RC60F Transmission swap including 4th Gen Taco

I am curious about what info the ECU uses and what it can ascertain from it. Again, hopeful, but issues would not surprise me. The IMT trucks that match the downshift rpm have an additional sensor that measures speed...

 

The only thing that affects towing capacity is curb weight. So, 4x2 ACs have the highest. 4x4 DCLBs have the lowest.

My best guess is that it is reactionary, which is crazy if you are thinking about how it is reacting to clutch slip and such. In my mind, the only place per-gear maps have any use would be one map for R, N, and 1st through 4th and maybe another map for 5th and 6th.

 

In regards to transmissions, towing is typically restricted by cooling (AT) and clutch force and robustness (MT). In the case of the Tacoma, neither are the bottleneck so towing values are similar. This isn't always the case because heavy towing is brutal to the clutch in a take-off situation and people don't always want to deal with the stiffer or longer clutch that comes with beefing it up.

In regards to the ECU, it's likely 100% economy related. Knowledge of the driver's actions (e.g. clutch-in) allow responsive programming to a direct input (clutch switch) vs reactive programming based on some other factor (RPM falling due to clutch-in).

Maps per gear make sense as well because 6th can have a lighter map as the cruise gear whereas 3rd and 4th need more aggressive tuning due to them being the passing gears. Again, instant and positive recognition of the gear change allows for faster response than if you trust something like an RPM to Road Speed table.

 

Sub for additional info

 

I was simply parroting this:






It is all the real info that we have other than axle codes.


I respectfully disagree. While I agree that everything is tuned for efficiency, we should all be able to agree that Toyota dropped the ball massively on the engine and AT tuning. While they may have been trying to do some smart things with mapping, they hoarked up most of it where it is important for MT owners. Toyota usually does a great job. Every shift had to be carefully executed on 04B12. 04B13 was a huge improvement and could almost be considered acceptable until I tried the OVT FOB tune. That sort of ends the 3.5l versus 4.0l debate for me and was hard evidence that Toyota just wrapped up the tuning to meet a deadline or some other BS.

If we get a single map on OVT 2.0, then I will be more than happy. I'd like an efficiency map for the OD gears, but as is, I am over the moon with the numbers that I get.

In the end, a freaking neutral map is just about the dumbest thing that I have heard of next to the accumulator.

 

Your ordered this as a brand new trans from Aisin/Toyota? Or is this an import reman. Unit.

 

This is a brand new unit from Toyota. They have, for some reason, been elusive over the years.

 

In your list, GRN305L-PRFSHA and GRN305L-PRTSHA are both the DCSB 4x4 SR5 with the only difference being MT and AT, respectively. Both have the same rated tow capacity which means they both share the same weak link. The only difference is GCVR where the MT is 20 lbs heavier - the same difference in curb weight because the MT config is 20lbs heavier.

Other towing differences in the chart are related to config (DCLB is heavier, 2wd lighter, ACLB ligher, Limited has more weight from equipment, Pro has softer suspension). Either way, the Tacoma isn't transmission limited like Jeeps frequently are, for example.

I'm also not really sure where you disagree... everything on this truck is clearly programmed for efficiency and frequently that means sacrifices that affect driveability. I'm not saying these are good sacrifices and I'm not saying Toyota did a good job, only making the point that more information almost always allows for more effective programming for whatever the defined goal is.

It's also not that they rushed it. They made the conscious decision to focus on economy because they're not even hitting 70% or their CAFE rating on these trucks and they're selling more and more as time goes on. They're taking a big hit with every one they sell and even 1-2 mpg decrease to vastly improve driveability negatively impacts their corporate average.

 

I never said that either gearbox was less capable, just that truck weight was what governed towing capacity as shown above.

The part that I disagree with is that per-gear maps are not good, and in this case, more info is not helping them with either customer satisfaction or CAFE. For me:

19.4 with about 10k on 04B12
20.0 with 04B13
20.5 on early loads of OVT (both 1.05B FOB and Base)
21.5 on the last load of 87 FOB
22.0 on 2.0 Beta with close to 2k on this tune and over 25k on the Taco

Toyota left something on the table with both driveability and MPGs. They screwed up. Thankfully, there are fixes for those that want it.

OTOH, sales are beyond expectations and I also understand why that is.

 

You can do the 2WD low mod for $100

 

2WD low doesn't help crawl ratio, the useless 5th gear, or economy in 6th. It would also give a ~20% improvement to crawl ratio over stock and would make it a million times better in traffic with the ability to better slow roll 1st or be in 2nd before 10mph without bogging as soon as you give it any gas.

With this transmission I could even go up to 5.29's on 33's and still cruise the freeway at 80 around 2750 with a massive improvement to crawl ratio.

 

Yeah it’s just for reverse

 

Staying tuned for some great info

 

Nice, but this Trans is available here in the US also or did you order from overseas/Mexico?

 

Yes, some versions are available right through USA dealers, but good luck on getting them to actually sell and release those. I've tried many times over the years.... if you know the right parts guy, it could happen. This one is coming from the Middle East, delivered to my door via air freight, same price.

 

That was what @RedBeard1 said that he did in the past. Good luck with the mod!

 

Thanks Tony for the @RedBeard1 recommendation. While I have not spoken to him, he does supply some good info Several different posts.

 

You're welcome! I was hoping that he would jump in here. He is a busy guy though.

 

OP,

Thank you for sharing this project! Looking forward to the results.

And thank you to others for sharing their info too.

I almost went AT this time but glad I went MT now. Love driving my ACLB MT!

 

I just found a post by @RedBeard1 where he says the bellhousing is the same length. That is likely very good news! Red definetly deserves a lot of credit here... he ventured into this swap well before I did. Maybe he'll beat me to it?

https://www.tacomaworld.com/threads...ont-like-the-most.530916/page-2#post-17003760