Speedo Gear

[mey6t6]

What speedo gear do I need for a 904 a/t with an 8 3/4 rearend 742 (Housing) 3.23 Gear Ratio? The wheels are 14" 195/65 r14

 

[MoparBrit]

Program I have caluclates 35.31 for the speedo gear. If I remember my direction right (someone please chime in if I got it backwards) the closest is a 35 and the speedo will read slightly higher than you are actually going. As I said, someone please chime in to make sure I remember right that it will show faster and not slower. If I'm right, then a 36 would show you going slower than you are actually going (not a good thing in my book) and the amount of speedo error will be greater than it would be using a 35.

Hope that helps.
Cheers

 

[fishy68]

MoparBrit I think you nailed it. You can go either way on which gear you use. If you take into consideration tire wear that will affect it some the 36 tooth gear would be more accurate when the tires get worn down. Either gear probably won't be off by more than 1-2 mph.

 

[mey6t6]

Thanks for the help:cheers:

 

[Charrlie_S]

What speedo gear do I need for a 904 a/t with an 8 3/4 rearend 742 (Housing) 3.23 Gear Ratio? The wheels are 14" 195/65 r14

What year is the trans?
The gears are different 65 older, or 66 newer.