What gears? 351/C4/D20?

[rtreads]

With 37's what gears do you run??


I am thinking that I will need to go a little lower with the 37's I will be installing. I currently have 4.10's and worn 36" swampers. I will be going to some new 37's. I have a 351 that seams to push the truck along fine now... but I think I am pushing it. I currently get 8/9mpg, but I am not 100% sure that isn't partly due to a carb that isnt correctly adjusted to a mile high. The truck came from kansas.

 

[Broncobowsher]

4.56 should put you into a real nice zone for the trail to the highway

 

[COBlu77]

Ryan,

Check this out http://www.grimmjeeper.com/gears.html According to this calculator you'd be at 3000 rpm at 69mph with 4.56's.

My .02 - 4.56 for lots of highway and 4.88 for mostly offroadand around town.

 

[justinoshea]

I run 4.56s and they are too steep for 37s on the highway. 75mph is 3500 rpm with T/C slip. 4.30 would be ideal for a torquey motor, but I would leave the 4.10s 'cause one ratio is a waste of $1000.

save that $ for an Altas, stak or doubler for trail use.

 

[malcolmzilla]

True 35's, 302, C4 and 4.56's rev's a bit high on the highway for my liking... I might go to 37's. Around town its fun. My 302's a dog tho.

Try the 4:10's with the 37's 1st and go from there... How fast do you want to cruise? 55-60 with 4.56's and 37's would be not too bad for rpm's...

 

[Broncobowsher]

33" tire and 4.10 is a great combo. I don't see how 37's could be good on the same ratio?

 

[rtreads]

Ok so the responces are all over the place... I think I will try it with the 4.10's and go from there. Thought I really want to be able to drive on the highway. I would like to be able to run 70 mph. That would make trips to Moab and Ouray (?) a little better.

What do you think about the MPG? I have heard from some that having sich a tall gear is the cause of my 8-9 MPG?

Thanks again

 

[Broncobowsher]

37" tires and punching a huge hole in the wind, 8-9 sounds about right. Barns are not known for there aerodynamics at highway speeds.

I think you will be disappointed with 4.10 and 37s. I know that 4.10 and 33" was a great overall combo. Friend did the same and went to just 35" and could really tell a difference. When loaded he now sometimes pulls grades in 3rd (NP435) becasue it won't pull it in 4th anymore. And he has some poneys under the hood as well.

 

[86caprirs]

I have 40's and 4.88's. Not really a hiway gear.......more for offroad work.

 

[rtreads]

I have 40's and 4.88's. Not really a hiway gear.......more for offroad work.

what do you suggest? 4.56? keep the 4.10??

So yours is too low then? 37" to 40" Is a HUGE difference in rolling distance. much more than worn 36" to new 37".

 

[starkypdx]

On the 77 I've got an overdrive 4 speed. the 4.10 w/ 33's and works great for around town and on the trails. When I run the 35" boggers it was noticeable difference.

When I calc'd the Brown Hornet with a C4 auto for 37's I figured 4.56's would be a daily driver number w/ 4.88's being more of a weekender with little on highway use.

I can't comment on how the 4.88 gearing is quite yet because THE BROWN HORNET IS DOWN....

 

[bax]

I have 4.88's with a 37'' tire. great off road and good on the streets going up through the gears. Not an interstate gear. I did have an AOD and it was great with the 4.88's and 37's I have a big motor and lots of low end so going 70 was easy. Now with the c6 a 4.30 would be my gear of choice because of the big motor. if I had less motor a 4.56 would be my gear.

 

[sprdv1]

Ryan,

Check this out http://www.grimmjeeper.com/gears.html According to this calculator you'd be at 3000 rpm at 69mph with 4.56's.

My .02 - 4.56 for lots of highway and 4.88 for mostly offroadand around town.

X2 on this one sir..

 

[A4x4Junky]

I was never able to find a gear I liked for around town / offroad as well as highway without an overdrive of some sort. With a 1:1 top trans gear you will have to sacrifice something.

Anthony