Staghound Hydramatic Transmission Question

[rob love]

Malcolm: Of course it is on the transmission that is still hiding under the ammo bin/cover, but I will give it a look. The linkages appear to be the same as on the other transmission. I may put a gauge on each plug, and run up the engine and see what each shows. I'll try and get a decent shot of the transmission in question tomorrow and get your opinion.



Acklands Grainger carries the required hobbs switches, and if you get any kind of a corporate discount, the price is quite favourable. Unfortunately for me, the local Acklands Grainger was closed up a couple years back and now the nearest one is Winnipeg.



This thread turned out to be quite timely for me....sorry for the hijack.

[rob love]

Luckily for me it turned out to be the transmission that was accessible, so today I installed a 90° elbow and a 60 psi NC switch. I am now in the process of installing the second switch on the other transmission....it's a lot tighter working on that one.

For switches I used a pair of 60 psi switches from the MLVWs...they were rated for air or liquid, and have the bonus of even being adjustable if need be. NSN is 5930-00-434-5441. I modified this one for one wire, the other will remain 2 wire.

[marco]

Rob,

The "old position of sending unit" actually is the hole were the indicator rod is visible when adjusting the front band.
No oil pressure there...

Marco

[rob love]

Thanks for the confirmation Marco. I got sucked away to other projects the last day or two....hopefully tomorrow I can finish up this part and run up the vehicle to confirm the warning light operation. Then I can get back to buttoning up the panels below the turret and some items on the turret basket.

At that point, the vehicle should be able to move under it's own power to the other building, which will be all I am after at this point. I have 5 or 6 other vehicles/guns to prep for VE day. My preference is to drive them in as opposed to pushing them in....we'll see how it goes.

[Malcolm Towrie]

Your setup is the same as the Staghound, see photo. Nearest the engine is the cover for the front band adjusting indicator pin, as Marco says. The cover's missing in the photo. Then the front band adjuster, the pressure switch, the rear band adjuster, and the rear band adjusting pin.

GM had designed the Hydramatic just a few years before and, boy, did they modify it on the fly. First no band adjusting pins, which I think you said is like your other tranny. 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.

I don't know how far you are getting into the trannies on the M5, but the adjustment of the linkage between the carb and the tranny is critical. The tranny needs to know engine load so it can delay shifts, increase pump pressure, clamp bands and clutches tighter under load, etc.

Malcolm

20200213_184003.jpg

[rob love]

Thanks for the explanations Malcolm. Am I OK with merely having moved the plug from the pressure port over to the hole for the pin? The pin does not end up protruding up, does it? When I was looking onto the hole, it didn't look like it could. Edited to add: instead of being so lazy, I read the manual. The Stuart manual covers both type of transmissions. The pins would come up to the level of the boss if properly adjusted, so to that end the plug I moved over from the center port will not be suitable. I am going to probably use a short 1/8 pipe and a cap.



I'll plan those linkage adjustments for when it comes back from display in about 9 months. I would like to think something is right on this vehicle, but as I mentioned before, for every job done 3 more seem to show up. As to the transmission, it was out about 1 mile ago (which is also about 7 years ago) so it would be a nice thought that it was adjusted at that time, but he is no longer around to ask. I did see blue RTV on the side pan when I removed one bolt to use as a ground for the switch.



I managed to get the last switch installed and wired up at the end of the workday. I went to try it out at the control panel, but the bulbs are all removed, so that will be done tomorrow morning.

[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.