[Iatros]

I wonder if anyone has attempted to wire 5V straight to the VTM-4 solenoid as to bypass the relay / computer system that sends less as you increase in speed until it's cut off. It'd also maybe allow you to have a more "traditional" 4 wheel drive system in the sense that if it's wired straight to a switch in the cab you could theoretically be in any gear and engage the VTM-4 system, basically giving you a "traditional" 4-hi. I know that the computer might not be happy about that, so that could get tricky. And maybe I'm just hoping and dreaming, but certainly I hope I'm not the only one who's thought of doing something like this, so maybe there's someone out there that's tried it I'd love to hear if anyone has, or thoughts about it.

 

[Dnick]

I wonder if anyone has attempted to wire 5V straight to the VTM-4 solenoid as to bypass the relay / computer system that sends less as you increase in speed until it's cut off. It'd also maybe allow you to have a more "traditional" 4 wheel drive system in the sense that if it's wired straight to a switch in the cab you could theoretically be in any gear and engage the VTM-4 system, basically giving you a "traditional" 4-hi. I know that the computer might not be happy about that, so that could get tricky. And maybe I'm just hoping and dreaming, but certainly I hope I'm not the only one who's thought of doing something like this, so maybe there's someone out there that's tried it I'd love to hear if anyone has, or thoughts about it.

If you're talking about VTM-4 Lock, you'd burn up your clutches mucho-pronto. There's no slip built in to the lock mode. Bad juju except when used as intended.

If you're just talking about a "fixed" amount of torque to the rear wheels.... someone else will have to comment. Why is my only question.

FYI, lock-mode is the only thing that is "cut-off" after a certain speed or that is limited by what gear you're in ..... so it does sound like you're talking about the "lock"..... Don't do it!

 

[AG87BlkLX]

I don't believe anybody has tried this mod. Go ahead & do it. Then report back your findings.

 

[Dnick]

I don't believe anybody has tried this mod. Go ahead & do it. Then report back your findings.

Seriously??? Don't you want to at least apply some caveats to that "go ahead & do it" advice??? After all, this is OP's first post, so I'm thinking he's looking to get some valuable insight via the collective knowledge & experience of our membership. I'd hate to see him screw up his truck to the tune of $thousands w/o at least knowing what he's getting into.

 

[henni]

This brings to mind Csimo/Joe's wise words

They will not tolerate slippage for long (a few seconds) and results in a silent failure (the driver has no indication that the clutch no longer engages or only holds a very low limit of torque)....there are a lot of non or partially functional VTM-4 units out there..

 

[speedlever]

If you're talking about VTM-4 Lock, you'd burn up your clutches mucho-pronto. There's no slip built in to the lock mode.

Actually, they will slip above a certain, undefined torque value. I demonstrated that in my VTM-4 lock test:
VTM-4 Lock Video by speedlever | Photobucket

From this thread:
http://www.ridgelineownersclub.com/forums/471230-post257.html

And further supported here:
Honda/Acura VTM-4

Be that as it may, your overall point of burning up the clutches is well taken.

 

[Dnick]

Actually, they will slip above a certain, undefined torque value. I demonstrated that in my VTM-4 lock test:
VTM-4 Lock Video by speedlever | Photobucket

From this thread:
http://www.ridgelineownersclub.com/forums/471230-post257.html

And further supported here:
Honda/Acura VTM-4

Be that as it may, your overall point of burning up the clutches is well taken.

You are correct that my statement was over simplified.... being focused on the intended message. So maybe more correctly stated; there is no "designed in" accommodation for intended or "sustained" slippage at low speed. Certainly it will slip when overcome (if sufficient resisting torque is applied)..... and therein lies the problem, given the absence of any designed-in disengagement of those clutches in that scenario (under 6MPH, lock on). They will eventually burn up due to unintended slipping...... and according to Csimo's insights, this doesn't take too long to happen. There's a reason those warnings are there in our OM regarding when & when not to use VTM-4 lock mode.

The point at which damage is initiated or the degree to which damage is done (in "lock" mode) would seem near impossible to predict, given the variables involved in real world scenarios of driving on hard surfaces (variable engagement force between 6 & 18 MPH, and the unmeasured amount of "uneven" counter-torque applied, as when turning, ...... or just resisting torque in general). And in my opinion, the biggest problem remains the absence of any overload or damage indicator, other than performance observation.

In your case Speedlever (video), I believe there was speculation at the time (which I share) that you were suffering the silent failure yourself. I don't believe you should have seen what you did with VTM-4 locked, unless you had a failed differential. Which more or less reinforces my "don't do it" response to this suggestion of hard-wiring full VTM-4 lock independent of speed.

We are already at risk of overloading the system when in VTM-4 lock mode, if we are not careful about when & for how long it's applied. I can't imagine a differential surviving long at all if that lock was made permanent. And how much of our typically outstanding VSA performance would be lost as a result of failed VTM-4 clutches would also seem hard to quantify.... but would surely be unfortunate, given how much that does for us in adverse weather conditions. (VSA does use VTM-4 torque variability, does it not??? or am I just goofy there?)

 

[speedlever]

You have some good points that I cannot answer. All I can say is that my RL had very few miles on it at that test. My Pilot had about 40k more miles on it and the results were identical between the 2 vehicles. In subsequent years, I have demonstrated that my rear diffs function normally and with VTM-4 manual lock engaged, I get rear wheel spin in the snow.. and literally nothing (front or rear wheel spin) in the dirt... which would indicate to me that the rear diff clutches are working normally.

In addition, I've been stuck in deep snow when in default drive conditions. When I shift to 1 and engage manual VTM-4 lock, I can drive right out.

There has been a ton of speculation on the VTM-4 clutch holding capacity and consequential silent failure, but I would suggest that my results simply do not show any sign of silent failure.

Those who have effectively removed the rear diff from the equation by disconnecting the propeller shaft have said the RL will burn rubber and has a ton of torque steer when FWD only is available. I have literally no torque steer (and have posted videos to support that) and can't even get wheel spin in dirt when locked, let alone on dry pavement. I would think that a silent failure of the rear diff would show up as excessive torque steer and front wheel spin in an aggressive start.

Opinions? Thoughts?

 

[Dnick]

And so the mystery persists. It would be nice if somebody someday conducts a comprehensive test of this VTM-4 system that would explain to us some of this seemingly contradictory behavior with the system. It's entirely possible that things are working as intended, and we just don't have all the particulars explained as to how that is.

In the meantime.... ignorance is bliss. We'll just have to live with what we know. :wink:

 

[speedlever]

True. The ROC would definitely benefit if a knowledgeable Honda drivetrain engineer would participate.

OTOH, the VTM-4 system is now old tech and has been replaced by iVTM-4. Perhaps that will bring its own mysteries for us to ponder.

 

[fastdrvr]

I remember a post on the Honda Pilot Forums a few years ago back when we had a pilot (Piloteers.org or something like that)... it was by a couple of the engineers at the plant in Alabama. They set up a Pilot to run rally-cross with. Besides swapping in a 3.7L V6, gutting it with a cage and setting it up for racing. They had set up a controller for the VTM system allowing varying degrees of rear lock.. pretty cool, I'll see if I can find it. This is the closest I could get, long read, but since the hosted site went down can't find the complete specs.... There still some information as you read through the thread.

2010 Rallycross pilot - Honda Pilot - Honda Pilot Forums

After watching your videos on the vtm-4 lock speedlever, I'm going to try that in my front yard tomorrow. I've got a similar off camber rise coming out of a ditch that's still slightly slick from rain. Since I'm currently only driving my Ridgeline in my yard to keep it up, 5 acres seems small when you don't get out on the road... hopefully the airbag parts will unleash it back on the roads before summer is over.

 

[bulwnkl]

I would have thought that the signal to the box (which causes clutch lock) would be pulse width modulated, like many Subaru 'center' clutch pack diffe are.

Lots of Subie guys have wired constant voltage to those control solenoids. It works perfectly. ...and then the solenoid fails. Not weeks or months later, either. They overheat and fail very shortly.

Does the VTM-4 box control system not also operate this way? I don't know.

 

[Iatros]

I don't believe anybody has tried this mod. Go ahead & do it. Then report back your findings.

No stranger to sarcasm but thanks everyone for their feed back. i realize it's not something the RL is designed to do, just trying to think of ways to improve on it as much as we can.

 

[AG87BlkLX]

No stranger to sarcasm but thanks everyone for their feed back. i realize it's not something the RL is designed to do, just trying to think of ways to improve on it as much as we can.

I'm serious, do it. Then you could leave it in D & not have to worry about it only active in 1, 2 or R. As long as you're intelligent about how you use it, not flying down the freeway at 70mph, I think some might find it useful.

I know the Tacoma guys do this in a couple different ways. They have a Locker Anytime Mod where the TRD Off-road trucks can turn their Locker on anytime. Then there is the Yellow Wire Mod that gives the non TRD Off-road trucks TRAC in 4Lo. Where the SR5 & TRD Sport have open diffs in 4Lo. TRD Off-road has ATRAC for 4Lo which asks like lockers all the way around. You can have only one wheel on the ground & the Truck will send power to that wheel. TRAC is a weaker version of ATRAC. Bottom line is someone had to be the first to try these mods & see how they work. The ones that find it useful do the mods too.

 

[Carsmak]

If you read all the stuff the Honda Alabama boys did to the Rallycross Pilot, I bet the VTM is stronger than known as is the J35...

 

[Apex]

All I can say is the vtm4 is working all the time. I drove for a month with no prop shaft. Very eye opening, torque steer, John force burnouts, all the norm. I do question the ultimate holding power of the vtm4, however the unit Is functioning even daily driving and I doubt constant voltage would improve the capabilities of the RL.

Bottom line, it is what it is. If you want locked 4x4 get a xterra, wrangler, 4Runner, full size truck, etc.

 

[Jwing08RL]

Did anybody actually attempt this?

 

[dom79]

Did anybody actually attempt this?

Late but i made it

I send 2V with isolated DCDC in 9-36V out 3.3V 4Amp need 4 diode to isolate between 2 clutch each clutch have 1.7 ohm for 1.2Amp each side i plug it // with vtm4 module

when i plug it i can't turn tire with hand to much torque for only 1.2A 2.4 watt

after 10 min vtm4 light come but close contact and all is ok 2V in lower to break anything

but wow in offroad easy to make donut in sand cut vsa and go

 

[zroger73]

According to Honda service information, the rear clutches are modulated by varying the amount of current to the coils using battery voltage.

There has been a ton of speculation on the VTM-4 clutch holding capacity and consequential silent failure, but I would suggest that my results simply do not show any sign of silent failure.

Since your post, Honda revealed in an article on the 2019 RDX that the 4th generation SH-AWD system (same hardware as iVTM-4) can handle 3,000 N·m which is 2,213 foot-pounds.

The G2's engine develops 262 foot-pounds of torque and the overall drive ratio in first gear is 14.276:1 resulting in a maximum torque of 3,740 foot-pounds which becomes 3,641 foot-pounds because of the 2.7% overdrive inside the iVTM-4 unit. Honda states that "up to 70% of available torque" can be sent to the rear wheels. 70% of the available torque would be 2,549 foot-pounds. Typical drivetrain losses are 10-15%. A 13% drivetrain loss would result in 2,213 foot-pounds which is exactly the limit Honda stated. I think we've found our answer - any amount of torque above 2,213 foot-pounds being applied to the rear wheels results in clutch slip.

As to how this applies to the G1... Honda stated in the same article that the 4th generation SH-AWD (iVTM-4) improved torque capacity by 40% over the previous version which was limited to 2,200 N-m or 1,623 foot-pounds. The G1 produced 247 foot-pounds of torque and the overall drive ratio in first gear was 3,019 foot pounds or 2,969 after factoring in the VTM-4 unit's lower 1.7% overdrive. 70% of this number would be 2,078 foot-pounds. Assuming a 15% drivetrain loss, the torque to the rear wheels would be 1,766 foot-pounds which is reasonably close to the 1,623 foot-pound limit (Honda did say "around" 2,200 N-m in the article).

I think we've found our answer - any amount of torque over 2,213 foot-pounds in the G2 or 1,623 foot pounds in the G1 being applied to the rear wheels results in clutch slip. No wonder the G2 runs off and leaves the G1 in the dust!

 

[dom79]

i made it for winter when i run in snow and ice the rear does'nt work at constant speed i will test soon the best constant current need to have good traction in snow

i will put my test here for futur use


i tested 1 amp each clutch in a 90 degre turn 20km/h to 60 at max accel and rear tire screech little bit more than with vtm4 module in same curve VSA off in D on asphalt

i don't see less or more MPG at 1 amp at 50 or 100 km/h


futur project start to make selector 0.5 1 2.5 5 Amp and 2wd or i go with ucontroller and i can have each wheel speed from VSA

i like to measure actual sleep at 1A but i need serious big torq wrench

or i will measure it at lower current and make y=mx+b estimate

schema of VTM4

Honda Ridgeline. Manual - part 259