what gears do i have??

first off, this is a great site and i'm a jeep newbie. when i was having a no start problem this site was helpful. just recently realized it was a xj site (i guess naxja should have been a clue) but i wasn't to familiar with the lettering, oops.

now for my question, i have a 88 wrangler (yj) 2.5 5 spd with 31's. my car does 62 mph on the gps at 2500 rpm's. i know 4.10's were stock, but it seems like i'd do less rpm with 31's and a overdrive. i built a race/semi street mustang that did around 60 at 2500ish with 26-27" tire and no overdrive (1:1). my old bronco with 33's and a granny 4spd (no overdrive, 1:1) seemed to get similar rpm's and mph. was never concerned with those 2 vehicles as i knew it didn't have an od.

think these are 4.10's?

also, has stock shackles and don't think there is a lift and only get very slight rub on the plastic fenders in the back. from magazine reading it says i should not be able to fit these without a 1-2 lift. are the mags wrong or is there i lift that i don't know about?

tks

easiest way to tell is to jack up one end of the vehicle and use a paint marker to make a mark on your driveshaft. also mark a point on your tire with some chalk or something. put the t-case in neutral. then rotate the tires exactly one revolution, if there is no limited slip or locker have a friend help you, and make sure you both turn the wheels. exactly one revolution in the same direction. count the revolutions of the DS as you do this.

3.5 turns of ds to 1 revolution of wheels=3.55
3 and 3/4 turns=3.73
4=4.10
and so on

takes about 20 minutes and theres no mucking about with conversion factors, odd tire sizes, transmission overdrive ratios etc.

My son's YJ has a 258 and runs about the same RPM as you with his 31's and 4:10's.

Check your diff covers for the ID tag, lower left hand corner should have the ratio. 3:07 or 4:10.

And a site more along the Jeep newbie line... www.jeepsunlimited.com

your 88 YJ 2.5L 5 spd has 4.10:1 stock ratio. your RPM sounds right about where mine runs on 31s too.

jurob said:

my car does 62 mph on the gps at 2500 rpm's.

Click to expand...

Blasphamey you don't drive a car do you

tks, just making sure. seemed kind of high.

your right! not my car, my jeep! lol

jurob said:

... not my car, my jeep! lol

Click to expand...

Never a car, never a car, always a Jeep, always a Jeep!