I am wanting to lift my Bronco some but not to the point where it will hurt my MPGs alot.

I'm at stock height and the 31s look so puny on a big truck. It's ashame a Ford Ranger uses the same size tire for stock. I also hate how the back is so jacked up yet the front is lowered.


I was thinking about a 2.5" lift but about $100 more I could get a 4" lift from Rough Country (from what I could tell)...OR I could get 2" front spacers....


What do yall think?

 

I did Moog springs up front and it leveled out very nicely, was cheap too and I still have the factory ride quality. I would not do that 2.5" lift, prolly wont see much gain in it. What size tire is you goal?

 

33s maybe...something that won't look to small on the Bronco now....I mean its pitiful now...looks like a fat chick with skinny legs...it just don't match

 

A few guys have stuffed 33's under the truck with no lift at all and only minor rubbing. I would look into the Moog coils if you just wanna lift the front a bit to level, but if you are set on lifting the truck, I'd go with at least a 4" maybe one with the option to make it a 6"

 

Its not the lift that will affect your mileage. Its the change in tire size that will. If you increase tire diameter the wheels cover more ground per revolution. That translates to fewer RPM's turned by the engine. If the RPM's turned by the engine drop too low at regular cruising speeds, it will push the engine out of it s optimal power band. This causes the engine to actually work harder to achieve the torque and horsepower because it is not spinning fast enough to put the power to the pavement.

So, lift all you want... just RE-GEAR the axles appropriately when you change tires sizes. This is the most critical and most often overlooked REQUIREMENT when increasing tire sizes.

 

With that, do you feel it is necessary to re-gear going to 33's?

 

Yes, as a matter of fact it is. Do the math and it becomes obvious. Unless you happen to have a Bronco equipped with a relatively rare 4:11:1 gearing, 3:55:1 pushes the 302/351 well below power band making it necessary to either keep a manual in a lower gear longer or causing the automatics to "hunt" gears incessantly especially at 30-40 mph cruising speeds.

 

Hmmmm.....when I had the '95 EB automatic, I put 33's on it and had no issues at all. I would bet it had the stock gears too. I drove that one a bunch and did not loose much at all, plus the odometer was adjusted for the tires.

Anyway, was just wondering.....thanks.

 

manfred, i take it your looking to do this on your 90 bronco with the 300-6. let us know what gears are in that bronco. some 300-6 equipped broncos had a very tall gear ratio like 3.08's for instance. if you where to go to a 33 with this ratio it would KILL mileage.

azpete, if the speedo was calibrated to the size tire that will help to some degree but still put the motor outside its optimal power range. you probably lost at least 2mpg both city/hwy driving.

 

I KNEW the issue the minute I drove my 92 (same transmission as a 95 would have had). Gear-hunting, lousy passing and hill-climbing power and sucked down fuel like it was water as well. 3.55's with 33's

Just to show what I mean:
60 x 3.55 x 336 / 29.5 = 2,426 RPM (60 MPH x axle ratio x constant x actual "31" tire diameter)

60 x 3.55 x 336 / 31.5 = 2,272 RPM (same thing using actual "33" diameter)

You are already well below the typical small block V8 power band with 33's here and look what happens when you throw in the fact that the E4OD has a 0.71:1 overdrive gear in the fourth slot.

60 x 3.55 x .71 x 336 / 29.5 = 1,722 RPM (.71 OD ratio which kicks in unless you disengage it).

60 x 3.55 x .71 x 336 / 31.5 = 1,613 RPM (and now you are down to just over 1500 RPM at cruising speeds?! When/where does the engine get to build some torque for passing or hill-climbing with this setup? Certainly NOT at 1600 RPM.)

Now in all honesty, the 300 will actually fair better with shorter gears simply because is reaches peak output at about 2200-2300 RPM which is 300-500 RPM LOWER than the V8's.

 

Good info....I have some 30" tires on it now which I detest the look. I plan on 31-32's when I have to replace them. The speedo reads 10% fast now so the increase in size should fix that. The 33's are just a bit more than I want on this truck.

Oooohhhh the fun.....

 

I've known about the taller tires with not the right gear ratio does hurt it to a point but I am wondering, if I get bigger tires with the right ratio...with it affect my gas mileage at all?

 

You're always going to sacrifice somwhere. If you gear it for the bigger tires then you are losing a bit of MPG at highway+ speeds. Not that that should be a huge issue for most of us.

 

I have Moog front springs......33" tires and a 300 I6......with 3.08 gears and 5sp trans....it pulls them well with little notice in fuel mileage......but I don't run it on long trips......I am going to put 3.55's back under it to compensate......I do need a lower 1st gear with it

 

I was surprised when I installed a 2 1/2" RC lift. I got a lot more lift than I expected. The only problem with the 2 1/2" lift is 33's are the max. tire. With 32's stock gears were ok. When I went to 33's I couldn't stand it, I ordered gears within a week, it pulls good with the 4:10's. When I bought the Bronco it got 13.5 mpg. average, with the lift and 33's and 4:10's the average is now 12.5
Kenny


stock height, with 15x8 wheels and 32's

2 1/2" lift, the same wheels and tires.

2 1/2" lift, with 15x10 wheels and 33's