DONT BUY GEARS! there is no point. good god, thats the point of a diesel, is the low end tq. if anything, i'm gonna go taller like 3.5s or 3.7s if i can find em

 

Regarding gears, I did some math and some homework. I've never actually dealt with buying Toyota parts, so I'd appreciate some input on the homework.

On 31's, at 120kph the axles will be spinning at 821rpm. With stock 4.10 gearing, the driveshaft spins at 3369. With a .838 OD gear (R150 and 151), the engine will be at 2823. With a .75 gear (R154), 2527. I was looking into using the Supra's R154 as another way to lower highway gearing, but it has input shaft incompatibilities and would probably end up costing more than buying front and rear gears. For someone with machineshop access, maybe not.

4.10: 2823/2527
3.90: 2685/2404
3.73: 2566/2297, 3062 in 1:1 4th
3.58: 2463/2204, 2939 in 1:1 4th
3.42: 2353/2106, 2807 in 1:1 4th
3.15: 2167
3.07: 2112

What gears came in what trucks (according to Car-Part's database for 4wd axles)
79-80: 4.38
81: 3.90
82-85: 4.10
86-88: 4.10, 4.38
89-92: 4.10, 4.56
93-95: 4.10, 4.30, 4.56, 4.88
96-99: 3.58, 3.91, 4.10, 4.56 (cannot use in pre-Taco front because high pinion)

And for 2WD rear axles:
79: 4.10 (also 4.11 for 3/4 ton)
80: 3.42, 4.10 (also 4.11 for 3/4 and 1-ton)
81: 3.42, 3.58, 3.73 (1/2 and 3/4 ton), 3.91 (diesel), 4.11 (1-ton)
82-83: 3.42, 3.73 (1/2 and 3/4 ton), 3.91 (diesel), 4.11 (1-ton)
84: 3.15, 3.58, 3.73 (1/2 and 3/4), 3.91 (diesel 2wd), 4.10 (1-ton), 4.30 (diesel 4wd)
85: 3.07, 3.42, 3.58, 3.73, 3.90 (diesel and 1-ton), 4.10, 4.30
86-90: 3.07, 3.42 (v6), 3.58, 3.73, 3.90 (1-ton), 4.10 (1-ton)
91-95: 3.42 (v6), 3.58, 3.73, 3.90 (1-ton), 4.10
96: 3.15 (v6), 3.42 and 3.58 (i4, 8")

What ratios are available in 7.5", 8", and Tacoma 8" (for upgrading the rear or SAS front to a TRD e-locker). The Taco 8" has a different boltpattern on the gears and is incompatible with the older 8" diffs.
3.07 - 7.5 and 8, so it'll fit an SAS or IFS setup but without the elocker
3.15 - 8 and taco 8, SAS only, with or without elocker
3.42 - 7.5, 8, and taco 8; sas or ifs with or without elocker
3.58 - 7.5 and taco 8; ifs with elocker, or sas with front and rear elockers
3.73 - 7.5, 8, and taco 8; sas or ifs with or without elocker
3.90 - 8 and taco 8; sas with or without elocker

It's that last section that I'm least sure of.

 

Really too bad about the taco incompatibilities cuz a set of the 3.42 or 3.58s would be sweet

 

I dont think thats really true, I mean if you can get everything fabbed up its not that bad! just takes time ot be through. Im about to post my swap now, I haven't gotten the motor out of the car but ill start soon. My bro and pops will fab everything for me at the steel shop they own. I got the diesel for free. My friend is a diesel mechanic.

 

i thought these diesel's torque came at the same rpm that the 22r's torque comes at, unlike the cummins 4bt whose torque is there from 0rpm. I won't know how it feels till its in, but 4.10's for this engine with 37" rubber doesnt sound good. I'll definitely let you guys know once its in. The good thing is I'll get it in sooner since I won't have to save up for taller gears, granted the 4.10's work well enough.

 

The peak tq is in the same area but the curve is totally different. I can't say what you would or wouldn't like but in my opinion, I would prefer taller gears. I have been pondering the idea of doing some trimming and stuffing some 35s in there though too. And the other point of contention with going lower (numerically higher) gears is the ring gear tooth count increases of course. Which is a good thing since fine threads have more surface contact than course threads making them stronger. But the other side to that is the pinion gets smaller and less teeth, effectively making it weaker. And I know someone on here is going to say "well my 400 hp 22re with dual cases and 7.75 has never stripped a pinion" that's not what I am getting at. This diesel makes gobs of tq everywhere. It makes almost as much tq at idle as the 22re does ever! So unless you are just going crazy Crawler with your rig, don't gear down. Like I have said before, I have been sqeaking almost 35mpg out of it. And if you look at the SAE paper for the development of the OM617A you would realize the bsfc (brake specific fuel consumption) is more optimum in the 2400 rpm range. Currently on the freeway, I'm at 2900 at 70mph in 5th. I would like to lower that a little bit

And no offense, but please stop thread jacking my build thread

 

Still running like a champ, I see...

 

I have a question about your alty power, I know there is a little custom wiring involved, im not worried about glows or starter or motor kill, Mostly alternator and powering the toyota lights and accessories as well as weeding out useless wires. How'd it go on your swap?

 

To be totally honest really well. I weeded out all the BS harness like emissions controls and coil. Stuff like that. And I ended up killing my GM 1 wire so I went from a 60A 80's small case GM alternator to a 145A 2005 K2500 one wire unit with dual belts and haven't had a problem since.

 

I opened up the stock MB alt bracket cut a new tension bracker and made a spacer wasent that bad and its all plug in

 

Lol. That alt is tiny!

 

soooooo..........what on that truck do you need 145A for?

 

Dual 950CCA industrial batteries, 30A of dual cooling fans, 1200 watt Rockford amp, and soon my warn 8k winch.

 

3.58 would probably work if you put a Taco diff (E-locker or not) in both the front and rear of your solid-axle truck. I know it can be done to the rear 8", and I assume to the front solid-axle 8" as well.
3.42 would work in any combination as it's theoretically available in all three sizes/boltpatterns. Actual, real-world availability is another question, however.

 

That won't work since the front gears drive reverse of the rear

 

??????????

You know that you can take a rear third and put it in the front, that its the tcase that spins in the opposit direstion? or am i missing your point?

are you just running your truck on the road with 31s or are you going to put bigget tires on it? mine did perfect with 33s, 4.10 and non turbo trans now that i have 35s it struggles at take off and the top end struggles too I just couldent see putting lower gears in mine.

 

Ah ha I see well since im only running a 10A cooling fan and no boom box i guess i didnt see the point, I think im going to have my alt rewound and call it good hvent had an issue yet

 

were the drive by vid???

 

Thank you for that! I knew 4.10's werent good enough for 35's/37's

 

yeah tons of power with the 33s then i got a set of 16.5 6 lug rims and wraped them with the 37" goodyear mititary take offs and it just about wanted to fall on its face in first and second gear so i put the 37s on the other 4runner and bought 35s for the diesel and what a difference but i still want a little more so i have a set of 4.30s that im going to try.