Weird Acting 727 Trans

[bordin34]

My SB 727 seems very weird. When it is about 2 pints low on fluid 1st gear doesnt slip at all and reverse kicks in at about 2k rpms but slips. When I fill it to the proper fill level 1st gear slips like crazy and reverse doesnt work at all. I check and fill it while idling in neutral.

[djdmotorsports]

i dont know a ton about the 727 but if its a piston that engages the first gear clutch pack it might be leaking around the seal. Thus when the fluid is low (and not as much is going to the piston) it doesent seem to slip, but when it has full line pressure it blows by the seal.

[bordin34]

The trans does leak and quite a lot actually. In about a month after full it will lose a pint to 1 1/2 pints after that the leaking slows. Is there an easy remedy.

[djdmotorsports]

if its a piston leaking down then the trans has to be rebuilt. easy way to diagnose would be to get a trans pressure gauge and watch the line pressure at idle. Then put it into first and it if it slowly blows of pressure when put into gear than thats more than likely it. could be a check ball thats getting stuck as well if its all gunked up.

[bordin34]

Anybody else have any ideas?

[Carlwalski]

May have nothing to do with what oil. Sounds like it's just your bands slipping and the oil is at certain levels it exaggerates or makes a change. I would look at replacing your burnt bands.


My 

[tactransman]

   hum............ that doesn't make sense at all. When you say when it is low and it has low (forward) and a partial reverse are you saying that after you have driven the car for a little while or when you first start it and check the level it moves ,and then you add fluid then it doesn't move?If so.....it sounds to me like the filter is blocking up,when it has sat not running for a while,debris floats away from the filter somewhat allowing fluid thru it.By the time you get the fluid level topped off ,it has pulled the fluid (with the debris) back into the filter blocking it up where there is insufficiant flow again. Drop the tranny pan, I think you will find your answer in there!

[bordin34]

About 2 months ago I filled it to the proper level. After it was full when I drove it the trans slipped. The car sits and only get driven about once every 2 weeks and only for 300ft. Now that the fluid is low the trans has stopped slipping in first and slips less in reverse. It works just as good when just started as it does when fully warmed up in both scenarios.

[tactransman]

So you are saying it is low now,and it working better than when you had it full 2 months ago? Maybe try filling it full again and see if it does the same thing again. No transmission should work better low instead of full. Now over full could create a problem.

[bordin34]

Thats exactly what I am saying. I will try to fill it up and see what happens.

[ChallengerHK]

Are you sure the dipstick is measuring properly? Especially if it's not seating right, it could read a correct amount offluid when the trans was over-filled.

[bordin34]

I am 83% sure that it is measuring right unless it was changed sometime in its life.

[ChallengerHK]

Another possibility is that the dipstick tube isn;t seating completely, which would give you the same result. I've had cars with the wrong dipstick as well.

[bordin34]

I was adding trans fluid to it today and remembered last time I filled it up I put an entire bottle of Lucas Trans Fix in it. It probably didn't kick in until it was low on fluid because it doesn't get driven much. Now I gotta put some stop leak in it to stop the leaking and it will be a fully functional 727 without good reverse. 

[tactransman]

it will be a fully functional 727 without good reverse. 

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