PDA

View Full Version : Overdrive partly engaging



mike gaines
09-17-2006, 04:53 AM
Being a first time Stud owner , every problem seems insurmountable untill a find an explanation on this site. I have now sorted my suspension problems , left rear sping hanger bolts were loose , oil leak through the crank shaft pulley also sorted when I found that the wrong woodruff key had been used and allowed oil through the keyway.Mycurrent challenges are ;
1. My 58 silverhawk came with a modified overdrive and seems to operate as follows, it engages od from start up and there is a switch on the gearlever that is supposed to disengage the od. Needless to say it doesnt work. Before installing an original system i would like to understand the problem. What happens is the following,at start up the od partly engages in so far that the car will freewheel in gear but the gear ratio is the same as when the od is not engaged! When i press the switch on the gear lever the engine momentarily switches off and comes back on when i release the switch, this action is supposed to disengage the od , which of course it fails to do.If i hold the switch down , the engine cuts out and has to be restarted at the key ??????? What is happening ?

2. Can someone explain in idiot terms how i wire up a rev counter, tachometer .

Thanks for all the great assistance

64V-K7
09-17-2006, 07:59 AM
Here's the tachometer setup
http://ncsdc.com/TechnicalPages/Tachometer.htm

Here's the (correct) OD setup..

http://ncsdc.com/TechnicalPages/Overdrive/Overdrive.htm

whacker
09-17-2006, 11:04 AM
The switch on the shift lever replaces the "Kickdown" switch on the throttle linkage. It is used to temporarily kill the engine so the overdrive can shift. The overdrive doesn't have a clutch, and is electrically pushed in, and spring loaded out. When in overdrive, the gear is kept engaged by engine torque. In order to downshift ("passing gear") when the throttle is floored, it engages a switch that causes the engine to stutter, and releaves the pressure on the overdrive gear so overdrive disengages and you run in direct drive to the rear end. The switch on your gear shift lever has been added by a previous owner to give you more control over this function.

Roscomacaw
09-17-2006, 02:04 PM
Holding that switch down kills the engine long enough for it to come to a stop (as opposed to just momentarily blipping it and the engine still turning long enough to recontinue once the switch is released - same as reaching down and flipping the key off and then back on in an instant!) Thing is, with the O/D section in the freewheel mode, the car's rolling energy can't be transmitted from the wheels thru the drivetrain while coasting, to restart the engine again once the engine's been killed by you holding the switch down too long.
As I keep saying to others who are bound a determined that they know better than the designers of this system, the automatic O/D was very cleverly designed to provide optimum performance. Once one tries to defeat this arrangement, he might get a "benefit" one way or another, but overall he loses.
Is there an O/D knob under the dash? Is there a kickdown switch on the accelerator linkage at the aft of the engine? 1958 should have no O/D relay on the firewall and sport a 3-terminal solenoid on the left side of the tranny. That and a governor (centrifugal) switch on the right rear of the tranny.
When you state that it partly engages O/D from the startup, you're really saying that the tranny's mechanical O/D control lever (the one an O/D knob would control) is all the way rearward - or "in" the O/D mode.
Assuming there's no knob and cable to actuate this lever, if you went under the car and flipped it forward, the tranny should act like a straight 3-speed transmission. Try that and see what happens.;)

Miscreant adrift in
the BerStuda Triangle!!

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

mike gaines
09-18-2006, 12:57 AM
Thanks for the quick response , I now have a clearer understanding of the switches function but what I cant understand is why the OD does not engage in the lower OD gear ratio , yet the freewheel function operates. It would appear that the installer of this system intended that the OD should operate as normal ie engage at the normal speed by releasing the accelerator and the switch was to allow the disengagement of the OD instead of the normal kickdown switch.The car is fitted with a cable operated accelerator and there is no kickdown switch and there are two relay swiches mounted on the firewall.

Roscomacaw
09-18-2006, 11:14 AM
It's hard to say WHAT the previous owner was trying to achieve with his rigged setup. I think it's safe to say that if it hasn't worked since you've had it, it probably never worked for the previous owner too![xx(]
Two relays, manual switch - just about impossible to guess what was intended without being able to actually LOOK at the system and the way it's wired (and even if we COULD look at it "hands on", there's no guarantee we could come to an understanding!).
Just because it freewheels doesn't mean it should drop into overdrive. Freewheeling is only half the equation and is a thoroughly mechanical function. It takes a working solenoid and able circuitry (the other half of the equation) to cause that solenoid to function as required before it's gonna actually GO into overdrive.[8D]

Miscreant adrift in
the BerStuda Triangle!!

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

whacker
09-18-2006, 01:36 PM
I think your best bet is to purchase a new overdrive harness and rewire your overdrive the way it was designed. The only fly in the ointment seems to be the cable throttle linkage. I'm sure you can figure that out somehow, or find a good used linkage from someone and replace that cable system. The overdrive harness is not expensive and is available through several vendors. If you can't find the original throttle linkage, you can rig a switch to perform that function at full throttle just like the original.

skyway
09-18-2006, 01:42 PM
Am I missing something here? Are you letting off on the gas?

Sounds like the car starts and the overdrive is not locked out, in otherwords, it freewheels. Depending on whether you press and release, or hold, the button, you interrupt or kill the engine.

If that's the case, what you have to do next, while driving down the road, is press the button and let off on the gas. The revs should fall, until you feel a little "Clunk" and now you are in overdrive. Release the button, and continue but with a 1/3 reduction in engine speed, and no freewheeling. You may have to play around to determine how long to hold in the button.

If that gets you into overdrive, getting out (kickdown)would be the opposite. Let off on the gas,press and release the button, and step back into the gas. You are now back in direct drive with freewheeling.

Similarily, when in OD and approaching a stop, let off on the gas and press and release the button. You should feel the ransmission "fall" out of overdrive.

Finally, to disable the freewheeling, pull out the OD handle, or crawl under the car and move the lockout level all the way forward.
Now you have a traditional 3 speed with engine breaking (and a non-synchro. first gear.

My GT Hawk has a similar system, but with an old Hawk toggle switch on the front of the console. No holding the button, rather its either electrified or not depending on which way the toggle is thrown. Alas, I can't remember the exact wiring, just that it works.

skyway
09-18-2006, 01:54 PM
I forgot, I was assuming that there was power to the OD solonoid. Also, if the governor is still there, you have to also be going faster than about 25/30 mph before trying to get into OD.

If the solonoid is wired up but not working, don't forget that there is a set of points inside the cannister that sometimes get oil fouled/dirty, and need to be cleaned up. If they are oil fouled, look into new seals to keep trans oil out of the Solonoid cannister.

mike gaines
09-18-2006, 02:15 PM
Again thanks for the thoughts on the OD switch , I will try Skyways suggestion once I complete the oil change tomorrow. I have found that both the gearbox and Od box where only half full of oil, could this cause the OD not to engage. How do I check that the OD solenoid is in working condition, I certainly am no auto electrician.

Roscomacaw
09-18-2006, 02:33 PM
Mike,
ASSuming the wiring's still pretty much as it should be, if you get under the car and short out terminal# 4 to ground, the solenoid should make a sound to indicate it's working. If it doesn't, check for power on terminal# 8 (these terminals are numbered on the case of the solenoid and might be obscured by and grunge on the case.
#8 should have power to it at all times. It's fed thru a 14amp fuse and thru one side of the kickdown switch (which MAY have been eliminated or modified, given what you've described to us about how your car is configured)
That #4 terminal is the one where a ground is provided from the governor, so your shorting #4 to ground is, in essence, mimicing what would happen once the governor was spinning fast enough to engage it's internal contacts.;)

Miscreant adrift in
the BerStuda Triangle!!

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

mike gaines
09-21-2006, 01:01 AM
Well , I have now removed the solenoid and the governor cover and found the following
1. The solenoid did not click when I shorted the live feed with the govenor lead.
2. When opening the solenoid cover I found that the points had stuck closed because the bolt holding the open arm of the points had come loose and allowed it to move thus closing the points , which had arced and were largely destroyed , I will replace the solenoid.
3.On opening the govenor top cover , I found the points to be almost cosed together , I am not sure if there should be a bigger gap?
4. Is there a recommended gap specification for the solenoid and govenor points , they dont appear to have been designed for adjustment ?
5. Howdo you test a govenor to see if it is working correctly ?

Roscomacaw
09-21-2006, 01:15 PM
Testing the governor: I've never really tried to since I've never been confronted with one that was troublesome. That said, if you could hook an ohmmeter - one lead to the case and the other to the connection - and spin the shaft, say, with a variable speed drill - it should reach a speed where the centrifugal weights fly outwards and cause the contacts to close and afford an indication of continuity on the meter!:D

Miscreant adrift in
the BerStuda Triangle!!

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

DilloCrafter
09-22-2006, 01:33 AM
How to test a governor? If a governor has been sitting a while, such as ours has here in Texas, an election is a good way to test him. ;)

http://rocketdillo.com/studebaker/misc/images/Current_Avacar.gif[/img=left] - DilloCrafter

1955 1/2 Ton Pickup
[i]The Red-Headed Amazon
Deep in the heart of Texas

mike gaines
09-24-2006, 02:43 AM
Thanks everybody , OD working like a charm , what a pleasure to drive ! Taking the Baker to the old car club for first time today.

Roscomacaw
09-24-2006, 02:54 PM
Well Mike, DO tell what it took to get it working again!:D

Miscreant adrift in
the BerStuda Triangle!!

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe