Overdrive inspection advice

[Jeff T.]

My three year old pooped out early last night so I finally got a chance to run my V8 T86 overdive through the spin test, turn input shaft.. shift transmission, see if output shaft turns... it does The transmission is sitting on my workbench in the basement and I still have to pop the top cover off to look inside. With any luck all I need is to flush out the old lube and fill it up.

Before I open it up to inspect and clean the T86, what should I inspect short of dismantling the transmission (if it ain't broke rule). I have has good luck over the years finding good transmissions from donor cars and I hope my luck holds but this is my first overdrive.

thanks for any advice

Jeff T.

"I'm getting nowhere as fast as I can"
The Replacements.

[StudeRich]

Jeff, you need to be looking at the very small little pointy synchromesh engaging teeth on the Second sliding gear, and input shaft along with the brass blocking rings and synchromesh unit. These can be more important than the actual main teeth on the Gears, they need to be very pointed, not blunt.

The other wear point often overlooked is the INSIDE of the aft end of the Input shaft and the mating outside of the Main shaft where the rollers ride, unfortunately this requires dis-assembly.

As far as the O.D. goes, there is not much you can check without dis-assembly, you can shift the lever to the rear and should find that the output shaft freewheels in all but Rev. and drives with the lever forward. And look at the oil that comes out of both cases for metal material.


StudeRich at Studebakers Northwest -Ferndale,WA

[gordr]

You can bench-test the overdrive function, too.

First, check the free-wheeling and lockout as Rich told you above.

The following instructions assume a 2-terminal solenoid, and a single-terminal governor. For other types, you had best consult a wiring diagram to determine how to do these tests.

1. get a battery of the right voltage for the solenoid in question
2. run a clip lead from the ground side of the battery to the transmission case (might as well observe "as installed" polarity here, though it really doesn't matter for the purposes of this test.
3. connect a clip lead to the other battery terminal, and touch the other end to each terminal on the solenoid. One terminal should do exactly nothing; the other should show a small spark and cause the solenoid to click or go "thunk". The sound is pretty loud in a quiet room.

If you get a fat spark, but no sound, chances are the coil is shorted or burned out. If the solenoid cycles normally from one terminal, but the other gives you a fat spark, then the internal grounding switch may be shorted.
4. Now connect a test lamp (any 6 or 12 volt lamp, as needed) between the two solenoid terminals. Then apply power to the terminal which you have determined is the one that causes the solenoid to activate. You should hear the click or thunk, and see the lamp come on as the sound happens (not before). That tells you the grounding switch is working, which is needed for the full-throttle kick-down function to work.
5. Now put small flags of masking tape on both input and output shafts as pointers for counting turns, and ensure that the lockout lever is all the way back against its stop. Energize the solenoid, and begin turning the input shaft by hand. You may hear or feel some action in the transmission early-on in the first turn as the internal parts shift into OD ratio. From that point on, it should turn smoothly, and you should see the pointer on the output shaft moving faster than the one on the input shaft. For every 7/10 of a turn on the input shaft, the output shaft should make one full turn. You should also, at this point, have no free-wheeling. Turning the output shaft either way should cause the input shaft to turn the same, only a little less far. So far so good? We now know it can go into overdrive.
6. Now disconnect power from the solenoid, and continue turning the input shaft. You should hear some sound, and then observe the output shaft turning in lock-step with the input shaft, provided you are turning it forward, which is clockwise as viewed from the front of the tranny. If all you own is a digital watch, I'm sorry, you are out of luck. You should be able to see that it free-wheels again.
7. Now, we'll bench-test the governor. First, remove it from the transmission. A pipe wrench works well, if used with care. They normally aren't in there super-tight. Chuck the tip of the governor shaft in a variable speed electric drill, or use a piece of rubber hose as a coupler. Connect one lead from your battery to the governor case, and connect a test lamp between the governor terminal and the other post of the battery. Holding the solenoid in one hand, and the drill in the other, slowly spin up the drill. At some point, the governor should click or bump (perhaps more easily felt than heard), and the lamp should come on, and it should stay on as the drill revs faster. Now slow the drill down, and the lamp should go out, but at a slower speed than which it came on at. You may want to cycle the governor through this on-off cycle several times, to be certain that the turn-on speed is in fact higher than the turn-off speed. This "dead band" is important, because if it were not present, the entire overdrive unit could cycle repeatedly if you drove at exactly the cut-in speed, which traffic might force you to do on occasion.

If you can feel the governor's action, but the lamp does not come on, first check your connections, since these ad-hoc hookups can fall apart sometimes if you aren't paying attention, ask me how I know. If you are now sure that the governor is