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Overdrive Now Fully Functional!
#1307329 Tue Apr 16 2019 06:33 PM
Joined: Mar 2019
Posts: 131
S
Shop Shark
My 3-speed with overdrive now operates as God intended! There are already several threads regarding how to wire overdrive. However, I thought I would share what I've just learned, to hopefully aid others who want the automatic overdrive functionality. I may break this into several smaller posts, for readability and clarity.

I bought my '61 Apache last year...my wife and daughters call it " 'Mater Jr.".

It has a Jasper crate engine with an aftermarket Carter YF carb. It appears that when the engine swap occurred, the original bracket and kickdown switch would not fit the new carb, so the owner never bothered to reconnect the overdrive. The gentleman I bought the truck from had installed an overdrive relay, but no kickdown switch.

Since an original switch wouldn't fit anyway, I made a bracket and switch by using two SPDT micro-switches. I mounted this to the Carter YF, so that at full-throttle, the switches are engaged by the throttle linkage. I went with a carb-mounted switch rather than an under-the-pedal switch because: a) carb-mounted is most like the original, b) I didn't want to drill a hole through the floorboard, and c) I didn't want the switch where a floor-mat or other object could get caught and possibly interfere with operation.

I did my homework; there are numerous wiring diagrams on the web, but some of them are unclear, misleading, or downright wrong. One pole of the switch is normally-closed, which allows power to the overdrive relay. The other pole is normally-open, which is connected between the overdrive solenoid and the negative side of the ignition coil. At full throttle, the switch engages...one pole removes power from the overdrive relay, and the other pole grounds the ignition coil through the overdrive soleoid, which momentarily impedes the spark and creates a 'torque pause', allowing the overdrive to mechanically disengage. When the overdrive solenoid is disengaged, the path to ground is broken internally, and ignition coil function is restored. This whole process is very quick, and feels just like kicking into 'passing gear' on an automatic transmission.

On the test drive, when I tried to engage the kickdown function, the ignition would lose spark as long as I had the pedal pressed...the solenoid would never break the ground circuit. The full-throttle loss of spark would occur even when overdrive was not engaged, which shouldn't happen at all. I immediately suspected that the solenoid was internally grounded.

Attached Files
Bringing Mater Home.png (891.64 KB, 135 downloads)

This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"
Re: Overdrive Now Fully Functional!
Shakey61 #1307331 Tue Apr 16 2019 06:40 PM
Joined: Mar 2019
Posts: 131
S
Shop Shark
I uninstalled the solenoid, and removed the cover. I found this oily fibrous mass inside the cover, as well as other fibers inside the backing plate. I'd read that there was supposed to be a leather insulator inside the solenoid, so I suspected that's what I was looking at. I removed the backing plate, and found more fibers. There were two rivets where the insulator had been attached to the plate.

Attached Files
Solenoid.jpg (101.81 KB, 128 downloads)
Backing Plate Insulator.jpg (78.59 KB, 127 downloads)

This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"
Re: Overdrive Now Fully Functional!
Shakey61 #1307332 Tue Apr 16 2019 06:57 PM
Joined: Mar 2019
Posts: 131
S
Shop Shark
On the attached solenoid diagram, the location of that insulator is the red line. The relevant ignition ground contacts are circled in red.

I removed the rivets, and cleaned away all the old insulator material. I took some measurements of the hole pattern, and estimated the insulator thickness at less than 1/8". I then 3D-modeled a new insulator, and 3D-printed a new one in a flexible rubber-like material that is petroleum- and chemical-resistant. I installed the new insulator with some small rivets, and reassembled and reinstalled the solenoid.

Success!

The replacement plunger insulator works perfectly. The overdrive system kicks in and out as intended. Last night, I gave the wife and one daughter their first lesson with the overdrive. I guess a family that shifts together sticks together.

-Kevin

Attached Files
Solenoid Diagram.png (264.51 KB, 127 downloads)
Plunger Insulator Removed.jpg (84.42 KB, 126 downloads)
New Plunger Insulator.jpg (48.79 KB, 126 downloads)
New Plunger Insulator Installed.jpg (71.54 KB, 125 downloads)

This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"
Re: Overdrive Now Fully Functional!
Shakey61 #1307337 Tue Apr 16 2019 07:54 PM
Joined: Sep 2011
Posts: 669
B
Shop Shark
Nice!


BC
1960 Chevy C10 driver
1949 GMC 250 project in waiting
1960 C60 pasture art
G.M dealer tech since 1980 & counting
Re: Overdrive Now Fully Functional!
Shakey61 #1307344 Tue Apr 16 2019 08:46 PM
Joined: Jul 2018
Posts: 66
S
Wrench Fetcher
Nice to hear such a clear and concise overdrive function description and explanation.
Nice you were able to trace down the trouble accurately and remedy it.
I’d guess there are overdrives scrapped unnecessarily over similar situations!
I once put an extra manual interruptor switch to the solenoid on an old Plymouth, so that I could “downshift” with a slight lifting of the foot feed. Seemed so much calmer than the “flooring it”move! I love overdrives!


I have a large carbon footprint. That’s why my wife makes me take off my boots in the house.
1963 Chevy half ton stepside short box 230
1954 GMC 3 ton 302
And several more Chevy camper and work trucks 1979 1987 1996
Re: Overdrive Now Fully Functional!
Shakey61 #1307539 Thu Apr 18 2019 06:54 AM
Joined: Jun 2000
Posts: 2,773
F
Shop Shark
You done good! The only overdrive I ever operated was in an early 50s Ford car which was mechanical, operated like a 2 speed differential, but the control was mounted under the dash.


Fred
52 3600
69 C-10
Re: Overdrive Now Fully Functional!
Shakey61 #1307821 Sat Apr 20 2019 03:22 AM
Joined: Mar 2019
Posts: 131
S
Shop Shark
I often find joy in making the original technology work as intended!


This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"
Re: Overdrive Now Fully Functional!
Shakey61 #1307860 Sat Apr 20 2019 01:31 PM
Joined: Aug 2012
Posts: 1,742
V
Shop Shark
Impressive, using modern 3D technology to reproduce long-gone and no longer produced material, cool. Thumbs up for sharing.


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