Reverse Clunk, your opinons

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
So trans is all refreshed and working beautifly, but now i got me a clunk goin into reverse. Sometimes is worse than others as far as how hard it clunks in. only does it going into reverse, wont do it going into forward. tried all stock tuning, thought it stopped it for a while, test drove it and tired it again and no, still there. i was running a 600 idle in the truck and it was really bad with that low idle. bumped it back to 680 and its not near as noticable but still there. driveshaft, u-joints, carrier bearing and rear diff are all in good working order. you can hear a very noticable clunk when you put it in reverse and watch the driveshaft make a quick twist like it was under load, then lost load for a split sec, then got it back. i cant tell if the clunk is in the t-case though even with a long bar used as a "stethescope". no pump rub, 168k on t-case. goes into 4wd low and high jsut fine. has a vib above 35mph but thats due to the front driveshaft having the u-joints at different angles (f'in lift kits).

Ideas? shes been runnin 5w-30 full synthetic for the last 20k. ill be pulling the drain plug tonight and see what comes out.

here is a vid, if you turn it up you can here it clunk. when the driveshaft starts turning counter clockwise, the trans has been put in reverse
[YOUTUBE]8gK-P4tGABY[/YOUTUBE]
 
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TeaBagger2006

Im a Garrett Nut Swinger
May 11, 2008
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Bis ND
Your lb7 is giving you all sorts of trouble. I think it's time to send her to thre grazing grounds. I think it's your tcase
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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lol trust me, ive been thinkin about pullin the motor and trans, puttin stock stuff back in and selling it for a low mile stock lbz. just cant get over the smile i get in the truck when i give the go go juice though :D
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Sounds like t case to me, I had one do that to me. T case was just worn out

rebuild worthy or just get another whole t-case? not looking forward to that chunk of change to drop but then again, shes put up for a long time under my abuse, had pump rub once and was out of oil for a long time, put a new back half on and ran it since (put 78K on it).
 

delong_1

<< my work
Dec 5, 2008
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Similar happened to that t case also, caused a ton of wear. The shift forks were worn out, the pads were completely gone etc. it just progressively got worse. I would say take it apart. Shouldn't cost much to fix
 

adeso

wait, what?
May 30, 2011
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heavy grease helped that for me, mine was so bad it felt like I would get hit stopping at a light. that also seems like a lot of travel in the driveshaft, you sure something isn't worn?
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Its not the splines. Notice the sudden and great amount of twist that occures when it "pops". Not to metion the shaft is nice and tight in there. Ive had the clunking you guys are talkin about and ot happened in drive aa well. This clunk never happens in drive,only when initially put in reverse. Not to metion the noise that happens when it clunks does not come from the driveshaft
 

adeso

wait, what?
May 30, 2011
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So is it me or is that more than normal play in the amount that the driveshaft turns?
James did you let bri bri work on your truck at any time?
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Yeah ill be yankin the t-case wednesday. Want to enjoy a/c driving for two more days lol
 

adeso

wait, what?
May 30, 2011
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Minot, ND
just in general, I just was messing with my truck and it seems about half that amount but IDK what the spec is on it
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
Remember this is with the motor running under load. There isnt much slack in the driveshaft if i get under there and try to turn it by hand with the trans in nuetral. Add in trans and motor mount flex, suspension flex, what ever is clunking, and the very slight frontward or backward movement of the whole truck and it looks like there is a bunch more movement.