HELP: Which Gear Ratio?
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Senior User
Joined: Apr 2004
Posts: 283
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From: Bogota, Colombia
HELP: Which Gear Ratio?
Hi all, I currently own a 1994 fullsize XLT 5.0L (302), E4OD, 3.08 gears, all stock. In addition, I have the Compressed Natural Gas tanks in the back which add an extra 400lbs to my truck's empty gross weight. In my town we have an altitude of 8.000ft, plus lots of hills and heavy traffic. With the natural gas equipment on (50% savings on fuel costs) power is reduced by about 30%, and even with regular gasoline on, my truck struggles driving uphill (especially with passengers, of course) towing or even when resuming driving after a traffic light (with the CNG on, though). I was initially thinking on upgrading to a 351W via an engine swap, but I have ruled out this option ($ issues) in favor of a change in gear ratio. Now, given the above explained situation, which gear ratio should I get?: 3.53, 3.73 or...? Thanks a bunch...!
The Southernmost Mod
Joined: Dec 2004
Posts: 6,902
Likes: 21
From: Caracas, Venezuela
It depends on wich tire size you're running, you probably should be using 31 x 10.5, wich would run nicely with 3.73 in normal conditions (that's the ratio that came stock on mine), but since you're having that much trouble, i would put at least 4.10 or 4.11, remember you should match both front and rear.
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
are you sure about that 3.08 ratio. i bet you have 3.55 gears as those where the most common for that year model with you engine combo. the 3.08 gears were mainly in the rigs with the 300-6 motor.
i would also think a motor swap would be cheaper then a gears swap or pretty close to the same the only difference is you can do a motor swap vs a gear swap will need to be done by an experienced mechanic.
i would also think a motor swap would be cheaper then a gears swap or pretty close to the same the only difference is you can do a motor swap vs a gear swap will need to be done by an experienced mechanic.
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
I'll second Kem's response regarding gearing in the truck already. And I will second/third Encho and Conanski's comments about 4.10's. Just keep in mind when you do the swap that the 8.8 rear axle and the D44 front axle will not get identical gearing. The 8.8 gears will be .01 taller and this is true across the board. In other words if you put 4.10's in the front the closest you will get in the rear will be 4.11's. This is just the nature of the gearing setups fro the two different axles.
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Senior User
Joined: Apr 2004
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From: Bogota, Colombia
Uh, yes, I forgot to mention it, I am running 235-75R15 tires, which give me better handling than 31x10.5 R15s, which my rig had when I bought it. I have the Venezuelan version of the Bronco, all of which came stock with 3.08 gears since Venezuela is around sea level with very few hills as opposed to Colombia, aside from the much cheaper gasoline. My first Bronco (2001-2005) was a carbed 1992 300 BB6 C-6 with 3.08 gears, and as a result, I don't see much of a difference between the 302 vs. 300. Maybe I would with a 351, a 460 or a stroker. The thing is that a used 351W EFI costs about $2.000 down here, whereas a carbureted, older 351W costs about $750. I do need the EFI since I'm running mostly on Natural Gas. I do have a great mechanic however, which also happens to be a Ford expert. The idea is to get better torque and power but not to the expense of mileage (too much, anyway)...
Hotshot
Joined: Jul 2002
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From: Bend,OR
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The Southernmost Mod
Joined: Dec 2004
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From: Caracas, Venezuela
Well, mine didn't have 3.08, it had 3.73 (has), i've already oppened the differential and changed my gears (not myself that time, but i searched for the replacement), so i know what i'm talking about here. This just means not all Broncos in Venezuela (bought in the country's Ford dealers) had 3.08. Btw, we also share a part of Los Andes, wich means we also have high grounds around.
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Thread Starter
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Senior User
Joined: Apr 2004
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From: Bogota, Colombia
Well, let's not make this discussion a binational dispute as our presidents have engaged in for many years... I know there are hills in Venezuela like in Merida, etc., but I usually drive from Bogota toward lowlands or highlands with very steep roads (roads are much better in Venezuela, of course). Now, the Broncos assembled CKD in Venezuela (Valencia, I think?) for the Colombian market have mostly 3.08 stock gears and parts dealers usually have replacement for 3.08s only, in my experience, yet with the junkers you can find second-hand imports from the US and Venezuela...
Junior User
Joined: Mar 2010
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what do ya'll thnk of this.... buddy at the fire house who is a pretty stinkin knowledgeable mechanic mentioned rpm's t highway speed.
i told him that im running 2000+ rpms at 60 mph. he said he wouldnt mess with them then. if i was running 1500 or so then yeah. change em.
sorry bout the grammer errors, holding a baby and typing one handed.
edit:
running 37's
i told him that im running 2000+ rpms at 60 mph. he said he wouldnt mess with them then. if i was running 1500 or so then yeah. change em.
sorry bout the grammer errors, holding a baby and typing one handed.
edit:
running 37's
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
There is no way it's turning 2000rpms at 60mph in overdrive with 3.08's in the axles and 37" tires. Either the truck has 3.55 gears and your're not using OD or the tachometer is completely messed up.
The Southernmost Mod
Joined: Dec 2004
Posts: 6,902
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From: Caracas, Venezuela
Tx, the problem you have running such big tires with 3.55 (if i recall right that's what you have) is you're really overworking your engine and tranny with your current setting. You'll see both gains in mileage (you won't be pushing the engine so much) and perceive a lot more power if you go with 4.56. You also will be breaking less things...
Junior User
Joined: Jul 2009
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just wanted to get some feedback, I am in the process of rebuilding my 8.8 out of my 94 Bronco which has the 3.55 gears. I am currently running 33 inch tires with a 3" lift and was wondering if I should put in the 4.11 gears or 4.56 gears. I am planning on putting the truck on 35's but not for maybe a year. I also will be swapping out a Ford posi diff inplace of the open diff and also would like to get input how difficult it will be.
Thanks
Thanks