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Mopar 727 Transmission Won't Go!!!

Posted By: MagicMan65

Mopar 727 Transmission Won't Go!!! - 10/15/12 01:39 AM

Gentleman,

I hope hoping you can help me out with this one. I installed a 727 tranny behind my 383
it has a reverse manual valve body with a 2800 stall. I bought this off my buddy who had it in his 65 alter-wheel base car; trans worked fine when pulled. I put this in to find out I am having troubles.

Here is what I am finding:
1. Trans fluid is clean/full check in neutral at normal operating temperature; trans does have a fresh filter.

2. Before I put the drive shaft in with the car on all 4 jack stands I shifted through the gears to find the tail shaft properly spinning.

3. With the drive shaft in I put it in gear and nothing happens.

4. At this point I raised just the rear of the car in the air and then put it in gear to find the rear wheels spinning.

5. I then again put the car back on the ground to find no wheel movement.

6. I pulled the trans cooler line to find the pump does work as it made a large mess on the shop floor.

What are your guys thoughts with all of this? I am beside myself. Thanks for the help in advance.

Regards,
Tar
Posted By: 4406bbl

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 02:25 AM

I had this happen on a trans I rebuilt for a guy, put it in and the car would not move, jack it up the tires turn, set it on the ground nothing. Turns out when his rearend was narrowed they cut one axle too short, it had a cone posi, longer axle fixed it. Make sure the driveshaft does not turn with both rear wheels on the ground.
Posted By: RapidRobert

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 02:31 AM

We're waiting for Kunkel to come to
Posted By: DAYCLONA

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 02:38 AM

Did you at any point run the engine, with the tranny/converter dry?...
Posted By: MagicMan65

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 01:21 PM

Thanks for the replies guys, in reponse:

1. I don't think it could be the rear axle, as I have run the same rear end in a previous setup

2. No I never ran the tranny without fluid it in; upon initial startup I had about 8 quarts in the trans and then adjusted accordingly.

Thanks for the help with this, hoping I can find some resolution.

Regards,
Tar
Posted By: YO7_A66

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 01:33 PM

Have you checked to make sure that the emergency brake is not dragging on the rear drums? (Does it roll forward/backward in N)
Posted By: MagicMan65

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 03:46 PM

The e-brake is dis-engaged; the car does move forward and backwards in neutral, when placed in park I cannot roll anywhere.

Thanks,
Tar
Posted By: 65Sat440

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 03:56 PM

Fluid pressure? What year is the tranny? Are you sure the fresh filter is correct for the year, i.e., are all fluid passages clear? Does it shift firmly when running on jackstands?
Posted By: 62maxwgn

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 05:23 PM

If this a 65 or earlier transmission and you changed the filter,do you have the correct filter ?
The later filter only has one hole and will block fluid to the pump.
Posted By: John_Kunkel

Re: Mopar 727 Transmission Won't Go!!! - 10/15/12 11:54 PM


No wheel movement in forward and Reverse?

The wheels turning on jackstands means nothing due to the "windmilling" effect of the released clutches. Never check transmission operation on jackstands.
Posted By: MagicMan65

Re: Mopar 727 Transmission Won't Go!!! - 10/16/12 01:59 AM

Thanks for the comments guys, yes this is correct I do not have forward or reverse movement when all 4 tires on are on the ground. You can tell the car wants to move forward ever so slightly but doesn't . When I do test the car in the air the wheels don't move slow but actually very fast and as you increase engin rpm so does the rpm of the wheels. So I am not sure if the natural "unwinding" of the bands would generate such velocities. Any other thoughts? Do you think I may have a bad torque converter?
Posted By: JohnRR

Re: Mopar 727 Transmission Won't Go!!! - 10/16/12 02:14 AM

What year is the trans ?

Did you try to stop the tire from turning , put a 2x between the ground and the tire with the engine at idle if you are afraid to do it with your foot .
Posted By: MagicMan65

Re: Mopar 727 Transmission Won't Go!!! - 10/16/12 03:29 AM

The Trans is a 69' tied to a 68' 383. No I haven't tried to stop the tires yet. You guys have any idea what may be going on here, this is driving me nuts!
Posted By: 4406bbl

Re: Mopar 727 Transmission Won't Go!!! - 10/16/12 05:05 AM

If the driveshaft does not turn when both wheels are on the ground in forward or reverse then,

Low fluid
low hydraulic pressures
oil filter clogged
Valve body malfunction
faulty oil pump
clutches non operational

Not much else anyone can tell you without a pressure check and an air check of the servos and clutches. Since you know you have cooler line pressure then I would suspect the valve body.
Posted By: John_Kunkel

Re: Mopar 727 Transmission Won't Go!!! - 10/16/12 06:10 PM


The pump has probably failed; even with the drive tangs broken there can be enough friction between the pump rotor and drive hub to create some pressure but not enough to engage a clutch.

Only way to know for sure is to hook up a gauge to the accumulator test port.
Posted By: Dodgem

Re: Mopar 727 Transmission Won't Go!!! - 10/16/12 08:21 PM

Quote:


The pump has probably failed; even with the drive tangs broken there can be enough friction between the pump rotor and drive hub to create some pressure but not enough to engage a clutch.

Only way to know for sure is to hook up a gauge to the accumulator test port.






I've even seen some get them to move with broken tangs but not good or far!
Posted By: MagicMan65

Re: Mopar 727 Transmission Won't Go!!! - 10/17/12 04:36 AM

Thanks for the input guys; my question is if you think the pump has failed then why do I have good fluid flow to the trans cooler? How hard is to change out the pump? Can you do it with the trans still in the car? Another question I have is regarding vaccum lines, does the 727 have vaccum lines going to it at all?

Thanks
Tar
Posted By: 4406bbl

Re: Mopar 727 Transmission Won't Go!!! - 10/17/12 05:39 AM

No vacuum lines, must pull the engine and converter to change pump in car, so it is easier to pull the trans. You need to check the line pressure for better advice.
Posted By: John_Kunkel

Re: Mopar 727 Transmission Won't Go!!! - 10/17/12 06:11 PM

Quote:

Thanks for the input guys; my question is if you think the pump has failed then why do I have good fluid flow to the trans cooler?




See my comment above, "even with the drive tangs broken there can be enough friction between the pump rotor and drive hub to create some pressure but not enough to engage a clutch."

Attached picture 7424747-Pumpgears.jpg
Posted By: Dodgem

Re: Mopar 727 Transmission Won't Go!!! - 10/17/12 06:21 PM

broken pump tangs may have enough grab to pump some fluid but not build the required pressures??


First thing I would do is make sure the shifter is properly adjusted and is moving the trans mission shift lever into detents. (unhook linkage and shift it by hand you will be able to tell.

Then Check the trans pressures if you can get a gauge.


Then pull the oil pan off and see if the valve body is actually getting shifted gear to gear.

then I would drop the valve body and pull out the accumulator and check it's compression ring.

do an air test to check front and rear clutch apply + the servos

If all is well and filters is lined up right try another valve body of you have one.

At this point you have to pull the transmission to check the pump and many other things that can cause a no go!

Posted By: Dave Watt

Re: Mopar 727 Transmission Won't Go!!! - 10/17/12 08:07 PM

Another possiblity is that one or both pieces of the Low/Reverse band apply link have broken. Kind of looks like this: 8=8 It happened to my 727 without warning.
Or the band is not adjusted properly/broken.
Posted By: fox

Re: Mopar 727 Transmission Won't Go!!! - 10/18/12 01:44 AM

On the passenger side of the trans there is an 1/8 pipe plug port.
Get a gauge with at least a minimum 200 psi and a hose.
This plug is angled towards the rear and is not at the servos.
Check pressure with it in drive.
get back to us with that number.
Posted By: Graham

Re: Mopar 727 Transmission Won't Go!!! - 10/18/12 03:43 AM

The 2800 stall converter might be the cause of your problem. Remember it won't perform properly until it passes it's rated stall speed. On the jack stands there is little or no resistance for the converter to stall against. So, put it all back together and see what happens when you engage the transmission and apply the throttle with all 4 wheels on the ground. Take the converter past the 2800 stall speed and see what happens. I would also think that if the ears(lugs)were broken on the internal pump gear you'd find metal contamination in the oil and on the filter.

transman
Posted By: TJP

Re: Mopar 727 Transmission Won't Go!!! - 10/19/12 03:07 AM

Quote:

Quote:

Thanks for the input guys; my question is if you think the pump has failed then why do I have good fluid flow to the trans cooler?




See my comment above, "even with the drive tangs broken there can be enough friction between the pump rotor and drive hub to create some pressure but not enough to engage a clutch."




if you want to solve the Issue, John's the man on T/F's. Nuff said
Posted By: stumpy

Re: Mopar 727 Transmission Won't Go!!! - 10/19/12 03:19 AM

Quote:

The 2800 stall converter might be the cause of your problem. Remember it won't perform properly until it passes it's rated stall speed. On the jack stands there is little or no resistance for the converter to stall against. So, put it all back together and see what happens when you engage the transmission and apply the throttle with all 4 wheels on the ground. Take the converter past the 2800 stall speed and see what happens. I would also think that if the ears(lugs)were broken on the internal pump gear you'd find metal contamination in the oil and on the filter.

transman



A 2800 stall will pull perfectly fine from an idle on. It's just fully locked at 2800.
Posted By: Dodgem

Re: Mopar 727 Transmission Won't Go!!! - 10/19/12 12:48 PM



transman



A 2800 stall will pull perfectly fine from an idle on. It's just fully locked at 2800.






LOL! Yes pretty tight heck I have a 5000 ultamite seems tight to me.

stock are 2200 to 2400
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