Posted By: GKMOPAR
727 3rd gear question - 03/07/11 04:11 AM
Just finished a rebuild on a small block 727 in my sons Duster. It has a Turbo Action Cheetah reverse manual valve body. The trans shifts great under normal acceleration and cruising. If you are accelerating at more than 1/2 throttle it does not want to go into third. If you let off it will shift. If you are in third and accelerate more than 1/2 throttle, it will slip. The fluid looks fine. What can cause this?
Posted By: calrobb2000
Re: 727 3rd gear question - 03/07/11 06:46 AM
hi
low fluid level
add 1 pt and retry ?
incorect clutch pack clearance
bad seal in clutchpack
Posted By: John_Kunkel
Re: 727 3rd gear question - 03/07/11 10:47 PM
Sounds like a sealing problem in the front clutch; either the metal sealing rings or the piston rubber lip seals.
Posted By: Dodgem
Re: 727 3rd gear question - 03/07/11 11:02 PM
I've had that happen with the shifter out of adjustment.
make sure the shifter leaver o the tranny is on good shape and tight!
Posted By: dOoC
Re: 727 3rd gear question - 03/07/11 11:06 PM
As mentioned above ... could be a rubber seal. You could have pinched it upon installation.
IF SO ... it might be at the bottom of the pan.
Posted By: GKMOPAR
Re: 727 3rd gear question - 03/08/11 04:32 AM
Fluid level looks good. I tried adjusting shift linkage and did not seem help. I will drain fluid and look for any evidence. Thanks
Posted By: GKMOPAR
Re: 727 3rd gear question - 03/09/11 01:28 AM
This is the same issue that killed the trans before the rebuild. Third gear went out & the clutches were toast. Is there anything else that can cause this or is it just a coincidence?
Posted By: GKMOPAR
Re: 727 3rd gear question - 03/09/11 03:23 AM
I could only hope so. Is there anything I need to check on the valvebody? The location of the steel balls, adjustment, etc? If I drop the valve body, where is the port that I can use to air test the front clutch?
Posted By: dOoC
Re: 727 3rd gear question - 03/09/11 08:29 AM
FC port ? ... FIRST round one next to the two rectangular ones. A farding sound will indicate a damaged rubber seal.
Posted By: DANA60
Re: 727 3rd gear question - 03/09/11 02:09 PM
I've also seen it as simple as linkage or kick down out of adjustment or both.
just my
Posted By: GKMOPAR
Re: 727 3rd gear question - 03/10/11 12:23 AM
It is a reverse manual valvebody so no kickdown linkage. Already adjusted the shift linkage. I think next step is to air test the front clutch. Sounds like I need to listen for a click when the clutch engauges and no hiss or fart sounds. I will try that and keep everyone posted. Thanks.
Posted By: dOoC
Re: 727 3rd gear question - 03/10/11 12:46 AM
TRY and get some ATF into the port during the air-test.
Posted By: GKMOPAR
Re: 727 3rd gear question - 03/13/11 07:06 AM
Got around to checking trans today. When I did an air check on the front clutch it was not working. I just got a hissing noise. I checked the rear clutch and I could hear it click. I dropped the trans and took it apart to investigate. By the looks of the clutches it looks like they were starting to slip. The rubber seals in the drum looked ok. When I checked the metal rings in the pump reaction shaft they were very rough. It looks like there is an issue here as they look like they are abnormally worn. I assume this is where I am not holding oil pressure causing my 3rd gear issue. The trans is a 1975 360 727 #PK3681862. I have some spare transmissions but does it need to be a 1971 or newer the have the same shaft size? I am also looking @ getting a 4 disc drum to upgrade the 3 disc drum. This drum had 9 springs on the piston and it will hold 15. Is there an advantage to add more springs? I want to do this right this time so I don't need to drop the trans again. Any advice would be helpful. Thanks, Gerry.
Posted By: John_Kunkel
Re: 727 3rd gear question - 03/13/11 09:36 PM
Your '75 should have the wide bushing front drum and matching reaction shaft support, it takes a different sealing ring than the '70 and earlier. If the rings wore prematurely they could be the wrong rings or the ring grooves/drum are excessively worn or there is excessive end play in the input shaft.
Most everybody recommends using 15 springs but I prefer 9 springs on the 15-pin piston.
Posted By: cjs69mope
Re: 727 3rd gear question - 03/14/11 02:57 AM
I run 10 springs in mine , i used the red alto clutches and kolene steels i think with the right top plate u can get 5 fictions in there
.
Posted By: 71yelladustr
Re: 727 3rd gear question - 03/14/11 03:52 AM
I agree with john k. Excessive input shaft endplay is a death sentence for front clutch pack. Try to elimainate as much endplay as possible and your tranny will thank you. Definately do the 4 clutch upgrade.
Posted By: dOoC
Re: 727 3rd gear question - 03/14/11 07:45 AM
x 55 on reducing input shaft end-play as much as possible. And bushing issues are also a consideration toooo. If the drum is sloppy on the reaction shaft it can even BREAK the rings.
CHECK the drum surface now .. it could be damaged.
I rebuilt a trans and after 60 miles lost high gear. Upon teardown found a very rough surface on the inside of the high drum where the seal rides. Was either a casting flaw or poor machining at Kokomo. Had to replace the drum. After that no more problems. Probably not the answer you want to hear. Take her down....