The Ford Barn

Ricosan · 07-25-2022, 09:41 AM

My speedometer is registering way off the actual speed. This morning I went for a ride and turned on the GPS speedometer I downloaded earlier this morning..
My speedometer registers a speed about 35% lower than actual.
It has a new cable I installed yesterday.

The cable is hooked straight to the back of the speedometer and then to the turtle on the torque tube. The speed indicating arrow is very smooth and steady.

Richard

TJ · 07-25-2022, 10:46 AM

If the cable change came about because the speedometer didn't work when you got the car, I suspect the gear in the turtle is wrong.

deuce lover · 07-25-2022, 12:03 PM

Its not the cable.Maybe the turtle or have the speedo serviced and calibrated.

Ricosan · 07-25-2022, 12:24 PM

This just occurred to me. In my initial description of my malady I didn’t mention that it has a Columbia OD. I removed the speed ratio thing that goes between the speedometer and the cable because it is binding up. I thought I would have a regular speedometer then. I’m new to columbias. Maybe some reason it’s showing such incorrect readings.

Richard

ford38v8 · 07-25-2022, 01:16 PM

Your Speedo should then be accurate until you engage the Columbia.

glennpm · 07-25-2022, 01:22 PM

Sponsored Links (Register now to hide all advertisements)

Quote:

Originally Posted by Ricosan

I removed the speed ratio thing that goes between the speedometer and the cable because it is binding up.

Richard

Richard, take the SW speedometer transmission apart and give it a proper cleaning and grease job.

Glenn

Ricosan · 07-25-2022, 01:54 PM

TJ, the speedometer worked when I took delivery back in January but the numbers were questionable even then. It worked for about 50 miles.
Deuce lover, it may turn out that this is the wrong turtle. No markings on the turtle that I can make out in the photo.
Ford38V8, that’s what I thought too. Is this a special ratio just for Columbia OD?
Glenn, yea, I think it’s time to take it apart. I’m a little concerned about the gasket.

Richard

glennpm · 07-25-2022, 02:15 PM

Richard,

I know that John Connely, https://www.columbiatwospeedparts.com/index.cfm carries them.

You may be able to save the gasket on now but it is just thin paper. You could make a paper one yourself or apply a thin coat on RTV blue gasket maker with a touch up brush for example.

Glenn

TJ · 07-25-2022, 04:42 PM

I saw your other post and that is one nice woody. It could be the car is already in the overdrive mode and that would cause the difference in the speedometer reading because you removed the unit that makes the change in the speedo and it is now hooked up direct.

Ricosan · 07-25-2022, 08:13 PM

Glenn, tomorrow I’ll take it apart and see what’s going on. I’m going to call John Connelly and see what he says.
TJ, thanks for the compliment. I’m thinking that the ratio for the turtle must be directly connected to the SW speedometer transmission. I’m going to call John Connelly tomorrow and see if he can shed some light on it.

Richard

glennpm · 07-26-2022, 06:10 AM

Hi Richard,

If your speedometer is being "lazy" when you have the Columbia engaged, then it is reading correctly just like TJ said above. The speedo would read 28.5% lower than actual. Remember that the axle and then the "turtle" will indicate a slower road speed since the Columbia rearend is gearing the axle to rotate faster than the axle input rotational speed. Make sense to you?

Glenn

Terry,OH · 07-26-2022, 06:21 AM

If the new speedo cable is running directly from the speedo to the turtle then the speedo will regester about 27% low when your Columbia is in high. You need the Columbia speedo gear ratio changer at the back of the speedo to correct the reading.

Ricosan · 07-26-2022, 09:34 AM

Hey Guys,
I’m beginning to understand. It looks like this turtle ratio is correct for the Columbia only. It requires the speedometer transmission to provide correct readings in non overdrive and overdrive?
I’m heading out to the garage now to take the speedometer transmission apart and clean ad lubricant.
Richard

glennpm · 07-26-2022, 09:39 AM

Yes Richard, speedometer will be correct when you are NOT in overdrive. SW transmission makes the difference when in OD.

Glenn

Ricosan · 07-26-2022, 11:38 AM

I’ve run into a problem. I can’t get the case to come apart. I’ve been pulling on it to take apart but it won’t move past this point. Is there something besides the 4 machine screws holding it together?

Richard

glennpm · 07-26-2022, 11:56 AM

Nothing else holds it in place. Try moving the flapper/actuator a bit. You may have to pry it carefully in several places in the gap with a thin piece of plastic for example.

glennpm · 07-26-2022, 12:26 PM

This is one of pictures I posted of mine in your other Columbia thread. Mine is the 37-41 transmission.

Ricosan · 07-26-2022, 08:05 PM

Success! I got it apart using a plastic knife. I was even able to save the gasket. I cleaned it and filled 1/2 with gear oil and put it back together. It didn’t work so I took it apart again and discovered I had a piece out of place. I put it back together and it will spin by hand.
I’ll be installing it as soon as I can.

glennpm · 07-27-2022, 05:37 AM

Great job Richard!

Plastic knifes and these mixing sticks for epoxy are great for jobs like this.

https://tinyurl.com/2p9fraea

Glenn

Terry,OH · 07-27-2022, 06:17 AM

The speedometer turtle is usually considered the device mounted on the torque tube. The speedometer cable attaches to it at the torque tube end and is considered a turtle due to it's unique shape. Fords name for this part is speedometer "Gear and Cap". Ford offered the turtles in different gearing. Their gearing has to match the vehicle rear differential gear ratio and the vehicle tire size for the vehicles speedometer to read correctly without the Columbia.

Many aftermarket Ford supply houses offer reprints of installation instructions and there is also a parts list for the Columbia. They can be very handy.
Your car appears very nice!

07-25-2022, 09:41 AM	#1
Ricosan Senior Member Join Date: May 2018 Location: Tallahassee Posts: 375	Lazy speedometer My speedometer is registering way off the actual speed. This morning I went for a ride and turned on the GPS speedometer I downloaded earlier this morning.. My speedometer registers a speed about 35% lower than actual. It has a new cable I installed yesterday. The cable is hooked straight to the back of the speedometer and then to the turtle on the torque tube. The speed indicating arrow is very smooth and steady. Richard

07-25-2022, 10:46 AM	#2
TJ Senior Member Join Date: May 2010 Location: Napa,California Posts: 6,037	Re: Lazy speedometer If the cable change came about because the speedometer didn't work when you got the car, I suspect the gear in the turtle is wrong.

07-25-2022, 12:03 PM	#3
deuce lover Senior Member Join Date: May 2010 Location: Southern France Posts: 5,308	Re: Lazy speedometer Its not the cable.Maybe the turtle or have the speedo serviced and calibrated.

07-25-2022, 12:24 PM	#4
Ricosan Senior Member Join Date: May 2018 Location: Tallahassee Posts: 375	Re: Lazy speedometer This just occurred to me. In my initial description of my malady I didn’t mention that it has a Columbia OD. I removed the speed ratio thing that goes between the speedometer and the cable because it is binding up. I thought I would have a regular speedometer then. I’m new to columbias. Maybe some reason it’s showing such incorrect readings. Richard

07-25-2022, 01:16 PM	#5
ford38v8 Senior Member Join Date: Jul 2011 Location: SF Bay Area Posts: 6,648	Re: Lazy speedometer Your Speedo should then be accurate until you engage the Columbia. __________________ Alan

07-25-2022, 01:54 PM	#7
Ricosan Senior Member Join Date: May 2018 Location: Tallahassee Posts: 375	Re: Lazy speedometer TJ, the speedometer worked when I took delivery back in January but the numbers were questionable even then. It worked for about 50 miles. Deuce lover, it may turn out that this is the wrong turtle. No markings on the turtle that I can make out in the photo. Ford38V8, that’s what I thought too. Is this a special ratio just for Columbia OD? Glenn, yea, I think it’s time to take it apart. I’m a little concerned about the gasket. Richard

07-25-2022, 02:15 PM	#8
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,982	Re: Lazy speedometer Richard, I know that John Connely, https://www.columbiatwospeedparts.com/index.cfm carries them. You may be able to save the gasket on now but it is just thin paper. You could make a paper one yourself or apply a thin coat on RTV blue gasket maker with a touch up brush for example. Glenn

07-25-2022, 04:42 PM	#9
TJ Senior Member Join Date: May 2010 Location: Napa,California Posts: 6,037	Re: Lazy speedometer I saw your other post and that is one nice woody. It could be the car is already in the overdrive mode and that would cause the difference in the speedometer reading because you removed the unit that makes the change in the speedo and it is now hooked up direct.

07-25-2022, 08:13 PM	#10
Ricosan Senior Member Join Date: May 2018 Location: Tallahassee Posts: 375	Re: Lazy speedometer Glenn, tomorrow I’ll take it apart and see what’s going on. I’m going to call John Connelly and see what he says. TJ, thanks for the compliment. I’m thinking that the ratio for the turtle must be directly connected to the SW speedometer transmission. I’m going to call John Connelly tomorrow and see if he can shed some light on it. Richard

07-26-2022, 06:21 AM	#12
Terry,OH Senior Member Join Date: May 2010 Posts: 4,752	Re: Lazy speedometer If the new speedo cable is running directly from the speedo to the turtle then the speedo will regester about 27% low when your Columbia is in high. You need the Columbia speedo gear ratio changer at the back of the speedo to correct the reading.

07-26-2022, 09:34 AM	#13
Ricosan Senior Member Join Date: May 2018 Location: Tallahassee Posts: 375	Re: Lazy speedometer Hey Guys, I’m beginning to understand. It looks like this turtle ratio is correct for the Columbia only. It requires the speedometer transmission to provide correct readings in non overdrive and overdrive? I’m heading out to the garage now to take the speedometer transmission apart and clean ad lubricant. Richard

07-26-2022, 09:39 AM	#14
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,982	Re: Lazy speedometer Yes Richard, speedometer will be correct when you are NOT in overdrive. SW transmission makes the difference when in OD. Glenn

07-26-2022, 11:56 AM	#16
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,982	Re: Lazy speedometer Nothing else holds it in place. Try moving the flapper/actuator a bit. You may have to pry it carefully in several places in the gap with a thin piece of plastic for example.

07-26-2022, 12:26 PM	#17
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,982	Re: Lazy speedometer This is one of pictures I posted of mine in your other Columbia thread. Mine is the 37-41 transmission.

07-27-2022, 05:37 AM	#19
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,982	Re: Lazy speedometer Great job Richard! Plastic knifes and these mixing sticks for epoxy are great for jobs like this. https://tinyurl.com/2p9fraea Glenn

07-27-2022, 06:17 AM	#20
Terry,OH Senior Member Join Date: May 2010 Posts: 4,752	Re: Lazy speedometer The speedometer turtle is usually considered the device mounted on the torque tube. The speedometer cable attaches to it at the torque tube end and is considered a turtle due to it's unique shape. Fords name for this part is speedometer "Gear and Cap". Ford offered the turtles in different gearing. Their gearing has to match the vehicle rear differential gear ratio and the vehicle tire size for the vehicles speedometer to read correctly without the Columbia. Many aftermarket Ford supply houses offer reprints of installation instructions and there is also a parts list for the Columbia. They can be very handy. Your car appears very nice!