More questions on my ’57 Chevy truck

Question:

I’d first like to thank you for printing my letter in the June 2008 issue, and for all of the people who responded with further advice and leads for a three-speed overdrive transmission for my 1957 Chevy 210.

I was able to purchase a really good 1968 Saginaw transmission (which is a stronger transmission and is fully synchronized, unlike the Borg-Warner unit used in the 1957 models), with almost everything needed for installation from one of your readers, a very nice gentleman from Virginia.

Now, I have a few remaining questions before I begin the installation.

One part I still need is the bracket for the kick down solenoid for the 235 engine. This bracket is being reproduced for the 283 V-8, but not for the 235-six.

Can anyone offer any leads for one or, alternatively, provide a picture or a good drawing, and maybe even some measurements so I can fabricate my own? The drawing in the Chevy assembly manual is pretty rough.

Another part I’ll need is the driveshaft yoke. I’ve been told that the 27-spline yokes, which is what the ’68 transmission has, are all identical; is this true? If not, can you provide me with the correct part number for the yoke I’ll need? The ’57 transmission has 16 splines.

My car has the standard 3.55 differential gears, and OD-equipped cars came with a 4.11 ratio. From what I’ve read, the 3.55 ratio will work fine with this engine, so I’m not planning on changing the gears. However, the speedometer will now be inaccurate.

Are the correct speedometer drive gears available for this transmission with a 3.55 rear axle ratio?

I understand that the ignition (specifically, the points) are grounded when the OD kick down is activated. I’ve installed a Pertronix ignition in this car. Will there be a problem with the Pertronix system when the ignition is grounded during OD kick down?

Once again, I want to thank all of the readers who responded with great advice, some of which was quite lengthy and included pictures, charts, part numbers and suppliers.

Auto Restorer and its readers are a tremendous resource.

Answer:

Mr. Nomad (mrnomad.com) lists an overdrive kick down switch bracket for “all models with a 2-barrel carburetor” under part number 10785.

All 27-spline transmission yokes are not identical.

The part number for the “correct” yoke for you depends on where you buy it as every retailer seems to assign their own number to the yoke. Denny’s Driveshafts (dennysdriveshaft.com) sells it under part number SY3R-27-CST and The Gear Box (thegearbox.com) sells it under part number 350/1330.

Speedometer gears are readily available from most of the major restoration parts suppliers, including Danchuk (danchuk.com).

There will be a problem with your Pertronix ignition if the overdrive kick down grounds it. This will ruin the ignition module.

Disconnect the grounding feature of the kick down circuitry to prevent this from happening.

(Editor’s note: In his earlier letter, “An overdrive for a ’57 Chevy,” Jim sought advice on finding a ’60s transmission with a synchronized first gear for his Chevy truck.)