Topic: 2.28x2.28 double low vs stock axles

[Lewis Hein]

Suppose a Hilux is equipped with stock axles and tires. The only drivetrain modification is a 2.28 crawl box put in with the stock 2.28 transfer case. Tire chains are put on all 4 tires the tires and they have an excellent grip on dry ground. The back of the pickup is chained to an immovable object while the driver revs the 22R to 3000 RPMs or so and dumps the clutch. Does a drivetrain component break, or do the tires lose traction? IF a drivetrain component breaks, which? I'm guessing probably the birfields.

Here's why I'm asking. I'm a big fan of the way these pickups are set up stock, where it is difficult to damage a drivetrain component using stock engine power and gearing. I would love to have a 2.28 crawl box but I hesitate because I don't know if the drivetrain will stand up to more than double the torque it was designed for. Ideally, the whole drivetrain would hold up and just make the tires spin (using stock tires) even under the scenario of idiotic abuse outlined above.

And before anyone asks, I have no plans to upgrade the axles. I can barely afford a crawl box and certainly not an axle upgrade too.

Thanks!

[blackdiamond]

Why would you ever need to drop the clutch at 3,000 rpm with dual cases?

You are aware that dual cases requires driveshaft modifications and sometimes rotating the rear differential?  There's more to the cost than the crawl box.

[Lewis Hein [OP]]

Why would you ever need to drop the clutch at 3,000 rpm with dual cases?

That's exactly the point: I wouldn't. As far as I can tell (admittedly not very far) the stock Toyota drivetrain is stronger than most things the 22R can put out, even if driven by a fool with a heavy foot. I regard this as a very valuable feature that I do not want to compromise. So I feel it useful to discuss the survivability of events that would very seldom happen in the real world, just to keep on the strong and safe side.

You are aware that dual cases requires driveshaft modifications and sometimes rotating the rear differential?  There's more to the cost than the crawl box.

I was planning on the driveshaft modifications, hadn't thought about rotating the rear diff.

[blackdiamond]

That's exactly the point: I wouldn't. As far as I can tell (admittedly not very far) the stock Toyota drivetrain is stronger than most things the 22R can put out, even if driven by a fool with a heavy foot. I regard this as a very valuable feature that I do not want to compromise. So I feel it useful to discuss the survivability of events that would very seldom happen in the real world, just to keep on the strong and safe side.

I was planning on the driveshaft modifications, hadn't thought about rotating the rear diff.

If you use the crawl box for crawling you should reduce the stress on the parts. I ran 4.70:1 gears with 33s and a limited-slip front differential in my 85 on OEM front axles in Moab without any broken parts.

Rotating the rear diff isn't always necessary I don't think, but don't be surprised. I'm sure it's wheelbase, lift height, and other factors that are in play.

[Snowtoy]

First off, no need to be concerned with the above scenario, as you would never need to dump the clutch with stock dual cases, you would just release clutch at idle/just above idle and accelerate.  If you were to attempt it, my guess would likely break a u-joint before anything else would go. With stock dual cases you are almost driving an automatic, so there is no need to load the clutch up. 

For a real world idea of just what the OEM drivetrain can handle, a few years ago I towed my Dad's 3/4 ton Chevy and trailer, about 12k lbs worth, off camber out of ditch back onto the pavement on a steep grade.  The engine cut out and he let gravity pull the truck and trailer backwards onto the side of the road.  With rear ARB. on 35 MT's, w/dual stock cases engaged, released the clutch, rolled about 1-2" to take the slack our of the chain, then accelerated, and pulled him w/o issue, just like tug pulls a boat, or a pushback does a plane.

I was planning on the driveshaft modifications, hadn't thought about rotating the rear diff.

If you have a 2pc d-line you can get away with just shortening the front half.

If you have a 1pc now, and still stock ride height, you shouldn't need to rotate the pinion since you are only shortening the driveline about 6", which shouldn't be enough to cause a binding issue with the u-joints

If you go with a 1pc to replace the 2pc, you will have to rotate the pinion down, so the diff side u-joints are at the same angle as the trans side.  This can usually be done with 2-3 degree shim between the springs and the perch.

[gnob]

The weak point will be the second t-case input or R&P.
Although i think it would be pretty hard to break anything on stock rubber.