08 SR5 V6 4.0 Re-gear

MarkinWMich said:
It sounds like if I decided to go with the 4.56s, then all I would need a different speedometer gear to achieve correct readings? I have the A750F ECT-5spd auto w/OD.
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some guys are using a "speedo healer" SpeedoHealer Calibrator V4 Black Box Only - SoloMotoParts.com

it wires in and corrects what the the computer sends out to display on the dash.

I can't say its necessary.. after regearing to 4.56 and running 33's my speedometer is off by maybe 2mph.. really not much of an issue at all. you can always run down the road with a GPS that monitors speed to see how far off you are after changes. then just know that 60 really means 58 or whatever the difference winds up.
 
Jumping in late here, but my experience and 2 cents....

I re-geared my '07 to 4.56's since I was running 33's. I also used it as an opportunity while doing a Torsen install in the rear and ARB up front.

I definitely saw a loss of power when travelling (especially with family loaded up with cargo in the back and a box on the roof). Truck would hunt gears on all inclines. Offroad I felt like I was in between gears, climbing an incline felt like was was in gear 1.5 - not in second, but not quite first. Was the stock gearing acceptable? Sure, but it definitely left me wanting.

Even around town I felt like getting off the line was more stressful on the tranny. Now since doing the swap the truck is no longer the daily driver (just worked out that way), and we've added another larger SUV to the stable so family travel isn't as important. But travel around town is much more manageable with good acceleration, towing is much improved and confidence inspiring, and highway driving isn't bad at all. Yes, the RPM's do turn a bit higher than stock gearing(~2300 rpm @ 70 vs 1900, 2050 rpm stock gear/tire), but it's actually usable on the highway. No more giving it a bunch of gas until it downshifts and hauls off or manually selecting gears. Just roll into the throttle to accelerate and merge like a normal car.

BTW - I went with ECGS' service. So simple to swap these out and very well done job by them setting it up.
 
So, it sounds like the 4.88s are not as "aggressive" as previously thought. If you are running 4.56s on 33 inch tires and at 70mph you are turning about 2300rpm, then 4.88s on 32 inch tires would be around 2500rpm at 70mph...give or take. That's not bad at all. I don't drive the beast much faster than 70 anyhow.

The beast has 130,000 on it, gently used for the most part. Do you think I would need new axles and differentials, as well, during the swap, especially if using aftermarket parts?
 
would it be safe to assume that with 35's and 4.56s' rpms at 70 would be closer to 2k? I'm looking at doing the fj 6" and 35s down the road but don't off road too often so id be more conceded with on road rpms and highway rpms
 
MarkinWMich said:
So, it sounds like the 4.88s are not as "aggressive" as previously thought. If you are running 4.56s on 33 inch tires and at 70mph you are turning about 2300rpm, then 4.88s on 32 inch tires would be around 2500rpm at 70mph...give or take. That's not bad at all. I don't drive the beast much faster than 70 anyhow.

The beast has 130,000 on it, gently used for the most part. Do you think I would need new axles and differentials, as well, during the swap, especially if using aftermarket parts?
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If you're not much of a highway driver then it may be acceptable for you. It does leave you room for future upsizing.

No need for new hardware if you don't need it. Just new seals while you're at it (OEM!) I would advise to definitely go with the solid pinion spacer as it's good insurance and consider the cost advantage to do ARB or LSD install while at it.
 
i have a 3in lift and 285/75/16 nitto trails and want to regear with a locker should i get a 4.11 or 4.56 gear ratio i just want my power back 2004 v6
 
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