727 Problems

Posted By: elmor

727 Problems - 02/18/13 02:54 AM

The 727 behind my 73 440 is giving me problems. I bought the truck 2 months ago, drove it 150 miles home with no problems. Now after 40 miles of in town driving, it slips on the 2-3 upshift. Was told the trans was rebuilt, but then I've seen a carb suddenly become rebuilt after being sprayed with carb cleaner.
Any ideas where I should start?

Posted By: Dodgem

Re: 727 Problems - 02/18/13 02:56 AM

Yes set the front band as soon as possible.
seen many set way to loose and that causes a 2 3 slip

Posted By: elmor

Re: 727 Problems - 02/18/13 03:01 AM

Is that the adjustment on the outter left side of the case?

Posted By: Dodgem

Re: 727 Problems - 02/18/13 03:16 AM

yes the easy one driver side 3/4 lock nut i would go wrist snug and back off 1 1/2 turns.
That's how I always do it!

Sorry I read 1-2 shift so I was wrong!

Posted By: 68_CONV_300

Re: 727 Problems - 02/18/13 03:58 AM

the second gear band wont cause a 2-3 slip ... it will cause a 1-2 slip ...if 3rd is slipping then it has to be the front clutch pack and or the associated seals

Posted By: dOoC

Re: 727 Problems - 02/18/13 04:46 AM

How well does reverse go into gear ?

Posted By: elmor

Re: 727 Problems - 02/18/13 07:28 AM

It goes into reverse without a hitch. Works fine in reverse and 1-2 shift. The 2-3 shift problem just started. Once it shifts into 3rd, I can stick my foot in it and it pulls no problem. It only slips when it does the 2-3 shift.

Posted By: 451Mopar

Re: 727 Problems - 02/18/13 08:34 AM

If it is slipping as described and the Kickdown and front band is adjusted correctly, then it sounds like there is excessive fluid leakage to the front clutches.
If that is the issue, the transmission needs to be removed to inspect the front drum bushing and sealing area (and seals), and the front drum piston seals. Also the clutch pack clearances.

Posted By: Tom Hand

Re: 727 Problems - 02/18/13 03:52 PM

Elmor, the others are correct that you need to check into the kickdown band adjustment. If the band is way too loose, it can drop off before the third gear clutches grab. Be sure the throttle pressure rod is adjusted correctly first.
Tom

Posted By: JohnRR

Re: 727 Problems - 02/18/13 04:15 PM

Quote:

It goes into reverse without a hitch. Works fine in reverse and 1-2 shift. The 2-3 shift problem just started. Once it shifts into 3rd, I can stick my foot in it and it pulls no problem. It only slips when it does the 2-3 shift.

WHAT EXACTLY is happening on the 2-3 shift , is it an RPM flare ???? If once it gets into third and it holds fine it's not slipping .

Here is how the 2-3 shift works , the front band release the front drum , at a certian point during that cycle the front clutches apply , a PERFECT shift you feel nothing abnormal , there is the tiniest bit of overlap between the shifts by design.

If you see the rpm just jump up , maybe 1000 rpm before it goes into 3rd then what is happening is your front band is releasing faster than the clutches are applying , this can be caused by a couple of things .... 1 is the front band is out of adjustment , 2 the front servo is releasing too fast , 3 the front clutch pack is not applying fast enough and that can be caused by 3 things , too much clearance , too many springs on the apply piston or a leak in the hydraulic circuit ...

Posted By: elmor

Re: 727 Problems - 02/19/13 05:30 AM

Yes, I guess you could call it an RPM flare. The engine revs big time when it shifts. If I let off the gas when it starts to shift, it isn't too bad. I've been afraid to stay in it when it shifts. It just started a couple of weeks ago. I bought it and drove it down the freeway 150 miles to get home. It shifted fine. I got in stop and go traffic for about 2 hours. It was then that I discovered a massive air leak around the intake. I had to keep working the gas and brake and shift between first, second and neutral to keep it running in stop and go traffic. Once I got it home, I swapped intakes and it started shifting like this shortly after that. I thought I had adjusted the kick down properly. It is possible that I didn't get it exactly right, but I have always set up my kick down linkage the same way and never had a problem on any of my other rigs. I will adjust the bands and recheck the kick down linkage to be sure.