Driving Techniques

I've seen two recent instances of folks with broken half axles.

Several folks have stated that this could have been prevented with proper driving techniques specific to the HMMWV, such as brake-throttle modulation (BTM).
I got no such specialized training with Mother Navy when I learned how to drive these things.

I get that BTM involves some two-foot driving with the throttle and brake pedal, but could you Master Drivers expound more on how it's done and when it's appropriate to use this technique?
Any other tricks you could pass on?

My wife's truck has teeny little 7k axles (for now) so anything we can do to avoid tearing them up would be appreciated.

This video shows soldiers being trained how to do it.

It is used when one or both corners are in the air.

The major reason people snap half shafts is from letting the tire in the air get spinning and then JAM on the brakes. The inboard brake rotor stops instantly but that huge tire/runflat flywheel is now delivering 1500 HP worth of hateful torque to the shaft. Snapity-snap...

The " Proper Technique" just means when you do find yourself crossed up like in the video and the tire starts spinning, just let the tire stop on its own/LIGHTLY brake to begin the BTM two-step.

Brake Throttle Modulation is the same idea as "Brake Torque-ing" a street car that has an open diff.

It works in any vehicle with a differential. The HMMWV is just unique in the fact that it comes with the Torsen type diff front and rear that is specifically designed to activate with BTM

Just Hold the brake and add power as you ease off the brake. The slight brake force holds the spinning wheel enough to cause the HMMWV's torsen type differentials to "lock up" and as you add power it will slowly overcome the light braking to move forward with all four wheels locked together

Fantastic. This is just what I was hoping for.

I think hitting the brake is instinctive. I'll have to work hard to fight that impulse.

I will tell you though, learning this technique will not guarantee no breakage. I did use this when on the trail as soon as I had any wheel slippage and it worked GREAT! I really do not know what caused mine to go, but then again it may have just been its time to go. It started making a grinding noise roughly an hour or so after the not time that I did have a little wheel slippage and had to use BTM. Mine was not the shaft itself either though, it was only the cage which caused the shaft to come loose from the wheel

Ajax MD said:

I've seen two recent instances of folks with broken half axles.

Several folks have stated that this could have been prevented with proper driving techniques specific to the HMMWV, such as brake-throttle modulation (BTM).
I got no such specialized training with Mother Navy when I learned how to drive these things.

I get that BTM involves some two-foot driving with the throttle and brake pedal, but could you Master Drivers expound more on how it's done and when it's appropriate to use this technique?
Any other tricks you could pass on?

My wife's truck has teeny little 7k axles (for now) so anything we can do to avoid tearing them up would be appreciated.

Click to expand...

Mods.... Stickie?

papakb said:

BTM works to a certain degree but it won't stop you from snapping a half shaft if you hillclimbing at full throttle and one wheel lifts off the ground and then slams back down after spinning up while airborn.

Click to expand...

if you are climbing a hill at full throttle, then you aren't using BTM.

If done properly it will lock the differential, and you won't be able to spin up a tire even if it is off the ground. It's also just enough throttle to override the brake pressure (or releasing the brakes just enough that you start moving, but still keeping pressure on the brake pedal). It's done at low to mid throttle, and you'll likely destroy more than just a halfshaft if you try to do it at full throttle.