Alright I have asked before, two months ago but no one could figure this out so for those of ou that are good with math here ya go.

2.8L turning 3700 RPM with factory tires and wheels, a 3.42 open rear end, and in 5th gear, how fast am I rolling? My speedo is broke. Thanks

-Buck

 

Did you look at www.f-body.org/gears/

 

Then if it is right i am rolling at 131 mph at 3700 rpm. That cant be right cause at 2500 rpm i am barley able to keep up with the flow of traffic and it says that i am rolling at 89 mph in a 55 mph zone. ???????????????? help please.

-Buck

 

What size tires are you using? height in inches from ground to the top of tire.

 

No F'n way you are pushing 2500 RPM's at 65 (as if trafic goes the speed limit) in 5th gear...
if that was the case you would need some small a$$ tires or 4.56 gears!

How certain are you that the tack is working correctly?

BTW the calc for the RPM range you say you are in with trafic, and going off of that then 3700 RPM's would be about 98 MPH!

 

Something is screwed up because your info give answers that are not realistic for a 2.8 in 5th gear.

 

Are you sure you're shifting to 5th gear? The #'s seem to work for 4th!!

 

My 1988 3.42, 2.8L, 5spd was cruising at 70mph@2500rpm in 5th. Or with the pedal to the floor in 5th, 100mph@4500rpm.

 

How about this answer. Go to a junkyard, E-Bay or something and BUY A NEW SPEEDO.