BW 1354 Strength

[Scott B.]

How strong is a 1354 case? Specifically, can it handle the power from a 302?

I'm not talking about a 400 HP torque monster, just a mild, torque-favored 302 (or, technically, a 306 due to the 0.030 bore...)

Most likely this will run behind an automatic transmission.

 

[IZwack]

The answer depends on tire diameter and gear ratio..

 

[Scott B.]

32" tires, 4.10 gears.

 

[Fordguy70]

They ran the 1354 behind a 5.0L in the explorers... Should have no problems holding up.

 

[4x4junkie]

They ran the 1354 behind a 5.0L in the explorers... Should have no problems holding up.

Who's "They"? (not Ford...)

Agreed though, the 1354 should be fine behind a 302 provided you're geared correctly for your tires (4.10s and 32s is fine).

 

[imp]

Why Do Tires and Ratio Matter?

Guys, I'm missing something here! Unless the tires spin on pavement, which limits the amount of horsepower to that level transferred by the T.C. to the wheels, why would tire size and/or gear ratio matter?

The engine is capable of delivering "X" amount of horsepower, maximum. This is delivered by the T-case to the wheels, right? When you push that maximum H.P. through the T.C., how would it "know" where the hell the power is going, or why? imp

 

[IZwack]

Guys, I'm missing something here! Unless the tires spin on pavement, which limits the amount of horsepower to that level transferred by the T.C. to the wheels, why would tire size and/or gear ratio matter?

The engine is capable of delivering "X" amount of horsepower, maximum. This is delivered by the T-case to the wheels, right? When you push that maximum H.P. through the T.C., how would it "know" where the hell the power is going, or why? imp

Not sure I understand the question but I'll give it a whirl:

The greater the tire diameter, the greater torque the engine will need to apply in order to move the vehicle from a standstill. Torque is an angular form of Force defined by the force * radius. So for example, lets say it takes 50 ft*lbs of torque to move a vehicle with a 1 ft radius tire from standstill. By Newton's third law (equal and opposite forces), the pavement must also exert 50 lbs of force at the tire. In addition, by Newton's third law, we can approach this problem by looking at the opposite - that is, how much torque the pavement is applying to the tire. Now, lets increase the tire diameter by two by throwing on a set of tires that are 2 ft in radius. The pavement still has to apply the same amount of torque to the tire - 50 ft*lbs - in order to move the same vehicle. But that 50 ft*lbs as measured at the axle shaft is not 50 ft*lbs, rather, we would measure 50 lbs * 2 ft = 100 ft*lbs of torque. That means, that the drivetrain has to produce this same amount of torque in order to move the vehicle - which is twice as much as using a 1 ft diameter tire. Increasing the gear ratio on the other hand, can counter this increase in tire radius and decrease the amount of torque required to move the vehicle.

 

[FROADER]

section525 has the 1354 behind his 5.0 with 4.56s and 37s. He hasn't reported any problems.

 

[4x4junkie]

Guys, I'm missing something here! Unless the tires spin on pavement, which limits the amount of horsepower to that level transferred by the T.C. to the wheels, why would tire size and/or gear ratio matter?

The engine is capable of delivering "X" amount of horsepower, maximum. This is delivered by the T-case to the wheels, right? When you push that maximum H.P. through the T.C., how would it "know" where the hell the power is going, or why? imp

Yep, IZwack has it. It's all about torque, not H.P.
Putting bigger tires on and not compensating for it by lowering the axle gear ratio puts tremendous torque stress on the t-case, driveshafts and transmission.

Try to do a burnout with 35" tires and 3.27:1 axle gears and you can kiss your rear output shaft (or driveshaft) goodbye. However with 5.13:1 gears and 35" tires (or 3.27:1 and 25" tires), you could do burnouts all day long if you want.

 

[imp]

Torque, H.P., yes......

Guys! The question was IF a given transfer case could handle the output of a 302 V-8.

A given engine, 302 in this case, can produce a maximum torque output at some given rpm. It also produces some maximum horsepower output, at some given rpm.

A given amount of torque may be applied to a mechanism at ANY rotational speed, including ZERO rpm. That is why power transmitting mechanisms are designated as "rated at such & such a torque value".

Horsepower, on the other hand, being transmitted by the shaft of a mechanism which is standing still, not rotating, is ZERO, since horsepower is a function of torque and rpm; if rpm=0, horsepower transmitted is zero.

Right? The transfer case may reliably (say for it's expected life duration) transmit a certain maximum horsepower, or torque value, but the means of "absorbing" that engine output level, tires, gears, shafts, clutch, etc., have NOTHING to do with the life expectancy of the transfer case. EXCEPT, in the case of non-continuous power transmission levels, such as shock-loads by clutches, intermittent loading due to wheel spin, wheel hop, and the like. Such loads can impose disastrously HIGH stresses on that transfer case, like a hammer peening metal, and mushing it all around.

If I'm full of **** here, please tell me so, but prove it in some way. imp

 

[IZwack]

Guys! The question was IF a given transfer case could handle the output of a 302 V-8.

I think that was answered by Froader a few posts back.

Right? The transfer case may reliably (say for it's expected life duration) transmit a certain maximum horsepower, or torque value, but the means of "absorbing" that engine output level, tires, gears, shafts, clutch, etc., have NOTHING to do with the life expectancy of the transfer case. EXCEPT, in the case of non-continuous power transmission levels, such as shock-loads by clutches, intermittent loading due to wheel spin, wheel hop, and the like. Such loads can impose disastrously HIGH stresses on that transfer case, like a hammer peening metal, and mushing it all around.

Exactly. Tires multiply stress loads because the torque being applied to the axle shaft by the rock, up the driveshaft, and to the transfer case, is being multiplied by increase in tire diameter. Again, back to Newton's third law example, you will get twice the torque from wheel hoping a 2-ft radius tire than a 1-ft radius tire. The tire's radius is the stress load multiplier as represented by the "x" variable in the torque equation T=F*x. And of course, gears can counter this and can isolate the stress loads to the axle shafts. On the other side of the drivetrain is the engine - of which the 302 will produce more torque than the v6 to counter the opposing force being applied by the rock/asphalt from the wheel hop and keep the tire spinning.

 

[rhauf]

Asking if the 1354 is strong enough is sort of a loaded question.. there is no simple answer.

for example...
if the torque passing through the t-case is limited to the max engine torque (multiplied by the transmission gear down ratio) then the transfer case is plenty strong.. it won't break.
it's when the transfer case is subject to high levels of shock torque that you will experience failure (such as bouncing, wheel hop, jumping it in 4x4, dropping the clutch on a stick shift, etc).

lower axle gear ratios (and/or smaller tires) will help relieve the t-case from shock torque, but it is always a factor. so it really depends on driving style... if the OP intends to do high-throttle rock crawling, and abuse it hard, the 1354 will be far more likely to fail than if he just street drives it (in 2x4) and muds it, gentle trail driving, etc.

i too, though, am interested in the strength of a 1354, mostly because im wondering how much abuse mine will hold up to before failure. for instance, will it fail before the U joint in the driveline?

 

[Scott B.]

I agree with rhauf - abuse anything, and it will fail.

I drive normal, with a careful and deliberate throttle. But off-road there is always a chance you will get in bad situation. With the 4.0, even in a bad situation, most likely, I wouldn't roast the transfer case. Can I say the same with the 5.0?

It sounds like the answer is yes.

 

[safn1949]

I took the 94 to Moab for 5 days,dead stock and did some fairly serious wheeling including Elephant Hill.Now to you guys with modified Ex's that might not be a big deal but stock it is and the 1354 held up there.

Like they said,get a wheel hopping and spinning and something will break.But I think you will break either a stub axle,hub or U joint first.I doubt the 1354 will let go before either of them.Will it hold up to a stock 5.0 and a driver that doesn't have dumbass disease? I will bet yes.

 

[IZwack]

I agree with rhauf - abuse anything, and it will fail.

Yes, but we're trying to go beyond that - of course anything will break if you abuse it. But what we're trying to do is define the variables which eventually feed into whether or not the 1354 will suffer damage. As we examine and analyze those variables and perhaps the equations which they go into, we can see exactly what we can do in order to mitigate the stresses on the drivetrain. Of course we havent quantified things like the exact torque spec, but given the fact that some of those factors are finite, we ignore them and make conclusions that if you increase a specific variable, then you will minimize the stresses on the transfer case. And we can do this because the drivetrains works off of ratios (tire diameter, gear ratios, etc..) and because ratios are basically one number being divided by another, we can see where we can optimize the design.

 

[4x4junkie]

It probably should be noted that slippage of the tires is what limits the amount of torque something like the transfer case would be subjected to. This does not change in relation to what HP or TQ the engine puts out (well I guess unless the engine is so anemic it can't spin the tires at all, even in low gear).
When you increase the diameter of the tire, it takes far more torque to make that tire slip. Increasing the axle gear ratio limits this extra torque to within the axle itself (which is robust enough that it generally can handle a pretty good increase before a failure would occur).

This all holds true just the same through dynamic conditions as well (shock loading, etc.). Shock loads upstream of the axle are reduced just the same by a lowered gear ratio, again reducing the chances of something like a t-case failure.