Re-geared to 4.10's & LSD rebuild/mod

Edit 2, thread title updated to: Re-geared to 4.10's & LSD rebuild/mod
Edit 1 thread title updated from: 4.10 or 4.30 re-gear on OE tires?

Considering swapping gears. I currently have 30.5" (265/65r17) tires and no immediate plans to lift or go larger as mine is a 2wd truck (and I'm not in socal playing in the desert).

I know the tow package came with 4.10's. Also both the DC and Sequoia have 4.10's readily available. Looking through part numbers I also see the v6 auto had 4.30 gears.

In any case, anyone driven both the 3.92's & 4.10's back to back and compare how they perform?

A little better around town performance and less engine load at 75-80mph is my goal.

 

I’d recco doing the 12 Port Injectors first. It ‘feels’ like the engine shifts differently almost like there is more gear at slower speeds. The transmission holds the low gear longer. I’m guessing its low end torque that has improved that ‘feeling’. Cheap ($350) and easy compared to new gears and you can always do the new gears as well for even better ‘feels’.

I’m at around 2250-2300 rpm at 75mph (in OD) on 3.92 Gears which is a super light engine load compared to some of the post re-gearing numbers I’ve seen from others.

 

Those numbers are on bigger tires 285/75/r16.

 

I haven't knowingly driven 4.30s or 4.10s. I went from 3.91 to 4.56 and would do it again in a heartbeat. I don't know that you would feel a difference worth the trouble on 4.10, given the choices I would go 4.30.

 

I have yet to see one of these trucks with a V8 and 4.10s. they pretty much all came with 3.91s, or 3.92 in the case of 2WD. After rehearing to 4.56, I don't think 4.10 would change enough to make it worth the extra time and money, especially not if running stock size tires.

 

I have a 2wd with the tow package and before I re-geared I had 3.91's w/ LSD on 265/65r17 and the truck worked great. I re-geared with 4.88's when I went to 34's and started towing. In my opinion, I wouldn't waste my money re-gearing until you size up on tires 33+.

 

This is where being able to do gears saves me a TON of cash. Even cheaper though, I can get a 3rd member from a Sequoia or Tundra for about $100 from the local junkyard. So just add fluids and gasket and I should be under $200 to swap.

Even better is finding one with an LSD. I missed an 02 1st gen with LSD in mid- October, it was crushed before I could get to it.

IIRC don't you have 33's? I would go 4.56 as well if so. Just like I went 4.88's on my Tacoma and 35's.

My truck was built with 245/70r16 (29") but was 'upgraded' to 265/65r17 at the dealer (30.5").

There's an 04 DC at the junkyard with 4.10's & V8 not too far from me. Looks like it has LSD too.

Also don't forget I have the 5sp trans, which will also make a difference. Mechanical advantage of a shorter gearset through ALL the gears is why changing a 'final drive' is a common performance upgrade.

Applied engine torque is multiplied by the gearing. Like the difference between using a ratchet vs a breaker bar on hard to remove bolts.

Spoiler: Math

Overall ratio calculation

A750
3.520 x 3.92 = 13.79
2.042 x 3.92 = 8.00
1.400 x 3.92 = 5.48
1.000 x 3.92 = 3.92
.716 x 3.92 = 2.80

3.520 x 4.10 = 14.43
2.042 x 4.10 = 8.37
1.400 x 4.10 = 5.74
1.000 x 4.10 = 4.10
.716 x 4.10 = 2.93

3.520 x 4.30 = 15.13
2.042 x 4.30 = 8.78
1.400 x 4.30 = 6.02
1.000 x 4.30 = 4.30
.716 x 4.30 = 3.07

A340
2.804 x 3.92 = 10.99
1.531 x 3.92 = 6.00
1.000 x 3.92 = 3.92
.705 x 3.92 = 2.76

2.804 x 4.10 = 11.49
1.531 x 4.10 = 6.27
1.000 x 4.10 = 4.10
.705 x 4.10 = 2.89

2.804 x 4.30 = 12.05
1.531 x 4.30 = 6.58
1.000 x 4.30 = 4.30
.705 x 4.30 = 3.03

2.804 x 4.56 = 12.78
1.531 x 4.56 = 6.98
1.000 x 4.56 = 4.56
.705 x 4.56 = 3.21

I am running stock size tires (or at least the larger of the 2 stock sizes). Which is the only reason I'm considering 4.10's.

I'd be in agreement if I had to pay someone else to do it. But I don't, so for me the option is on the table still.

 

Yes, I run 33s. My truck came with 265/70/16 and 3.91 (or maybe its 3.92). I have an SR5 rwd, it came with the tow package.

I initially wanted 4.30 but at the time they were hard to come by used and new were too expensive. I didn't have time to wait because my carrier was broken, so I went 4.56 and don't regret it.

To your case however, I agree 4.56 is too aggressive. On paper 4.30 is the closest match to stock ratio for 33s, 4.56 is one step beyond. Knowing how that went for myself, I would go one step beyond for the tires you have as well. I don't think 4.10 would give enough of a difference for the work, even if you buy cheap and install yourself. Worst case if you source one for $100 and don't like it, you can always sell it to get your money back. Really depends how much oomph you are after.

 

My truck is a 4WD V8, 4.10's with LSD. The 2004 DC's had 4.10s, 05-06 DCs and most other ACs have 3.91s I believe.

I don't have any experience with other ratios, but the truck was a blast on 265/65/r17s (I believe that was it previously had on) when it was my daily driver. I did notice the truck loose some oomph when I went to 285/75/r16. Re-gear is down the line though with lockers.

 

If you can get the 4.3 Gears you should do it. It will be an improvement on stock tires. I know I would at that $100-200 price. The 2WD seems plug and plug for a gear swap and looks like a no brainer. Do it!

 

Hmmm.

But 4.10's potentially will have an LSD. 4.30's will still be 1 tire fire


Gah! Indecision sucks

 

I think you’ll be surprised with the 12 Port Injectors. Might give you that little extra torque change you are wanting with less work.

 

So going back over things and doing some math before spending any time at the yard (or money for that matter).

Spoiler: RPM Calc's

Original tires: 245/70r16 = 29.5"
Dealer/installed: 265/65r17 = 30.58"

3.92 & 245/70r16
65 @ 2150
70 @ 2325
75 @ 2475
80 @ 2650

4.10 & 245/70r16
65 @ 2250
70 @ 2425
75 @ 2600
80 @ 2775

4.30 & 245/70r16
65 @ 2350
70 @ 2550
75 @ 2725
80 @ 2900


3.92 & 265/65r17
65 @ 2075
70 @ 2250
75 @ 2400
80 @ 2550

4.10 & 265/65r17
65 @ 2175
70 @ 2350
75 @ 2500
80 @ 2675

4.30 & 265/65r17
65 @ 2275
70 @ 2450
75 @ 2625
80 @ 2800

4.56 & 285/70r17
65 @ 2275
70 @ 2450
75 @ 2625
80 @ 2800

Gear ratio & tire size
MPH & RPM

Original setup
3.92 & 245/70r16
65 @ 2150
70 @ 2325
75 @ 2475
80 @ 2650

Current setup
3.92 & 265/65r17
65 @ 2075
70 @ 2250
75 @ 2400
80 @ 2550

If I go to 4.10's it's ever so slightly better. Better in this case being slightly lower geared, which translates into slightly higher engine rpm.

4.10 & 265/65r17
65 @ 2175
70 @ 2350
75 @ 2500
80 @ 2675

4.30 & 265/65r17 (or 4.56 & 285/70r17)
65 @ 2275
70 @ 2450
75 @ 2625
80 @ 2800

I'm leaning towards the 4.10's. As I'm not dealing with the extra weight of 33's.

I may do some testing with my OBD2 adapter and torque pro to see what the engine runs like at different RPM's. MAF g/s, Load % and RPM I'm thinking are what I should check with O/D off (4th gear).

It won't be an exact apples to apples comparison, as I won't be able to have the exact same load/wind resistance. I'm hoping it may help show me what RPM's the engine is happy at.

_______________________________________


Also worth considering is the transmission it'll be used with.

Spoiler: Overall Ratio Calc

Overall ratio calculation

A750
3.520 x 3.92 = 13.79
2.042 x 3.92 = 8.00
1.400 x 3.92 = 5.48
1.000 x 3.92 = 3.92
.716 x 3.92 = 2.80

3.520 x 4.10 = 14.43
2.042 x 4.10 = 8.37
1.400 x 4.10 = 5.74
1.000 x 4.10 = 4.10
.716 x 4.10 = 2.93

3.520 x 4.30 = 15.13
2.042 x 4.30 = 8.78
1.400 x 4.30 = 6.02
1.000 x 4.30 = 4.30
.716 x 4.30 = 3.07

A340
2.804 x 3.92 = 10.99
1.531 x 3.92 = 6.00
1.000 x 3.92 = 3.92
.705 x 3.92 = 2.76

2.804 x 4.10 = 11.49
1.531 x 4.10 = 6.27
1.000 x 4.10 = 4.10
.705 x 4.10 = 2.89

2.804 x 4.30 = 12.05
1.531 x 4.30 = 6.58
1.000 x 4.30 = 4.30
.705 x 4.30 = 3.03

2.804 x 4.56 = 12.78
1.531 x 4.56 = 6.98
1.000 x 4.56 = 4.56
.705 x 4.56 = 3.21

A750
1st 3.520 x 3.92 = 13.79
2nd 2.042 x 3.92 = 8.00
3rd 1.400 x 3.92 = 5.48
5th .716 x 3.92 = 2.80

A340
1st 2.804 x 3.92 = 10.99
2nd 1.531 x 3.92 = 6.00
4th .705 x 3.92 = 2.76

There is a fairly big advantage in gearing 1-3 vs 1-2 on the 5 speed trans, with a very slight O/D difference where the 4 speed has a hair lower freeway RPM's.
(Note: this is not reflected in the above RPM calculations, as I only ran #'s for the 5 speed O/D ratio of .716)

So for lifts/tires the 5 speed is a definite plus in getting the larger and heavier tires moving. Not applicable to me but food for thought for others.


As mentioned earlier, after doing the above RPM calc's I'm leaning towards 4.10's.

A750
1st 3.520 x 4.10 = 14.43
2nd 2.042 x 4.10 = 8.37
3rd 1.400 x 4.10 = 5.74


When I look at the gearing of the 5 speed and 4.10's vs 4.30's I almost want to go 4.30's, as 3rd gear is almost identical to the 4 speeds 2nd with 3.92's.

3rd 1.400 x 4.30 = 6.02
2nd 1.531 x 3.92 = 6.00

 

When I had my van's 3:55's swapped to 4:10's, I considered 3:73's but the customer service rep talked me into 4:10's. She said the 3:55 to 3:73 swap wouldn't be enough of a difference since my main objective was to improve the towing ability. She was right, the van tows so much better now. Now that I have a Tundra that tows even better than my van, I'm considering 4:30's in lieu of my stock 3:91's instead of 4:10's. The only reason it's even on my radar is because I thought I could benefit from installing a LSD in my Tundra. And if I'm going in there, I may as well..... you know how it goes. Sometimes I just can't leave well enough alone.

 

Kinda where I'm at. I actually mostly want an LSD. The one time I wanted to pull onto a main road and get up to speed, there was a bit too much 'one tire fire'.

I figure if I can source an LSD may as well do gears too. If I'm doing gears, may as well get what I want and lead me into this rabbit hole of thought.

The thing is, 4.10's are way easier to find with an LSD. 4.30's are rare and probably mostly without.

 

I'll probably just have to keep saving up and buy an aftermarket LSD then decide what ratio to go with.

 

Did some freeway testing in 4th the other night to see what the airflow and load numbers looked like at higher rpms.

G/s MAF / Load % and est. MPG.
The last "x#" is how many readings I averaged.

2800rpm 63mph 4th
41.0/31.3 15.5 x4

2600rpm 58mph 4th
35.0/28.6 17.0 x5

2500rpm 56mph 4th
31.2/27.0 17.2 avg x25

2400rpm 54mph 4th
29.4/26.0 18.7 x8

2200rpm 50-52mph 4th
25.2/23.8 20.1 x5

Also did 5th gear, 75mph+ numbers just get worse fairly quickly.

2400rpm 75mph 5th
52.2/46.8 14.6 x4

2250rpm 70mph 5th
42.1/40.4 16.8 avg x3

2150rpm 67mph 5th
36.8/37.0 18.3 x3

2000rpm 64mph 5th
34.9/36.4 18.6 x9

Spoiler: More useless #'s

RPM | MPH | Gear
G/S | Load % | Est. MPG (incorrect?)

2800rpm 63mph 4th
41.0/31.3 15.5 avg x4
44.1/33.3 14.4
41.6/32.2 15.3
39.5/29.8 16.0
38.8/29.8 16.2

2600rpm 58mph 4th
35.0/28.6 17.0 avg x5
35.7/29.0 16.6
35.8/29.0 16.7
32.2/25.9 18.4
33.3/27.5 18.0
38.2/31.4 15.5

2500rpm 56mph 4th
31.2/27.0 17.2 avg x25
32.9/27.8 17.4
33.4/28.2 16.9
33.5/28.2 16.9
32.4/27.8 17.5
30.0/25.5 19.1
30.9/25.9 18.3
30.3/25.5 18.9
32.5/27.8 17.4
31.9/27.1 17.9
31.5/26.3 18.0
31.9/27.1 17.7
32.1/27.1 17.6
36.6/31.4 15.5
34.5/29.4 16.4
34.3/29.0 16.5
32.8/27.8 17.3
32.0/26.7 17.7
35.0/29.8 16.3
34.4/29.4 16.5
34.3/29.4 16.5
34.6/29.0 16.4
34.6/29.0 16.6
34.3/28.6 16.7
33.5/28.6 16.7
34.7/29.4 16.3

2400rpm 54mph 4th
29.4/26.0 18.7 avg x8
29.5/25.9 18.8
29.0/25.9 19.1
30.8/27.5 17.6
30.3/26.7 17.9
29.0/25.1 19.3
26.5/23.1 20.4
29.9/26.7 18.1
29.9/26.7 18.1

2200rpm 50-52mph 4th
25.2/23.8 20.1 avg x5
26.5/23.9 19.4
25.2/23.9 19.9
25.0/23.9 20.1
27.1/25.9 18.5
22.2/21.2 22.6


2500rpm 78-80mph 5th
66.4/56.9 11.9

2400rpm 75mph 5th
52.2/46.8 14.6 avg x4
50.7/45.5 14.8
52.0/46.3 14.6
54.6/49.0 13.8
51.6/46.3 15.0

2250rpm 70mph 5th
42.1/40.4 16.8 avg x3
42.1/39.6 16.8
41.0/40.0 17.1
43.2/41.6 16.5

2150rpm 67mph 5th
36.8/37.0 18.3 avg x3
37.5/37.3 18.0
37.5/38.0 18.0
35.8/35.7 18.9

2000rpm 64mph 5th
34.9/36.4 18.6 avg x9
32.1/33.3 20.2
36.1/38.0 18.0
34.5/35.7 18.8
35.7/36.9 18.2
35.6/36.9 18.1
33.9/35.3 19.0
35.9/38.4 17.9
35.6/36.5 18.3
34.9/36.9 18.8

1900rpm 60mph 5th
27.2/30.2 22.0
27.2/30.6 22.0
30.4/34.9 19.5
28.6/32.2 20.9

Overall looks like once you hit around 2500 or so rpms there is diminishing fuel savings to be had. At least on my 05 VVT-i 4.7L.

2150rpms in 5th est. mpg was closer than I expected. I actually got 18.4mpg when I hand calculated freeway only mileage from pump to pump.

 

Picked up a 3rd member with OEM LSD and 4.10's from an '04 DC.




I'll probably clean it up and do a pattern check. I'm considering doing a solid pinion spacer too.


If I understand correctly, I'll have to swap my 2wd pinion flange on as the 4wd driveshaft pattern is different.

 

Done. Also did a solid pinion spacer and new pinion seal, since the flange had to be swapped.




Engine is less stressed on acceleration for normal driving and has a bit more get up and go. As expected of lower gearing.

 

Nice work!

 

Thanks.


So I did a TRD air accelerator (velocity stack) mod for my airbox and a tonnuea cover, prior to swapping gears. So I did some estimated mpg tests before re-gearing and earlier today did an after test.

Before with 3.91's
2075rpm 65mph 5th
34.6/35.4 19.1 x30

After with 4.10's
2150rpm 65mph 5th
33.8/33.3 19.4 x50

Key:
G/s MAF / Load % and est. MPG. "x#" is how many readings I took to average.

The estimated mpg is fairly close to my real world hand calculated results. Last mostly freeway trip was:
249mi / 13.1gal = 19.0mpg (@ 65mph)

 

Giving me 05 and newer jealousy. My best tank is 15.9MPG 303 miles all highway around 70 mph

 

All highway on my 2002 at 70mph is 18.5MPG

City is what sucks 10(winter) and 12(summer).

 

I wonder if it is a difference of double cab v access and gearing?

 

City short trips are bad regardless of gearing. Took me a month to go through a full tank with everyday driving.

 

DC's are a bit taller and heavier. The '04 DC had 4.10's to offset it a bit iirc. Same gearing as the Sequoia's.

 

Small update. The better low end acceleration (applied torque) has definitely helped around town city driving as my avg mpg has gone up.

(Hwy/city %)

Mileage w/3.91:
279mi/18.3gal=15.3mpg (60/40 @65mph)

Mileage w/4.10 (& tonneua cover):
367mi/20.8gal=17.6mpg (60/40@70mph)

 

Thats a great improvement. Nice work!

 

so your saying i should go up to 4.10s huh

but im thinking of 255/80r17 tires.. soo maybe 4.30s

 

FYI about .5 mpg improvement is from the tonneau cover. At freeway speeds anyways.

Updated my post to reflect this.