Re-gearing to use 5th gear when towing

Since my truck is used a lot for towing, work and play, I wonder if it would be a good idea to re-gear. My trans code is A04A which I believe is 3.73.
Currently I tow in 4th and when pulling my RV (3500 lb loaded) I'm usually at 2500 rpm @ 60 mph. Drive puts me down below 2000 rpm when locked and 2200 rpm when not locked. I feel that I could tow this fine if I locked in drive @ 2200 rpm. What have some of you done and are you happy with the change?

 

Curious, what would the advantage be of doing that over just putting it in 4 when towing? When I tow I just put it in 4 and forget about it. Although on long level highways I may put it in D. Re gearing may lower your every day mpg. I may be wrong but I see a lot of $$$ to change and no real advantage.

 

Exactly.

 

Transmission temp is what you want to monitor.

 

Would this cause significant wear on components when not being used to tow?

 

Technically, Yes. More RPM is more movement.

Doesn’t it really matter? Nope, not really.

I have to agree with the others here.
I see no difference in towing in 4th, or running a lower gear in 5th.
At least not with the 300 RPM difference OP is stating.
I would venture to say, @2,200 RPM the TQ Converter is still going to be Locking/Unlocking quite a bit.

2,500 RPM is producing more Engine Torque/HP than 2,200 RPM.
These trucks just pull better at 2,500+ RPM. It’s the nature of the engine.

If I was going to set up a Tacoma to Tow in 5th (I wouldn’t, I’d buy a different truck first)
I’d jump on up to 4.56+ and make sure there’s a gas station about every 300 miles.
At this point, you’re in the MPG range of a Full Size truck.

 

I wouldn't recommend towing in 5th gear. Fifth is an overdrive ratio (0.72:1 versus the 1:1 for 4th). This increases the load (in exchange for reduced speed/revs) for any given amount of power needed versus towing in 4th.

Our trucks drive trains aren't build like a big block or a turbo-diesel with massive power at lower/low revs.

They are moderate displacement motors engineered to turn revs for power.

Edit - regear would absolutely help both drivability and pull when towing. I'd still not tow in 5th even with a regear. Rev it out!

 

Actually there is a real advantage. Currently, when towing I only have a 4 speed. It works harder going up hills plus revs higher than necessary when on flat ground. If you buy a truck that is properly set up for towing then it will be geared properly. As far as the $$$ money spent on something which gives no return then look no further then Lifts, fancy rims, heavy winch bumpers, better stereos, and all kinds of other useless crap that some folks adorn their trucks with.

 

While all this is true in the vast majority of cases, it's not rationalization for your regear.

If you want to, do it. Just remember you have to do both axles if you are 4wd.

You made a good description of your use case, and some things may feel better to you with a regear.

But you'll be many years to achieve an ROI from the 'savings' that a regear offers.

 

Understand that our ecu formats multiple changes when “4” is registered. Timing, trans settings, and electric throttle are all different when driving in “4”. Personally I see .5-1.0 mpg increase when driving around in “4” compared to “D”. That is with light footed moderately hilled commute daytime driving.

 

How will you prevent the torque converter from locking/unlocking constantly and cooking the transmission fluid?

 

False.

putting the truck in 4th just limits upshifts to a max of 4th gear. Tables in our trucks are no different.

OP. You wont get better mpgs, and even if you do re-gear you would have to go beyond what you are stating. When unlocked you are creating a torque multiplier via the torque converter that wouldnt normally be there at those rpms.

Just leave it, rock 4th gear locked and 5th gear locked if you can. They key is to remain in a locked converter state if you like your trans to live.

NOW. A better option might be a tune via HPTuner's wherein you change where the up and downshift points are as well as the lock and unlock points are. My trans tunes have it so that the torque converter will lock up sooner and stay locked up longer into throttle input in 4th and 5th gear for this very reason.

 

Why are we supposed to only tow in 4th gear? Is 5th gear fragile somehow? I had a long talk with a tech at the dealership yesterday on the A750F transmission and he says there is no difference in the way 4th and 5th gear operate. I ask, "is 4th gear a solid shaft direct drive through the gearbox?" He laughed and said, " all the gears operate through a planetary system and 4th gear is no different than the rest". The only reason for towing in 4th is the rpm range it puts you in is more stable for towing and won't constantly be hunting. So, by changing the diff. to a 4.88 ratio, you are essentially putting the diff. into a lower gear. This means you can put the tranny into a higher gear and do the same thing except now you have a 5 spd instead of a 4 spd for towing. The only downside to it is that when you're not towing, you are running at a higher rpm and will have to live with that. Also the cost of changing both diffs. is a determining factor.

 

This all sounds very good but it doesn't change the fact that you are getting up to speed with only 4 gears instead of 5. Also, with my 32.16" tires and how tall 5th gear is, there is no way the TC will or should stay locked while towing at 1500 rpm. Currently, in 4th, I'm cruising 62 mph (100 kmph) @ 2500 rpm. On steeper inclines it drops to 3rd and the rpm jumps to 3500 rpm. If I regeared the diff. to 4.88, my rpm @ 62 mph would be 2200 in 5th and on inclines would drop to 4th and the rpm would go to 3000. With really heavy loads and really steep hills it will drop into 3rd and will rev 3500 rpm @ 50 mph. For those that think I should get a bigger truck... yah I'd prolly just get a bigger trailer and be back in the same boat again.

 

It has nothing to do with how robust (or fragile) the actual gears within the transmission are. It has everything to do with how often the transmission shifts (both up and down) and the added heat that those shifts generate. Heat is the number one enemy of an automatic transmission. More frequent shifts = higher transmission fluid temperatures = shorter transmission life. It's actually about that simple.

 

So the 6 spd trannys in the gen3 must be always running hot, I mean with the extra gear and the gen3 tranny not even sure what gear it should be in to begin with. Lol
No worries I'm joking because with your logic the ford 10 spds must be on fire with all that shifting.
So, in the end, after seeing the quote for the new gears from ECGS, I will be quite happy using 4th to tow.

 

If you operate the transmission with a towing load, at low engine rpm, the transmission temp will climb to harmful levels is a real world observation. Someone else can chime in why. Engine doesn't feel stressed, but not good for transmission fluid.

 

I get what you are talking about more gears within your usable speed the better! That stated the difference in how the truck makes power between 2000-2200 rpms and 2500-3000 rpms is quite drastic for a few reasons (how ACIS is tuned from the factory and power output of the truck). Even re-geared I highly doubt you would be able to utilize 5th locked much given this.

 

Towing in 4 keeps the torque converter locked, reducing friction and decreasing transmission temps.

When the torque converter is unlocked, the input shaft spins faster than the converter and the lockup plate slips on the converter housing creating friction heating the fluid.