6 speeds, can we drop out interstate rpm's with differential gearing ???

Haha...chill out, man. I assumed you wanted to lower RPM to get more MPG, in which case driving slower is an answer...it's just not the answer you want to hear. Which is why I also included the statement about the cost of regearing vs the cost of gas savings...which you also don't seem to like. But, since you want to go real fast regardless of cost, nevermind all of that. Sometimes it takes me a while to catch on.

I do feel your pain on one issue, though: Wanting something for your truck that isn't readily available. That does suck. Especially something you can't just make. Good luck...I won't mess up your thread anymore.

 

no you must change the front with the rear... problem is the way the OP wants to go no one makes gears that are a higher gear ratio <3.73 for the fronts... as NO ONE does this.

Like everyone stated.... get taller tires..

Or buy a truck with an auto ... no other way

/thread

 

Plenty of people run the Gear Vendors (and other brand) overdrive units only in the rear of 4x4 trucks. No, you can't use 4wd in this mode. 4wd really isn't an advantage at high speeds anyway. The folks I know that do this are driving diesel F350s and towing (gooseneck 4-horse) 8000-12000 pound trailers. They have appropriately low-geared axles front and rear for that purpose. The overdrive is for low or no-load trips, so the engine is loafing along at normal highway speeds.

Larger tires hurt braking and steering, and the effects are worse at higher speeds. This is a poor solution for high-speed highway cruising. Gears are the best way to get there safely.

Mike

 

I'm surprised no-one has came up with the obvious answer...

DON'T change the rear-end gear, change the TRANSMISSION 6th gear ratio.

It only changes 1 ratio, not all of them... And no trying to match-up ring gears for both pumpkins.

 

How much lower do you really want to go? At say 75 to 80 what rpms are you planning on reaching

 

FWIW, 2012 Tacoma gear ratios...

 

Those Gear Vendor guys look legit, I'd like to see someone with a 6spd Tacoma with one of their setups and what results they got. Quite pricy though.... STARTING at $2,800 yikes! Plus install and driveshaft!

 

How does one go about doing that?

I've also heard there is different model transmission that swaps in...

 

Bigger tires


To change the 6th gear ratio, you must pull the tranny apart. Change the gear on the main shaft, and the gear on the countershaft.

This isn't the taco trans, but it's the exact same idea.




...aren't manuals' cool inside?

 

Though I applaud the effort, with the poor aerodynamics of the truck I doubt you'll see much if any change in mileage and it would basically make 6th gear useless for towing or hauling at speed.

Now if you did a supercharger + tranny gear changes that might be a very interesting result....

 

Another option might be to use the transmission out of an FJ Cruiser. The final gear is higher than the Tacoma.
http://www.google.com/url?sa=t&rct=...4IG4Aw&usg=AFQjCNHMILQmIKwHjDW2KJEdkaCKfEYXEQ

 

Use a top speed calculator, a change from 3.73 to lower 3.1ish will only get you going 13 mph faster at the same RPM. But that is before aerodynamics and powerband come into effect.

Dont know if you posted this but if your are not concerned with mpg then what does it matter if your RPMs are 800-1000 lower?

 

I really don't believe you'll gain any thing by using higher gearing the main reason the auto reportedly gets better mileage is due more to transmission computer management than gearing. If you tow any thing you will soon find out that any thing below 2,000RPM won't cut it because the torque just isn't there. At highway speeds in 6th you can still use 6th gear while towing because the revs are high enough. The 6 produces it's power between 4 and 5.5 thousand RPM both in torque and HP so I guess what I am getting at the 6 spd is using a more efficient engine speed during highway use. I have no problem getting the same mileage as the automatic with my 6 spd but I am in an area where even the 2 lane roads are traveled at 55-60 mph. I just think the expense and trouble will ever be worth the effort.

 

I haven't seen this mentioned yet but when changing any gearing you'd effectively have to re-calibrate the speedo to be correct otherwise you're still getting false readings. sure rpms are nice but as others mentioned none of the taco engines are great at low rpms. torque and hp curves are above 3k for optimal performance but above 2.5k is diminishing returns on mpg. and having to shift/downshift more to meet speed is what kills (us people that live in hilly areas can attest)

and yes not all larger tires/wheels are worse, going up one size but decreasing from steel to aluminum actually saves weight. i noticed a difference going from AL to steel wheels to burn off winter treads.

edit: and changing gearing on the rear only is kind of a detriment on a 4x4 (why have it), unless you never plan to use it again, then just trade it for a PreRunner and do w/e

 

And you thought rear end gears were expensive---

 

I didn't read through this thread so I don't know what you are trying to achieve but I'm assuming fuel economy.

I went from 3.73 gearing to 4.88 gearing. With my 33" tires my rpm at 75 mph went from 2000 to about 2800 and it did not affect my mileage at all.

The motor has more of a mechanical advantage over the wheels with the lower gears so even though I am running at a higher rpm I now need less throttle to maintain speed and the two seem to have balanced each other out in terms of fuel economy.

If you gear higher you will see a lower rpm but it will lower your mechnical advantage and you will need more throttle and I'll bet you see no noticable change in fuel economy but you will notice the loss in acceleration and possibly see yourself having to down shift more on the interstate.

All car companies are under a lot of pressure to get the fuel economy as good as possible. Toyota had the option to run higher gears in the diff and went with 3.73's. I'd be willing to bet that was the ideal ratio for the vehicle to get good fuel economy at 75mph. If anything they would have geared the 6th gear higher but they didn't because you would be down shifting more and probably loosing mileage.

If you were going to a much smaller tire then it may be beneficial to regear higher but staying on factory tires I don't think you will see any gains from regearing only losses...

 

Actually, getting the tranny 6th-gear swapped out shouldn't be any more expensive than the 3rd member.

I can get it done (the exact 6th-gear swap we're talking about), albeit in my AUDI (which has a horribly low-geared 6th), for ~$700 plus install (6-7hrs @ ~$100/hr).

All said, that'd be about $1500... Actually cheaper than some peoples quotes (on this forum) for having the rear pinion swapped.

So I can't see it being much different (ie: more expensive) than a Tacoma. My S4 is ridiculously expensive to fix/upgrade...

* and these aren't custom gears, factory VAG (Volkswagen Audi Group) parts only available from Germany.

http://jhmotorsports.com/shop/catal...r-b6-b7-s4-rs4-p-1192.html?cPath=21_56_61_105

 

I think you are mixing up the just the rear price for the front and rear price. You can have just the rear done for a little over $700.

I paid $2250 to have my front and rear done and $900 of that was for the ARB in the front, so like $1350 with shipping and a few extras.

 

They are a much smaller gear set and you don't have to remove and completely dismantle the transmission to change them in the Audi. I'm not even sure you can buy a different ratio gear set for the Tacoma. The Audi trans is used in many different applications including the diesels so there are many different combinations of 6th gear ratios.

 

I'm sure someone has already chimed in with this, but honestly I'm too lazy to read through all 3 pages... You might see a minimal gain in mpg, but after you consider the cost of purchasing and swapping gears for 2 differentials, you'll have to drive close to 100,000 miles before the gear swap starts paying you back. At a 2mpg increase (which would bring us in line with the autos) figure about a $20 per 1000 miles driven @ 3.50 a gallon.