Hard to explain CRD jumping

asonyi · **Posted:** Thu May 31, 2012 12:20 pm

When pressing the brake, just before I come to a complete stop, the car "jumps" or "clunks" a little. Then as I release the brake, and just when I press the accelerator, it "jumps" or "clunks" again. It doesn't do it everytime or is dependent on how quickly I come to a stop. Any thoughts on what this might be?? Thanks!

ChooChooman74 · **Posted:** Thu May 31, 2012 2:20 pm

X2. I have been meaning to ask about this. It feels like a boot in in butt.

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msilbernagel · **Posted:** Thu May 31, 2012 3:00 pm

Three thoughts on where to look, off the top of my head:

1) motor mounts (engine rocks and the shift is when torque on the mounts reverses)

2) Rear upper control arm; it normally controls rotational torque of the rear axle/pumpkin. If the ball joint on top is failing it'll rock/tip forward and backward. Suppose it could involve the lower control arms but you'd be complaining about torque steer if it were significant.

3) Transmission issue. I don't recall if it's the torque converter or a check-valve failing but they can briefly seem to lock up (the T/C) rather than disengage do to this problem.

Mark

ChooChooman74 · **Posted:** Thu May 31, 2012 5:13 pm

It definitely feels like it is from the rear. I will check into it tomorrow after work.

Quiksilver · **Posted:** Thu May 31, 2012 5:20 pm

I also get a bit of this...

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CATCRD · **Posted:** Thu May 31, 2012 5:22 pm

Also check the rear driveshaft slip yoke. You can take it off and grease the splines.

Quiksilver · **Posted:** Fri Jun 01, 2012 2:47 am

Quote:

Also check the rear driveshaft slip yoke. You can take it off and grease the splines.

I've heard his advise before actually. How exactly do I do this?

Joe Romas · **Posted:** Fri Jun 01, 2012 8:14 am

Quiksilver wrote:

Quote:

Also check the rear driveshaft slip yoke. You can take it off and grease the splines.

I've heard his advise before actually. How exactly do I do this?

I've had this happen on several XJ's and on my 06 CRD.

Jack the jeep up, remove the bolts/nuts or whatever fasteners that are used on the flange holding the rear U joint to the rear differential flange.
Remove the clamp on the plastic accordian boot on the front of the driveshaft where it enters the transfer case.
Lower the rear of the drive shaft and slide the shaft out of the transfer case.
Apply grease to the splines of the shaft and reverse the above. I use a cable tie on the accordan boot :SOMBRERO:

patmaz · **Joined:** Sat Jan 01, 2011 2:52 pm **Posts:** 134

Joe Romas wrote:

Quiksilver wrote:

Quote:

Also check the rear driveshaft slip yoke. You can take it off and grease the splines.

I've heard his advise before actually. How exactly do I do this?

I've had this happen on several XJ's and on my 06 CRD.

Jack the jeep up, remove the bolts/nuts or whatever fasteners that are used on the flange holding the rear U joint to the rear differential flange.
Remove the clamp on the plastic accordian boot on the front of the driveshaft where it enters the transfer case.
Lower the rear of the drive shaft and slide the shaft out of the transfer case.
Apply grease to the splines of the shaft and reverse the above. I use a cable tie on the accordan boot :SOMBRERO:

X2 and also while you have the drive shaft out,check the u-joints,depending on the miles of the crd,they might need replacement to.... :wink:

CATCRD · **Posted:** Fri Jun 01, 2012 6:10 pm

Yeah make sure all the joints move nice and free while you have it taken off. If you're really careful taking the front boot clamp off you can reuse it.

sidebrake · **Posted:** Fri Jun 01, 2012 6:58 pm

All great suggestions above.

I had the same behavior with the addition of vibration around 50 mph... It was a bad U-Joint. $15 and not terribly difficult to replace once the drive shaft is off.

Tiarnon · **Posted:** Fri Jun 01, 2012 11:05 pm

I get the same. Seems to me like as the Liberty comes to its stop, the torque in the drive line rotates the rear axle slightly, and as you let off the brakes to accelerate again, it releases and gives that funny feeling. Doesn't do it if the brakes are released slowly - seems like it releases the stored tension smoothly rather then abruptly.

Going to get transmission fluid/filter changed within the next two weeks, I'll put it on my list of things to have looked into.

Quiksilver · **Posted:** Sun Jun 03, 2012 10:22 am

Just regular old anything grease?

Quiksilver · **Posted:** Wed Jun 06, 2012 3:50 am

Just an FYI, I changed the Diff oil this past weekend and since then I have not experienced the thunk. Might be a coincidence but thought I'd mention it.

grywlfbg · **Posted:** Thu Jun 07, 2012 7:27 pm

I had the same symptom (along w/ the hard 2-3 shift) and after a tranny fluid/filter change and quick learn both problems are gone.

Joe Romas · **Posted:** Fri Jun 08, 2012 11:43 am

Tiarnon wrote:

I get the same. Seems to me like as the Liberty comes to its stop, the torque in the drive line rotates the rear axle slightly, and as you let off the brakes to accelerate again, it releases and gives that funny feeling. Doesn't do it if the brakes are released slowly - seems like it releases the stored tension smoothly rather then abruptly.

What happens is when you stop the rear end raises and the drive shaft extends outward on the slip joint. Then when you release the brake the rear end drops pushing the drive shaft back in and the sensation you feel is the slip joint on the front of the drive shaft binding.
This has more to do with the short wheelbase and drive shaft length. As I mentioned XJ owners have experienced this for years with the 4.0L and Asin AW4 transmission :JEEPIN:

GM has/had a very expensive grease just for this. I just did a google search on GM slip joint grease and got many hits, yes it's a very common problem and not just on our Jeeps but here's what I was talking about.
GM recommends their Special lubricant high temperature PTFE filled non melting grease part # 12345879. Its darn high. This small can I have in my hand was $35 and that was at a discount

ChooChooman74 · **Posted:** Sat Jun 09, 2012 6:55 pm

I took my driveshaft off today. U-Joints look good. The splines on the transfer case looked dry. I cleaned them, and the yoke, and greased it all up. Feels A LOT better so far.

Hard to explain CRD jumping

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