What is this thing between the trans and speedometer cable?

[josh202221]

Hi everyone, I just swapped out the 245/60/15 tires for 275/60/15 tires onto my dad’s 69 charger with the 727 trans and I was wondering if I should remove this thing between my speedometer cable and transmission? I think it’s a speedometer ratio adapter. Using Mancini racings website I determined that I need a 33 teeth speedometer gear which will work with 28 inch diameter tires and 3.55 gear ratio. which I am planning to install next week. Thanks

 

[BeepBeepRR]

Probably some sort of feed for cruise control. Or just a 90 degree adapter. My friends Pontiac had something like that but it was for the cruise control.

 

[josh202221]

Probably some sort of feed for cruise control. Or just a 90 degree adapter. My friends Pontiac had something like that but it was for the cruise control.

Is it ok to remove? Do you think that’s how they came originally? I don’t see why it needs a 90 degree adapter and the car is definitely not equipped with cruise control.

 

[Jerry Hall]

That's something thats not original. I think it's perfectly okay to remove. If you are installing the correct speedometer pinion, then it's definitely not necessary even if it happens to be some kind of adaptor.

 

[Dave6T4]

I wondered if it was a ratio adapter to fine tune the speedometer reading?

 

[josh202221]

I wondered if it was a ratio adapter to fine tune the speedometer reading?

That’s what I’m thinking. I remember when my dad first got it restored the speedo would read 50 when going 30 and he took it back and they got it a little closer than before but not perfect. I am going to remove it and do things properly by installing a new speedometer gear from Mancini racing.

 

[dan juhasz]

Ratio adapter for correcting speedometer accuracy. Usually used on cars originally equipped with a high rear end gear ratio.

 

[Lefty71]

Dont throw it away. Post it up if you arent going to need it.

 

[GTXDAN]

Drive it with the new tires installed with someone to pace you so you know how far off the speedo is, then drive it again after the speedo gear change to see where it is then. That will tell you how much the adapter changes the speedo.

 

[RemCharger]

That’s what I’m thinking. I remember when my dad first got it restored the speedo would read 50 when going 30 and he took it back and they got it a little closer than before but not perfect. I am going to remove it and do things properly by installing a new speedometer gear from Mancini racing.

If it read 50 at 30, it sounds like a mph to kph converter.

 

[josh202221]

I just removed the old speedometer gear and it was a 26 tooth so that means to me that the right angle adapter was definitely some sort of ratio adapter. With a 26.5 tire which was what was on the car before and 3.55 gears, it calls for a 35 tooth gear. Not even close!

 

[kiwigtx]

If it read 50 at 30, it sounds like a mph to kph converter.

Might have been a Canadian car that was transferred south across the border.

 

[josh202221]

Do you guys find that the tire calculators online inaccurate?

 

[OneOfMany]

Might have been a Canadian car that was transferred south across the border.

Km weren't a thing here until 1977. No cars had km/hr gauges until then

 

[RemCharger]

Do you guys find that the tire calculators online inaccurate?

In what way?

 

[josh202221]

In what way?

Bf Goodrich and the tire calculator online said my 275/60/15 tires are 28 inches in diameter. When i measured them by hand they look to be 26.5 or so. With my new speedometer gear meant for 28 inch tires, the speedometer reads too fast by about 2-4mph around town and even worse on the highway

 

[Cranky]

Got any roads with mile markers and has at least a 60 mph limit or faster?

 

[Cranky]

Bf Goodrich and the tire calculator online said my 275/60/15 tires are 28 inches in diameter. When i measured them by hand they look to be 26.5 or so. With my new speedometer gear meant for 28 inch tires, the speedometer reads too fast by about 2-4mph around town and even worse on the highway

If you have a flexible tape, measure the circumference and go from there.....

 

[josh202221]

If you have a flexible tape, measure the circumference and go from there.....

I did that with a speaker wire and did the math equation to convert it to diameter and got 28.01. But when I do it by measuring just the diameter with a tape measure it looks to be 26.5

 

[josh202221]

Got any roads with mile markers and has at least a 60 mph limit or faster?

Yes do you want me to make sure the odometer rolls over in exactly 1 minute?