Re: 56 Ultramatic No Low Range
|
||||
---|---|---|---|---|
Home away from home
|
Nice detailed write up. So obviously the low range band is not engaging. Since it drives normal in High the control logic is probably fine. And there's no real way you can be in Neutral when you should be in Low and the rest of the transmission works, so I think your throttle pressure and your selector adjustments are satisfactory, at least for the time being. By the way, it will spin the tires in Low because of the natural drag in the high range clutch pack when it's disengaged. Normal on all automatic transmissions. But that tells me that your band is not engaging AT ALL. Not, for example, that it's too worn.
Unfortunately there is not easy or obvious reason that this is occurring. The short list is that the band tab is out of position or the actuator pin is f***ed up. I think it will be best if you drain then drop the pan. Grab a 1/2 in. drive socket and remove the reverse servo (4 bolts). Slide it so the tubes come out. Then remove the (I think) six valve body bolts. Do NOT switch to a different socket. Then slide the valve body away from the low range tubes. Remove the bendy tube (just twist/pull by hand) then remove the 3 bolts to drop the low range servo. Send a picture of the band tabs and inspect that they are seated in their actuators (the 90 degree angle pieces of cast metal on pin hinges). You should be able to engage the band by pressing the actuator once the tab is seated. Compare the low range operation to reverse; they are functionally identical. If the low range actuator is stiff then that's your problem. If those are OK then grab an air gun with a rubber cone tip and shoot like 100 PSI air into the two ports on the low range servo. One will do nothing but the other will actuate the servo. If not, then your problem is somehow in there. Or you could even be missing a jumper tube into the low range servo for some reason. Let us know what you find. By the way I'm in Pittsburgh if you would like to send it up.
Posted on: Today 19:15
|
|||
1955 400 | Registry | Project Blog
1955 Clipper Deluxe | Registry | Project Blog 1955 Clipper Super Panama | Registry |
||||
|
Re: 56 Ultramatic No Low Range
|
||||
---|---|---|---|---|
Home away from home
|
If the cover of the low range servo is distorted the piston inside will retract to a position where the inlet port is covered and the the servo will not move. They issued a heavier cover to prevent this from happening.
This is a rare failure and I'd rebuild Ultras for years and years before encountering it. The symptoms were just like yours--everything else worked just dandy, but absolutely no low. After you replace that cap be sure to readjust the low band.
Posted on: Today 21:47
|
|||
|