3 speed overdrive!!, now about getting it in.......

[jsmithbm]

Bump.........
Dumb question, how can i tell if my 70 has a saginaw or munice 3 speed

[gochoa]

Gianyveedub,

Thanks for the reply. I know what you mean, I use as many jacks as I can,,LOL. That is exactly what I want to do with mine. What type of relay did you use? Can I get a pictures of how you have it wired. I'm a "visual" kind of man...in other words, can't comprehend wiring for S***. You can send them private message.

[Gianyveedub]

Once I have it finished I'll send the pics. Today was family day and I was not able to touch my truck at all...

[NCD1966]

i'm glad you guys gave this old thread some new life. I too have a 7 bolt 3 speed w/OD. and was looking at for the gear ratio for the OD. So people said it had a .85 and some say .70

Looks like I have one with .70.

anyone know how much horsepower they can handle?

[Gianyveedub]

Here is my unfinished wiring of the overdrive


Here is a series of pictures that I took trying to explain how it will work. I have not been able to finish it like I would like today, but life happens.

My color code is as follows:
-Yellow from Ignition to on/off switch to light to relay (#85)
-Red is from batt (fuse 20 amp) to relay (#30)
-Black is Ground/Governor to (#86)
-Green is Solenoid to relay (#87)

This one is of the whole setup. I am wiring a light between the on/off push button switch and the relay as you can see in the second photo.



The second is a close up of the on/off and light.



The third one is showing the batt wire with a fuse.



The fourth is of the Governor/Ground Wire



The fifth is of the solenoid wire



These last two are of the relay socket and the relay itself. It is a bosh relay 30amps.






In regards to ratio, it is a .70:1 ratio. The trans is a Saginaw and I would expect that like anything that is well taken care of, it should handle quite a bit. Not 500 hp, but a small block should do fine. They used to put these things behind 283's.

[murdoc]

Gianyveedub:

Excellent job man!! Im glad to see someones finally posted a wiring setup for these overdrives. Keep us posted on how this wiring goes for you.

[NCD1966]

Originally Posted by Gianyveedub

In regards to ratio, it is a .70:1 ratio. The trans is a Saginaw and I would expect that like anything that is well taken care of, it should handle quite a bit. Not 500 hp, but a small block should do fine. They used to put these things behind 283's.

Thanks on confirming the ratio. The reason Im asking about the power is because I have a 355 sbc that will has around 375hp and 400 lb of tq. I will be just crusing the truck. I not planning on running the truck real hard or any doing wide open shifting.

[62 Barnfind]

Originally Posted by Gianyveedub

Here is my unfinished wiring of the overdrive


Here is a series of pictures that I took trying to explain how it will work. I have not been able to finish it like I would like today, but life happens.

My color code is as follows:
-Yellow from Ignition to on/off switch to light to relay (#85)
-Red is from batt (fuse 20 amp) to relay (#30)
-Black is Ground/Governor to (#86)
-Green is Solenoid to relay (#87)

This one is of the whole setup. I am wiring a light between the on/off push button switch and the relay as you can see in the second photo.



The second is a close up of the on/off and light.



The third one is showing the batt wire with a fuse.



The fourth is of the Governor/Ground Wire



The fifth is of the solenoid wire



These last two are of the relay socket and the relay itself. It is a bosh relay 30amps.






In regards to ratio, it is a .70:1 ratio. The trans is a Saginaw and I would expect that like anything that is well taken care of, it should handle quite a bit. Not 500 hp, but a small block should do fine. They used to put these things behind 283's.

I finally got my wiring done exactly like the above pictures minus the colors. When I activate the switch I get power to the governor (86). I am not getting power to the solenoid (87). Where am I suppose to get power to? I have all three gears when the lever is forward and when it;s pushed back I don't get anything. Need a little help please!

[frankslagoon]

This is how mine is wired
grounding the soliniod thru the governor will turn on the soliniod at approx. 25 mph and off when governor kicks back off at approx. 25 mph
the manual toogle switch is in the line coming from the governor so you can bring it out of o/d manually.
I took 12 volts from the ign side of the fuse blk. power on only when the key is on.
This works pretty good.

[62 Barnfind]

Originally Posted by frankslagoon

This is how mine is wired
grounding the soliniod thru the governor will turn on the soliniod at approx. 25 mph and off when governor kicks back off at approx. 25 mph
the manual toogle switch is in the line coming from the governor so you can bring it out of o/d manually.
I took 12 volts from the ign side of the fuse blk. power on only when the key is on.
This works pretty good.

Mine is close. I have the battery going to 30 and the ignition is going to 85. Something is wrong when I put the lever in the OD position. The wheels barely turn. It's like it's not fully engaged all the way. When I have the lever in the three speed mode works great. Power is going to 86 to the governor when the switch is activated and I guess it grounds out when to gets up to correct speed. Then it will send power to the solenoid?

[kieth]

I did not look at the above relay wiring job, he wired it the way he wanted to, the instruction below are for a relay that comes prewired. Kieth

You will find the relay which is shown above with the plastic cap already prewired. I use them all the time.

1. The Blue wire is the supply for the 12 volt power to the relay.( Hot all the time)

2. The yellow wire is the supply of 12 volt power when you activate the relay

3. The Red center wire is not normally used but it supplies 12 volt power when the relay is not activated

4. The black wire is the ground for the relay (used here cleverly to only activate the OD when it is in the correct range of speed. )

5. The white wire is the trigger wire (activates the relay and sends power to the yellow)--controled here by a switch with a light that shows it is engaged)

They are really simple but when you look at them for the first time it gets really confusing ........Kieth

Only question I have is when you slow down does it automaticly downshift out of OD ?

here is a link to the prewired relay and how it is set up.



http://kieth.smugmug.com/Trucks/66-G...916151_PDBdGJX

[joedoh]

could you use a pair of relays and tap into the brake wire as a latching input, so that when you tap the brake the overdrive disengages? if the brake wire isnt the desired input you could put a brake switch on the clutch pedal and do the same thing. I can help you design that circuit if needed.

Originally Posted by kieth

I did not look at the above relay wiring job, he wired it the way he wanted to, the instruction below are for a relay that comes prewired. Kieth

You will find the relay which is shown above with the plastic cap already prewired. I use them all the time.

1. The Blue wire is the supply for the 12 volt power to the relay.( Hot all the time)

2. The yellow wire is the supply of 12 volt power when you activate the relay

3. The Red center wire is not normally used but it supplies 12 volt power when the relay is not activated

4. The black wire is the ground for the relay (used here cleverly to only activate the OD when it is in the correct range of speed. )

5. The white wire is the trigger wire (activates the relay and sends power to the yellow)--controled here by a switch with a light that shows it is engaged)

They are really simple but when you look at them for the first time it gets really confusing ........Kieth

a relay is a low current to high current switch, it doesnt need a "ground" and no pin is required to have 12v "hot all the time"

looking at the bottom of a relay there are 3 vertical pins and two horizontal pins. the two outside vertical pins (85 and 86) are the low current switch, you can feed ground or voltage to either pin as a switched input, and use the opposite voltage of what is input on the other side. If you use 12v on 85 as your switch input, you will need a corresponding ground on 86. If you use ground on 85 as a switched input, you will need 12v on the other side. Your switched input is really any signal that you would like to energize the relay but is not strong enough or is the wrong polarity to energize the circuit.

The top horizontal and bottom vertical pins (87 and 30) are the high current switch. when 85 and 86 have the right voltage, 87 will be connected to 30. If you supply heavy gauge 12v to 87, when the low current switch is energized that sme high current voltage will be on 30 through connection internal to the relay.

87a, the middle horizontal pin, is to supply a normally open signal to 30. When the relay is not energized, 87a is tied to 30. when the relay is energized 87 is tied to 30.

[kieth]

Originally Posted by joedoh

could you use a pair of relays and tap into the brake wire as a latching input, so that when you tap the brake the overdrive disengages? if the brake wire isnt the desired input you could put a brake switch on the clutch pedal and do the same thing. I can help you design that circuit if needed.







a relay is a low current to high current switch, it doesnt need a "ground" and no pin is required to have 12v "hot all the time"

looking at the bottom of a relay there are 3 vertical pins and two horizontal pins. the two outside vertical pins (85 and 86) are the low current switch, you can feed ground or voltage to either pin as a switched input, and use the opposite voltage of what is input on the other side. If you use 12v on 85 as your switch input, you will need a corresponding ground on 86. If you use ground on 85 as a switched input, you will need 12v on the other side. Your switched input is really any signal that you would like to energize the relay but is not strong enough or is the wrong polarity to energize the circuit.

The top horizontal and bottom vertical pins (87 and 30) are the high current switch. when 85 and 86 have the right voltage, 87 will be connected to 30. If you supply heavy gauge 12v to 87, when the low current switch is energized that sme high current voltage will be on 30 through connection internal to the relay.

87a, the middle horizontal pin, is to supply a normally open signal to 30. When the relay is not energized, 87a is tied to 30. when the relay is energized 87 is tied to 30.

If you would use the pole #'s and cross reference them to the colored wires then it might make more sense since no one else can see the #s on the realay itself.......Kieth

Here I went back and looked here is how they are numbered on the relay:

Blue--30 fused and direct to the battery

black 85 ground for relay trigger (low amp) I believe he is using this in conjunction with the govenor, when the govenor completes the ground it allows the OD to be engaged if the switch is turned on. When the speed falls below 30 mph the ground is no longer complete so the relay is turned off and the OD disengages? (is this correct)

White 86 trigger wire for relay (low amp draw) switch activates this circuit

Yellow 87 30 amp 12 volt switched (by white triggger wire) turns the OD on but it only supplies power when the govenor is above 30mph (it does this by controling the relay ground black # 85?

Red 87Q what I referred to as unused since it is powered only when the relay is not switched.......it could provide power to a accessory that needs power when the relay is not engaged lets say a burglar alarm ??

Kieth

[gochoa]

Thanks to everyone, finally making sense and doesn't seem like a "major" deal. Just need to sit down and follow all the input.

[Gianyveedub]

I did use a prewired pigtail. If you look at the relay in the photos, you will notice that the colors near the relay are different than the one I crimped them to. I use the diagram as my reference so I didn't screw up the wiring.

What really matters when you use a prewired pigtail is that the wiring on the pigtail is in the correct gauge (or maybe slightly smaller gauge...bigger wire) than what you are wiring. My ignition to relay wire (#85) is a pretty small wire because all it is doing is creating the charge for the electromagnet in the relay. The ones that you really need to look at are the Batt (#30) and the one to the Solenoid (#87). These two are carrying the 20 amps and need the big wire to handle the current. Hope this helps

[SulphuriousSam]

Actually the more I read this thread the more confused I am. I think that's my clue to pay some one else to mess with any transmission issues I have...

[gochoa]

Where's the fun in that!!! what the worse that can happen, take it to a mechanic????

I thought I was getting the wiring things, until I kept reading...damn, back to head scratching..

[NCD1966]

great info in this thread, I been getting the itch to install my OD lately, since my truck is up and running.

[FAT TONY]

how can you tell if it is an overdrive tranny?

[slorio]

Fat Tony:
They are very distinctive with an electric solenoid sticking out the left side of the tranny and an overdrive governor sticking out the right side of the tranny. Here is the early model with four bolt side cover and non synchro first gear:
http://www.ebay.com/itm/GM-3-speed-S...027e08&vxp=mtr

Here's a spot with the original literature where you can read all about them:
http://www.speedprint.com/deves50/overdriveindex.php

Hope this helps.
Regards,
Steve
New Orleans

[FAT TONY]

did the muncie transmissions come out with o/d or just the Borg Warner...... went outside hoping to find a governor on the side but its regular .......... by the way whats the difference in the 4 bolt cover and the 7 bolt cover?

[Gianyveedub]

The four bolt cover has a non synchro first and the seven bolt had a synchro'd first. However if you have the o/d unit, when you shift into first, it will pop in just like a synchro'd first.

[FAT TONY]

i have the moncie 7 bolt...... what are the pros and cons of a synchro'd tranny?

[Gianyveedub]

There are none when it come to how it affects the overdrive.

[FAT TONY]

what if i dont have overdrive?