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| | | | Joined: Jul 2009 Posts: 90 Shop Shark | | Shop Shark Joined: Jul 2009 Posts: 90 | I just installed a new-to-me '57 borg warner overdrive in my '57 with a 235. I had a B/W overdrive in it previously.
In the old one, anytime I wanted to shift out of overdrive all I had to do was push the pedal to the floor to activate the switch and it would shift out at that moment.
With my new one, I have to let up off the gas a bit and then stomp the pedal to the floor and only then will it disengage. If I push the pedal slowly to the floor it doesn't disengage. I've checked, and the switch is being pushed at full throttle, so kicking it down is not simply pushing the throttle further. Also, sometimes, but not all the time, if I'm driving in overdrive, I can let up off the throttle gently and if I push it down gently again, it will shift out of overdrive.
Which of these is normal operation for one of these Overdrives?
Thanks,
Brandon | | | | | Joined: Feb 2004 Posts: 29,836 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,836 | The kickdown switch must momentarily short out the ignition to unload the drivetrain and allow the OD to disengage. It sounds like your kickdown switch isn't wired to do that. One of the wires from the kickdown switch needs to connect to the the distributor side of the coil, and I believe the circuit also goes through one of the contacts of the OD relay to prevent the ignition from staying shorted out more than a very brief period of time.
Jerry
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| | | | | Joined: Jul 2009 Posts: 90 Shop Shark | | Shop Shark Joined: Jul 2009 Posts: 90 | It was working with the previous transmission, so I assumed it is wired correctly. Perhaps in it's time in storage some of the connections have lost continuity to allow for the temporary cut out of the ignition. | | | | | Joined: Apr 2005 Posts: 2,099 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,099 | You may have a defective kick down switch. It sounds like everything is working normally except the switch.
The system is wired from the relay through the KD switch to the governor in the normal position. When the switch is engaged it connects the coil(-)and the #6 terminal on the solenoid.
It's possible a defective switch or a bad connection could
disengage the OD and cause the problem you are experiencing.
Fred
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine
| | | | | Joined: Jul 2009 Posts: 90 Shop Shark | | Shop Shark Joined: Jul 2009 Posts: 90 | Thanks, that makes sense. I'll try cleaning up the wire connections that go to the distributor. Hopefully that'll be the issue.
Thanks again,
Brandon | | |
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