Speedometer gear

[6packCuda]

My speedo is waaaaaaaaaay off. Which gear do I need with 3.55s and a 727?

[rallyechall]

Here is a quicky chart. you also need to know the tire size...

http://www.jimsautoparts.com/transmission_parts.htm

[MEK-Dangerfield]

My speedo is waaaaaaaaaay off. Which gear do I need with 3.55s and a 727?

Are you way off fast, or way off slow? I had to change my speedo gear once. It's a little messy and stinky, but not a bad job. You do need to know your tire size though. I can talk you thru it, if you don't know what to do. I'll guess you need something in the 35-40 tooth range.


  Mike

[purple1]

Oh, and don't forget the new o-ring.

Don't ask me how I know. 

Dave 

[Bullitt-]

here is a spreadsheet that will figure it out for you...need rear tire size too
http://www.moparts.com/Tech/tech/img/AUTOMATICchart.xls

[6packCuda]

Thanks guys. I know how to change the gear, just don't know which gear I need. The rear tires are 275s. The speedo reads high. When I'm following other cars that are going 60-65, my speedo reads 85-90mph.

[6packCuda]

Thanks bullitt99. That is very helpful. I come up with 33.82
So I guess I need a 34 tooth gear. Right?

[Bullitt-]

Thanks bullitt99. That is very helpful. I come up with 33.82
So I guess I need a 34 tooth gear. Right?

I don't know your tire size  275 is width but aspect ratio & rim diameter have to be put in too.
something like 275/60/14 or 275/50/15  275/40/17  any change will effect the outcome a little.

[6packCuda]

Yep, I put all that info in. They're 276/60/15s.

[Stacked440]

   That O-ring was harder to find than...well...hard to find!  Had to go to a specialty auto store just to find one the right size and thickness.  Then put it in only to find that the inner seal leaks   I don't want to jinx it but it has stopped for the last few days...

[purple1]

  That O-ring was harder to find than...well...hard to find!  Had to go to a specialty auto store just to find one the right size and thickness.  Then put it in only to find that the inner seal leaks   I don't want to jinx it but it has stopped for the last few days...

www.rockauto.com has them both.

Dave 

[tactransman]

I have plenty,if anyone ever needs 'em,they will fit in an envelope. 

[vinb]

275/60/15 Tire
3.55 Gear
Auto
67 mph @ 2900 rpm....
33 teeth , yellow gear...

[74 340 4speed]

I just saw this thread and I need a new gear for my speedometer as well.  On the website that was listed earlier, http://www.jimsautoparts.com/transmission_parts.htm, it says that a gasket kit is needed whenever changing these out.  Is this only for automatics, or does it apply to 4 speeds as well?  I will be putting the gear in an A-833 four speed.