Replace 6th Gear

It would be interesting to know if anyone would do this and the cost. My guess is that the cost makes it prohibited as it takes two gears for each range. My suggestion would to put 6th into 5th and make a taller gear for 6th. Current gearing.
Trans Type 6 Trans Description Cont. Manual First Gear Ratio 1) 4.17, Second Gear Ratio 1) 2.19, Third Gear Ratio 1) 1.49, Fourth Gear Ratio 1) 1.19, Fifth Gear Ratio 1) 1.00, Sixth Gear Ratio 1) 0.85, Reverse Ratio 1) 3.61

 

There is a reason its geared the way it is, Toyota has engineers that do this for a living and they aren't stupid I can assure you. I used to drive a 92 dodge ram with a 1st "crawler gear" which you wouldn't use on the street normally. 5th was the overdrive gear for highway. The problem was if you encountered any type of hill or incline you had to downshift to have power to go up it. Its annoying and even more so if you have any weight in the truck.

I guarantee people will be complaining if they had to downshift at every hill which is why its geared like that.

 

It is not about Toyota engineers being stupid. I have worked with engineers most my life and many times they do things just because as it gets their name on the design. They have a window to work with and they do just that. Since I have a 6 speed I know the top gear is too low and 5th is too close to 6th. It would not take a lot, but at least some.
Since 6th is currently .85 a .80 or .75 might help the truck on the HWY. It would need to be calculated at RPM. I assure you it has enough power for such a change and still make normal hills.
I agree if someone is doing a lot of towing it might not be advisable, but for HWY driving the change if possible would be nice if it is affordable.

 

I would love to be at 2k rpms at 75 mph. drove 2 weeks ago to Savannah, and was spinning 2900 RPMs at 80 mph. I got 16 MPG on that trip.

Thats the same mileage as our 07 suburban 4x4 with 5 people plus cargo.

 

I am trying to check and see if a gear change is even possible. I have made some calculations on current MPH verse RPM with stock tires (265-70-16) and stock main differential gearing (3.73).
1st gear at 2000 rpm 11.71 mph
2nd gear @2000 rpm 22.29 mph
3rd gear @2000 rpm 32.77 mph
4th gear @2000 rpm 41.03 mph
5th gear @2000 rpm 48.82 mph
6th gear @2000 rpm 57.44

If you change 6th to a .80 @2000 rpm 61.03 mph
If you go to a .75 @2000 rpm 65.1 mph.
If you go to a .65 @2000 rpm 75.11 mph, but I would guess this much change would tax the engine without a supercharger

 

agreed. 2000 Rpm at 75 mph would be ideal

 

Yet the I4 Stick, with a lot less torque has higher gears than the V6 stick.

Those engineers can't be right on both choices. I'm not downshifting my I4 at every hill, and there are lots of hills in Colorado.

 

No engineer here but wouldn't putting bigger tires make the rpm less at speed, although there are other factors, weight in such that would effect. Anybody with bigger tires that can chime in on this, I'm just shy of 2500 @ 75 on stock tires

 

The idea is not to just lower the RPM, but increase MPG. Larger tires lower MPG.

 

This!

 

wouldnt that depend on the tire, I put larger on my 09 base that where a/t and only lost 3/4 a mpg but the #s are based off a mileage log which would have also changed. I checked the ol' fashion way, by mile markers, the stock tires were off, tracking more miles then driven. New tires were dead on. Still wondering what rpm it would be at with larger tires, there got to be someone out there.

 

I checked with a company out of CA. called Specialty Gear & Transmission. They told me to their knowledge it is not possible to re-gear a standard transmission with different gears. I don't know if that is correct, but that is what they said. I have had other say it can be done but they do not know of anyone who does it, soooo. Others can also check if they like.

 

Here is a program that can give you the RPM, based on tire size, but you need all the variables to be accurate. I suggest a GPS to get the actual MPH speed.
http://www.bgsoflex.com/rpmmph.html

 

You can not change the 5th gear ratio it is what it is. 4th gear in a 5spd. can not be changed either they are not gear derived it is directly coupled to the input shaft. 6th is possible to change but in doing so you will lose the ability to tow in 6th. 1st is not that low it will do 30mph in 1st that being said it also makes towing a lot easier on the drive line and clutch. If you have no need to tow get the automatic.

 

Or perhaps a shorter reverse? I mean I cant remember the last time I needed to do 50 mph in reverse, but uphill in the snow or towing potentially means a lot of burning

 

Still not answered - can you swap internals from an FJ aisin 6 speed transmission into a Tacoma 6 speed ?

 

Pretty sure no answer after 3 1/2 years means 'No.'

 

Yeah my bad someone linked this thread in with the other 6spd thread and I replied without looking at the dates haha

 

That was me, but I'm glad you've bumped it. I'm still not satisfied that this is or isn't do-able.

I'd be happy to shift down into 5th for more power if my 6th dropped the revs (and hopefully upped the mpg).