3 speed overdrive questions
 

I recently bought an original, non restored 69 custom/10 pickup in good-average condition with a 307, and 3 speed manual with overdrive. Other than what few articles I have read here I know very little to nothing about this transmission. Here is what I know:
It has a 4 bolt side cover, not the perferred 7 bolt side cover
The housing number is 3744920 with r10k-1 on the tail shaft
It has a huge solenoid near the tail shaft, and a 4 prong plunger style solenoid on the intake and a cable mounted under the dash labeled overdrive

Here's the question, I'm leaning towards restoring this truck back to near factory specs, and i was wondering if the transmission option is worth restoring and how available are the parts? Does anybody know details on these transmissions? Seems that they originated in the fifties and best i can tell 69 was the last year for the option. Is the value difference of this original option worth the time/cost of restoring it worth it? Does anyone have one in a 69? Any help is appreciated, if i decide to discontinue this option in the truck, is anyone interested in the transmission, solenoids and cable?

Re: 3 speed overdrive questions
 

Congratulations and Welcome from California TJ! I'd Love to see pics of that set-up.

Re: 3 speed overdrive questions
 

Thanks, i will work on pics soon
Posted via Mobile Device

Re: 3 speed overdrive questions
 

:welcoem: this place is great to find info about these trucks and we love pics.
As far as I know those over were like .7X or something and not really strong. They are good for highway driving but not for racing. I might be wrong so take it with a grain of salt

Re: 3 speed overdrive questions
 

This is simply a restore, not a racer so this transmission should be fine for that right?
Posted via Mobile Device

Re: 3 speed overdrive questions
 

I know someone knows about these transmissions...
Posted via Mobile Device

Re: 3 speed overdrive questions
 

TTT

I dont know alot about these trans but I think it would be worth it to restore it. Have you tried the search at the top of the page. Click on the
67-72chevytrucks.com button and type in manual over drive

http://67-72chevytrucks.com/vboard/s...d.php?t=267415

Re: 3 speed overdrive questions
 

They are nice when they are working. But that 4.10 rear end is a pain when it isn't. Here is a little info on its operation from the '68 Owner's Handbook and a drawing. the firewall solenoid is an ignition cutout to allow unloaded shifting. IIRC it also freewheels so you don't have compression braking unless you pull the defeat cable.

Re: 3 speed overdrive questions
 

Great info Tim, thanks alot. Now the question is should i restore it to fully functional again or replace it with a standard 3 speed and change my rear gears?
Posted via Mobile Device

Re: 3 speed overdrive questions
 

Also what tranny is this exactly, muncie, saginaw or borg warner? They're easier to find parts when you know what you got lol
Posted via Mobile Device

Re: 3 speed overdrive questions
 

there are a few on here that have info on the trans (sombody else will chime in) a friend had one in a 67 behind a 292 it allways worked good but i think parts are a little hard to come by but they are kind of a neat unit i would keep it

Re: 3 speed overdrive questions
 

Thanks 67, i agree its pretty cool. This is my third 69, all of which were 3 speeds but none have had this option. This truck also has the "hockey puck" style round cab lights which i have never seen, also a very difficult part to locate.
Posted via Mobile Device

Re: 3 speed overdrive questions
 

To make that decision you should really first baseline what you have. Is it currently working?
No.... Then the '69 service and overhaul manuals would be my first stop to determine how much of the actuation and controls are still there. Like the solenoids and the related wiring. It might be something simple or yours may have been modified with an aftermarket shift conversion kit. It allowed the trans. to be shifted in and out of overdrive at will vs the semi-auto function GM intended. Sounds good but I understand the O/D section was not up to the lower gear's torque if it was just left in "High".
If it looks fairly complete you could start tracking down the missing parts or if it were me, the trans. would come out for an internal inspection before investing too much. The problematic solenoids are/were being rebuilt just need to run down the service.
The choice is yours so start by being informed. These seem to be more common in older vehicles so a web search should prove benifical as well as the manuals.

If you want to keep the truck stock then look into it and try. But your truck will be very useable with a gear change and a three speed which are often nearly free.

It is a Saginaw trans,.
http://macswebs.com/cddemo/66cd/etr/...on/manual.html

Re: 3 speed overdrive questions
 

So it's column shift?
Posted via Mobile Device

Re: 3 speed overdrive questions
 

Yes, looks just like the standard 3OTT except for a pull handle under the dash. It upshifts automatically when you let up the gas while in 3rd.

Re: 3 speed overdrive questions
 

On the other hand an S10 T5 swap would be very nice as well. Ask jocko.

Re: 3 speed overdrive questions
 

I don't know if it's operational or not, i bought the truck not running, the points distributor cap was off.I've got a new HEI distributor coming today and after installing it i should be able to determine what issues i have. The plunger style solenoid was attached to a bracket but just laying on the intake, but i traced the pigtail wires on it to the solenoid on the tailshaft, the cable is still attached to the linkage on the tailshaft and mounted under the dash and isn't froze up. It may be as easy as remounting the bracket on the intake, as I'm assuming the plunger is actuated my throttle linkage some how.
Posted via Mobile Device

Re: 3 speed overdrive questions
 

I would really like to keep the column shift regardless of which way i go, overdrive or not
Posted via Mobile Device

Re: 3 speed overdrive questions
 

That plunger switch is for the full throttle kickdown. The HEI probably won't work without some planning here. The system depends on bliping the igniton to shift gears. You are going to need a '69 manual to work this. There is a lot involved in this. So get some reference material either paper or CD before you start throwing money at it buying parts.

Re: 3 speed overdrive questions
 

Are you familiar with ways around this, cause i am definitely going hei for the reliability of that system vrs points.
Posted via Mobile Device

Re: 3 speed overdrive questions
 

Here this will give you an idea of the interaction. If the dizzy was pulled apart something in this circut may be the reason the truck was parked. Now consider this a generic schematic. It is not GM truck specific.

Lots of good stuff here as well.
http://www.classictruckshop.com/club...5n/rebuild.htm

Re: 3 speed overdrive questions
 

Electrical isn't my specialty by no means, but maybe i can figure it out once its running
Posted via Mobile Device

Re: 3 speed overdrive questions
 

It is an interdependent system. The surest way to success is to start with a stock setup, get it running then plan your mods. Just saying "I'm going to do this" is not likely to work without some planning. Now there may be a way to trigger an electronic ignition without frying it due to voltage spikes. Need to think about it and I'm sure there are EEs on the board that may offer a solution as well. You are just going to have to ask in a new thread. But before you do that get the correct schematic for your truck and research ignition possibilities so you can ask and provide in your post.

Re: 3 speed overdrive questions
 

I think you're exactly right tim, thanks on the input... to get running first i am going to go with hei, i may have to go back to points later to incorporate the od but for now running is my primary objective to ensure i have no other mechanical issues
Posted via Mobile Device

Re: 3 speed overdrive questions
 

I would try to keep it.If you can get it to work it will definitely improve hiway milage.There are at least a few members with them and they will probably help if they can.