Vibration on deceleration

dirtmover · **Posted:** Thu Jun 12, 2008 7:51 am

This should probably be in the KJ discussions forum but since the car is a CRD and this forum is more lively, here goes.

I'm noticing a strange vibration on deceleration. It starts very subtle at about 25mph and carries on becoming more pronounced and lower frequency until almost at a standstill. There is no sign of this at higher speeeds or when accelerating through this lower speed range.

I thought at first it was coming from the engine, it feels a bit like engine lugging, so I tried slowing in neutral but it is still present.

It is also present when I lift my foot off the brake so I'm assuming it is not brake related.

Any ideas as to what might be causing this?

truckbouy2 · **Posted:** Thu Jun 12, 2008 8:24 am

I'd start with the u-joints. Look for any binding or rust dust around the bearing caps. Look for obvious loose driveline parts.

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

Mine did the very same thing I had a bad rear u joint replaced it with a greasable joint from Oreilly auto parts. The tranny mechanic at my local jeep only dealer said to do it so he wouldn't see me again with this problem and the part was only $22.50 vs jeep $79.00 works great .

dirtmover · **Posted:** Thu Jun 12, 2008 9:39 am

kccrd wrote:

Mine did the very same thing I had a bad rear u joint replaced it with a greasable joint from Oreilly auto parts. The tranny mechanic at my local jeep only dealer said to do it so he wouldn't see me again with this problem and the part was only $22.50 vs jeep $79.00 works great .

I was kind of thinking this way, did a visual inspection last night and checked for play but nothing obvious. It's still under warranty so I'll get the dealer to sort it out for now and swap them out for a greaseable once the warranty expires since the only cost a few bucks.

The winters are harsh and salty here!

dgeist · **Posted:** Thu Jun 12, 2008 11:06 am

All: does this manifest itself as a wobble that feels like it might be an out-of round tire at low (bumper2bumper traffic) speed? I've rotated and balanced my tires already and the problem still persists. it's driving me crazy in traffic. I start to get a resonance and bounce up and down if I'm going just the right speed.

Dan

ATXKJ · **Posted:** Thu Jun 12, 2008 11:30 am

If you have a vibration thats in decelleration - but not acceleration - I'd focus on the rear differential - that's where your loading is significantly different acceleration vs deceleration.

dirtmover · **Posted:** Thu Jun 12, 2008 11:31 am

dgeist wrote:

All: does this manifest itself as a wobble that feels like it might be an out-of round tire at low (bumper2bumper traffic) speed? I've rotated and balanced my tires already and the problem still persists. it's driving me crazy in traffic. I start to get a resonance and bounce up and down if I'm going just the right speed.

Dan

In my case it feels like th rumble strips at the edge of the highway

dirtmover · **Posted:** Thu Jun 12, 2008 11:36 am

ATXKJ wrote:

If you have a vibration thats in decelleration - but not acceleration - I'd focus on the rear differential - that's where your loading is significantly different acceleration vs deceleration.

But isn't the entire driveline loaded differently? It's all being driven back to front i.e. from the wheels rather than from the engine.

The car has 38000km on it. I changed the diff oil about 12000km ago just before winter and the original oil was very clean at that point. Regardless, I'll open the plug and extract some tonight to check for signs of metal.

dgeist · **Posted:** Thu Jun 12, 2008 11:53 am

dirtmover wrote:

dgeist wrote:

All: does this manifest itself as a wobble that feels like it might be an out-of round tire at low (bumper2bumper traffic) speed? I've rotated and balanced my tires already and the problem still persists. it's driving me crazy in traffic. I start to get a resonance and bounce up and down if I'm going just the right speed.

Dan

In my case it feels like th rumble strips at the edge of the highway

Mine is only when unloaded or lightly loaded and it feels like a broken belt.

MooseMeat · **Posted:** Thu Jun 12, 2008 1:20 pm

It was the U-Joints on my 2006, almost felt like you're on a rought road. 49,000 miles.

bdptp73 · **Posted:** Thu Jun 12, 2008 2:17 pm

dirtmover wrote:

dgeist wrote:

All: does this manifest itself as a wobble that feels like it might be an out-of round tire at low (bumper2bumper traffic) speed? I've rotated and balanced my tires already and the problem still persists. it's driving me crazy in traffic. I start to get a resonance and bounce up and down if I'm going just the right speed.

Dan

In my case it feels like th rumble strips at the edge of the highway

My jeep is doing the same thing. It starts at light throttle around 50 MPH and goes all the way through deceleration till I completely stop. Sounds exactly like the grooves they put in the highway for sleepers.

I was going to take mine in to the dealer next friday and have them figure it out, but now I can tell them what it is. :lol:

Scott Langohr · **Posted:** Thu Jun 12, 2008 5:52 pm

I was having the same problem that started suddenly (not a gradual problem). It went on for about a week and the CEL finally threw me a P0402 code which has to do with the FCV & EGR. Something about to much exaust gas or something you can look up the code. I had the SEGR circuit running at the time which should have the EGR valve closed and no power to open it. I cleared the code, plugged in my bypass plug, and drove it about 10 miles. The problem corrected itself 100%. I put the SEGR back on line and all has remained fine for this entire week. The guys in the SEGR thread seem to think it might have been a problem with the FCV but I have not had the time to remove it and be sure the butterfly is working freely yet. It is not causing me any problems now so it does not seam to be a priority. I would never of thought the EGR was the problem since the SEGR mod disables it. I imagined all kinds of drivetrain problems before the code was sent. It wasn't a drivetrain problem as they do not come on suddenly or correct themselves. I don't know if you are running the SEGR mod. but if the CEL gives you a P0402 code your EGR or FCV may need to be looked at or plug in your bypass plug if you are. It worked for me.

dirtmover · **Posted:** Thu Jun 12, 2008 8:39 pm

I did take a look at the diff fluid and it's as clean as the day I put it in 8 months ago.

I took a closer look at the U joints and the seal on one of the arms on the rear joint is split and starting to fall out. It must have been facing upward when I checked it yesterday. I suspect that if this isn't the problem it soon will be

nescosmo · **Joined:** Sat Jul 14, 2007 11:17 pm **Posts:** 202

dirtmover wrote:

I did take a look at the diff fluid and it's as clean as the day I put it in 8 months ago.

I took a closer look at the U joints and the seal on one of the arms on the rear joint is split and starting to fall out. It must have been facing upward when I checked it yesterday. I suspect that if this isn't the problem it soon will be

I had that problem with a Ford Van and I took it to the dealer and it was the Tranny. I think that they replaced the pump or the TC. or both.

nescosmo.

dirtmover · **Posted:** Fri Jun 13, 2008 5:06 pm

Just got back from the dealer with a new U joint installed and no more vibrations

bdptp73 · **Posted:** Fri Jun 13, 2008 6:12 pm

dirtmover wrote:

Just got back from the dealer with a new U joint installed and no more vibrations

That was fast.

arengant · **Posted:** Fri Mar 04, 2011 8:32 pm

Old thread I know (search engine worked!)

Mine is starting with the exact same problem, almost exactly on at 25mph while decelerating, thought at first something with the engine because it feels like the front, then I thought steering, because the steering wheel vibrates... I'll check the u-joints tonight!

Thanks for the suggestions though!

Scott Langohr · **Posted:** Fri Mar 04, 2011 9:11 pm

I had the problem and shook every u-Joint under the truck and all seemed very tight. I looked everywhere else I could think of but nothing helped for any long term period. Turned out it was the rear joint at the differential. It was the easiest to try to jerk or twist around too. The point is even if you think the u-joints are good they probably are not.

arengant · **Posted:** Sat Mar 05, 2011 5:43 pm

Good point!

Mine were nice and tight, but I did find a little wet spot on the u-joint by the rear diff, so that is the one I am going to replace first.

bhc04 · **Posted:** Sat Mar 05, 2011 6:14 pm

Good for you. Problem easily resolved and lesson learned for the Jeepers on the forum. Thanks.

Vibration on deceleration

Who is online