Controlling overdrive transmission
I plumbed a cooler line from the governor port up to the back of the intake where I mounted two adjustable pressure switches from Nitrous Express.
Those two switches (one for OD and one for Lockup) activate relays, which in turn activate OD and Lockup at whatever speed I set them for.
On the back of the intake makes it easy to change engagement speeds with an Allen wrench.
Then I added two rocker switched inside the cabin to enable or disable the relays.
With both switches inside in the “auto” position, overdrive and lockup engage and disengage at whatever speed I set them for completely automatically.
As those pressure switches are set right now my car goes into OD at 50mph and lockup at 70mph.
I used an adjustable vacuum operated switch for kickdown.
When manifold vacuum drops to your set level, the vacuum switch breaks the ground for the lockup relay causing lockup to disengage.
I can turn off either or both switches inside the car and it will only shift 123.
One thing to note is that OD will ONLY engage once the trans is already in 3rd, as OD uses the hydraulic circuit of 3rd to engage.
I found that the vacuum kickdown stuff really isn’t needed.
The trans drops out of lockup once below 70 and OD once below 50 all automatically.
If I ever need to stand on it that hard I just turn the switch inside the car off.
I run 3.55 rear gears, so if I’m doing 80mph I really don’t need to drop to third anyway.
Passing in OD and or lockup is not a problem anyway.:D
Or, just buy an expensive controller.
The governor in the trans varies the pressure and is directly related to the speed of the car.
I plumbed a cooler line from the governor port up to the back of the intake where I mounted two adjustable pressure switches from Nitrous Express.
Those two switches (one for OD and one for Lockup) activate relays, which in turn activate OD and Lockup at whatever speed I set them for.
On the back of the intake makes it easy to change engagement speeds with an Allen wrench.
Then I added two rocker switched inside the cabin to enable or disable the relays.
With both switches inside in the “auto” position, overdrive and lockup engage and disengage at whatever speed I set them for completely automatically.
As those pressure switches are set right now my car goes into OD at 50mph and lockup at 70mph.
I used an adjustable vacuum operated switch for kickdown.
When manifold vacuum drops to your set level, the vacuum switch breaks the ground for the lockup relay causing lockup to disengage.
I can turn off either or both switches inside the car and it will only shift 123.
One thing to note is that OD will ONLY engage once the trans is already in 3rd, as OD uses the hydraulic circuit of 3rd to engage.
I found that the vacuum kickdown stuff really isn’t needed.
The trans drops out of lockup once below 70 and OD once below 50 all automatically.
If I ever need to stand on it that hard I just turn the switch inside the car off.
I run 3.55 rear gears, so if I’m doing 80mph I really don’t need to drop to third anyway.
Passing in OD and or lockup is not a problem anyway.:D
Or, just buy an expensive controller.