R1 Enduro, requested behavior test

[R.I.P.]

As requested, I left the DM Enduro machine in "All purpose" mode yesterday when I went out trail clearing. It is extremally slippery up here right now, with ice, melting snow, and the greasy red clay underneath; so it was a good day to get the answers you have been wanting.

Rules for the test were that I had to leave the vehicle in "all purpose" mode to test the vehicle's automatic reactions to the conditions. I was free to select appropriate vehicle heights and traction control levels.

Overall, it was a pretty boring test. Had I not been watching the telemitry carefully, I would have not known or felt the difference from other trips with the vehicle locked into four wheel drive mode. The times I was going fast enough for the rear axle to disengage, the truck instantly re-engaged the instant it felt slip; as stated above, had I not been watching the telemitry I would not have even noticed it.

An area of particular interest to me in the test was the super-slippery down-hill test. Locked into 4 wheel drive, the DM is very controllable on slippery down hill slopes (unlike the QM) because it does a very good job of using both axles to drag as much inertia off as possible while not compromising the lateral stability of the truck. This is important, because the majority of the larger trees we were cutting out really only have truck-wide spaces cut out of them; so get sideways at all coming back down and you are in for some nasty body damage. This caused some pucker factor for me in "All Purpose" mode, as this mode typically biases the regen entirely to the front. My fear was that this was going to cause the vehicle to "plow", reducing steering.

My fears were unwarranted. The instant the vehicle sensed slip, it seamlessly engaged the rear, and I watched as it searched back to front looking for the most traction on the descents.

At the end of the day, yeah; lock the truck into four wheel drive, and take all the "guesswork" out of it. But even if an inexperienced driver were to do nothing but point the rig in a direction and leave it in fully automatic mode, the truck does an impressive job of adapting. No modes needed, just go.

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[TTedP]

Yours is a regular DM and not Performance correct?

 

[Riviot]

the DM is very controllable on slippery down hill slopes (unlike the QM) because it does a very good job of using both axles to drag as much inertia off as possible while not compromising the lateral stability of the truck.

What does the QM do instead?

 

[R.I.P.]

What does the QM do instead?

Slip all 4 trying to find grip, yaw sideways & go in the ditch.

Explained in prior posts.

 

[sgec]

"This caused some pucker factor for me in "All Purpose" mode, as this mode typically biases the regen entirely to the front. My fear was that this was going to cause the vehicle to "plow", reducing steering."

I've noticed that even in "Snow" mode the regen is biased entirely to the front below ~10mph. This causes a real problem on roundabouts when super-slippery as they tend to be off-camber to begin with. If you start to slip and let off the accelerator the front wheels lock up and you plow towards the curb. I experimented with putting it in neutral and modulating the brakes, much better as you don't have to deal with the regen but not ideal. Now I use left foot braking while feathering the accelerator to cancel the front wheel regen. Works wonders as the front wheels don't lock up.

QM, stock 20" Pirelli Scorpions

 

[R.I.P.]

"This caused some pucker factor for me in "All Purpose" mode, as this mode typically biases the regen entirely to the front. My fear was that this was going to cause the vehicle to "plow", reducing steering."

I've noticed that even in "Snow" mode the regen is biased entirely to the front below ~10mph. This causes a real problem on roundabouts when super-slippery as they tend to be off-camber to begin with. If you start to slip and let off the accelerator the front wheels lock up and you plow towards the curb. I experimented with putting it in neutral and modulating the brakes, much better as you don't have to deal with the regen but not ideal. Now I use left foot braking while feathering the accelerator to cancel the front wheel regen. Works wonders as the front wheels don't lock up.

QM, stock 20" Pirelli Scorpions

What you are feeling is the inherent instability of the QM system. The DMs don't behave that way. It has differentials to help stabilize the vehicle laterally.

 

[sgec]

What you are feeling is the inherent instability of the QM system. The DMs don't behave that way. It has differentials to help stabilize the vehicle. Laterally.

I think the same front regen/braking bias applies when in reverse too. We have a steep driveway and when backing down under super-slippery conditions it feels like the front wheels lock up and the front end starts swinging around. Scary as I've never had this happen with any other vehicle. Putting it in neutral and modulating the brakes ameliorates the issue as does left foot braking.

Good to hear the DMs don't behave that way. I have a newfound respect for differentials since reading your posts. Thanks for your explanations.

 

[R.I.P.]

I think the same front regen/braking bias applies when in reverse too. We have a steep driveway and when backing down under super-slippery conditions it feels like the front wheels lock up and the front end starts swinging around. Scary as I've never had this happen with any other vehicle. Putting it in neutral and modulating the brakes ameliorates the issue as does left foot braking.

Good to hear the DMs don't behave that way. I have a newfound respect for differentials since reading your posts. Thanks for your explanations.

The unloaded front wheels on the QM can only find the traction coefficient by slipping all wheels; so if it is real slick, sideways you go.

Your diff equipped vehicles will maintain the rolling friction (without having to break it), helping keep the vehicle from moving sideways.

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