Using VTM4 Lock for Braking

[mudbog]

Has anybody ever used the VTM4 lock button and D1 or D2 to slow the Pilot down when going down a hill in inclement weather? Over the holidays I had to travel on snow covered country roads. When going down many of the hills, I would drop the tranny into D1 and lock the rear diff with "VTM4 lock". It worked well. My theory was that using engine compression to brake 3 wheels (1 front, 2 rears locked) is better than braking with only 2 wheels (1 front, 1 rear).

After a few hills, however, I started second guessing my tactic because I believe I read somewhere in the past that the VTM4 system should not be left locked for a long period of time. Am I just imagining things or is there some truth to that? I would hope the system would protect itself. But sometimes I overestimate the intelligence of vehicle systems like VTM4. I don't want to burn up the clutch packs or coils.

[rjackal]

Interesting use-case. From everything I've read (from here: Ridgeline Owners Club | Variable Torque Management VTM-4 Explanation) it sounds like VTM-4 is designed for and most useful during acceleration, not deceleration.

[RSQ Pilot]

Originally Posted by mudbog

Has anybody ever used the VTM4 lock button and D1 or D2 to slow the Pilot down when going down a hill in inclement weather? Over the holidays I had to travel on snow covered country roads. When going down many of the hills, I would drop the tranny into D1 and lock the rear diff with "VTM4 lock". It worked well. My theory was that using engine compression to brake 3 wheels (1 front, 2 rears locked) is better than braking with only 2 wheels (1 front, 1 rear).

After a few hills, however, I started second guessing my tactic because I believe I read somewhere in the past that the VTM4 system should not be left locked for a long period of time. Am I just imagining things or is there some truth to that? I would hope the system would protect itself. But sometimes I overestimate the intelligence of vehicle systems like VTM4. I don't want to burn up the clutch packs or coils.

Don't know what speed you were travelling but...VTM-4 will automatically shut off when wheel speed exceeds 18 mph regardless of gear selection or VTM lock engagement. VTM-4 design to power the wheels in low traction situations not stop them.
ABS and VSA along with throttle control and gear selection all can work together to control speed and handling the Pilot. Depending upon the grade of descent/ascent gear selection can help on dry and wet pavement but could cause wheel slip/skidding on slick pavement if abruptly engaged at the wrong time/speed.

[mudbog]

The vehicle was crawling less than 10MPH. I engaged VTM4 lock before descending down the hill. It never unlocked automatically due to speed when going down the hill. On the longest downhill descent, the lock was engaged for about 4-5 minutes max. Once at the bottom, I bumped the tranny up to "D" and VTM4 was automatically unlocked.

[RSQ Pilot]

Originally Posted by mudbog

The vehicle was crawling less than 10MPH. I engaged VTM4 lock before descending down the hill. It never unlocked automatically due to speed when going down the hill. On the longest downhill descent, the lock was engaged for about 4-5 minutes max. Once at the bottom, I bumped the tranny up to "D" and VTM4 was automatically unlocked.

Don't see any problem with that, VTM engaged helped with traction through the snow... not so much with braking. No 2WD AWD or 4WD system can increase your stopping power...watch some of those You Tube videos of folks sliding downhill on roads covered with packed snow or ice

[mudbog]

The idea is the same as dynamic braking used to slow down a tractor truck. Having 3 wheels linked up to the driveline causes more friction than having 2 wheels linked to the driveline. Think of the extremes: if engine compression is used to slow a vehicle with say 100 wheels, do you think having all 100 wheels linked to the driveline would slow it quicker than just having 1 wheel linked to the driveline.

When you say you "don't see any problem with that" are you agreeing that it is OK to leave VTM4 locked for 5 minutes with no worry of damage to the clutch packs or coils?

[RSQ Pilot]

Originally Posted by mudbog

The idea is the same as dynamic braking used to slow down a tractor truck. Having 3 wheels linked up to the driveline causes more friction than having 2 wheels linked to the driveline. Think of the extremes: if engine compression is used to slow a vehicle with say 100 wheels, do you think having all 100 wheels linked to the driveline would slow it quicker than just having 1 wheel linked to the driveline.

When you say you "don't see any problem with that" are you agreeing that it is OK to leave VTM4 locked for 5 minutes with no worry of damage to the clutch packs or coils?

Engine compression braking (jake brake) and downshifting are methods of slowing a vehicle and more wheels on the ground would equal more friction. The Pilot only has 4 wheels that are braking, sometimes with ABS and VSA involvement. (also no engine compression or exhaust retarders). Pavement co-efficient of friction is always another variable in stopping distance. But the Pilot VTM-4WD system engaged isn't braking... its pulling and pushing the Pilot.

Driving under 18 mph with a properly maintained VTM system will not hurt anything. Actually the VTM-4 system is automatically engaged whenever the 4wd Pilot is driven in forward or reverse up to 18mph without any driver involvement.

http://www.ridgelineownersclub.com/V...planation.html

[Strate L O S S]

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