904 Shift Problems

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lilgrems86

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I have a 75 Duster with a 318 w/ a 904 trans. When I got the car about 6 months ago it was a rocket considering only having a 318. One day I went to a small burn out contest with some guys I grew up with. Since that day the trans has been goofy. Now this was not a high rpm burnout or a long burn out, I really didnt want to fry the new tires, so Im sure the trans isnt blown. But anyway, the issue was the car would no longer shift into second. and I had to wind her out to get her in third. So I knew something was wrong, I talked to some guys, they looked at it, and suggested I put a spring to pull the kick down linkage forward. Now I know nothing about transmissions, I have built motors from block up, but I never got into trans work. So I took their advice. Now I have really week and quick shifts, the trans will shift from second almost instantly into third with out building any rpm in second gear. So in town and just normal driving around, the car now drives so sluggish it is destroying my nerves. Can someone please maybe explain what may have happened or what I can do to fix this problem.
 
If the trouble started imediately after this burnout I would think you've stirred up some debrie that clogged something in the valve body. There are steel balls rolling back and forth in channels. If a ball was sent past where it normally travels it probably stuck there.
If you can rebuild an engine it's likely you can service the trans.To drop the valve body and seperate it to clean it requires a manual so the correct size balls go back in the correct places. May as well pplan on replacing the selector shaft seal though. That can be the hardest part of it.
 
Sounds like the kickdown lever may have gotten stuck to far back during the burnout if you didn't have a return spring on. That would explain the shifting prob. after burnout contest. Do you have a 4bbl or stock 2bbl. Is the linkage stock. This all affects kickdown motion & proper pressure. Hopefully it is just kickdown adjustment that you need. Remove carb & kickdown springs. Set it up initially by moving kickdown rod attached to carb all the way back towards firewall, some have holes in mounting plate to insert small rod to keep it place while you adjust.(this will be max pressure) then move carb attaching point to wide open throttle & adjust linkage so it just fits on mounting point. Re-attach springs. For more pressure lengthen the rod. For less shorten it. Be carefull lengthening it to much or your carb will not open all the way. It's a tial & error thing especially with a modified setup but you ned that trans pressure right or good by trans. quick. Heres a link with some kickdown diagrams.Yours should be the last one.
http://www.moparts.org/Tech/Archive/auto/35.html
Good luck

Oldschoolcuda
 
lilgrems86 said:
I have a 75 Duster with a 318 w/ a 904 trans. When I got the car about 6 months ago it was a rocket considering only having a 318. One day I went to a small burn out contest with some guys I grew up with. Since that day the trans has been goofy. Now this was not a high rpm burnout or a long burn out, I really didnt want to fry the new tires, so Im sure the trans isnt blown. But anyway, the issue was the car would no longer shift into second. and I had to wind her out to get her in third. So I knew something was wrong, I talked to some guys, they looked at it, and suggested I put a spring to pull the kick down linkage forward. Now I know nothing about transmissions, I have built motors from block up, but I never got into trans work. So I took their advice. Now I have really week and quick shifts, the trans will shift from second almost instantly into third with out building any rpm in second gear. So in town and just normal driving around, the car now drives so sluggish it is destroying my nerves. Can someone please maybe explain what may have happened or what I can do to fix this problem.
Click to expand...

You do need the return spring pulling the rod back towards the firewall, not forward.
 
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