[Charged up]

My car came w/ the 160mph speedo and it has 3.55's
now. It did have 3.73's and the guy I bought the car
from said both use the same speedo gear. The problem
is the faster you go the more off it is. I was at 5300rpm
in forth and the speedo said 80mph. My heart rate said
it was way off(had to be going well over 100)

 

[Mars_302]

yea its off a bit
are there different size tires on it too?

 

[Charged up]

It has 245/45/17's

 

[MeZapU]

on my 85 I am running a red in color 21 tooth gear for my 3.73's. I installed the 170 mph speedo from Brothers and it is very accurate after I got the speedo head calibrated in town. Brothers couldnt cal my speedo even though I knew it was reading slow and sent it back to them twice. Got P/O'd and spent the $36 to get it cal'd locally.

 

[Charged up]

ne1 else

 

[MeZapU]

It shouldnt matter that you have a 160mph speedo either. A Ford speedo is a ford speedo, and they are all calibrated to 60mph @ 1000 rpms. They wont interchange into your cluster but they are all cal'd the same.