727 help

[68plymouth383]

I drove my truck into work the other day. It ran, and drove perfect. No slipping, or weird noises. I go to park, and I reverse, and I only have park, reverse, and neutral. I was thinking bad shifter cable. I go to leave, and disconnect the cable, and still have only those 3 gears. I pulled the neutral safety switch, and all gears are there. What happened? I bought a New neutral safety switch, and it does the same thing...

 

[mr. fix it]

Something is sounding like it is stuck
What kind of cable are you referring to?

 

[68plymouth383]

I have a b&m megashifter.

 

[mr. fix it]

I'd be checking to make sure the braces are aligned and square to the cabling and transmission housing

 

[Davea Lux]

Sounds like the band for the forward gears is not engaging. Could be a bad servo or something might have gone south in the valve body so that you are not getting oil pressure to operate the servo. Another possibility is that the adjusting pawl for the band has worked loose and disengaged. You can check this by removing the transmission pan to see if everything is still in place. If some catastrophic failure has occurred, there will probably be parts loose in the transmission pan.

Dave

 

[CBODY67]

Reverse and Manual Low use the same band, as I recall, so manual low should have been there too. Not sure why removing the neutral safety switch would make a difference? Which automatic trans and where is the neutral safety switch located? Do the shifter detents feel any different?

CBODY67

 

[70bigblockdodge]

Sounds like shift lever came loose and shaft slipped down and loosing contact with selector valve.

 

[Davea Lux]

I'd be checking to make sure the braces are aligned and square to the cabling and transmission housing

I drove my truck into work the other day. It ran, and drove perfect. No slipping, or weird noises. I go to park, and I reverse, and I only have park, reverse, and neutral. I was thinking bad shifter cable. I go to leave, and disconnect the cable, and still have only those 3 gears. I pulled the neutral safety switch, and all gears are there. What happened? I bought a New neutral safety switch, and it does the same thing...

You are going to have to drop the pan to fix whatever is wrong here, Some things to check:
1.) Check the valve body to be sure it is not loose, a loose bolt or two can cause the valve body to case gasket to leak or blow out. This usually is the cause of no forward gears.
2.) Check the band adjustment on the front band, if it is too loose, the forward gears will not work.
3.) Check the front servo to be sure it is not stuck, if it is stuck, the front band does not engage and you will have no forward gears.
4.) Another cause of no forward gears is a burnt out front clutch pack, if this has happened, the transmission pan will be full of clutch debris and the transmission needs a rebuild.
5.) Neutral safety is not the cause of no forward gears, the worst it can do to you is to cause the engine to not start, or start with a gear engaged.
6.) It is also unlikely that the shift cable is causing your problem in this case since you still have reverse, neutral and park. If the cable breaks or comes loose inside the transmission, usually you will be stuck in whatever gear you were in when it failed.

Dave

 

[68plymouth383]

I appreciate all the replies. This gives me something to go on. I will drop the pan, and let you guys know what I find.

 

[68plymouth383]

Dave, your right... I pulled the valve body, and the line pressure screw is bent... it's allowing the shift shaft to drop down, and not engage the rooster comb. I have a spare valvebody here, and will swap parts. Transmission looks cherry inside.

Sounds like shift lever came loose and shaft slipped down and loosing contact with selector valve.

 

[Davea Lux]

Dave, your right... I pulled the valve body, and the line pressure screw is bent... it's allowing the shift shaft to drop down, and not engage the rooster comb. I have a spare valvebody here, and will swap parts. Transmission looks cherry inside.

Odd failure with no good explanation as to why it might have occured, but at least it was something easy and relatively cheap to fix.

Dave