727 losing reverse

[BlaineKaiser450]

I have a 727 behind the 440 in my 1969 Plymouth that is slowly losing reverse gear. What I mean by that is it will still go into reverse, but only at idle speed. If I rev the motor at all to try and get it moving backwards faster than a crawl, it makes zero difference. Basically, the best way to describe it is that it feels as if one of the bands is just barely holding on enough to engage it slightly, but not enough to really hook up. The trans has a fully manual valve body with zero automatic characteristics and a torque converter with a stall of around 2800. The whole setup has less than 50 miles on it, so it is basically brand new, and it was built by a reputable transmission shop, so I would assume it was assembled correctly, but who knows. Also, it hasn't been ragged on or anything like that as I haven't even done a burnout in the car yet and have only driven around my neighborhood to get the motor dialed in for street use. Does anyone know how to fix this or what the problem could be? Also, I have almost no knowledge of how an auto works, other than the basics, so please bear with me! 

[charger496]

   That happened to me back when my '71 was my only car. I drove it without reverse for about 6 months, because I couldn't afford to fix it. Made for some interesting driving. I believe your first/reverse band has shat the bed. First gear on take-off is fine, right? Drop it to first and pull away normally, letting the motor rev to maybe around 2500ish. Let off the gas, and I bet you don't feel the motor slow the car down. Feels like it's in neutral? Yeah. Broken band. Has to be torn down to be repaired, so a full rebuild is in order. Or... just drive it until a U-haul backs in to you at a light, and you can't back out of his way before he nails you. That happens.

[NMike]

reverse uses the front drum and the rear band. most likely pressure loss going to either circuits. might be as simple as a rolled seal on the actuator for the band. may even be a bad valve body.

you can check it for yourself if you pull the body and pressure test the trans. google it

[John_Kunkel]

I would pull the pan and visually inspect the rear band lever and servo piston. Check to see that there is springback when you pull down on the lever, if there is none something is broken...if there is springback but you can pull the lever down more than 1/2" try adjusting the band.

If the lever looks OK, look up into the piston bore to see if the piston is cocked or if there is visible rubber seal debris. In some rare cases, the stamped steel spring retainer will distort and pop out of its bore allowing the servo piston to cock in its bore.

[Dmichels]

Take it back to the trans shop before you touch anything. If you start messing with it they might tell you you are on the own.
Dave

[BlaineKaiser450]

Thanks guys!

Take it back to the trans shop before you touch anything. If you start messing with it they might tell you you are on the own.
Dave

thats my plan exactly, I'd rather be safe than sorry.

[TwistedShifter]

Any updates on the transmission issue? I was backing my Charger and it started going really slowly even unless I rev it higher than normally it won't hit 3rd unless I pop it manually. I'm hoping for a band adjustment. 

[John_Kunkel]

A band adjustment won't help 3rd gear. Reverse and 3rd share the front clutch which is probably the source of your problem.

[TwistedShifter]

I guess it sucks being me.    I am hunting for a replacement transmission now. I am just looking to get in up and running while I get some other projects completed. I would like to eventually score a 360 with a 727 for it, a complete big block package wouldn't hurt either.

[John_Kunkel]

Pressure leakage at the front clutch can be caused by worn metal sealing rings or hardened/shrunk rubber seals. Not much you can do for the rings except replace them but the rubber seals can sometimes be rejuvenated by the use of an additive like Trans-X or Lucas....fairly cheap and worth a try.

[BlaineKaiser450]

My car is at the trans shop now, It will be back on Monday and I will be able to tell you guys what was up!

[TwistedShifter]

Any updates, good sir?

[BlaineKaiser450]

Reverse band was no good, and while at the shop it developed a problem of locking up the rear wheels during the 1-2 shift, attributed to a faulty valve body. Got a new manual-reverse valve body to fix all the issues!

[John_Kunkel]

and while at the shop it developed a problem of locking up the rear wheels during the 1-2 shift,

I hope it wasn't on the lift when that happened, very common when the rear wheels are elevated and more so with some shift kits.

[BlaineKaiser450]

and while at the shop it developed a problem of locking up the rear wheels during the 1-2 shift,

I hope it wasn't on the lift when that happened, very common when the rear wheels are elevated and more so with some shift kits.

thankfully not, it was in the street you can actually still see skid marks from it