Geez just lost reverse

[3sloppydogs]

pulled the charger on the lift just to look at things before winter sets in I won't drive it. I let it down to move it for storage and it would not back up unless I spin the motor up then it moves away slow. So I guess I have a winter project.

 

[Don67Satellite]

Checked the fluid lately?

 

[Geoff 2]

If not fluid, low/rev band. Which is adjustable.

 

[Don67Satellite]

Actually I lost reverse one day, but could still go forwards in all gears, took it to the shop and somehow the low/reverse band nut had backed itself off, likely had been slowly for some time. Quick, cheap fix.

 

[tubalcain]

A possibility is the low-rev drum lip seal. You'll have gears forward but no backup.

 

[3sloppydogs]

Fluid level is proper
I will check the band though

 

[1 Wild R/T]

A possibility is the low-rev drum lip seal. You'll have gears forward but no backup.

There is no low/rev drum lip seal... There is no low/rev clutch.... This isn't a Chevy.... It has a band for low/rev..

The fact it suddenly stopped after a cold start and dropped into rev points to a band failure... The end where the band attaches to the strut has been knowm to snap off....

 

[Dave6T4]

You might be suffering from torque converter drainback. If your car has been sitting for a while, start your car in neutral, and let it idle for a minute to allow the transmission pump to refill the converter. This condition is more noticeable in reverse, because this circuit requires more pressure to operate than forward gears. Most TorqueFlights suffer from this as they age.

 

[toolmanmike]

Actually I lost reverse one day, but could still go forwards in all gears, took it to the shop and somehow the low/reverse band nut had backed itself off, or had been for some time. Quick, cheap fix.

Same happened to me. The link between the band and adjuster was laying in the pan.

 

[Dave6T4]

Over my years of rebuilding 727's , I have seen a few catastrophic reverse failures. Most of these have been associated with no or improper kickdown linkage. Some guys had no linkage, so they tied the kickdown lever back. This makes the transmission operate at maximum pressure all the time. So, when the transmission is shifted from neutral to reverse, there could be almost 300 psi. on this circuit. I have seen broken band anchors and broken band apply links. The worst case I saw was an exploded reverse apply piston, with the spring and retainer hanging on the apply arm. Another time, a customer's truck was in such poor tune, that he had to keep his engine revved up to keep it running when shifting from neutral. This one broke the reverse band anchor.

 

[Cranky]

Over my years of rebuilding 727's , I have seen a few catastrophic reverse failures. Most of these have been associated with no or improper kickdown linkage. Some guys had no linkage, so they tied the kickdown lever back. This makes the transmission operate at maximum pressure all the time. So, when the transmission is shifted from neutral to reverse, there could be almost 300 psi. on this circuit. I have seen broken band anchors and broken band apply links. The worst case I saw was an exploded reverse apply piston, with the spring and retainer hanging on the apply arm. Another time, a customer's truck was in such poor tune, that he had to keep his engine revved up to keep it running when shifting from neutral. This one broke the reverse band anchor.

Was told years ago by a transmission guy that it's a good idea to touch Drive before going in the Reverse. Does doing that make a difference in pressures or something when engaging Drive first?

 

[tubalcain]

There is no low/rev drum lip seal... There is no low/rev clutch.... This isn't a Chevy.... It has a band for low/rev..

The fact it suddenly stopped after a cold start and dropped into rev points to a band failure... The end where the band attaches to the strut has been knowm to snap off....

The component terminology is probably causing confusion here. I have built 30 or so 727's and each one got a new low- rev lip seal. That is the part that seals the L-R piston in the L-R drum which applies the rear clutch. In other words, the rear clutch lip seal.
And when that seal fails, you'll have forward gears but no, or minimal, reverse.
As an example of the terminology,

Mopar invented the high drum, designed it, produced it, and named it. TECHNICALLY the ONLY correct name for this drum is "Front Clutch Retainer, "which is what Mopar named it.


Some of the CORRECT names for this drum are: High Drum, High/Reverse Drum, Front Drum(in front part of the transmission), Forward Drum(in the forward part of the transmission, not to be confused with the next drum which controls the forward MOTION of the vehicle), Kickdown Drum, Direct Drum, Reverse Drum(not to be confused with the Reverse Brake drum in the rear of the transmission), all of the above with "Clutch "inserted before "Drum, "and all of the above with "Drum "replaced by "Retainer "or "Cylinder. "These are just SOME of the American English names for this drum.


Don't you just love the terminology in the transmission business?

 

[tubalcain]

The picture bout says it all. Memories from 40 years ago with complaints of no foreword but reverse worked. A bit different huh. Sorry if I caused anyone gastric distress. I'll be more cautious about quick posts as misinformation upsets me too. My humble apologies.

 

[tubalcain]

If the examination of the LR band- linkage-servo shows no problem, look in the front clutch retainer. likely a lip seal. The loss of the front clutch will cause a no reverse situation.

 

[Dave6T4]

Was told years ago by a transmission guy that it's a good idea to touch Drive before going in the Reverse. Does doing that make a difference in pressures or something when engaging Drive first?

With the kickdown lever at rest, there would be minimum pressure in the circuits, so I see no benefit in going to drive before selecting reverse.

 

[Stumper]

Sounds like my car when I first pulled it out this spring. After the fluid check I dropped the pan to adjust the band and saw lots of band friction material and metallic "sparkles" in the bottom and fluid. Was still able to adjust the band to spec but about ran out or threads on the adjuster. Needless to say the band was shot and coming apart and it had gotten into the drum and damaged it pretty bad.