Need Help 2nd Opion

[Mopar4Play]

I recently changed my rear end gears from 278 to a 391 in my 8.25 rear end. I am running 17" rims. My spedo is off about 30MPH at 55. I am being told that the only way to correct this is with a custom built gear reduction box because they don't make a spedo gear large enough. What do you think?:glasses9:

 

[oldkimmer]

..................What # gear do u need, should b do able , did u use the calculator.....................kim........

 

[mopar340dave]

You prob need a 35, 37 or 38

http://www.yearone.com/yodnn/tech/T...Q/MoparSpeedoGearChart/tabid/415/Default.aspx

 

[dgc333]

I can't imagine that there is not an appropriate gear available. Between cars and pickups there was a wide range of tire diameters and rear gear ratios. The rim diameter is irrelavent, it's the diameter of the tire you have mounted on the rim.

 

[Mopar4Play]

I have to admit, That I know nothing about how this stuff is calculated. I was told the largest gear was a 42 and that isn't going to handle it because I am so far off.

 

[yellowdartdave]

http://www.mymopar.com/speedometer.htm

 

[mopar340dave]

mopar 4 play, what diameter is your rear tire?

PS your tire would have to be less than 23" in diameter for you to need a 44 tooth gear

 

[Mopar4Play]

Thanks everyone, I am away from home but will be back tonite and will get the information you are asking.

 

[Mopar4Play]

mopar 4 play, what diameter is your rear tire?

PS your tire would have to be less than 23" in diameter for you to need a 44 tooth gear

My rear tire diameter is 29"

 

[dgc333]

You need a 35 tooth gear. Brewers is a good place to get them.

 

[Mopar4Play]

You need a 35 tooth gear. Brewers is a good place to get them.

Installed Orange 35 and it works GREAT:cheers:

 

[mopar340dave]

Thats great, and ya learned something new in the process that applies to pretty much all our old mopars.
Its nice to be able to fix it yourself.