I dropped my truck off this morning. Getting my gears changed out from 3.55 and going up to 4.56. I currently have 33" tires but will be getting 35" next time (if the 33" BFg's ever wear out). I checked with some of the calculation links that have been posted on this site to see what range I will be in. If I read it correctly, I should be slightly better then stock, which is what I was going for, to get some more umph. The truck is not my daily driver but I'm still hoping my highway mileage will not be effected that much and hope to gain MPG in the city driving.

Does anyone have 4.56 with or around a 33" tire? Thanks.

 

4.56 is going to be a bit high for 33" tires, but should work good for 35's.

I have 4.10s in the ranger and they were perfect with 33's. Now i have 35's and would like to switch for 4.56s but i scrapped that idea since i am probably going to sell it.

 

yeah, I figured it was gonna be a gamble going that high with 33" tires. But I think I made the right choice since it's not my daily driver and since I do plan on going to 35" eventually. Thanks for the info.

 

I think you will be fine, Bud. I know what you mean about wanting more go. I spend most of my offroad time in the sand to get away from everyone and fish in peace. I was gonna do the same as you with my 33s but I changed my mind and went with the fabtech 6 instead of the rancho 4 so I bought new 35" tires. I bought 4.88 gears now. i havent insalled this yet but Im planning on getting it done the day after I get home, (three weeks from now). My truck is no longer my daily driver also. I asked MANY questions about this to anyone who would answer and most said they woud want the same if their truck wasnt a daily driver. You will lose some mileage but I know none of us bought a truck because of the fuel economy.

 

I just got 4.56s put in with my 37s, it put me almost dead nuts on stock

 

I think you're gonna be real happy with them 4.88 gears and 35" tires.

1BDF150, that's a sweet truck man!

Thanks to everyone else who replied-

I just got back from pickin up my truck and I am very impressed with how the truck responds with the 4.56 LS. I was pretty surprised to see I was doing 85 mph and getting passed like I was doing 60... oh wait... I probably was. I just made the adjustments with the XCAL2 and went for a test drive again, much better now.

I was doing just a lil over 2000 RPM's at 70mph. I guess that is rather high rpm's at that speed but I was expecting that. The truck takes off from a start much better but the biggest surprise was how responsive it was while doing 70mph. I was worried that 4.56 was a bit tall for 33" tires but I think I made the right choice. Hopefully these gears will still do good for me when I eventually get 35" tires.

 

I'm debating on the same thing man...4x4 ext. cab 4.6L 5-speed with the heavy Flareside bed and 33's on 3:55 open diff. As it is I'm running 2075 RPM @ 70mph corrected with the Xcal II. The calculators say that I'd be running 2665 RPM @ 70mph if I ran 4.56 gears, and I regularly run 75-80 so I can't make up my mind. That would put me @ 2900 RPM over 75mph. Is it hard on an engine to turn it that fast for long periods of time?

Many 2WD and Lightnings run 4.10's, but then again they have the auto tranny so they turn fewer RPM's than I do right off the bat. I take it you found it to be well worth the $$$ spent? Sucks that you have to turn right around in 500 mi. and drain / fill the diffs. again. I'm hoping they can refill with the Royal Purple that's already in there (20K mi. new) and I can replace it after break-in.

 

hmm, that's a tough one man. I'd say since you run 75-80 mph regularly, and if you plan on keeping the same size tires, maybe look into 4.10 with the limited slip. I think you'd be quite happy with that set up. I think you hit dead on by stating you'd be turning higher RPM's with the 5 speed.

I'm not sure if running at that high of an RPM is hard on the engine or not. I had read on here that it's not that bad to to run the gears I have with the size tires I have since I have the auto tranny. But like I said, my RPM's are a bit higher then where I would like them to be as of right now, but I do plan on switching to 35" tires. The truck is much more fun to drive around town though so IMO it was money well spent. I have 90K on my truck so I suspect I would have had to get the rear rebuilt in another 20 - 30K miles anyway.

 

Did you go with a Ford LS or aftermarket? Prob. just had the clutch packs replaced on the factory one huh? Yea, there is an almost 300 RPM difference between the auto and manual tranny with otherwise identical setup. In fact, I just realized something:

Auto w/ 4.56 = Manual w/ 4.10

I can't imagine trying to move these meats with an auto 3:55 setup. Especially one that hasn't had Mike's tuning, e-fans, pulleys, intake / exhaust. The 5-speed makes up for not having the 5.4 in the final drive ratio as well as driveline paracitic loss, especially with the Hurst prototype in there. Almost everything I've done so far maximizes throttle response, so I bet gears would just make a world of difference.

I'd like to go 35's, but I had to trim my lower valance as it is because these are so much beefier than the regualar 33" AT's, (switched from ProComp AT's to the X-AT's) so I doubt they'd fit without a minor lift.

 

I went with Precision gears. I've heard both positive and negative things about them so we'll see. Precision seems to be a fairly popular, aftermarket product so that is why I went with them.

You're right, having the XCAL2 is the best mod I've done by far, it was awesome to be able to get home and make the changes in the gear ratio myself using the XCAL2 and then take her out for a spin. I'm envious of the mods you have done, I'd like to get that set up eventually as well, one thing at a time right....

 

That's no kidding man, I've had her paid off for over a year now and haven't been able to get much accomplished like I thought I would. Mostly because I've done the cheapy mods and anything more would require lots of time / money and serious surgery. I also can't stand to let other people work on my truck so I'm hesitant most of the time. I don't have squat for mods like many here do though. At 64K miles I am very happy with it the way it's setup though. I've already had the pass. side head gasket replaced and the driver's side is barely "seeping" so when that goes I'll prob. rebuild the top end and do some head work and cams. Think I'll head down to the gear shop and see if he can't talk me out of some money. Thanks man. ...I think.

BTW, isn't Precision OEM Ford parts too?