Regearing after new wheels and tires

Recently installed a rough country 4" lift, 33"x10.5" tires on 17" wheels. I've been noticing a pretty significant rumble and vibration when I go over 25mph or when I'm under 5mph (i.e. rolling through a parking lot). A friend of mine told me I should look into regearing the differential to resolve the issue. I've been doing a bit of research on this topic and it seems like it would help but I'm not sure what the best fit would be. I've been seeing alot of 4.88 for 2nd gen and 5.29 for 3rd gen Tacomas. I have a 2012 4x4 TRD automatic that I plan on eventually adding some weight to (bumpers mostly) and using to tow a small-medium size boat with. Also, after looking at the drive shaft while switching between gears, it has roughly a quarter of a turn of play in it before it catches. Could this also be a cause?

UPDATE: so installed new u joints, vibration still there. Beginning to lean towards the idea of improper driveline angles. But that's way outta left field for me as far as how to correct it. Side note; regearing the dif to 4 56 sounds like a much more viable option after looking at the conversion with the new tires. But that will come later.

 

1/4 turn sure deems like a lot.

 

Sounds to me like an issue with your driveshaft. Try greasing your U-joints first if that hasn't been done in a while. If it's still an issue, I'd pull it off and check out much play the U-joint have in them. Maybe one or more of them needs replacing.

 

I'll make sure to give that a look. Thank you

 

I wonder why 3rd gen owners regear their vehicles lower than the 2nd gen owners because 3rd gens do have considerably more power. 3rd gens look lighter too but I don't have a clue if they are lighter.

Axle wrap resulting in a driveshaft vibration possibly? 1/4 turn is way too much play, it could be u-joints or a problem inside the 3rd member as well. You're going to need to see what is and what is not turning while analyzing that 1/4 turn play.

 

Your issues are not related to your axle gear ratio but likely lift related due to improper driveline angles. What type of lift are you running?

 

I'm running the 4" tacoma lift from rough country.

 

Is that a drop bracket lift?

 

Not sure what you mean by drop bracket. Sorry I'm still kind of new to everything lol

 

it would have to be. If not his cvs will be shot soon.

 

Like uncle K said, gear ratio has nothing to do with it. See where that 1/4 turn of slack is coming from, that should be where the vibrating & rumble is also coming from. 1/4 turn just seems way too much. Of course, just my opinion.

 

From what I’ve read it has to do with the transmission gear ratios for f the 3rd gens. The rpm stay too low to put it in a better point of the powerband.

 

Gear ratio correlates with tire size, with 33s stockish power would be around 4.11 assuming you started with the 3.73. I have 4.56 and 35s and it's still a little torquey.

4.88s would be a hell of alot.

 

Good info. Transmission type will also make a big difference. 2nd gen auto transmissions run around 2200rpm on the freeway at 75mph with stock gears and tires where manuals run closer to 2600rpm with the same stock setup.

 

Yea If I'm strictly highway miles and stay at 75 mph I can squeeze almost 18 mpg which I think is decent for 35s and a 6ish inch lift. At 75 mph I'm pulling 2500 rpm. More information for your decision.

 

i have a 2012 with 33.6" tires mid-travel Radflo setup. I have had a number of these problems and it has nothing to do with re-gearing. First off there was a revised transmission/transfer case mount toyota released based on complaints and a TFB. I have some MTR tires that were out of round and one took 11oz of weight during a 3500 mile trip it destroyed my carrier bearing. Take it to a Driveshaft place they can put it up on a lift and run the car. My 3 out of 5 tires were out of round on my truck with only 3500 miles. I run a high clearance bumper with tire and 2 6 gallon containers which will cause my truck to oscillate at about 55-60 mph because of the swing gate FYI. To deal with my larger tires and pulling 5th on the highway and because I'm running fully armored rig with camper I will go to 4.88 gears later. Borrow someone elses tires or take them back to be balanced again. Toyota's are hubcentric and sometimes the balancer won't use the adapter and it will be off.