Topic: third member gearing

[Greiner]

i was doing research on rebuilding front axles and i am having a hard time finding anything that explains the gearing in the third member. I guess my question is are the specific gears you want to use with different size tires? I was looking at doing 30 spline longfeild aussie locker and a v6 housing and i want to run 37" tires

[Dr Phat]

Well yes. I forget the exact conversion but you use gears to bring the drive ratio back to stock gearing for DD. If your crawling just go with 5.29s. They will work great with 37's.

If your running a v-6 housing in the front just buy a hi-pinion 3rd member. Same parts, stronger, more clearance.

[-Jake-]

5.29 are perfect for 37s. 

[Greiner [OP]]

this is also going to be a daily driver so will 5.29 bring it back to stock? my plan was also to do a crawl box.

[-Jake-]

this is also going to be a daily driver so will 5.29 bring it back to stock? my plan was also to do a crawl box.

My speedo is dead on with 5.29s and 37s.  So yeah it'd be just like stock gearing.

[Dr Phat]

DD and dual case? lol


Or do you mean 4.7s low range?

[Greiner [OP]]

DD and dual case? lol


Or do you mean 4.7s low range?

i still have alot to learn? lol but my gess was you could set up the dual transfer case so you could have stock gears (besides the 5.29s in the diff) and low gears for wheeling?

[Dr Phat]

Well doing a dual case is alot more expensive than putting in 5.29's.

Look at it this way.

Stock transfer case in low range and 5.29s will give you a final drive ratio of 47.4 for $300

Dual transfer case both in low range and stock gears will give you a final drive ratio of 84 for $600 + cost of 2nd transfer case + new drive shafts front and rear.

I would do diff gears first then work my way to a dual x-case and maybe drop 4.7's in your single transfer case (98 final drive) so your all setup for ultimate duals when you do dual case it for a whopping 223 final drive.

[Greiner [OP]]

that does make a lot more sense

[crazykooter]

A little correction regarding the gears to tire size and speedo correctness.
1st 5.29s are spec'd for 35" tires.   37" tires will work fine with them besides the dropping to 4th on hills.
If your running 5.29s a single case and 37"s when say doing fordyce or con your gonna be on your clutch a lot.

5.29x2.28x3.93=47.4 crawl ratio
A 47 ratio is fine if your running smaller tires.

Now if you add a second tcase with stock gears you get this:
5.29x2.28x2.28x3.93=105.6
This ratio is MUCH more suited for a trail/dd rig. but still imo not nearly good enough to push 37"s on the trail.

As a rule of thumb the ideal crawl ration for a trail rig is 150-180.  I would say if you plan to wheel some of hard trails this summer then going dual cases with 4.7 gears im rear case would make it a lot less stress on drive train and your left foot.

W/ 4.7 gears
5.29x2.28x4.7x3.93=222.8

Also when people refer to crawl ration the including my calcs about are using 1st gear.  You be surprised how often you'll be in 3rd gear as main crawl gear with dual cases and 4.7 rear. 
I am running dual cases with marlin 4.7 rear case gears and stock front.  Basically the last calc above.  My rig is more then fine on tires up to 40"s but ive also built everything else to handle bigger tires and extreme trails.  It takes money but in the end its well worth it.  Mainly your not being towed out of the trail by your friends who still wanted to keep wheeling. 

[Dr Phat]

Thank you for the correction Kooter!

[79coyotefrg]

DD and dual case? lol


Or do you mean 4.7s low range?

whats funny about dual cases in a daily driver??  the first major mod i did on my truck that i commuted 50 miles one way 6 days a week with.    I had 32's and 4.37 stock gears for several years after doing dual 2.28 cases.     it wasnt till after my wreck that i went to 5.29's and 35's which by the way puts my speedo about 3 mph off, when it reads 55 i'm actually doing 52

[Greiner [OP]]

thanks kooter thats alot of good info to know about gearing and crawling