Possible transmission issue?

[d9103365]

I have a 77 cordoba w/ 400 V8. When driving slowly around my neighborhood, it seems to rev briefly before switching to 3rd gear. So far, I haven't noticed this when I'm accelerating harder on the open road. It only seems to happen when I'm accelerating very slowly from a dead stop.

the fluid looks ok...a little darker than fresh fluid perhaps but still very red. Didn't notice any burnt smell or debris that I could see. Don't know when its been changed last. I found a sales brochure on this car and noted that it said that the trans was maintenance free, that the fluid should never be changed. I'm fearful that a fluid/filter change may do more hard than good on an old car like this.

Maybe its not really a problem..I haven't noticed it actually slipping out of gear...yet. Any advice?

 

[rumblefish360]

maintenance free, that the fluid should never be changed?

Whew! Ya, OK, I have a bridge to sell ya too. LOL

The tranny fluid should be chaged every once in a while. No doubt. So should the filter. This will cause issues if not done. But before you change any fluids and the description sounds like a good color, theres a service you can do outlined in even the Chilton books for the 727's. It's adjusting the bands. Tightening them up.

Now, I'm no tranny guy and perhaps a been there and done that will chime in. But I myself would start with the band adjustment and then on to the fluid and filter. I allways add a deep pan. Summitt racing has excellent deep pans.

 

[72 Charger SE]

You will be doing a fluid change when you adjust the bands, since the rear band is accessed by removing the pan. The front band is externally adjustable. You will need an inch-pound torque wrench to set the preload on the bands before backing them off and tightening the nut that holds the band adjustment screw in place. I think both bands are 72 inch-pounds, then backed off 2 turns, but I would double check that in a manual for your year of transmission. The newer electronic-controlled transmissions based on the Torqueflite have different adjustment settings for different years, but I don't know about the older ones.

 

[racedodge]

72" lbs on front and rear. back of rear 2 turns, back of front 2 1/4 turns. you will need a specialty socket to tighten the bands (8pt).

 

[Cranky]

Also check the linkage ie kickdown lever etc. It should move exactly when the throttle moves...if not, that may be your problem but if you don't know when the fluid and filter was changed, I'd go ahead and do it and while in there, adjust the bands. There should be a light return spring on that linkage too. It should be all the way forward at idle.

 

[PDFROGMAN]

if it is flaring going into third it's a matter of time before the those clutches burn up. a kickdown band adjustment will have no bearing on third gear
neither will the rear band.
little tech on a 727
when you put the selector to the D position
the rear clutches are applied. this locks the ring gear of the front planet to the turbine shaft which is splined to the stator in the converter. making it the driving member of the gear sets
the front ring gear will now drive the front planets around the front sun gear. the front planet carrier is spline to the output shaft.
the front sun gear is also linked to the rear plant the sun gear will want to rotate but cannot because the rear planet carrier is splined to the rear drum in turn the rear drum will be held stationary by the rear sprag which is spline to the case.
confused yet???:icon_hang:
the only difference between D and manual low or 1 is the rear band is applied not allowing the the rear drum to free wheel when there is no torque applied IE you take you foot off the accelerator you get engine braking because the band prevents free wheeling

once governor pressure over comes throttle pressure
it will stroke the 1-2 shift valve and apply the kick down band via the kick down servo giving you second gear.
the front drum is now being held, the rear clutches are still applied. the front drum is splined to the sun shell so the sun gear (which is common for both sets of gears is now locked so both sets of planets are now rotating around a stationary sun. so the front ring gear is the input member and rear ring is driven and id the output which is splined to the output shaft giving you second gear
:sleepy2:

I know I know I have had to have lost someone bear with me once you understand this it becomes pretty easy to know why the trans is acting the way it does.

now again governor pressure has to over come throttle pressure to stroke the 2-3 shift valve
once that is accomplished the kick down band comes off and the front clutches are applied this locks the whole gear set
the front clutches are splined to the rear clutch drum. the front clutch is splined to the sun shell( we established before) and is now driving the sun at the same RPM as the front ring gear so we get no gear reduction and essentially the gear set is "locked" meaning all the gears are forced to spin at the same RPM giving you a 1-1 ratio
now what I have been leading up to
if the front drum is not applying properly(most likely due to the center seal of the piston in the drum either dried out or rolled) the unit for a split second is down shifting to first gear giving you the rpm flare
it's not slipping per say but the shift timing is off due to big lag in applying the front clutches

now in Reverse the front clutches are applied the rear clutches are off and the Low reverse band is applied
the rear drum is still spinning because it is tied to converter the front drum is not locked to the rear drum via the front clutches and is now making the sun gear the driving member of the gear set
the low rev band is holding the rear drum steady which in turn is splined to the rear planet carrier the planets are the driven member of the gear set and because it is held and not allowed to rotate it will cause the rear ring to rotate in the opposite direction the rear ring gear is splinned to the output shaft.
now the failing front drum seals may not be as prominent in reverse because pressure is bumped up when the trans is in reverse

:icon_hang: I know it's dry
Take the unit out and have it rebuilt could just be a paper rubber rebuild could be the front drum bushing is wearing a little causing the drum not ride true on reaction support ( u can tell there will be wear in the drum where the sealing rings ride
depending how long it's been acting up the clutches will start to glaze and begin to burn.

another note torqueflites do not have cooler flow in park ( thus why we check them in neutral) so if the car is running in park for extended periods of time the fluid will heat up and start to break down causing deposits, it's loses it's lubricating properties. there is a mod for that in shift kits

sorry for the long read maybe one of these days I'll set up a video camera and do a trans break down and rebuild. my 19 year has read the handbook several times and suggested I do some sort of video just reading it's tough to understand without actually seeing it
sorry for the long read hope someone got something out of it

 

[Redhorse719]

Great info but I'll have to wait for the movie. :happy1:

 

[1badstroker]

Forgot the beginning by the time I got to the end. I think it was a senior moment. Just kidding, It does make a lot of sense. Thanks for the break down.

 

[PDFROGMAN]

I figured as much it can really dry :happy1:
believe it or not this is one of the simpler designs out there