Swapping out ring and pinion on front and rear diff question

[74bronk]

I have a 5.5 inch lift on my bronco with 35 inch tires and 3.5 gear ratio... How hard would it be to change ring and pinion out on front and rear diff? And what would be the best gear ratio to go to with 35 inch tires?

 

[treihesse]

What tranny are you running, t case, and engine power?

 

[74bronk]

What tranny are you running, t case, and engine power?

I have a 302 v8, c4 trans, and Dana 20 transfer case

 

[treihesse]

I would go to a 4.88 or 5.13

The 9" is pretty easy the dana 44 is a little harder and requires some special tools

 

[gtnorga]

Take a read here http://www.pirate4x4.com/tech/billavista/Gear_Setup/
for the Dana 44. Though it's a Dana 60, the work is the same.
Here for the 9" http://www.ford-trucks.com/article/idx/9/065/article/Ford_9_Inch_RebuildGear_Setup.html.
I tried to do my 44 but it took me forever and still wasn't right. I ended up taking the axle to a local gear guy, 2 days later it was done. If you do the work of pulling the axle out yourself you'll save a bunch. I haven't done my 9" yet but by the article it doesn't look too bad.

 

[75junebug]

456 or above for gear ratio. You will have toget new carriers for both I believe. It will be a good time to go ahead and upgrade your rear axles to 31 or 35 spline. I did both in my garage as a first time experiment. I didnt have the fancy machinists tools for measurment, but I did use a die grinder to shave away the inner suface of the used bearings so I could instal/adjust shims without having to presson/press off the new bearing. 9 inch was easy, front 44 I lost a lot of skin on my knuckles a a couple of finger nails over the 3 times I have changed ratios. Definitly remove the tie rods on the driver side.....
I had 350's and 35" tires with an auto, went 456 gears until I installed the NP435. Tried 350's again(I was running the interstate every day) and finally settled with 411 gearing.

 

[bronconut73]

4.56 is commonly believed to be a good ratio for 35's and a C4. If you go with an overdrive tranny you'll want 4.88 or 5.13. As was said the 9" is easy, really easy in fact but the 44 is a completely different kettle of fish. I do not care to ever see the inside of my 44 again. Haha.
If I had to do it over again I would still do the 9" but would take the 44 to a gear & axle shop. I have since found a place that will set up the front gears (with your parts) for $200 bucks "if" you bring in just your axle instead of your whole truck.
Yup, that's what I will do next time.

 

[okorangebrnco]

I would go with 4.30's. You will either need thick cut gears for the Dana 44 or a new carrier. As for set-up goes the 9" is a walk in the park, but the 44 can be a bear if you get in a rush.

 

[Broncobowsher]

Don't fear the gear. 4.30 is my first pick for a non-overdrive 35" tire. Maybe 4.56 depending on your exact situation. 302s need RPM, C4 needs RPM to be happy at highway speed. The upper part of the 2000s is a pretty good place to keep a 302 that is under load (and pushing the barn door of a Bronco on the highway is putting a 302 under load).

Start with doing just the 9". It is fairly easy, gears are cheap. This way you can drive it and make sure you like the gear. If it is too much or too little you can pull the gears and put another set in fairly cheap (and recoup a fair amount from selling the test drive set). Once you are sure you like the gearing choice then spend the coin on the front axle. No sense in spending money to set up a front axle and commit a lot of money without a test drive first.