speedo gearing

[2nd69charger]

any ideas of how many teeth that I need to go up or down (3.23 GEARS)  440 4speed
actual speed 65-speedo reads 50
                   60                      45
                   45                      35
                   35                      28

[cdr]

any ideas of how many teeth that I need to go up or down (3.23 GEARS)  440 4speed
actual speed 65-speedo reads 50
                   60                      45
                   45                      35
                   35                      28

How many teeth now ?

[2nd69charger]

not sure have not look at it. org a 318 auto car. will pull gear out sunday

[XH29N0G]

If it were me, I would start with information from gearing and tire size using a table like this one.  http://www.moparts.org/Tech/tech/pages/speedo.html
Brewers has pinion gears.  I have an old orange gear with a 323 rear, but I do not know what the tire sizes were (they were supposed to be g78 x 14 which would be 27.1 inch diameter)  I know those were the tires we had originally.  I do not know if that is what it was designed for. 

[Kern Dog]

The speedometer pinion is actually in the transmission tail shaft. Some weirdos have stockpiles of them in different sizes.
(Like me)

[Kern Dog]

any ideas of how many teeth that I need to go up or down (3.23 GEARS)  440 4speed
actual speed 65-speedo reads 50
                   60                      45
                   45                      35
                   35                      28

No matter what, you need a speedometer gear that is smaller so it turns faster than it is doing right now. Turning faster will raise the speed shown on the gauge.

[Nacho-RT74]

It seems you need less teeths than you actually have.

However, it doesn't matter what do you have now and how many teeth less, just match tire diameter and axle ratio on tables and you'll be done getting that the the count gear.


It seems you need a 25-30%  less teeth variation from what you have now.

[John_Kunkel]

I admit to being anal when it comes to speedo accuracy. Three things I've found:

1) The odometer is the best way to determine the correct pinion, some speedo heads have an error in mph, the odometer is direct drive.

2) The best way to determine the actual tire diameter is to measure the rollout and divide by pi. (3.1416)

3) Charts have errors, do the math.

[XH29N0G]

What was just said.  I forgot to mention checking the odometer.  That is a big one and can tell you if the speedo itself is the issue.  I had that one.  The pinion can also be optimized and you can back out the basic formula from that table and optimize for your specific diameter as determined that way.

[Kern Dog]

I admit to being anal

I love a joke about ass sex  but I really wonder how or why THIS word is better than meticulous, strict, a stickler, a perfectionist, etc ?

[RallyeMike]

Three things I've found:

1) The odometer is the best way to determine the correct pinion, some speedo heads have an error in mph, the odometer is direct drive.

2) The best way to determine the actual tire diameter is to measure the rollout and divide by pi. (3.1416)

3) Charts have errors, do the math.

Yes. After getting the closest speed gear, I've then timed the speedometer against mile markers, figuring how far off it is, and buying tires that were an equal percentage smaller or larger in advertised revolutions to correct the error. My speedo is right on the money (for as much as you can tell on a 150 speedo without using a magnifying glass!).

[John_Kunkel]

I admit to being anal

I love a joke about ass sex  but I really wonder how or why THIS word is better than meticulous, strict, a stickler, a perfectionist, etc ?

I think it's a shortened version of "anal retentive" which means marked by excessive orderliness, extreme meticulousness, etc. An individual can be anal regarding certain subjects or generally anal which is akin to OCD.

[Kern Dog]

Yeah, I did know that. Thank you.
The term just grabs my attention due to the fact that my first impression of almost everything goes directly to a literal interpretation.
The paint looks a mile deep.
I held my breath for 5 minutes.
I banged her brains out.
I've been there a million times.
None of those statements are true, they are exaggerations. The literal interpretation is just funny to me.

[XH29N0G]

For me, 'anal retentive' has always sounded like stopped up.  I like free flowing, like in exhaust.....

And to think the opposite of algesia (I read greek for pain) is analgesia, .......... but it wouldn't seem that way if you misread the meaning and used it on your butt.  

You know I heard a saying yesterday: "We are just two cheeks on the same ass" that I think works in many cases here.  We disagree on some very basic things but we agree on Chargers and in this case speedos.  

well maybe the car type speedo.

[Kern Dog]

 

[Finoke]

Some more questions....

Are 883 and 727 speedo gears the same or do you need to purchase for specific manual or auto trans?

Do you need to drain the trans to change out or are they above the liquid level?

Who are the preferred venders for auto trans speedo gear? I have a 70 Charger.

Thx!
Tom

[John_Kunkel]

Yes, 833 and TF use the same gear. Jacking the car up from the left side will prevent fluid loss when removing the pinion adapter.

As for vendors, just look for the best price...used ones on E-bay are usually the best deal, they rarely "wear out".

[XH29N0G]

I don't remember lifting up the left side of my car and having significant leaks when I swapped it out.I had a three-speed manual though. It might be different for an 833. I also swapped my tremec and didn't have leaks

So I imagine a small amount of tilt is all you need at most and you may not get much at all.

[Finoke]

Yes, 833 and TF use the same gear. Jacking the car up from the left side will prevent fluid loss when removing the pinion adapter.

As for vendors, just look for the best price...used ones on E-bay are usually the best deal, they rarely "wear out".

thanks John! 

[sccachallenger]

It seems you need less teeths than you actually have.

However, it doesn't matter what do you have now and how many teeth less, just match tire diameter and axle ratio on tables and you'll be done getting that the the count gear.


It seems you need a 25-30%  less teeth variation from what you have now.

Agree, just go by the percentage off, start with number in now, multiply by percentage off.

[Nacho-RT74]

Just use this excel table calculator, with your axle ratio and tires size, no matter what you have now! and you be done!

http://www.moparts.org/Tech/tech/img/AUTOMATICchart.xls

I posted about the speedo gear variation as curiosity, but that won't matter really making the maths to get the correct gear teeth count. The 25-30% rate could be not matching the piece he needs, because speedo doesn't work as a direct drive with the cable, but by magnetism and inertia with a spring loaded wheel.

[Lighthorseman]

"...which is akin to OCD."


What is CDO?

The letters OCD....but in the RIGHT ORDER!!