To re-gear or not to re-gear? (4 Viewers)

[ROMR NTX]

It's a balance of concerns and it's very possible to go too far. Part of the criticisms of 8-speed owners is already that there's too much gearing on the bottom end. And too many shifts. Evidenced by comments of shift smoothness and preference for the 6-speed. Focusing on highway cruise is going to miss issues with drivability around town, part throttle low speed downshifts, etc.

There's also the aspect of tuning. The transmission tuning was designed around assumptions of speed and load for various gears. Can't just drop in that dramatic of a change and expect it all to work. Even minor tailoring can result in unexpected changes to shift quality and torque converter lockup.

Maybe it can help to put this into perspective. 4.3s to the 8-speed is equivelent to 5.29s on the 6-speed. No one is asking for that. Maybe with 42" tires?

I've read a lot of your posts on towing and I'd like your thoughts on re-gearing as it relates to towing MPG. I have a ~4,000lb camper that I recently took on a road trip and the gas mileage drop was horrendous(2013 LX). I had to slow way down to 60-65 and then I could get 11ish MPG, but that speed is pretty painful for me.

I'm on 33" tires, and I saw in one of your posts that you air higher when towing. I will try that next time. I realize the answer is probably to suck it up and keep it slow, but I was wondering if a re-gear would help the MPG specifically. I do plan to go to 35s eventually.

 

[linuxgod]

I've read a lot of your posts on towing and I'd like your thoughts on re-gearing as it relates to towing MPG. I have a ~4,000lb camper that I recently took on a road trip and the gas mileage drop was horrendous(2013 LX). I had to slow way down to 60-65 and then I could get 11ish MPG, but that speed is pretty painful for me.

I'm on 33" tires, and I saw in one of your posts that you air higher when towing. I will try that next time. I realize the answer is probably to suck it up and keep it slow, but I was wondering if a re-gear would help the MPG specifically. I do plan to go to 35s eventually.

Not really. If you're lucky you'll pick up 3-5%. Most likely it'll hurt your MPG.

I used to tow in 4th with stock gears because I couldn't keep the TC locked up in 5th. Now I can tow in 5th with the TC locked up most of the time. I gained maybe 3% MPG... so instead getting 7 MPG I might get 7.2. If I try to use 4th after re-gearing my MPG goes to hell.

Highway mileage is down or about even if I'm averaging 80. At ~60 my mileage is worse. City mileage is better at least. I pretty much get 12-13 whether I am highway or city, and 7-8 when towing depending on speed

 

[DesmoPilot]

It's a balance of concerns and it's very possible to go too far. Part of the criticisms of 8-speed owners is already that there's too much gearing on the bottom end. And too many shifts. Evidenced by comments of shift smoothness and preference for the 6-speed. Focusing on highway cruise is going to miss issues with drivability around town, part throttle low speed downshifts, etc.

There's also the aspect of tuning. The transmission tuning was designed around assumptions of speed and load for various gears. Can't just drop in that dramatic of a change and expect it all to work. Even minor tailoring can result in unexpected changes to shift quality and torque converter lockup.

Maybe it can help to put this into perspective. 4.3s to the 8-speed is equivelent to 5.29s on the 6-speed. No one is asking for that. Maybe with 42" tires?

Maybe I'm in the minority here, but I love the 4.30 on 34's with the 8spd. It doesn't feel like it is shifting too often and highway cruising is comfortable and still relaxed. With peak torque at 3600rpm, this engine can benefit from a couple of hundred extra revs. Particularly when you add lift, tires, extra weight, etc.

I got home recently from 10k+ mile trip up the Dempster to Tuktoyaktuk and over to Alaska and back to Arizona. I was extremely happy with the gearing and wouldn't change a thing. Love it!

 

[Artie]

Maybe I'm in the minority here, but I love the 4.30 on 34's with the 8spd. It doesn't feel like it is shifting too often and highway cruising is comfortable and still relaxed. With peak torque at 3600rpm, this engine can benefit from a couple of hundred extra revs. Particularly when you add lift, tires, extra weight, etc.

I got home recently from 10k+ mile trip up the Dempster to Tuktoyaktuk and over to Alaska and back to Arizona. I was extremely happy with the gearing and wouldn't change a thing. Love it!

I’m juggling between the 3.90 and 4.30 options on the 8sod. I like the 3.90 because they are Toyota gears but it’s not like I’ve read about any issues with the nitro 4.30’s. It’s just such a major mod that it’s giving me commitment issues .

 

[bloc]

I’m juggling between the 3.90 and 4.30 options on the 8sod. I like the 3.90 because they are Toyota gears but it’s not like I’ve read about any issues with the nitro 4.30’s. It’s just such a major mod that it’s giving me commitment issues .

You can get toyota 4.3s easily. The whole front diff chunk from a tundra drops in and will have been set up by toyota, for the rear you can run 100-series gears or source the ROW 200-series 4.3s.

 

[DesmoPilot]

I’m juggling between the 3.90 and 4.30 options on the 8sod. I like the 3.90 because they are Toyota gears but it’s not like I’ve read about any issues with the nitro 4.30’s. It’s just such a major mod that it’s giving me commitment issues .

The Nitros have been great for me. I did have them cryo'd and REM polished before they were installed. They are dead quiet and I would use them again. Over the years, I have used both factory and aftermarket gears with mostly good luck. I think there was only one time on one of my Jeep builds that I used an aftermarket gear set that I was not happy with. That was many years ago.

For my use case, I would have been unhappy if I had gone with 3.90s.

Either way you go, you will benefit from a regear. This engine is not a torque monster and needs some revs to be efficient.

 

[bloc]

I do remember a report in this section of break in with some aftermarket gears producing an unacceptable amount of metal on the magnetic drain plug, but I think ended up subsiding and the user had no more problems.

I just don’t think we can safely say aftermarket will comfortably go 4, 5, 600k like factory toyota gears. But then who really needs them to? It is even plausible that different alloys or heat treats could make the gears wear more quickly but better resist breaking during shock loading.

I just know toyota gears have an incredible track record of strength and durability, and I plan to stick with them if at all possible.. and it turns out they are available in a bunch of different ratios if we are willing to do the work of tracking them down.

 

[linuxgod]

Drove 700 miles back from VA to IL this weekend. 34s and 4.88s and the 4.88 gears made for a gear ratio for driving 85+, passing, etc. The only thing they didn't help with was my gas mileage, in which I struggled to hit 12mpg. If I drove 50 I could've gotten 16-17 (based on a few miles I did through a construction zone right after filling up) but I saw no reason to turn an 11 hour drive into a 20 hour ordeal to save a few bucks...

 

[TeCKis300]

I've read a lot of your posts on towing and I'd like your thoughts on re-gearing as it relates to towing MPG. I have a ~4,000lb camper that I recently took on a road trip and the gas mileage drop was horrendous(2013 LX). I had to slow way down to 60-65 and then I could get 11ish MPG, but that speed is pretty painful for me.

I'm on 33" tires, and I saw in one of your posts that you air higher when towing. I will try that next time. I realize the answer is probably to suck it up and keep it slow, but I was wondering if a re-gear would help the MPG specifically. I do plan to go to 35s eventually.

The answer is it depends. It's possibly that it may not actually result in better MPG, as there are great factors at play. From my experience for the 6-speed, 33s create that magical 4.5 gear as stock gearing resulted in 4th gear being too much, and 5th being too little. At least for my aero and tow load.

Here's a longer winded analysis I wrote in another thread that may or may not help.

This is great to hear. Sounds like your hypermilling is on point to touch those kind of numbers! Interested to hear your impressions outside of breaking in, but I trust you'll find as much success as @grinchy found with this combo.

Towing may be a different story, at least for my setup. Your aero and setup differs so your experience may be different. Just something for others to be aware of as they pick and choose how they might tailor their rigs.

From my earlier post here


To help others analyze how this plays out. Those of us with 6-speeds don't have as fine selection with the in-between gears so it's a big rpm jump between usable gears. A .5MPG decrease is what I saw re-gearing with 33s. Reason is I find that the optimal towing RPM to be about 2600 for my aero profile and load at 65mph. For those that tow a lot, this may be how to assess where you want to be, at least for hauling MPG.

View attachment 2658812

As from my earlier post, I got the best MPG with
- (1) stock gearing with 33s. This 2673 RPM @65 was great as it kept the torque converter locked, while having torque reserves for some minor wind and hills, and kept excess RPM down.
- (2) My experience going to 4.3s with 33s was as I quoted above. Excess RPM @2941 for the same 65mph, meaning windage losses while keeping excess power reserve in gear. Losing about .5MPG vs (1).
- (3) Now that I have 35s with 4.3s, I have 100 more RPM to turn bigger tires, but relatively the same as (1), so I'm probably spitting distance in MPG minus minor losses hauling around the bigger 35s.

So a way to look at this for heavy towing usage is to find combos that put you around 2600rpm @65mph as a first approximation. Again, I'm stock aero, 1" lift, 35x12.5s. If you have bumpers, add ~100rpm to your target rpm. Roof rack, add another ~100rpm. That sort of thing. Try the different gears in your towing setup now to come up with a sense of where you think the car wants to be in RPM when laden, to cross check the optimal gearing (for efficiency).

@linuxgod the orange is where you'll roughly land with your 4.88 setup. If you towed in 4th gear prior with stock gearing and 34s, that was probably around 2600rpm as a reference. It'll be interesting if you can grab 5th with the new setup. Though I know you also tend to keep a higher speed so 5th gearing may work out per the 75MPH table below and you have a chance at sitting pretty.
View attachment 2658817

 

[Artie]

The only thing they didn't help with was my gas mileage, in which I struggled to hit 12mpg.

12mpg at 85+… some of us may see this as bragging.

 

[Drivn N Cryin]

Hey all - 2021 LX 570 here... I have normally traveled in 4Runners in the past, and always had East Coast Gear Supply do my regears and lockers... I've put 285/75/17 tires on this new ride, and I'm adding some internal weight with a medium build out, AND I'm pulling an Off Grid Trailer (3100 lbs), so I am really starting to feel the need to regear. Unfortunately, ECGS isn't very familiar with this platform. I contacted Cruiser Outfitters, and they seem to only be doing full builds these days. I don't mind driving to have the work done since I'm always on the road anyway. Does anyone have 1) a recommendation of where to go from stock (which I think is 3.31?), and where I might go to get it done?

 

[lx200inAR]

Hey all - 2021 LX 570 here... I have normally traveled in 4Runners in the past, and always had East Coast Gear Supply do my regears and lockers... I've put 285/75/17 tires on this new ride, and I'm adding some internal weight with a medium build out, AND I'm pulling an Off Grid Trailer (3100 lbs), so I am really starting to feel the need to regear. Unfortunately, ECGS isn't very familiar with this platform. I contacted Cruiser Outfitters, and they seem to only be doing full builds these days. I don't mind driving to have the work done since I'm always on the road anyway. Does anyone have 1) a recommendation of where to go from stock (which I think is 3.31?), and where I might go to get it done?

Easiest is swapping in gears/carriers from a 6 speed to get you to 3.91.. I do t have an 8sp, but I bet most people here will tell you that you probably don’t need gears for a 34” on the 8 speed..

edit: i take it back, go with at least the 3.91.

 

[CharlieS]

3.91 is perfect for 34" tires on the 8 speed.

 

[Drivn N Cryin]

Easiest

3.91 is perfect for 34" tires on the 8 speed.

Great to hear!

 

[linuxgod]

3.90 gears, you can get most of what you need from an earlier model LC but there are some bits @CharlieS or someone else can tell you what you’ll need to find.

Gear setup and size is the same as a 4WD 4.7L Tundra so any shop with experience with those can do it

 

[DesmoPilot]

Hey all - 2021 LX 570 here... I have normally traveled in 4Runners in the past, and always had East Coast Gear Supply do my regears and lockers... I've put 285/75/17 tires on this new ride, and I'm adding some internal weight with a medium build out, AND I'm pulling an Off Grid Trailer (3100 lbs), so I am really starting to feel the need to regear. Unfortunately, ECGS isn't very familiar with this platform. I contacted Cruiser Outfitters, and they seem to only be doing full builds these days. I don't mind driving to have the work done since I'm always on the road anyway. Does anyone have 1) a recommendation of where to go from stock (which I think is 3.31?), and where I might go to get it done?

I am running 4.30s on my 2021 with 34" tires. I pull a Patriot trailer, which weighs a few hundred less than your OGT. I am so happy I didn't go with 3.90s. Regardless of which ratio you choose, you will be happy with the improvement.

 

[bloc]

This may have been mentioned already so I apologize if it’s redundant. But an important point is that gearing can be quite subjective and there probably isn’t a true “perfect” setup, and what works for one person might not for another.

Personally I know singing along at 3k on the freeway would drive me nuts, even with the knowledge that it wouldn’t really hurt anything other than fuel efficiency.

But then I’d also go nuts having the torque converter unlock with every gust of wind or slight incline because the revs are too low. That’s my current status with stock 3.9s behind a 6spd on 285/70r17s. For me 4.30s will be perfect.

If at all possible people considering gears should try to take a test ride in someone’s rig that already has them. Or at the very least try to emulate your resulting highway cruising RPMs using different transmission gears before pulling the trigger.

 

[ROMR NTX]

This may have been mentioned already so I apologize if it’s redundant. But an important point is that gearing can be quite subjective and there probably isn’t a true “perfect” setup, and what works for one person might not for another.

Personally I know singing along at 3k on the freeway would drive me nuts, even with the knowledge that it wouldn’t really hurt anything other than fuel efficiency.

But then I’d also go nuts having the torque converter unlock with every gust of wind or slight incline because the revs are too low. That’s my current status with stock 3.9s behind a 6spd on 285/70r17s. For me 4.30s will be perfect.

If at all possible people considering gears should try to take a test ride in someone’s rig that already has them. Or at the very least try to emulate your resulting highway cruising RPMs using different transmission gears before pulling the trigger.

How can I tell when the TC is unlocking?

 

[lx200inAR]

How can I tell when the TC is unlocking?

Usually your RPM will ramp up even though you don't change speed/gear...or you can monitor it with OBD readers.

 

[bloc]

How can I tell when the TC is unlocking?

When your truck hits the top gear allowed (6 or 8 depending on year, or your S speed) you should see a few hundred rpm drop that isn't quite another upshift, usually a few seconds after it hits that gear, as long as you aren't dipping back into the throttle.

TC unlock is the opposite. If looking closely you'll see a slight few hundred rpm rise that doesn't equate to a change in speed, especially if very slightly rolling into the throttle.. less than is needed to trigger an actual downshift to the previous gear.

Basically for my setup the truck has enough horsepower at cruising RPMs to push it through still air on flat ground with the larger tires. Introduce any more load and it unlocks the TC to get a bit more HP, but it doesn't quite call for a downshift yet.