[BFix] Gearing for Best Mileage

Sun May 4 20:36:01 MST 2008

All good points. I really wasn't considering a 5 mile long hills but they are out there. One thing I liked when I had my 33" tires was I really didn't need to pull it out of OD for most hills. But then I got thinking that OD is for flat open travel. In every other vehicle I've ever driven I needed to down shift out of OD on really big hills (steep / long grades). So I figured I'd set the Bronco up to do the same. I've pulled some good long grades in PA, NY, NH & CT and yes, lost some speed but all in all held my own in OD. If I wanted to gain speed I'd down shift. Isn't that what OD it's for? To give you a little more gearing for the flat open road and drop the RPMs to try and conserve a little fuel and ware and tear?

Ken

 68 EB 5.0L / ZF 
35" BFGs / 3" Lift
4.56 ARB Front & Rear

----- Original Message ----
From: Brian Cooke <nvrstuk at elltel.net>
To: FRANK w <bbronko at msn.com>; bfix at broncofix.com; Ken <broncokak at yahoo.com>
Sent: Sunday, May 4, 2008 7:43:12 PM
Subject: Re: [BFix] Gearing for Best Mileage

Depends if you want to go a bit slower off road AND if you  want to be able to climb any freeway hill in OD.

I ran a 351W with 4.10's and 35" M/T's for close to 8 yrs.  I'd shift down (out of OD into 4th) on 6% grades or more to accelerate at  all.  Since I have a doubler for low gearing it really doesn't matter what  rear end ratio I run for trails but it really does for street.

I ran a 351W with 4.10's and 37" SSR's for 2 years. I  still had to shift down on 6% grades or more just to maintain  70mph.

I just put in 4.56 gears with the 37" SSRs (6months now)  and I still have to shift down on 6% grades or more!  :)

My buddy runs a very stout 351W stroker, now a 408 with  4.56 gears and 37" M/T's and has to shift down on the same 5 mile long 6% grade.  He's dyno'd over 425 HP, so gearing makes a HECK of a difference.

Long story short....     I'd suggest  the 4.88 gearing with the ZF and 35" tires.  Especially for lower gearing  off road if you aren't running a doubler or equiv.

Brian @ Columbia River Broncos...20 forward gears & 4 reverse to choose  from.
----- Original Message ----- 
From: FRANK w 
To: bfix at broncofix.com ; Ken 
Sent: Sunday, May 04, 2008 3:07 PM
Subject: Re: [BFix] Gearing for Best    Mileage

So if you were to keep the 35's all the time would you stay with the 4.56    or would you go with the 4.88. I have a 5.8, ZF 5 speed, 35" tires and    getting ready to buy gears. I thought of going with the 4.88's. Thanks.

Frank 

----- Original Message ----- 
From: Ken 
To: NHieger at aol.com ; q.dusenberry at comcast.net ; bfix at broncofix.com 
Sent: Saturday, May 03, 2008 4:21      PM
Subject: Re: [BFix] Gearing for Best      Mileage

I have a 5.0L Explorer motor and the ZF 5 speed, 4.56 gears and 35"      tires. When I drove to VA for the Round up last summer I constantly got      20MPG on the hi-way if I kept the tach below 2500RPM (70MPH) the worst I got      was 13MPG and that was traveling at 80MPH. I too thought about going with      the 4.88 gears but after driving both on road and off. I'll keep the 4.56      gears and maybe run some 33" street tires for all the around town drive I      do.  Last fall I drove about 75 miles from home (150 round      trip) to run with some J**p guys and spend 6 hours in low range and      only used 7 gal.s of gas. I've never really checked the mileage doing around      town driving but I'll have to some day.

Ken

 68 EB 5.0L / ZF 
35" BFGs / 3" Lift
4.56 ARB Front & Rear

-----      Original Message ----
From: "NHieger at aol.com"      <NHieger at aol.com>
To: q.dusenberry at comcast.net;      bfix at broncofix.com
Sent: Saturday, May 3, 2008 5:23:35 PM
Subject: Re:      [BFix] Gearing for Best Mileage

FWIW, I have 4:56's in my 77 5.0 sefi/AOD, 35" BFG's. Everything was      pretty good when I was running 33's, but now that I am running 35's I kind      of wish I had gone with 4:88's. I just seem to be a bit over geared when on      long extended climbs at freeway speeds & heading into strong winds. What      I need is gear right between 3 & 4th. Having said that if I keep the      speeds down (55 or less) I can get around 17 mph.

Norm

In a message dated 5/3/2008 11:50:04 A.M. Pacific Daylight Time,      q.dusenberry at comcast.net writes:
Thanks for the        reply. That sounds about right to me. 4.56 for 33 with OD and 4.88 for 35        with OD. I'm tempted to go with 4.88’s in the event that I end up with        35’s in the future.

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