904 flare up issues

[Reed]

Same problem on both my 83 Dodge van (318/904) and my brother's 83 Dodge van (225/904). My 904 is the 1983 original lockup version, my brother's 904 is a 1973 non-lockup unit out of a Dart (there's the A-body link).

Symptoms:

Slow engagement into 1st, random flare up at 1-2 shift, flare-up at 2-3 shift, flare-up at 3-2 downshift or kickdown-2 shift.

Already adjusted the front band (the one accessible on the outside of the transmission case), going to be adjusting the rear band in a week or so (the one you have to pull the pan to do). Transmissions are full with ATF+4 and fresh filters.

What might cause these flare-up problems? How do I diagnose them? I have a shop manual and gauges to test line pressures, should I be using those?

While we are in the transmission pan, what tricks can we do (short of installing a shift kit) to firm up shift and reduce gear overlap? Remove accumulator spring? Adjust line pressure? ???

Transmissions are completely stock, no shift kits or other modifications have been done. Any tips will be greatly appreciated. I hate knowing nothing about how an automatic transmission works....

 

[fishy68]

Have you tried adjusting the throttle pressure linkage? Set it so that at WOT the linkage is pushed all the way back and try it. If it hangs in gears too long back it off a little at a time until it shifts when you want but doesn't flare up.

The only trick I would do to make it shift better is to remove the accumulator spring and install a blocker rod in it's place. Turning up the line pressure on an old trans. is not advisable. That may cause blown seals. If you want it to work great spring for a Trans-go TF2 kit.

If you want to know how a Torqueflite works buy this book

[ame="http://www.amazon.com/s/ref=nb_sb_ss_i_0_8?url=search-alias%3Daps&field-keywords=torqueflite&sprefix=torquefl"]Amazon.com: torqueflite[/ame]

Tons of great information and pictures in it along with a complete explanation of how the torqueflite works. 904's and 727's work the same.

 

[Reed]

Thanks. Kickdown is adjusted as you suggested. Where might I obtain a "blocker rod" for the accumulator piston? I have heard about removing the spring, but not putting in a blocker.

I may very well purchase that book since I have been through five transmissions in the last two years in my brother's van, including two 727s. And the van has a slant six.

 

[70aarcuda]

block rod is 3/8 diameter...and 3 inches long...

you can easliy make one...

 

[fishy68]

Tony beat me to it. Real easy to make.

The reason to use a rod to block it is so the accumulator doesn't slam back and forth and break.