February 18, 2004I have a friend who asked me how you would find out the gear ratio on a read end that your not sure what it is. I have no Idea so I though Id ask you guys. He has a rear end that is already off of the rig and has no idea what its ratio is. He would like to put it in a 78 firebird so what would be a good ratio to have??
Forums : General Tech Questions : Whats the Ratio????? (118 Views)
February 18, 2004Matt 89
Pull the rear cover. Count the teeth on the ring gear and the pinion gear, then divide the pinion into the ring gear.
No metal tag on the diff cover?
February 18, 2004jack the rear diff up so the tires are off the ground, mark the driveshaft position, and mark a tires position. rotate the tire one revolution (if its a limited slip/locked rear end, twice if its an open diff.) while rotating the tire, count how many times the driveshaft revolves, if it rotates 3 and 3/4 its a 3.73 gear ratio, 4 times and a bit, its 4.11 gear ratio. etc.
removing the cover and counting the teeth is the only sure way of telling the ratio, i would look for a tag like superdave asked before taking the cover off.
February 19, 2004if it is still in the original vehicle, call that make`s dealership and they can run the vin..or look up the vin and one of the vin`s #s or ltters will tell you...that is what a vin is, is all the stuff on the vehicle....a dodge vin will tell you everything about it.