Transmission problem (????)

[Frank Z]

Hopefully someone out there might have some experience with this...

My XJ recently developed a rattling noise that I'm fairly certain is coming from the AW4 transmission. The noise is most noticeable during acceleration and immediately after taking my foot off the gas. My initial thought was gears in the rear diff since I just installed new 4.56's. So far I've been able to exclude the gears as the sorce of the noise by removing the driveshaft and running the engine and transmission. With the drive shaft removed there is a slight rattle. After re-installing the drive shaft the rattle was back, but only in Drive and 3Rd gear. When the transmission is put into 1st/2nd gear the rattle goes away completely. Because the noise only occurs in Drive and 3rd I'm pretty sure it's a transmission problem and not a transfercase problem.

The fluid is not burnt and the color is good, the fluid and filter were changed approximately 10,000 mile ago. Fluid level is good.

Flexplate bolts were also checked and found to be tight.


So, now what? I'm stumped.

[Jess]

Possibly the u-joints...I noticed similar symptoms with mine at the same times (while accelerating or just after taking my foot off the gas).

[90xj06]

is it your catalytic converter?

[Frank Z]

After re-installing the drive shaft the rattle was back, but only in Drive and 3Rd gear. When the transmission is put into 1st/2nd gear the rattle goes away completely.

No, the u-joints are not the problem, and it's not the cat either.

[goodburbon]

push the t-case selector handle forward while driving and see if that helps, also inspect your motor and tranny mounts, the fact that it isnt occuring under load suggests something may be shifting position.

[90xj06]

maybe your shift linkage is off.

[Frank Z]

Could be I suppose, but I haven't done anything to the XJ that would affect the linkage. Something else to check out....

[Frank Z]

TwistedCherokee is the man!! He said pinion angle, so I stuffed some 6deg. shims inbetween the perches and the leafs...no more noise!! SAW-WHEAT!
This just blows my mind. I haven't done anything unusual to the heep. I recently installed a newer 4.5" RE leaf pack for the bastard 4.5" leafpack I was running. The newer RE's had a major sag issue on 1 side only so a new set of Big Offroad leafs (4") went in.
I'm about 99.9% sure that I didn't need to swap out my brand spankin new 4.56's for even newer 4.56's......:mad:
Well, botom line is that my junk is on the road again!! WOOT!

[goodburbon]

reallllllly would have helped us to diagnose if you had mentioned these things!

[Frank Z]

Really, the noise was there before the springs were swapped.

[BrettM]

you should replace those joints, they don't usually last long after you change the angle on them since they basically break into a particular angle.