finding the right gears

[BIGROTT88]

best of luck, keep us informed on what you decide to go with and how it runs

[WRENCH MAN]

According to Advance Adapters, the Warn/Saturn OD has a .25% over drive, your tire size should e the final factor included, with 31's the 4.56's would be good, with 32's the 4.56's or 4.8's would be ok and if you run 33's the 4.88's likely would be best, if you do the math the final is lower than the stock 4.27's and direct, but the tires were smaller too!

[kb'sforme]

was just playing with the calculator. and it ask which t-case we have, well it list 2 different ones for a dana/spicer 18. it's either a 1.97 or a 2.43
i have no idea which it is? the dana 18 gears were stuffed into a 20 case. but other than that they are the origanal gears from the truck. it's a 1962 if it makes a difference. i still have the dana18 case if there are any stampings that tell.

[Comanche Scott]

According to the Novak Adapters website it should be 2.46:1.
There might be something here in the FAQ section that has the gearing.

Scott

[kb'sforme]

thanks Scott! i'm hoping thats what it is. not a huge difference but still.
ok my vote is for 4.56!
after playing with the numbers i feel that will be the best all around for what this truck will be. the calculator had no way to factor in the OD. but as i said before even though you could shift the OD in every gear. theres just no point. so i ran the numbers based on that. i was surprised at the results. we could most likely run a 4.88 with out any issues. but i think it would be a little too low just based on the fact it will have the motor at higher rpm to do the same work. so for that i'm sideing with the 4.56
so since we are in agreement on the ratio.
what say you on carriers? lockers, limited, ect?
remember this truck will be a daily driver in houston!

[Eric VanBuren]

The low range T-case gears has no bearing on this equation as the concern is not the crawl speed but the top speed from what you've indicated thus far.

The key to gearing is where the engine makes its peak torque, none of the info you've given about the engine indicates any change in that. If anything you'll be raising that torque peak by porting the engine.

So lets go about this another way. With stock gearing and stock tire size the OD would put you right where you want to be for being able to cruise at 75mph comfortably considering the stock truck would cruise at 60mph. So that means that your gearing should compensate for the increase in tire diameter. The stock tires are about 28" so going to a 33" you'd want your gears to be about 18% lower, 31" tires you'd want about 10% more.

for 33" 4.27 x 1.18 = 5.04 so 4.88 or 5.14
for 31" 4.27 x 1.10 = 4.69 so 4.56 or 4.88


The calculator does have a way to factor in the OD just select the trans and then switch the number of gears to 5 and enter .75 as the ratio for "5th" gear.

[kb'sforme]

Eric, thankyou! i'm no math wiz. given that info it went back and played some more but i think i'm still good with a 4.56 ratio.

[kb'sforme]

given the calculations support that a 4.56 would be a good choice. they are still that just calulations, a theoretical idea of preformance. i hate to drag this out. but want to get it right the first time as we wont have the luxury of swaping gears in and out to fine tune it.
drive line shop is closed today so i'll find out for sure tomorrow. but does anyone know.
what the lowest gear (numericaly high) set is that we can bolt up to the carriers we have? given it had 3.07 gears in it. keep reading about "thick" and "thin" gears and what fits what.
i was just thinking that we might be able to save some money if we can get close like maybe a 4.11 or something. which would not be the most grunt possible but a huge cost savings. and would be adaquite for the truck. just curious.

[Carl Wiese]

The carriers you have are for 3.92 and numerically lower (3.73,3.54,3.33....). You'll need to swap carriers for anything numerically higher. Thick and thin gears refer to the thickness of the ring gear. As the gear ratio get numerically higher the pinion gear gets smaller and moves away from the carrier, hence the difference and need for two carriers. Thick gears are used I believe in the Jeep Rubicon so there is no need for different carriers. Basically it will let you put a 4.xx gears on the carriers you have. Since they are thicker they compensate for the pinion diameter reduction.

[Bill usn-1]

I recommend going to the source for info.

http://www.ringpinion.com/b2c/PartsL...4WD&DiffID=135

You can see the ratios avail in thick...for mounting higher gears on your carriers and the standard gears.

I recommend going with a good posi front and rear or run tru tracs so there is no clutches to wear.