727 transmission clunks into drive or reverse

[GassMann]

Hey all,

I rebuilt my 727 trans (66 Charger) when I moved it from the 318 housing to a big block housing. When I put it in gear, it clunks into drive or reverse. Fluid level is good. Wondering if it is a setting. Maybe I need to tighten the bands?!?

FYI... I have never rebuilt a trans before this. I followed a field training video I found on line... it was excellent. The car does move and it shifts gears without a clunk. But putting it in drive or reverse... CLUNK!!!

 

[turbine68rt]

How old are your u joints?

 

[Jerry Hall]

What about slack in the axle, I assume 8 3/4. Also U joints as mentioned above.

 

[1 Wild R/T]

Yup. the clunk is slack somewhere & it may be completely normal.. What's the idle RPM? Lower RPM = softer engagement = less clunk... When you built te trans, did you add a shift kit? Or bump the line pressure? Cause higher pressure = firmer engagement = louder clunk...

 

[MWbirdLOVER70]

How old are your u joints?

Exactly my thoughts

 

[GassMann]

How old are your u joints?

U Joints are new... had not thought of that but yea... old joints would cause that. But not that.

 

[GassMann]

Yup. the clunk is slack somewhere & it may be completely normal.. What's the idle RPM? Lower RPM = softer engagement = less clunk... When you built te trans, did you add a shift kit? Or bump the line pressure? Cause higher pressure = firmer engagement = louder clunk...

Idle is set to 650-700. Good question about the shift kit. When I was a kid (17 or so) I had the transmission rebuilt by a local co in Tacoma WA. They guy said he put in a shift kit but I didn't notice it and he could have been blowing smoke. Stupid kid that I was, I would not have known at that age. Years later, I had no clue what to look for. I checked fluid and I am a smidge over filled.

I know there is a band adjustment and I thought I set it to specs but there's a big difference between bench specs and operational clearances. Do you thing the bands could be lose because of break-in?