yes. Front coils measured to a little over 16" and rear coils measured a little over 12".
4) Did you recently hit your rear driveshaft while driving offroad so it might be out of balance and cause vibration under load
I have not taken it offroad in the month or so I've had it. The u-joints look tired but not clapped out, I don't hear them banging when going into drive/reverse and they don't feel loose when wrestling them in hand. The rear driveshaft has no obvious impact dents/scratches and I don't see anything to suggest it's missing one or more balance weights.
5) Tell us anything else you can think of that might help diagnose.
The family friend expressed to me that the driveline vibration was a known maintenance item, he attributed the vibration to the driveshaft being out of alignment. The gentleman owns and has enjoyed a lifted TJ for years, I'm confident he's in the know about these things.
Couple pictures for consideration, I'd tried to make sure these were well lit and generally square in frame.
Based on guidance in another like-thread, I measured some angles and documented them per this guide: https://4xshaft.com/blogs/general-tech-info-articles/slopes-vs-angles
I know I have adjustable upper and lower control arms in the rear. What I'm not clear on is what angle(s) I should be shooting for and/or what if any impact my tinkering with the pinion angle will have on the overall vehicle alignment. As always, I appreciate the wealth of knowledge and comradery here. Thank you.
Your rear pinion angle is too high for that type of driveshaft. With 2 U-joints, the pinion shaft should be parallel to the transfer case shaft.
Read this and watch the excellent videos:
https://4xshaft.com/blogs/general-tech-info-articles/driveshaft-angles
Read this and watch the excellent videos:
https://4xshaft.com/blogs/general-tech-info-articles/driveshaft-angles
Oh man, I just flashed forward 20 years and imagined my grandson - LJ - typing this exact post on this exact forum…
Sorry for your loss, Don. My grandfather has been gone over 20 years, and I still miss him every day. I am a gearhead 100% because of him. So glad you wound up with his Jeep, that’s pretty cool.
LONGJP2
TJ Expert
The longer (LJR) rear shaft can handle more angle/lift than others. However,15yrs of being misaligned has probably taken its toll.
Even if you rebuild it, adjusting it to the proper rear diff angle would put even more stress on both joints.
IMO, the better solution for that amount of lift would be to replace the rear shaft with a double cardan one (3 joints).
Then adjusting the rear pinion accordingly.
It also wouldn't hurt to disconnect the front shaft to help isolate the vibration.
Looks pretty clean for a Michigan Jeep.
@OldBuzzard thank you for the resources.
@NashvilleTJ Appreciate the sentiment. I'm grateful my grandmother didn't have to sell it to a stranger.
@LONGJP2 I reached out to Tom Wood's to acquire a replacement DC driveshaft. Depending on how energetic I'll be this weekend, I may attempt to improve what I have in the interim.
@NashvilleTJ Appreciate the sentiment. I'm grateful my grandmother didn't have to sell it to a stranger.
@LONGJP2 I reached out to Tom Wood's to acquire a replacement DC driveshaft. Depending on how energetic I'll be this weekend, I may attempt to improve what I have in the interim.
Good decision to go with Tom Wood, his product is outstanding and his pre/post sales support is unsurpassed. I have installed 4 or 5 of his driveshafts over the years.
I have purchased multiple Tom Woods driveshafts for my XJ and TJ over the past 20+ years and have never had a problem with any of them.
As JB stated above; a quality product with great customer service.
As JB stated above; a quality product with great customer service.