c6 transmission issue
lilwhitelude
05-16-2011, 02:55 PM
I have a 86 bronco full size 351w with a c6 in it. My transmission front pump bushing came out and dropped all my fluid and caused a pretty big problem. I replaced the front pump and completely rebuilt the transmission. This is my first automatic to rebuild so it was a little venture. After building it,it works great, except it shifts way too smooth. I checked the modulator valve and it holds vacuum well. Any suggestions on what would cause my transmission to shift so smooth that I can't really feel it shift? Thanks for any reply.
DM112375
DM112375
MagicRat
05-16-2011, 08:20 PM
2 things come to mind.
First of all, the C6 is supposed to shift like this, in many applications. Very soft smooth shifts was "programmed" in to about a bazillion C6 tranmissions, particularly when used in large Ford, Mercury and Lincoln cars. If you changed the valve body or springs, you may have just "programmed"it for such soft shifts.
My other guesses are:
If the trans really does feel wrong, there may be something stuck, leaking or improperly assembled in the valve body, and/or the line pressure may be too low. For example, somewhere in the valve body is a tiny check ball held in place with a tiny spring that looks like it came from a ball-point pen. If these two components are installed in reverse order, you get very mushy 1-2 shifts, and a slipping second gear.
Finally, you might have an improperly-adjusted second-gear band.
First of all, the C6 is supposed to shift like this, in many applications. Very soft smooth shifts was "programmed" in to about a bazillion C6 tranmissions, particularly when used in large Ford, Mercury and Lincoln cars. If you changed the valve body or springs, you may have just "programmed"it for such soft shifts.
My other guesses are:
If the trans really does feel wrong, there may be something stuck, leaking or improperly assembled in the valve body, and/or the line pressure may be too low. For example, somewhere in the valve body is a tiny check ball held in place with a tiny spring that looks like it came from a ball-point pen. If these two components are installed in reverse order, you get very mushy 1-2 shifts, and a slipping second gear.
Finally, you might have an improperly-adjusted second-gear band.
lilwhitelude
05-18-2011, 12:28 AM
When I rebuilt the transmission. I didn't do anything but clean out the valve body. I was careful to take pictures and visually inspect and clean ever part. The check balls are about 1/4 inch in diameter and seating in the original location. I guess I should have replaced the seals on the pistons in the valvebody. THis transmission always shifted firm before the bad stuff happen. Ive been looking for an excuse to put in a shift kit. I guess if the valve body comes back off, it's gettting one. Before I pull the pan again, Id like to know if is possible that a weak spring in the servo could cause smooth shifts. Thanks for replying.
Dm112375
Dm112375
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