Speedometer Drive

-
grassy

grassy

Well-Known Member
Joined
Aug 20, 2009
Messages
5,352
Reaction score
86
Location
Nova Scotia
Is the speedometer drive the same unit for all the MOPAR auto transmissions ?

Thanks
ian.
 
Depending on differential gears and tires the gear in the tranny is changed to give the correct speedo reading.So the diff gears and tire size need to be posted and a compared to the chart and a gear is give for the right amoount of teeth to give the right reading,mrmopartech
 
Not sure what was in it originally. The car was a /6,auto,7 1/4 rear end.

I am putting in an electric speedo that shows kms.

An a727 is going in and I will be using an Auto Meter speedometer sender unit # 5291 so I can dispense with the usual problems of tire size and number of teeth.

With this unit, you drive a specified distance. You press a button at the beginning, drive the distance at any speed you desire and press a button at the end. The unit does the rest. Change tire size, repeat above.

I was having nightmares trying to figure out what tooth number I would require with my set up and have it read correctly on an analog speedometer that reads kms..

So you need the length of the gear shaft...what is short / long ?

Thanks
ian.
 
The HOUSING that holds the speedometer gear is the same on all 66 to early 70's transmissions manual and automatic. Earlier years used different housings and later models and trucks did as well.
speedohousing.jpg
 
I tried that speedo and never got it to work, needle jumped all over
 
gregpurcell said:
The HOUSING that holds the speedometer gear is the same on all 66 to early 70's transmissions manual and automatic. Earlier years used different housings and later models and trucks did as well.
Click to expand...

Great. Mine looks like that. Other than putting it into the transmission, how will I know if it will work or not ?



Thanks
Ian.
 
grassy said:
Great. Mine looks like that. Other than putting it into the transmission, how will I know if it will work or not ?



Thanks
Ian.
Click to expand...

Since your talking about using an aftermarket part it's nearly impossible to say if it'll work. The factory housing works fine when indexed correctly which means aligning the number set on it to the indexing mark on the tail housing that correlates to what tooth speedo pinion your using.

In other words, if you have a 36 tooth speedo pinion you install the housing and turn it to where the tab on the ext. housing is aligned to the mark next to the 32-38 on the speedo pinion housing. Hopefully that's clearer than mud
 
fishy,

I follow. Ok..count the teeth and and look for the part on the 727 housing to sync with the number of teeth.

Do I worry about shaft length. Need to pull trans out of storage.

Thank you
Ian.
 
grassy said:
fishy,

I follow. Ok..count the teeth and and look for the part on the 727 housing to sync with the number of teeth.

Do I worry about shaft length. Need to pull trans out of storage.

Thank you
Ian.
Click to expand...

Yep, you got it Ian. As far as I know 66-up all used the long speedo shaft. I have seen pics of the short speedo shaft but I have never actually saw one in a trans. The oldest trans I've worked on was a 66 so it must have been before that when they used the short one. The only thing I'm not sure about is the adapter for your electronic speedo. It may be made for the long shaft or the short shaft, no idea since I haven't messed with one. Does it say in the instructions anywhere about it being for certain year transmissions?
 
I tried that speedo and never got it to work, needle jumped all over

The needle jumping all over is a probably a separate issue unrelated to speedo gear alignment. In my experience if the gear is not aligned it just won't work. A bad cable or a speedometer going out will cause the needle to jump around. I just replaced the gauge cluster in my 72 Valiant because of that. The replacement worked great
 
Fishy,

I am taking the word of Auto Meter. I told them what I have and they gave me the model number. I am far enough into the build to have ordered this unit yet but I am hoping it is going to be soon. I will post how it goes.

ian.
 
gregpurcell said:
I tried that speedo and never got it to work, needle jumped all over

The needle jumping all over is a probably a separate issue unrelated to speedo gear alignment. In my experience if the gear is not aligned it just won't work. A bad cable or a speedometer going out will cause the needle to jump around. I just replaced the gauge cluster in my 72 Valiant because of that. The replacement worked great
Click to expand...

good points there Greg. Those things can do it too. I had one that jumped around like that and it wasn't aligned right. Apparently the gear was just barely catching the output shaft splines. The speedo gear was also roached possibly due to slipping. Put a new gear in and it worked fine.
 
grassy said:
Fishy,

I am taking the word of Auto Meter. I told them what I have and they gave me the model number. I am far enough into the build to have ordered this unit yet but I am hoping it is going to be soon. I will post how it goes.

ian.
Click to expand...

Gotcha. Auto meter is real good so I'd wager they gave you the right part #'s
 
You must log in or register to reply here.
-

Back
Top