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Discussion Starter #1
302/C6/stock T-case, '86, stock rear near as I can tell.

getting a pretty solid/loud clunk when I shift into reverse, and not quite as severe going back into drive. Seems to be a new development, considering this is my 3rd day driving the truck. Feels like the tans or t-case is shifting, but I've been under it having someone shift it and no luck. not finding any play in u-joints or slip joint either.
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Should be a solid clunk type feel but not really any noise.

Is it while shifting? After shifting but before pressing the gas? Or when pressing on the gas?
 

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Discussion Starter #3
Should be a solid clunk type feel but not really any noise.

Is it while shifting? After shifting but before pressing the gas? Or when pressing on the gas?
shifting, no gas, at a stop on the brake. I get a bit of movement at the rear tire, like moving the rear tires about an inch. I'd take a video, but I think it'd be hard to hear over the exhaust.
 

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85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Sounds maybe like the input shaft is still applying torque to the gear set.
 

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Two really easy things to check, Trans fluid level, and drop the rear shaft and grease the slip joint. They like to hang up and can contribute to a whole lot of drive line issues. FWIW my ebay rebuilt transmission is hard into reverse when cold unless I put it in first gear and then reverse and only at first start in the morning, otherwise ok. Got to love these old girls.......
 

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302/C6/stock T-case, '86, stock rear near as I can tell.

getting a pretty solid/loud clunk when I shift into reverse, and not quite as severe going back into drive. Seems to be a new development, considering this is my 3rd day driving the truck. Feels like the tans or t-case is shifting, but I've been under it having someone shift it and no luck. not finding any play in u-joints or slip joint either.
Mine does exactly the same thing.

I’ve let the drivetrain unload via a stop in neutral with no change in noise.

Tranny mounts look good. Engine mounts less so. I’ve not crawled under it to see what’s going on.

Rear driveshaft was out for a pinion side u-joint swap and pinion seal replacement. No issues with either.

I’ve understood Reverse to use full transmission line pressure that is let down by a valve that is prone to sticking. Valve sticks = hard shifts. I put a bottle of Lucas transmission treatment in it that got good reviews for fixing this sort of issue but I have no change in the couple hundred miles I’ve put on since.

I haven’t found the tranny on the ground yet so I’m going with what I got.
 

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Discussion Starter #7
I'll do as suggested, this weekend when I can have her down overnight if an issue arises.
 

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82 XLT Lariat 351w, Edelbrock 1406 4bbl ,C6 auto, auto locking hubs ,33x10.5x15
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Two really easy things to check, Trans fluid level, and drop the rear shaft and grease the slip joint. They like to hang up and can contribute to a whole lot of drive line issues. FWIW my ebay rebuilt transmission is hard into reverse when cold unless I put it in first gear and then reverse and only at first start in the morning, otherwise ok. Got to love these old girls.......
I've just had my rear driveshaft rebuilt/replaced and mine still has a solid clunk into reverse warm or cold... But it's not like a bad clunk like something's wrong. Just like a good solid engagement of the gears. It's not jerking the rig when it engages like it did before the rear shaft was rebuilt... know what I mean?
 

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Yo Jimmy,
Ford advises;
Noise In Reverse
  • Torque converter assembly​
  • Shaft spline fit​
  • Slip yoke, park gear​
 
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