Purchasing Rear Servo for TF-727

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JoJo

JoJo

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I need to purchase a Rear Servo for a TF-727 and was wondering what was needed for the fix. Do I just purchase the piston alone or ???

Browsed eBay...
http://www.ebay.com/itm/TORQUEFLITE-727-Low-Reverse-Band-Servo-Piston-1974-/370390861813#vi-content

Browsed Google...
Transmission Parts Online:
http://transpartsonline.com/tpfile/tpcat.asp?TransPartsOnline=727&TransPartsType=727

Performance Automotive and Transmission Center:
http://www.transmissioncenter.net/727transmission.htm

TSR Racing Products:
http://tsr-racing.com/shop/chrysler...ory=TorqueFlite+A727+Servo+Pistons+Components
 
BRONZEBEE said:
Try your local transmission shop for a used one,probably cheaper.:D
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Transmission shop here closed a couple of years ago... Online is my main source of getting one. Other places don't have or quickly sale Chrysler transmissions.
 
Did you break the original servo?If just the piston broke,then buy the replacement and change it over.
 
BRONZEBEE said:
Did you break the original servo?If just the piston broke,then buy the replacement and change it over.
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Went to the store and back home... Parked for 5-10 minutes and vehicle wouldn't back up, lol. Online diagnosis was the rear servo piston since everything else checked out. I assume it's just the piston itself. They said it was a common problem for these transmissions.
 
I would pull the pan and check the servo and the band strut,if 3rd gear works good you might get lucky and it will be the servo.I have also seen the one of the lugs from the band in the pan also.
 
The band is fine and all of the gears are fine including 3rd gear.
 
It'll be the weekend before I can mess with it again. I wanted to go ahead and purchase the part so that I can have it on hand when I do pull it.
 
I've never been in a 727 so I'm no expert by any means, but I've been in a lot of 47RH/47RE/48RE Dodge diesel truck transmissions which I hear are pretty similar. This was a common occurance in them as well. If you're just wanting a stock one to throw back in it and get you by then I would just replace the cover with a regular cover. If you're wanting one that should never give you any issues then I would go with the high performance top cover with the teflon stabilizer ring from PATC. I've installed several of those and they are nice pieces.

I know on the newer stuff you're supposed to remove the tailsection to get the linkage pivot pin out and make changine the servo easier. I've wrestled them in before without doing this, but the HP servo will be a lot more difficult because it has to go in 100% straight on where the stock cover can go in at a little of an angle and turn once it's in there. Good luck, and hope you get it taken care of.
 
So, part #46RES on PATC's site is all that's needed?

I reuse the o-ring and the clip or whatever that holds it in?
 
Not saying it can't happen but in my 30 yrs. of rebuilding 727's I have yet to see a rear servo actually break. I've seen a lot of blown seals and a few broken bands but no actual pistons break. I'm sure it can happen but it's not a common occurrence. It's super easy to air pressure test the servo to check it and that's the 1st thing I'd do. Generally when things break (such as a servo piston) they fall apart and you said things look good so that tells me you've had the pan down inspecting things, right?

Here's a picture of the air pressure test ports. Inject approx. 30 psi of air to test each item. Naturally the valve body needs to be dropped to test things. And to answer your question of what to replace if the servo piston needs replacing. By all means replace the seal. The seal is how many yrs. old and your asking about re-using it?
 

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fishy68 said:
Not saying it can't happen but in my 30 yrs. of rebuilding 727's I have yet to see a rear servo actually break. I've seen a lot of blown seals and a few broken bands but no actual pistons break. I'm sure it can happen but it's not a common occurrence. It's super easy to air pressure test the servo to check it and that's the 1st thing I'd do. Generally when things break (such as a servo piston) they fall apart and you said things look good so that tells me you've had the pan down inspecting things, right?

Here's a picture of the air pressure test ports. Inject approx. 30 psi of air to test each item. Naturally the valve body needs to be dropped to test things. And to answer your question of what to replace if the servo piston needs replacing. By all means replace the seal. The seal is how many yrs. old and your asking about re-using it?
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Yes, I've had the pan down, valve body out and tailshaft cover off (park selector shaft was being a pain). The transmission is 34 years old :grin: I always see the servo piston pictured, but didn't know if it came with anything else. I see the seal is included. I will test the ports when I get back under it.
 
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