Speedometer recalibration place.

['65 chevy lover]

Does anyone know a good speedometer recalibration place in the Ft Worth/Bowie, Tx? There used to be a place in Weatherford (I think), Tx but, I can't find it. Anyone have suggestion's?

[LostMy65]

Originally Posted by '65 chevy lover

Does anyone know a good speedometer recalibration place in the Ft Worth/Bowie, Tx? There used to be a place in Weatherford (I think), Tx but, I can't find it. Anyone have suggestion's?

It may not be that your speedometer needs recalibrating. There should be a little replaceable gear in the transmission that coordinates with your gear ratio of your rear end so that your speedometer reads correctly when running stock size tires.

[bhap]

TCIauto.com has a formula and calculator for speedometer gears. You need to know the gear ratio in rear end, tire diameter and final ratio in transmission. You also need to know the "drive gear" ratio in your transmission which you can figure out from your current "driven gear" tooth count. As long as your current speedometer is consistently wrong, a "driven gear" change should get you close.

['65 chevy lover]

Originally Posted by bhap

TCIauto.com has a formula and calculator for speedometer gears. You need to know the gear ratio in rear end, tire diameter and final ratio in transmission. You also need to know the "drive gear" ratio in your transmission which you can figure out from your current "driven gear" tooth count. As long as your current speedometer is consistently wrong, a "driven gear" change should get you close.

Ok, thanks, I'll give it a shot!

['65 chevy lover]

Originally Posted by LostMy65

It may not be that your speedometer needs recalibrating. There should be a little replaceable gear in the transmission that coordinates with your gear ratio of your rear end so that your speedometer reads correctly when running stock size tires.

Yes, we're talking about the same thing.

[geezer#99]

If you determine what percentage your speedo is off you don’t even need tire height, gear ratio, or gears in the trans.
Use a ratio adapter like this..


http://www.texasindustrialelectric.com/speedo.asp

[LostMy65]

Originally Posted by geezer#99

If you determine what percentage your speedo is off you don’t even need tire height, gear ratio, or gears in the trans.
Use a ratio adapter like this..


http://www.texasindustrialelectric.com/speedo.asp

Funny, I was looking for something like those awhile back. I'm mobile and clicked around, but couldn't find a price. About how much do those cost?

[geezer#99]

50-60 bucks.

[geezer#99]

Guess the price went up since I bought one.
88 clams on here.


https://transmissioncenter.net/shop/...ratio-adapter/

[bigmoe]

You don't need an expensive adapter. Take your speedo cable off at the trans. Pull out the plastic gear. Count the teeth. If your speedo reads too slow get one with fewer teeth and vice versa.

[geezer#99]

Originally Posted by bigmoe

You don't need an expensive adapter. Take your speedo cable off at the trans. Pull out the plastic gear. Count the teeth. If your speedo reads too slow get one with fewer teeth and vice versa.

That’s possible until you hit the point where you need to get into the tailshaft to change the drive gear.

[cwcarpenter98]

Originally Posted by geezer#99

That’s possible until you hit the point where you need to get into the tailshaft to change the drive gear.

This right here is crucial. I hit that point with my truck. The driven gear number of teeth that I needed ended up not working well at all with the drive gear that's in my transmission. I don't want to pull the tail shaft off since that would require me to also pull the overdrive unit off (it's the same unit), so my speedo reads about 5 mph slow still

[AcampoDave]

Originally Posted by cwcarpenter98

This right here is crucial. I hit that point with my truck. The driven gear number of teeth that I needed ended up not working well at all with the drive gear that's in my transmission. I don't want to pull the tail shaft off since that would require me to also pull the overdrive unit off (it's the same unit), so my speedo reads about 5 mph slow still

I did that too. Took off driving after putting in the wrong stuff and the speedometer needle to a bounce and the little plastic gears got munched. The tranny guy said the pices wont hurt my old 3 speed so I just gave up and now I drive by tach readings.

[geezer#99]

And a simple (maybe simple) gear change always snowballs.
New yoke seal, tailshaft gasket, new gear and clip, and while it’s apart let’s do the u-joints.
And then you find you’re still off 5 mph.
Ratio adapter works for me.
Sure wish I still had the Stewart Warner multi adjustable ratio adapter I had 40 years ago.
I’d take a pic for you guys.
Awesome piece. One housing that’s easily opened with multiple gears and charts for infinite adjustment.

[LostMy65]

My speedometer hasn't been correct for years. I owned one of those little digital gps speedometers for a time, and sometimes use my phone.
https://www.amazon.com/dp/B07HQCCFWB..._PMiIFbW8JN78M
.

[DPowers]

http://www.laspeedometergear.com/

[forestb]

I used an app on my phone to figure out how much mine was off and then put little markers on my spedo to indicate my actual speed. It sounds hokey but works for now. I did not want to take the spedo cable off of the trans because I used to have a Turbo 350 that kept on leaking from that location.