46RH pressure switches plumbing

[Duodec]

I'm spec-ing out how I'm going to mount the two pressure switches used to control the OD and lockup functions of the 46RH I'm installing in the Challenger.  I don't want them hanging directly off the transmission's governor pressure test port, and would rather have them accessible from the engine compartment, assuming having the switches at the end of a few feet of tubing isn't a problem.

If I use one of the bellhousing to engine bolts to hold a bracket to mount the manifold with the two switches at the rear of the engine, I can then use nicopp or other bendable metal tubing (with adapters) from the test port forward and up the bell to the manifold; no need for a flexible hose then.

If the switches are mounted on the actual firewall or inner fender, then I do need flexible hose involved.  Whats the best way to go from 1/8"NPT on the transmission to 1/8"NPT on the switch manifold?  Obviousy part of it could still be metal tube, perhaps still fromthe test port to a bracket on the rear of the engine, then flex to the manifold.

I do not want to use rubber hose and barb fittings with clamps; I'd rather use a braided hose with flare or equivalent fittings.  I saw some adapter fittings that go from 1/8" NPT to 1/2" flare (5/16" tubing, not sure what size the equivalent flex hose would be).  What would work best?  And roughly how much flex hose would be needed to compensate for the relative movement of the transmission/engine to the body?

Thanks for suggestions!

[Katfish]

I only have 1 switch, used trailer brake hose, and some aluminum to sandwich the adjustable pressure switch.
Adjusted the trip point 10yrs ago, and haven't touched it since

[Katfish]

Some people use toggle switches, but I wanted a better solution.
The problem is not shifting into OD, it's downshifting that can be an issue.  During a panic stop, or even just normal stopping, you forget to flip the switches back and the car lugs.





Completely automatic, wanted my daughter to be able to drive it.
The control module automatically turns on/off the overdrive and lock-up for the transmission.

The 518 (46RH) is hydraulically controlled and uses 2 servos to enable the OD and LU.
The 3-pin connector on the transmission supplies the control voltages.
The center pin always has 12V power connected.  The 2 outer pins are switched grounds.  The front pin is the OD ground, the rear pin is the LU ground.

The module works according to the following sequence.
1) The 12V toggle switch supplies voltage to the relays and transmission center pin.
2) When the hydraulic pressure trips (50mph/adjustable) the pressure switch, ground is supplied to the vacuum switch.  When speed is below 50mph, hydraulic switch opens, disabling OD.
3) When there is enough vacuum, the vacuum switch closes, providing  the OD relay ground.  Under heavy acceleration, vacuum drops, opens switch, OD is disabled.
4) When OD relay has ground and 12V, it waits 10sec, then supplies 12V to the LU relay and ground to the transmission OD pin, enabling OD.
5) Now the LU relay has 12V, it's already grounded.  It waits the 10 sec programmable delay then provides ground to the transmission LU pin. So lock up doesn't occur until OD has been enabled and on for 10sec.
6) The programmable delays for both relays fix the situation when speed is fluctuating around 50mph.  This would normally cause the OD to kick on/off, the 10 sec (programmable) delay stops this from happening.

Flipped the washer pump bracket and it makes a perfect cradle.

[Duodec]

Some people use toggle switches, but I wanted a better solution.
The problem is not shifting into OD, it's downshifting that can be an issue.  During a panic stop, or even just normal stopping, you forget to flip the switches back and the car lugs.
......
Completely automatic, wanted my daughter to be able to drive it.
The control module automatically turns on/off the overdrive and lock-up for the transmission.

The 518 (46RH) is hydraulically controlled and uses 2 servos to enable the OD and LU.
The 3-pin connector on the transmission supplies the control voltages.
The center pin always has 12V power connected.  The 2 outer pins are switched grounds.  The front pin is the OD ground, the rear pin is the LU ground.

The module works according to the following sequence.
1) The 12V toggle switch supplies voltage to the relays and transmission center pin.
2) When the hydraulic pressure trips (50mph/adjustable) the pressure switch, ground is supplied to the vacuum switch.  When speed is below 50mph, hydraulic switch opens, disabling OD.
3) When there is enough vacuum, the vacuum switch closes, providing  the OD relay ground.  Under heavy acceleration, vacuum drops, opens switch, OD is disabled.
4) When OD relay has ground and 12V, it waits 10sec, then supplies 12V to the LU relay and ground to the transmission OD pin, enabling OD.
5) Now the LU relay has 12V, it's already grounded.  It waits the 10 sec programmable delay then provides ground to the transmission LU pin. So lock up doesn't occur until OD has been enabled and on for 10sec.
6) The programmable delays for both relays fix the situation when speed is fluctuating around 50mph.  This would normally cause the OD to kick on/off, the 10 sec (programmable) delay stops this from happening.

Flipped the washer pump bracket and it makes a perfect cradle.

Thanks!  The PATC setup is what I'm planning on using but I'll give your setup consideration; I found (reportedly) American made adjustable pressure switches, and I had picked up a 10 second delay relay already from a recommendation online (maybe it was you here before), reportedly desirable in a 2-switch setup as well.   I prefer having the pressure adjustments available under the hood, and also away from undercarriage hazards.  But I don't think I want an obvious control box under the hood.

The trailer brake hose looks like a great choice, assuming they are still available in transmission-fluid-proof material.  Might even use that if the switches get mounted off a bellhousing bolt since it eliminates the need to precisely bend the tubing and flaring it (I don't have a good flaring tool, and good ones that work well are not inexpensive).

[Katfish]

Can you post info for the switch you found.
The 50lb adjustable I used is no longer listed at JEGS.
These are common switches, but I can't seem to find it elsewhere.

Thx

[Duodec]

Amazon adjustable pressure switch

Not cheap but again, the info I've found says its US made and well reviewed.

[Katfish]

Thx, this was the closest I found

https://a.co/d/1Wvw8Ct

[Duodec]

That one in addition to being chinese, is pneumatic, not hydraulic.  Might work for a while but probably not a good solution.

[Katfish]

That one in addition to being chinese, is pneumatic, not hydraulic.  Might work for a while but probably not a good solution.

Good catch, missed that it was pneumatic.

[Katfish]

Finally found the source.
Honeywell is manufacturer, others copy or resell.
I'm using the 5000 series.
Called Jegs and the guy said they (Jegs) made it, funny.