RC60F Transmission swap including 4th Gen Taco

Exactly, I think the angles were way off and that's what caused the issues. I'd be mindful of even 1". Hell, lots of people complain about vibrations in a stock trucks so it might not take much to throw it off.

 

Right. It's a risk for sure. It's interesting also that they sell an entirely different rear axle housing for the long wheelbase OR diff. The carrier bearing mounts the same distance from the pinion, but the angles just from the extra 13" of DCLB front half driveshaft length changed enough that they use a different diff housing to match the angle. Of course, that's lengthening the front half, and not shortening it like you did. But just goes to show that the little details are pretty important and so I am hesitant to make any changes. Might just do a manual part time case, but I'm not sure I want it badly enough. The electronic stuff works decently well enough and I don't use 4x4 much anyways, and am capable of fixing it if it does give me trouble.

Don't want to turn this into a transfer case thread though so I'll stop

 

Thank you for the detailed explanation of the trans swap, super useful!
For my use case (basically stock, tuned M/T Sport that lives on pavement 99.99% of the time), the ratio changes in the gearbox alone would work great. I have the same gripes as mostly everyone who isn't 100% satisfied with the RC62F - too tall reverse, 1-2 ratio gap too wide (well, 2nd not low enough for 'FKS I suppose), and 6th a touch too low for flat highway cruising. What I'm seeing in the RC60F is the answer to these shortcomings, without doing a regear.

 

You are correct! The transmission would basically address your gripes just about perfectly. It would put your 2nd gear where mine was with 5.29s, which was quite nice. Although I like it more now of course. But the initial bump was way better than stock. It would drop cruise rpm from 2430 at 70 to about 2190.

It's interesting to me that Toyota came up with the RC62F specifically for our 3rd gen application. I mean seriously, so much of it is not ideal, this is the best they could do?? Lol. I have a feeling the reason the ratios landed where they did was due to wanting to share parts. Since the RC60/61 existed first, my guess is they wanted to reuse the R-1-2 cluster, and then due to how they wanted some other gears to be, it ended up stuck with what it got, including a crappy reverse. They could have come up with anything if they had more R&D, but we all know they want to invest as little into manuals as possible. So that's my guess why we got such an odd set of ratios in stock form. I didn't hate it, but I always thought it could be a lot better. My engine really did not like 2nd gear at low speeds when it was stock. Just bogged down so hard and was so resistant to pick up speed.

 

I’m in full agreement that regear helped but wasn’t / isn’t the final solution to making this truck what I’d want it to be.

I’m oddly anti tune from a lifetime in software and hating the excessive time suck of tinkering with numbers. I’m sure some performance can be squeezed out but where do you stop on that train? Driving Tony’s tuned AC just didn’t feel that different but he does have bigger tires and a lighter body, not sure how comparable it was.

There is just no finish line with 1’s and 0’s but rather an endless series of imperfections.

 

Right. Regear helped a ton, but it makes some aspects undesirable. If I could totally have my way, I would keep the stock gears and mix and match gears between the transmissions, and tweak a few of them lower if I could make any change I wanted.

I struggle hard with the tunes. I like them and how they feel, but they don't solve the low end laggy feel enough for me, and they make the throttle harder to control at low speed. So it's a mixed bag of pros and cons still, which makes me somewhat anti-tune. With the low gearing I have, the stock throttle settings where it takes some serious pedal movement to start rolling, seems to be easier to control. I don't like the low stock redline rpm though, so I have an edited stock tune that lets me go to 6800 rpm. That definitely helps when I'm feeling spirited and need a bit more rev range headway. So an edited stock tune w/ higher redline is basically what I've landed on. It's only okay, not special, but I think it's what I'm living with at this point.

 

Honestly, if we could bypass electronic throttle entirely and have direct wire via servo, that would be worth pursuit. Probably havoc and maybe poor MPG if untrained but could be sweet to have old school control. Would need smarts to trick the ECU.

 

I completely get your take on tuning.
You're right, there is no finish line and nothing is 100% perfect. I guess the only thing I can say from my perspective (as a tinkerer of sorts) is that I can tweak certain tables to my liking to get a response that's more in line with what I want/expect. I had to drop it at some point though, as I had dozens of files with only slight changes between them (and ridiculously long file names to differentiate).

 

Interesting. Literally the first time I've ever heard of issues like that..well, now you're making me second guess my current mindset of having a local custom shop mod the shafts rather than dink around with refurbing old ones..especially since I am in a much more po-dunk part of the country than Plano; if there aren't any good shops there, I'm not confident in my odds here, even if I'm not geared (would also play in to my recurrent theme of, "with almost no exceptions all the local services here have been mediocre, if not shit").

 

If you're keeping things the stock design, you'll probably be fine. And who knows, I would bet I have about a 90% chance of being fine. But I'm scared to try. Mainly because like I said, I don't know if it worked well or not until I've already got the transfer case installed and made the mods to support it. So that gives me some hesitation.

 

One interesting note about this transmission is it’s silent in the overdrives, but 3rd gear is whiny. My stock trans had an incessant whistle at high speeds - the regear made that speed 70 where it begin. Sounded like a tea kettle. Well, this transmission has none of that, but 3rd is definitely noisy. I don’t think it’s a problem but I find it interesting. Kind of sounds like a supercharger when I’m at 30-40 mph or so and start to accelerate. Doesn’t happen in any other gear. If I’m accelerating hard into the 70-80 range getting into the highway in 3rd, it’s quite noticeable.

 

You think harmonics? Or mechanical / vibration?

 

I think it’s a harmonic of some sort relating to the gear tooth counts or something. I don’t think it’s a problem. Definitely not a vibration. Toyota/Aisin seems to quality control check these units so well (rarely hear of any failures at all) that I’m not concerned about it being a real problem. Actually, so long as it is not a problem, it sounds cool to my ears lol.

 

Make a manual so crappy that no one will want it.

Then sell more manual tacos than competitors sold of entire models ... And now they have to keep them.

Sort of.

This is so accurate, it hurts.

You can thank a certain group of 435 (give or take) individuals for mandated throttle by wire ....

 

Thanks. I have a disc from Firn that I've been ignoring for over a year now. Maybe in the Spring...
(Mine's in my center arm console, did you check there? )

I see now that the gap between 1st and 2nd is larger (2.36 vs 1.96) on your new transmission so that rec wait is probably longer now. At least reverse looks much nicer as does 6th. I agree that there's probably a mix and match of gears between the two that would make us much happier!

 

Lol. I didn’t check there but I checked all the rear seat storage and no dice! Pretty sure it’s in the house somewhere because I assembled it in my living room….who knows.

The new gears are 4.784 and 2.423, vs stock 3.982 and 2.017. So they are further apart, but they actually proportionally identical. The actual gears making up R-1-2 in both transmissions are the exact same part number. The difference that makes the RC60F so deep in those gears is the tailset reduction (the fixed gears connecting counter shaft to output shaft). That one is 19T/25T vs stock is 21T/23T. So you now have a lower tailset gear ratio by about 21%, which is what makes those 3 gears exactly 21% lower.

Which means for 5th and 6th to now be roughly 10% taller, they had to make the actual gears around 30% taller to make the net 10% taller since you factor in the lower tailset.

This is a neat chart showing the different gear tooth counts in all the gears across the RC60, 61, and 62 transmissions. @Jeff Lange made it.

 

3.5 hour road trip today (230 miles). The new 6th gear eeks out maybe 1 mpg better, maybe slightly less than that. I just did this same drive a week or two ago at the same temperature and the same 10 mph wind against me. I kept the speed at the same 73-80 the whole way just like I drove last time. It is for sure much quieter in 6th gear than before at the lower rpm. I do find myself creeping up to higher speeds without realizing because of the lower noise level, so it feels like I’m going slower than I really am.

After about 400 miles now, I LOVE this swap. Gearing changes are always a learning curve. Even though I spent enough time on the calculator for the last 2.5 years that I could tell any of you what the rpm would be at X speed in Y gear, that doesn’t prepare you for actually driving it. I think the most drastic differences are felt in R, 2, and 3. I at first didn’t think 3rd had much change, and it still doesn’t, but you really start to feel it when you use 3rd aggressively at mid range speed, like a fast pass at 45+ mph or so. The 9% gearing reduction is noticeable for sure.

2nd gear hauls ass with me using the same go-pedal travel as before. It doesn’t “feel” lower really, but you notice it picking up speed significantly easier.

1st is significantly lower, but honestly I never had complaints with 1st gear, so I think this is actually the least significant change for me, because with the regear, I didn’t need change in 1st to begin with. But I’m happy with the change in it regardless. It’s low and slow but I still can easily start in it and shift out of it quickly enough for a smooth switch to 2nd. So no downsides, it’s just an improvement I didn’t need. But I’m certainly happy with it.

Reverse is very much appreciated, nothing else really to say there. We creep in it only, and don’t drive in it, and it is better at that than stock.


Something is weird with 4th and 5th. I had a third member leak that started a couple weeks ago. I fixed it Sunday afternoon. We used RTV only during the regear (in lieu of the OEM gasket) and then this Sunday I used an OEM gasket instead. I am wondering if the RTV allows the diff to sit further in slightly and bind the axle shafts or something? It’s hard to say, and may be placebo, but I swear my 4th gear is better than before. Maybe just the transmission has lighter bearing preload than my stocker and I didn’t notice it until after the leak repair? I don’t know. It could also just be the taller ODs make the downshift to 4th feel better because 4th is now further away from 6th and 5th? I don’t really know, but 4th even feels better when I’m coming from 3rd, so I think it’s something more than simply the relativity between it and the overdrives. It feels like a better passing gear than it did before.

5th in theory should feel worse than it did before (less rpm, less pulling power), but honestly it feels about the same as before. It’s a small difference in ratio change, so maybe it’s just not enough for me to feel. I actually really like it, I can use it comfortably up to 70-75 for pulling grades which is nice without hearing the motor scream but still having enough torque to pull it.


Overall I am truly enjoying this swap and I will be posting a concise thread about it in the next few days. Not a write up exactly but with as much info as I can think of to share. I also took some acceleration videos between the two transmissions and I’m going to try and find time to post them on YouTube and share here, just for some simple comparison.

Still weird to think I’m driving around on a new, unnecessary transmission. Lol.

 

FWIW, 33521-04020 is the part that was different, my list was stating it is different and needs to be swapped, but I understand Toyota’s description doesn’t match the common vernacular.

Great to see it all went well though!

Jeff

 

Makes sense - I was definitely wondering if I misinterpreted. Thankfully, either way it was only a 2 minute swap with a ratchet and Loctite.

 

I was afraid it would be this good