Clunk...Rattle. This is a long one.

[BIGSLVRXJ]

Hey guys..been trying to diagnose a problem and can't figure it out. My 90 4.0 AW4 clunks into reverse but as its going it jerks you real bad.(I've posted that before) Also I've started to notice that this problem is only when its warmed up, when its cold in the morning its smooth as all get out. Also, when it does this jerking motion, after its engaged in reverse and fighting the brake, there is a really loud rattling. I checked all my exhaust clamps and they're all holding on tight but thats what it sounds like. I have tightened the tranny crossmember but when the idgets rebuilt my tranny(4k ago) they left one bolt out so theres only 3 holding the crossmember on. Would this be whats causing the rattling and clunking or is it something else?
TIA,
Collin

[sidriptide]

Originally Posted by jeepguy1990

Hey guys..been trying to diagnose a problem and can't figure it out. My 90 4.0 AW4 clunks into reverse but as its going it jerks you real bad.(I've posted that before) Also I've started to notice that this problem is only when its warmed up, when its cold in the morning its smooth as all get out. Also, when it does this jerking motion, after its engaged in reverse and fighting the brake, there is a really loud rattling. I checked all my exhaust clamps and they're all holding on tight but thats what it sounds like. I have tightened the tranny crossmember but when the idgets rebuilt my tranny(4k ago) they left one bolt out so theres only 3 holding the crossmember on. Would this be whats causing the rattling and clunking or is it something else?
TIA,
Collin

do you have a high-idle problem too??? is that why its shifting hard? the rattling could be your tailpipe interfering with the rear spring shackle.. i have it myself...

[TUFFXJ]

Originally Posted by jeepguy1990

Hey guys..been trying to diagnose a problem and can't figure it out. My 90 4.0 AW4 clunks into reverse but as its going it jerks you real bad.(I've posted that before) Also I've started to notice that this problem is only when its warmed up, when its cold in the morning its smooth as all get out. Also, when it does this jerking motion, after its engaged in reverse and fighting the brake, there is a really loud rattling. I checked all my exhaust clamps and they're all holding on tight but thats what it sounds like. I have tightened the tranny crossmember but when the idgets rebuilt my tranny(4k ago) they left one bolt out so theres only 3 holding the crossmember on. Would this be whats causing the rattling and clunking or is it something else?
TIA,
Collin

I am by no means an Auto Tranny guy but my first guess is that you have a sticky check ball in the valve body. They are like little steel balls that move back and forth in the valve body (looks like a maze) and depending on the flow they fall into a little hole just enough to block fluid flow. 4k ago should still be under a warrenty of some type...most shops offer a 12k. Did you have them do anything to it when they rebuilt it..such as brazed convertor or kevlar bands higher RPM convertor..etc etc if so trannies will shift "harder" after they are built up

[BIGSLVRXJ]

I had them do a standard rebuild. I have absolutely no idea about any tranny/suspension stuff so you guys probably have a better idea than me. They say its cause it idles too high but I've taken my idle down to 200, and shifted but it still does it...when its warm. I just want to know if its tied to the tranny or not because I want to take it back sooner than later for warranty.