gear ratio choice help

[chileanbronco67]

hi. whats the perfect gear ratio for me. i have a 67 bronco with the stock 389 engine dana 20 and 3 speed trans. 35 tires. i am plannig in 1 or to years swap to a od trans ax 15 or nv 3550. i dont do rock krawling or extreme off road. but some times light to medium trails.
i thought 4.56 or 4.88
what do you thing about that.
are youkon the best brand for pinion and ring?
thx

 

[Madgyver]

4.56 for 35"

 

[Broncobowsher]

.78 or .79 OD ratio. So not a lot of overdrive when compared to other options (4R70W is .70 for example).

I also presume that the engine size is a typo. really a 289?

4.56 X .79 = 3.60 effective gear ratio in OD, 4.88 is 3.86:1

4.88 without overdrive might be a bit tough on the highway. 4.56 with overdrive is likely to struggle a bit.

Check location, Chile. OK, that makes things a bit more challenging. Do you have fast freeways? I'm guessing that you don't have the high speeds that we travel at here in the states. Probably not doing 120km/h much.

I would lean toward the 4.88s. Speed isn't as important. Good gearing for the tall tires.

 

[chileanbronco67]

nice info. yep i am from chile. we have fast freeways but its not my goal to do 120km/h but i wold be very if i could do 100km/h easy or confortable. i dont now what do you mean with a typo engine size. my 289 v8 is std. sorry for my english i hope you guys understood

 

[Broncobowsher]

As for the typo, the original post states 389 engine. You just confirmed it is really a 289. So a typo of a 3 where it should be a 2.

For those playing at home (and not accustomed to crossing a border) 100 km/h is 62 MPH and 120km/h is 75 MPH.

Not to worry about the english, better than many around here.

 

[sprdv1]

4.56 for 35"

yep....
agree

 

[sprdv1]

nice info. yep i am from chile. we have fast freeways but its not my goal to do 120km/h but i wold be very if i could do 100km/h easy or confortable. i dont now what do you mean with a typo engine size. my 289 v8 is std. sorry for my english i hope you guys understood

we figure it out eventually

 

[chileanbronco67]

hahaha 289 sorry.
2 votes for 4.56
the other questions its the brand i am looking the yukon in WH.
worth the extra money?

 

[blubuckaroo]

hi. whats the perfect gear ratio for me. i have a 67 bronco with the stock 389 engine dana 20 and 3 speed trans. 35 tires. i am plannig in 1 or to years swap to a od trans ax 15 or nv 3550. i dont do rock krawling or extreme off road. but some times light to medium trails.
i thought 4.56 or 4.88
what do you thing about that.
are youkon the best brand for pinion and ring?
thx

Don’t depend on an evolution of mods to work out. It really all depends on how realistic your plans are for an overdrive tranny. I had 32s, and went to 4.11s so towing our trailer would be easier. It towed great, but sounded like an airplane when on the freeway without the trailer. That’s when I installed the NV3550. Since then I’ve changed tires to ‘33s. For me it worked. With 33s, 4.11s, and a .78 overdrive, the engine runs a perfect 2350 RPM at 70 MPH.

 

[taipeichris]

Hi,
I have a 66 with 302, NV3550, 33s and was at 4.11 but have been 4.35 for several years and love it. From what I read if I upgrade to 35s the 4.56 would be perfect! You can always gear the rear first and try it to see what you think. BUT never drive in 4wd with different ratios, something will go boom and it won’t be pretty.
Good luck with your Bronco!
��

 

[chileanbronco67]

Just buyed 4.56 yukon. Thx for the help

 

[hammer189]

You will like the yukon gears. Mine are nice and quiet. I run 4.56 on 32" with NV3550 trans. Good set up.

 

[chrlsful]

"... i dont do rock krawling or extreme off road. but some times light to medium trails...." and mostly 2 lane black top, some freeways, se`?
...an 80% on rd / 20% off...
no? Cuentanos mas...