Re-gearing for Performance?

[gamefreakgc]

So this is new territory for me. I normally just ignore all the re-gearing threads since they pertain to tire size and I'm not switching sizes ever, stock tires here. I am getting a Truetrac installed by a local differential shop in about a week's time. He asked if I was also re-gearing and I said no, but I'm thinking maybe I should?

I currently have 4.10 gears. If I switch to 4.30 or possibly even 4.56 gears, I have two questions for those who have done it:

1. Does it change your speedometer reading?

2. How much higher are your RPMs (if I'm understanding this correctly), say at freeway speed around 65-70 MPH?

All opinions are much appreciated! I've never re-geared before so this is all new.

EDIT: Thanks all for the ideas and help. I also found this site which was super helpful in explaining things: https://www.roundforge.com/articles...gine_do_you_have?_Is_it_modded?_Is_it_tired?_

 

[Scramble]

So this is new territory for me. I normally just ignore all the re-gearing threads since they pertain to tire size and I'm not switching sizes ever, stock tires here. I am getting a Truetrac installed by a local differential shop in about a week's time. He asked if I was also re-gearing and I said no, but I'm thinking maybe I should?

I currently have 4.10 gears. If I switch to 4.30 or possibly even 4.56 gears, I have two questions for those who have done it:

1. Does it change your speedometer reading?

2. How much higher are your RPMs (if I'm understanding this correctly), say at freeway speed around 65-70 MPH?

All opinions are much appreciated! I've never re-geared before so this is all new.

People re-gear because of the power loss that comes with bigger tires. I dont think you need to. I like your hi-performance build. If my 3RZ was at 2700 rpms at 70mph it's now around 3000 rpms with 33's.

It's expensive if your not just swapping diffs.
It cost me $800 to have my stock 4.56 rear installed into my new e-locker diff carrier. That's the rebuild kit & labor. You'd be paying for new gears front & rear plus labor.

 

[gamefreakgc]

People re-gear because of the power loss that comes with bigger tires. I dont think you need to. I like your hi-performance build. If my 3RZ was at 2700 rpms at 70mph it's now around 3000 rpms with 33's.

It's expensive if your not just swapping diffs.
It cost me $800 to have my stock 4.56 rear installed into my new e-locker diff carrier. That's the rebuild kit & labor. You'd be paying for new gears front & rear plus labor.

Ah, I didn't think about the front. I don't use 4WD a ton and I don't have part-time 4WD (AWD) but I guess I would eventually want to do that as well.

 

[phattyduck]

1. Does it change your speedometer reading?

2. How much higher are your RPMs (if I'm understanding this correctly), say at freeway speed around 65-70 MPH?

All opinions are much appreciated! I've never re-geared before so this is all new.

1. Your 4Runner has ABS, so it uses the ABS system for the speedometer. Regearing will not change your speedo accuracy, only changing tire size will.

2. You can calculate this change yourself. Take your current RPM at whatever speed, multiply by the 'new' ratio and divide by the old ratio:

For a current 2000rpm cruising in top gear (mine is at 2k rpm in OD around 67 mph indicated):
4.1 to 4.3 = 2100rpm (~5% increase in engine RPM and wheel torque)
4.1 to 4.56 = 2225rpm (~11% increase)
4.1 to 4.88 = 2380rpm (~19% increase)
etc.

From those numbers, you can see why guys go straight to 4.88's most of the time... (going from 30.6" stock tires to 35" tires is a 14% change)

-Charlie

 

[gamefreakgc]

1. Your 4Runner has ABS, so it uses the ABS system for the speedometer. Regearing will not change your speedo accuracy, only changing tire size will.

2. You can calculate this change yourself. Take your current RPM at whatever speed, multiply by the 'new' ratio and divide by the old ratio:

For a current 2000rpm cruising in top gear (mine is at 2k rpm in OD around 67 mph indicated):
4.1 to 4.3 = 2100rpm (~5% increase in engine RPM and wheel torque)
4.1 to 4.56 = 2225rpm (~11% increase)
4.1 to 4.88 = 2380rpm (~19% increase)
etc.

From those numbers, you can see why guys go straight to 4.88's most of the time... (going from 30.6" stock tires to 35" tires is a 14% change)

-Charlie

You're awesome, I didn't realize the math was that simple!

I was thinking either the 4.3's that come with the e-lockers or the 4.56, that's what my old 5-speed Toyota had. Was a manual too with undersized tires and it was awesome in first gear but the rest all sucked and would drive at 2800 RPM on the freeway with an aftermarket muffler LOL.

Since it doesn't affect the speedo, might have to ask the wife if I can do this as well...

 

[Acorn22]

Gear Ratio Calculator

Plug everything into this and it should give you a good insight as to how it will effect speed/RPMs

 

[TonyB66]

Might there be a good thread here that discusses desirable tire sizes for various gearing options?

As an example, it seems that I have 4.30 gearing (Limited with e-locker). Wanting a bump-up in tire size, I imagine 32's (265/75/16) would be ok gearing-wise, but 33's maybe not, 35's more so...

gamefreakgc, sorry if seen as an intrusion.

 

[3rdgenfan]

Might there be a good thread here that discusses desirable tire sizes for various gearing options?

As an example, it seems that I have 4.30 gearing (Limited with e-locker). Wanting a bump-up in tire size, I imagine 32's (265/75/16) would be ok gearing-wise, but 33's maybe not, 35's more so...

gamefreakgc, sorry if seen as an intrusion.

I have the 4.30 gearing. I ran 285s (33s) for 2 years. I think 4.30 is fine with a 33. I just changed to a 315s (35s) and it definitely needs a re-gear if I keep these. My gas mileage took a huge hit even with the supercharger.

 

[GSTMike]

People re-gear because of the power loss that comes with bigger tires. I dont think you need to. I like your hi-performance build. If my 3RZ was at 2700 rpms at 70mph it's now around 3000 rpms with 33's.

Wouldn't it take less RPM to achieve 70mph with larger tires? I read the above as the inverse of that?

 

[phattyduck]

Might there be a good thread here that discusses desirable tire sizes for various gearing options?

As an example, it seems that I have 4.30 gearing (Limited with e-locker). Wanting a bump-up in tire size, I imagine 32's (265/75/16) would be ok gearing-wise, but 33's maybe not, 35's more so...

gamefreakgc, sorry if seen as an intrusion.

The tire size is only part of the equation, and it will be a highly personal decision.

Lager tires also have higher rolling resistance and are heavier - along with adding weight (armor) and drag (roof racks) people often want 'more' gearing that just a straight numerical calculation might otherwise say. There will also be a trade-off of worse highway mileage when higher (numerically) gears than necessary are installed.

-Charlie

 

[gamefreakgc]

Might there be a good thread here that discusses desirable tire sizes for various gearing options?

As an example, it seems that I have 4.30 gearing (Limited with e-locker). Wanting a bump-up in tire size, I imagine 32's (265/75/16) would be ok gearing-wise, but 33's maybe not, 35's more so...

gamefreakgc, sorry if seen as an intrusion.

WHAT THE HECK, GET OUT OF MY THREAD :gun5:

Naw it's totally fine, this is the internet after all. I just wanted to find out what people though of changing gears only for more torque down low, since every other thread on here relates only to changing tire sizes.

Those factory e-lockers really are a gem aren't they?

 

[TonyB66]

Thanks for the input. Looking to make the 4.30 gearing work. Good to hear that 32's and even 33's are not particularly problematic. I think 32's will do the trick for me though...

I've only used the factory e-locker a few times on the dirt in the front yard, mostly just to check if I can lock after the blue or grey wire mod. I knew I wanted a Runner with an e-locker for sure...

 

[2016 4Runner SR5]

Ah, I didn't think about the front. I don't use 4WD a ton and I don't have part-time 4WD (AWD) but I guess I would eventually want to do that as well.

You have to do both diffs at the same time, can't mix and match. Not worth the $2000 investment for stock tires.

 

[octanejunkie]

Thanks for the input. Looking to make the 4.30 gearing work. Good to hear that 32's and even 33's are not particularly problematic. I think 32's will do the trick for me though...

I've only used the factory e-locker a few times on the dirt in the front yard, mostly just to check if I can lock after the blue or grey wire mod. I knew I wanted a Runner with an e-locker for sure...

4.3 with 31" tires are just fine, really not much of a difference than 4.1 gears

I have 32" tires now and under compression turning the front tire hits the inside of the rear of the front wheel well

Going up in tire size is not just a bolt on operation

 

[theesotericone]

There will also be a trade-off of worse highway mileage when higher (numerically) gears than necessary are installed.

-Charlie

I've got true 33's and am not so patiently waiting for ECGS to get my locked 5.29's to me. It was a pretty hard decision to make. Almost everyone runs 4.88 in that size. I'll let you know how bad of a mileage hit I take and how spun up the RPM's are at 75. lol

 

[JZiggy]

If you already have 4.10's I would not bother with the time and expense to regear unless you made a serious step change like 4.88. The 4.30 or 4.56 options just aren't that different.

 

[octanejunkie]

I've got true 33's and am not so patiently waiting for ECGS to get my locked 5.29's to me. It was a pretty hard decision to make. Almost everyone runs 4.88 in that size. I'll let you know how bad of a mileage hit I take and how spun up the RPM's are at 75. lol

Close to this, probably

 

[theesotericone]

Close to this, probably

I already did the math. Using math I did myself and using my rigs current RPM's in 3rd and OD.

75 MPH in 3rd I'm currently at 3050ish RPM's

5.29/4.1=1.290243
1.29 x 3050=3935 RPM

In OD at 75 MPH I sit at 2100 RPM

5.29/4.1=1.290243
1.29 x 2100=2709 RPM

The problem is currently my truck is almost never in OD. It lacks power to pull even the slightest grade so I'm usually in 3rd anyway. If these gears allow my rig to stay in OD I'll end up with BETTER gas mileage. Like I said I put a lot of thought and research into my choice. Plus I'll be going to a bigger tire eventually. lol

 

[phattyduck]

The problem is currently my truck is almost never in OD. It lacks power to pull even the slightest grade so I'm usually in 3rd anyway. If these gears allow my rig to stay in OD I'll end up with BETTER gas mileage. Like I said I put a lot of thought and research into my choice. Plus I'll be going to a bigger tire eventually. lol

Have you calibrated the speedo for the larger tires? You might be going even faster than 75...

I'd say up to around 2500rpm would still be pretty comfortable for cruising. You are used to 3k+ often though, so you know what you are getting into. You'll love the gearing anywhere but the highway.

My fun experience with gearing was when I swapped to a 4.10 from the stock 3.73 gears when I still had the small tires (15" wheel truck originally - 225/75-15, baby!). It was about like driving with 4.56's on 265/70-16's. That extra 10% is pretty noticeable. I didn't run it that way long enough to get any mileage comparisons though.

-Charlie

 

[theesotericone]

Have you calibrated the speedo for the larger tires? You might be going even faster than 75...

I haven't re-calibrated my speedo. I did do some math and used a GPS speed app to verify the math is good.

I'm currently 8% off in both miles and speed. That 8% gets calculated into my gas records as well. Right now I'm averaging about 15.5 MPG. I'll get a Dakota Digital to re-calibrate it eventually but that 80 bucks has other places to go for the near future. lol