TH400 conversion
#1
TH400 conversion
Hi guys,
I purchased my 1970 Cutlass Convertible for $50 in 1981. It’s been a long journey, but she’s finally getting to be the car I envisioned. I installed a 455 w TH400 trans that came out of a buddies 71 Olds 98. Motor and trans working great and I’m finishing the last of my open items. Kickdown on the trans is one of these. I know the kickdown is electric, what will I need to get this working?
I purchased my 1970 Cutlass Convertible for $50 in 1981. It’s been a long journey, but she’s finally getting to be the car I envisioned. I installed a 455 w TH400 trans that came out of a buddies 71 Olds 98. Motor and trans working great and I’m finishing the last of my open items. Kickdown on the trans is one of these. I know the kickdown is electric, what will I need to get this working?
#2
You need the kickdown switch and bracket that mounts under the gas pedal. If your car was originally a th350 it will have a clip on the gas pedal for the th350 kickdown cable, that may need to be ground off or you can replace the pedal. Your factory harness has the wiring built into it.
#5
Th350 kickdown uses a cable attached to the gas pedal. Th400 uses an electric switch attached to the gas pedal. All the factory harnesses have the wires for the th400 whether car came with one or not. You just need the switch and the bracket.
#6
The underdash wiring for the kickdown is there. You will need to add the wire to the engine harness. You need a male series 56 terminal, and a 1/4 inch female quick disconnect, and enough 16 wire to go from the firewall bulkhead connector to the trans kickdown connector.
id suggest using a hair dryer or heat gun to soften the sealer the factory put on the connector. The stuff Oldsmobile applied probably turned from sealer to glue during the Reagan administration. Loosen the bolt (it won’t come out) apply some heat, and wiggle the plug. You will need to look at the factory wiring diagram to figure out what cavity to insert the 56 terminal.
#7
The underdash wiring for the kickdown is there. You will need to add the wire to the engine harness. You need a male series 56 terminal, and a 1/4 inch female quick disconnect, and enough 16 wire to go from the firewall bulkhead connector to the trans kickdown connector.
id suggest using a hair dryer or heat gun to soften the sealer the factory put on the connector. The stuff Oldsmobile applied probably turned from sealer to glue during the Reagan administration. Loosen the bolt (it won’t come out) apply some heat, and wiggle the plug. You will need to look at the factory wiring diagram to figure out what cavity to insert the 56 terminal.
id suggest using a hair dryer or heat gun to soften the sealer the factory put on the connector. The stuff Oldsmobile applied probably turned from sealer to glue during the Reagan administration. Loosen the bolt (it won’t come out) apply some heat, and wiggle the plug. You will need to look at the factory wiring diagram to figure out what cavity to insert the 56 terminal.
#8
Is the kickdown wire in the engine harness on the 68-69 cars? I knew the kickdown switch wire was included in the dash harness regardless of year, I thought the engine harness was transmission specific?
#9
Yes, the wire from the firewall connector to the trans is included in every A-body Olds built from 68-72.
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