Speedo changer for Columbia 2 Speed

[uncle buck]

I am not familiar with these speedo changers. I got this with some 42-48 Columbia parts. I have heard big trucks also used them but they operate
backwards? I imagine that it probably needs to be disassembled and lubed
and am wondering if and how to change it from truck to car style if possible?
Also are new bellows / diaphragms available?
Thanks

[uncle buck]

Try again

[Kurt in NJ]

The truck ones used only 1 diaphram with spring return---same as truck 2 speed rear, the car columbia used 2 diaphrams, I think the whole innards have to be flipped over so it shifts between direct and turning the speedo faster

[uncle buck]

Does this picture help identify this one

[Kurt in NJ]

it's for truck -one vacuum diaphram, spring loaded return, most common on 42-47 big trucks--some had different ends or bushings in the end to adapt in later years, plus a little square drive connecter ----

[Bored&Stroked]

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I think the real issue will be the diaphragm . . . if it is shot (and it probably is), then you'll need to find some sort of replacement. This is the same issue with the dual-diaphragm Columbia units.

Hey - anybody know of a new/replacement that can be used in the dual-diaphragm Columbia setup? Inquiring minds need to know! LOL

[Kurt in NJ]

The car changer has 2 diaphragms, the other are from big trucks, some are designed to fit only on the back of speedometer, others can go in between sections of cables

I have reground pliers jaws to open the crimps and replace diaphragm, sometimes re riveting the operating shaft, sometimes drilling and tapping for nut or small screw

[RobR'35]

That's pretty cool. I've never heard of anyone tearing into the diaphragms and make repairs.
By chance do u have any photos?

[uncle buck]

Originally Posted by Kurt in NJ

The car changer has 2 diaphragms, the other are from big trucks, some are designed to fit only on the back of speedometer, others can go in between sections of cables

I have reground pliers jaws to open the crimps and replace diaphragm, sometimes re riveting the operating shaft, sometimes drilling and tapping for nut or small screw

That's good info. I have heard in the past that you can use the big truck unit by flipping the gears? Is that true?

[deuce_roadster]

Yes, Gary Duff switched the truck ones for my 2 Columbia units for my 40s. Mine don't have any diaphragm. I believe he takes the gears off their shafts and switches them. You might talk to him.
There is a picture of the Columbia controls in my 40 coupe album.

[uncle buck]

Originally Posted by deuce_roadster

Yes, Gary Duff switched the truck ones for my 2 Columbia units for my 40s. Mine don't have any diaphragm. I believe he takes the gears off their shafts and switches them. You might talk to him.
There is a picture of the Columbia controls in my 40 coupe album.

Thanks Mike, My neighbor has a survivor 40 deluxe coupe with everything stock and his doesn't work so we are trying to figure these out.

[RobR'35]

Found this in some of my records.
Maybe it'll help.

Sent from my SM-G955U using Tapatalk

[motordr]

Hey - anybody know of a new/replacement that can be used in the dual-diaphragm Columbia setup? Inquiring minds need to know! LOL

Sure, get some NOS choke diaphragms and modify them to fit, that is what I did and works like a charm.

[Bored&Stroked]

Originally Posted by motordr

Hey - anybody know of a new/replacement that can be used in the dual-diaphragm Columbia setup? Inquiring minds need to know! LOL

Sure, get some NOS choke diaphragms and modify them to fit, that is what I did and works like a charm.

Would you happen to know what year car and/or type of carb? That is a great idea - never thought of it - thanks! Any help you can give to point me in the right direction, just getting ready to rebuild a Columbia for my 32.

[motordr]

Any early seventies GM Rochester 2-barrel diaphragm would work, will see if I can find the part number for you. Requires some cutting, bending and mig welding to keep heat from damaging the diaphragm.

[motordr]

The choke pull-off I used is an aftermarket product CP452 by Avatar AIP Company. Listed applications: chev 1975-73 R1 250 engine, so the six cylinders. I would think that others would be adaptable too, just try to get two the same.

[G.M.]

Originally Posted by Kurt in NJ

it's for truck -one vacuum diaphram, spring loaded return, most common on 42-47 big trucks--some had different ends or bushings in the end to adapt in later years, plus a little square drive connecter ----

You are on the right path. I used 3 or 4 of these but it was 40 years ago.
I remember machining an adaptor and I think it was mounted backwards.
Can't remember any more. G.M.

[Bored&Stroked]

Originally Posted by motordr

The choke pull-off I used is an aftermarket product CP452 by Avatar AIP Company. Listed applications: chev 1975-73 R1 250 engine, so the six cylinders. I would think that others would be adaptable too, just try to get two the same.

Thanks a bunch - that is exactly what I'll pickup - or something similar. Again, great idea to solve the problem.

[Ggmac]

Originally Posted by Bored&Stroked

I think the real issue will be the diaphragm . . . if it is shot (and it probably is), then you'll need to find some sort of replacement. This is the same issue with the dual-diaphragm Columbia units.

Hey - anybody know of a new/replacement that can be used in the dual-diaphragm Columbia setup? Inquiring minds need to know! LOL

I was just cleaning out my 40' container of old car parts and found a possible diaphragm. I've never had a Columbia or know anything about the diaphragm part but after looking at the picture , this may work . Do you have the dia and aprx travel . The parts I've put aside are from 1970-80s air cleaners on carbureted engines . It's the vacuum control on the air cleaner that controls the flapper in the inlet .
Hope it helps .