Staghound Hydramatic Transmission Question

[rob love]

Originally Posted by Malcolm Towrie

. This requires removal of the tranny to adjust the bands, which was a routine task!
Then two pins to allow external adjustment of both bands.
Then they made the rear band self-adjusting, so only the front band had the pin. The Chaffee has this setup.

Attachment 111940

The manual covers adjustment of the older transmission. It is just a matter of torqueing the screw to a certain torque (engine running for the rear band) and then backing off a certain amount of turns. It is something I'll try in 9 months when I get the tank back to here.

I ran the vehicle up this morning and both warning lamps are staying on. Before I get the pressure gauge out, I'll check the levels of both transmissions. They both leak, and the vehicle has not been fully operated in 7 years or more.

[rob love]

Man, the previous work on this vehicle is starting to annoy me. I ended up adding 3.5 quarts of fluid to the left transmission, and while the transmission was giving forward movement, the warning light would not go out. So I removed the sending unit, added a gauge, and on start up, and at idle, the transmission was reading almost 90 psi. Nothing wrong with that. That's when I noticed that even though the wire was disconnected, the warning light was still on. It turns out that on top of two wrong (and different) pressure switches being initially installed, with one of those on the wrong port, they had wired the two wires to the wrong transmissions. Well, except for the wires they left hanging, but process of elimination kind of dictated where they were going.

Had I started both engines at the same time, everything would have looked fine.

Anyway, I switched the two wires from left to right, and all is well.

I am going to close up the access panels, re-install the ammo bin, and worry about the wires on the engine next week. I think I have had enough Stuart tank for one week....it's time to let all the bruised legs heal for the weekend.

[Malcolm Towrie]

Well spotted on the pin, Rob. The pin is rigidly attached to a tang on the front band, so restricting its movement would prevent full band clamping, unless the pin is sized to buckle or something. You can see the pin and the tang in the right hand window of Marco's photos.

The Staghound engines had pressure and temp senders for engine oil and coolant installed but they hadn't been wired to the gauges on the instrument panel. I can see why. The senders were modern design which are totally incompatible with the old school radium-illuminated gauges on the panel. The original temp gauges need a 25 to 250 ohm variable resistance from the senders, but modern senders work more on the 2500 to 100 ohm range. Same with oil pressure. Modern senders don't work with 1940's gauges. So I gave up on the gauges and installed warning lights on the I/P, using modern switches set at 250F for coolant, and 5 psi for oil pressure.

I figure a bright red LED light will get more attention than a gauge going off-scale high or low anyway.
Malcolm

[rob love]

Stewart Warner still makes sending units in the ranges you need for the original gauges. I was just researching the subject tonight, as I need to replace/match up some of the gauges to their sending units. They have a very good webpage showing all of their gauges and sending units. That said, their prices can be intimidating if you are not careful about where you order from.

[Malcolm Towrie]

I checked out the Stewart Warner site but it seems the temp sender info doesnt give any degree-to-ohms calibration info (at least I couldn't find it), so they can't be matched to an original gauge, just a new SW gauge. Which is still a good option.
Also, none of the pressure senders, which do give psi-ohm calibrations, match the 0-30 ohm/0-60 psi calibration I found the original gauges have.

However, I did find this good information on all the NAPA Echlin senders and switches which allowed me to find a 5 psi low oil pressure, NC, 1/8"'NPT warning switch and a 250F high temp switch.

In hindsight, maybe I could have found senders for the original gauges with this list.

Malcolm

https://s3.amazonaws.com/pageturnpro...uide112011.pdf

[daninnm]

Hi!> I used a wire wound potentiometer to the gauge wire and turned the pot to get a full scale and then a low scale reading......reading the pot resistance at each point will give you the resistance range sender that the gauge wants to 'see' from the sender....
BTW::::: I have a ton of NOS Cadillac hydramatic parts including NOS clutch discs.
We are driving he Staghound and just moving onto finishing the radio and parts instalaltions in the turret and the upholstery in the turret basket.
DaninNM 5052692056

[Malcolm Towrie]

Dan, I did that for the pressure and temp gauges. I found the oil pressure gauges took 0-30 ohms to go from zero to full scale and the temp gauges took 25-250 ohms.
I have a database of all the senders that NAPA sells. Modern senders don't work anywhere close to these ranges. Have you managed to find senders that match these old gauges?


Malcolm