3b RPMs (1 Viewer)

[jcaron]

My 60 is turning 2500 rpms at 60mph. 3b with 4 speed 32" tires. 3.73???

 

[slammed41]

ummm...not sure what the question is.

are you wondering what the ring/pinion ratio is for a bj60?

 

[Roberto]

question??

My BJ42 at 65mph with 5 speed, 32" tires and 3.70's was around 2200 RPM

R

 

[UpsideDown]

My 60 is turning 2500 rpms at 60mph. 3b with 4 speed 32" tires. 3.73???

The gears are 3.70 (not 3.73), and you need to correct for your tire size if you haven't done that. Your speedometer to RPM reading is a fixed relationship, but you may actually be traveling faster than indicated as the larger circumference of your tire has an influence on things.

Further, a 32" tires is not really 32" tall as most tire manufacturers are overly optimistic about how tall their tires actually are (although some offer accurate numbers - but mostly with metric tire sizing).

A 255 85R16 (a true 33" tire) will go about 100 kph at 2050 RPM with 3.70 gears when the speedo is corrected.

Also, a 3B is totally happy turning these kinds of RPM all day long for the life the engine (about 500,000 to 750,000 kms with average maintenance)

~J.

 

[jcaron]

Yes the questions is what ring and pinion ratio (without pulling out the third) that is 60 on a gps. 32" bfg a/t. Tranny is in a 83 fj60 (motor swap).