Transmission Stuck? RV won't move

[travcojim]

Okay, not sure what I have done, if anything.  But here is the story, Dodge 727 tranny, hooked to a 440, in a Travco.  All in almost new shape, new meaning around 14000 miles on the rebuild.  Never had a problem with the tranny  before.  But I was backing up on some leveling blocks and I had to give it some power to get it onto the blocks.  After getting everything level and set, I thought, I decided not to put it on the blocks, So I went to move forward and it was like the parking brake was stuck on.  I could not move more than an inch in both directions.  I could push down on the throttle and it was like I was up against a wall.  I had the parking brake on earlier, but it seemed to release okay.  Just in case I checked the fluid and it was okay, So, any suggestions?  Anyone else had this problem?  It is on my land so there is no hurry to move it, I just want to make sure I haven't trashed the tranny or something stupid.

[DaveVA78Chieftain]

My guess is the parking lock mechanism in the transmission tailshaft is frozen in park.  It's described in the chassis service manual.

Dave

[travcojim]

I can shift the gearshift okay, I can even feel it go into gear.  But thanks for the info, it gave me something else to look at this weekend.

[DaveVA78Chieftain]

From my 727 manual:
With the gear selector in Park, there are no friction elements engaged; a rod connected to the manual valve body engages a pawl that in turn engages a notch on the outside of a flange that is splined to the output shaft.  This action locks the flange to the transmission case effectively holding the vehicle stationary.
You did say no movement.
Dave 

[Slantsixness]

Wow... Haven't seen this happen in a long time!
Please make sure your parking brake is free, whether its on the driveshaft or the rear brakes (remove the driveshaft, if you have too, to verify this)..

but what I think has happpened is this:

Yes.. the Park Pawl is stuck, and may be bent. It'll still go in gear though. when the pawl gets stuck, the valve body will still shift, but the pawl doesn't release.

When this happened to me years ago, I was able to "unstick" it by rocking the transmission between reverse and drive a couple times... and by a couple I mean do it twice, drive reverse than drive reverse again don't do it any more than you have to if it doesn't free, STOP! (maintaining about 2000 rpm while switching gears). Scared the livin crap out of me since I was in a 1 ton truck (72 dodge D300) and a trailer about 1000 miles from home with not enough tools or money to fix it...
keep in mind that rocking the trans like this (neutral drops..ouch!) can damage the trans or the pawl, but I drove that truck another 6 or 7 years and it never had any further symptoms with the tranny after that one time.

A different (and proper) way to fix it if you can, is to remove the trans pan and look for the park rod and release it (towards the rear of the trans vale body behind the servo.  You'll probably also have to take the driveshaft off or jack up the rear end to allow you to take the load off the park rod. With a little luck, it hasn't bent and jammed, just got stuck!
you can also try a strap wrench on the drive shaft, rotating the shaft aggressively and have someone manipulate the gear selector aggressively at the same time.. this used to fix the problem on the old 904 transmissions... which are very similar.

Why did this happen? when you backed up on the blocks, you stuck it in park and the movement of the wheels loaded the park pawl backwards and jammed it. It's common in cars of all ages, but the weight and force of a motorhome rocking back from reverse to park can jam the mechanism (kind of like parking on a hill without a parking brake...). Once the mechanism jams at the pawl or the park rod, it won't come unjammed without some brute force.

So... enough of the backyard fix.... there is one more reason it might have locked up:
something could have happened to the low/reverse servo, and the low reverse band is way too tight on the gear.. this could be a stuck servo, broken band, broken servo spring... and a host of other things... but I seriously doubt that that's the case here.

hope this helped!

[travcojim]

Thanks for the rundown,  I know what I am doing Sat....
 

[travcojim]

just an update...  It has rained every weekend for the past month, so no work on the Travco.  The minute I get out there and it moves across the drive,, I will let you guys know what was the problem was...
 

[Beachcomber]

Just wanted to add my experience to an old post, but one that sends shudders running through your wallet when it happens to you. I purposely parked our 1974 Chieftain with a slight rearward slant to shed rain while it was parked over the winter, only to experience the exact same "something's broken in the transmission" panic. For me, it was a simple situation of the rear of the vehicle sinking an inch or so more in the soft earth of my new parking spot, putting extra weight on the parking pawl, and not allowing the shifter to move from the park position. I was lucky enough to be able to force the transmission into gear, and all has been well since. Two options to avoid this panic situation....put emergency brake on before shifting into park, and park with transmission in neutral, with brake on, wheels blocked. These are tough transmissions, but they're moving a lot of weight and if its all on the parking pawl, ....well you know the feeling...its probably just simple physics pushing your buttons a bit. D:oH!

[Froggy1936]

CAUTION  be very careful and shure of what you are doing under veh when trying to free up / release whatever is holding it park Pawl, Em Brake or Main Brakes , removing driveshaft could release veh to roll off blocks therby seriously decreasing distance between frame and ground (where you will be)  Remember it could roll either way   Frank