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Discussion Starter #1
400 hp 460 - 1987 c6 - 9" detroit locker with 3.70 gear.Trans rebuilt with cheeta valve body and 2000 stall converter 3500 miles ago.Lately when changing between gears at a stand still I'm getting a load clunk which sounds like a u joint but its not the joint. Some noise coming from the detroit but alot of it is coming from the trans tailshaft. When I turn driveshaft by hand back and forth seems like a lot of play and the tailshaft yoke has some movement up and down.Trans works perfect with firm and consistent shifts and no slippage thats percieved.So should the c6 tailshaft/yoke have (any) movement up and down?

Btw the u joints are 1330 non greasers

<font size=-1>[ This Message was edited by: FoMoCo on 7/11/02 5:02am ]</font>
 

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The yoke should be pretty tight. It will normally have a small amount of play, but very, very little. The clearance between the yoke and it's bushing is around .015-.020". That freeplay is probably where your clunking noise is at. Also, have the rear case bushing checked, it's most likely wiped as well. Hope it didnt hurt the case.
 

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Discussion Starter #3
If bushing clearance is 015 - 020 at the bushing movement at the end of the yoke would be a little more (not much). The rear end is all new except the case and axles.My knowledge of transmissions end when the case is opened,are there gears in the tailshaft section because it really sounds like gears clanging in the tailshaft?
 

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no, there are no gears inside the tailhousing, unless you consider the speedometer gear, but it's made as part of the output shaft. The only thing in there is the governor. If the clunking noise is from the tailshaft area, its possible that the one-way roller clutch has gone south inside the transmission. It's at the very rear of the case, and if it wont hold, it makes a loud clunking/rattling sound. Also, maybe the spring came off of the parking mechanism, allowing the pawl to engage the parking gear.
 

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Take it apart. Guaranteed the end play is way out of whack.
(been there, done that).
I like to set all my transmissions up to the minimum spec tolerable. Figure they're going to wear loose anyway, right?....
In either case, if you're even out over .020=30, it'll clunk like a bastard.
Good luck, have fun.
 

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Discussion Starter #8
If its worn why does it only clunk once and awhile?And if worn would it not tear up the rear seal causing it to leak (which it does not)?
 
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