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Axles+tires=gears

5K views 57 replies 20 participants last post by  Carbon 
#1 ·
I have a front Dana 44 and a rear corp 14 bolt out of a 79 3/4 gmc that I installed under my 76 Scout II with a 345 v8. Currently I have 4.10 gears. My plan is to run 40's and would like to regear to 5.13 or 5.71. My question is, will both axles accept this size gear set?
 
#38 ·
terra low is complete junk..don't waist your money.i have one in my garage in pieces.
 
#39 ·
there is a lot better ways to do the driveshafts then just calling tom woods. build your own using northerndrivetrain, just order the parts and weld them or give some local shops a call..
 
#44 ·
You need to be able to flex your suspension from full stuff to full droop. Measure yoke to yoke in both positions and that tells you want your driveshaft lengths need to be.

At full droop you need to use a protractor to see what angle your driveshaft is at. That will tell you if you need single or double cardan joints.
 
#45 ·
Ok I'll do some research on building drive shafts. I'm sure there is a ton of info out there. Thanks for your help. I'd rather snap some home made shafts getting it right then blow $800+ on shafts. I could use that money for high horse power stickers and stuff.
 
#46 ·
A Dana 20 is not bullet proof and anything can break given enough stupidity.

I have a completely rebuilt/never ran sm465/d20/18 with every option herm the overdrive guy could install in it that is collecting dust for over a year because I upgraded to an engine that will break the case in two with my "F it I can make that" attitude.

Yes, a terra low kit will be harder on your joints and pinions. That's why I recommended larger joints and beefing the pinion. I don't know why you wouldn't go double cv the cost is not much more.

4.10x2=8.20
4.10x3.15=12.91
5.38x2=10.76

Lots of guys myself included have got to the top of hills many times with nothing more then a 40/1 ratio. They had 100x raitos, big blocks, and big azz tires. I had a 4 banger, 28" tires and a welded rear.

Gear ratios and big tires don't mean jack if you can not get traction.

I don't see whats wrong with the 38's and ratio you currently have. Shave that pig and install a locker. If you feel you need more gear you can install it later.
 
#47 ·
Thats actually a solid plan. I will get the drive line finished and play with it as is to see what I need. I don't know how much longer I can look at in my garage and not be able to drive it around the yard.
 
#48 ·
If you stay with 4.10 gearing and 38's and do much serious technical wheeling you will regret it. There's a reason that most (unlike cerial) go deeper gears with taller tires.

I've never bothered to calculate final drive ratio as much as knowing what works by usage and observation. Regarless of the ratio of your tranny 1st gear, it seems that transfer case and axle ratios come more into play in the real world.
 
#50 ·
I run 4:10 gears, stock ford 205 and 46" tires. whats the gearing work out to be?

my point is depends on your setup.i have a nv4500 with a low first and awesome second.so I run 2 and 3rd low wheeling, first for crawling and hi for the dunes and going fast.i like a big ring and pinion. and wheel speed when needed..but I am the 1% president..:teehee:


crawling is for babies! :finger:
 
#52 ·
that's me and I have many pictures on here if you look at my build thread or the picture thread.
 
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