having some 727 problems

[Runner]

i posted this at moparts, but ill post it here as well sence chryco, ron and john all post here.   

rebiult a 440 and a 727 for my daughters 69 coronet (super bee clone).


the engine runs good but the tranny is having some issues.

reverse works fine, i have no automatic features at all. from a stop the tranny takes off in 3rd gear. if i down shift to second it down shifts into 2nd but wont down shift into 1st manually. if the selecter is in manual low the car takes off in second. when up shifting from manual low to manual 2nd it stays in second. manual second works fine and when i up shift into drive it shifts very nice, not harsh at all and no over lap. i loaned my carl monroe 727 book out a couple monthes ago and havent gotten it back. this was a swap from a 318-904 to a 440-727. i didnt take the valve body apart when i did the tranny. i did air check both clutch packs. my guess is its a valve body issue but i dont know any help would be apreciated

[firefighter3931]

Mike, are you sure the linkage is properly adjusted ? Assuming that it is....then it is most likely a valvebody problem.

I would start by disconecting the shifter linkage and manually placing the selecter in 1st gear and see what happens.


Ron

[Runner]

ron, positive on the shifter linkage adjustment, i was pretty sure i was having a problem with it on monday when i drove it around the block before i got my lokar kickdown cable. ( had the kickdown arm tied back and drove really mildly) so i rechecked it today.  i have the 904 tranny that was behind the 318 that i could swap the valve body out with  and give it a shot.    im pretty sure the 904s and 727 valve bodies enterchange?

[Runner]

ill also add that when im in dsrive and i give it a good bit of throttle it will downshift to second on its own

[firefighter3931]

Yep, the valvebodies are the same. I would still crawl underneath it and manually place the selecter in low....just to satisfy in my own mind that it's not a linkage issue. It's possible the internal shift mechanism isn't placing it into first gear....something else to look at. Is this a known good trans ?


Ron

[firefighter3931]

ill also add that when im in dsrive and i give it a good bit of throttle it will downshift to second on its own

Sounds like the kickdown is working fine....that's not the problem.

Ron

[Runner]

tranny is fresh, i rebiult it and it went in with the motor so who knows i might of screwed some thing up   .   i did NOT take the valve body apart when i did it, just cleaned it up and installed it. it did NOT get a shift kit ( at least not from me).   i know i should have taken the v alve body apart and cleaned it but i ididnt. .

[firefighter3931]

If it's a fresh rebuild then take it out for a spin and let it work out the kinks. I remember when we installed Kamcuda's rebuilt 727 in the cuda and it was shifting wierd. The tranny shop that rebuilt it suggested he put some milage on it and sure enough it worked fine after about 50 miles of driving.


Ron

[John_Kunkel]

I would hook a gauge to the governor test port and check the pressure in gear at a standstill.

[Challenger340]

Sounds like governor pressure is too high, or pump pressure too low/leaking somewhere in the valve body ?

So you have no manual low whatsoever ?

I forget now, been years since I was in a 727, was it the front/high and reverse are the same clutch on a 727 ?

Guide me here for troubleshooting, I've long forgot this stuff;

1 st; in auto(D), rear clutch engaged, sprag is reaction member, no band or engine braking
2 nd; in auto (D), same as above but engages front band
3 rd; in auto (D) , front band disengages with same fluid pressure that engages front clutch, rear clutch still engaged(both planetaries locked)
Manual 1 st; rear clutch and rear band engaged. Rear band assists sprag holding as reaction member, but also provides the engine braking on decel.
Reverse; front clutch and rear band

I'm still thinking valve body  ?  Somehow, the 2 nd band is satying engaged in manual 1 st, giving you 2 nd  when it ain't outa ba ?

Is above correct ? Anybody ?

[Runner]

i swaped valve bodies and its still messsed up, i also checked the govenor presure ine gear as john sugested and it was 0 psi in gear with tires not moving. 

[firefighter3931]

i swaped valve bodies and its still messsed up, i also checked the govenor presure ine gear as john sugested and it was 0 psi in gear with tires not moving. 

Are the servos leaking ? If not i would suspect the pump ? Sorry to hear this Mike....i know you were hoping to have it on the road by now 


Ron

[oldkimmer]

u will have to take off the tailshaft housing and free up the govener, your problem will then be solved.This happens all the tine to trannys that have sat around for a long time.

[Runner]

ron i air checked the servos and the all worked great. both front and rear closed the bands nice and fast.  im pretty sure it isnt a presure (pump) problem sence all the gears work great except 1st. if i understand what john is telling me, if i test presure at the tailshaft test port with it in gear it should be under 2psi and it was.   if i understand this right,  the presure then gets increased to get it to shift from 1st to second.      i did use the tail shaft and gear train out of 70 tranny and put it in this tranny that i believe is a 77.  the 70 tranny i had in the roadrunner and it was my first tranny that id ever worked on and i had lots of issues with that one.               at this point im thinking about getting another core and staerting from scratch,


    the govenor was taken apart and cleaned about 2 monthes ago when i biult the tranny.

[John_Kunkel]

The only things that would cause the trans to take off in 3rd are high governor pressure at a standstill (already eliminated) or a crossover of line pressure due to mismatched parts or a warped case.

As long as line pressure is allowed ot override throttle pressure, the trans will be in a higher gear than it should be.