Wavetracs Differential, maybe not different from others at all.

[SRT101969]

So I need some help to clarify an issue.
I bought and installed WV diff.

As everyone can read at Wavetracs pages, http://www.wavetrac.net/technical.htm:
"The problem: Loss of drive during zero or near-zero axle-load conditions.
Zero axle-load is a condition that occurs during normal driving, but creates the most noticeable problems when driving in extreme conditions. Zero or near-zero axle-load is the condition that exists when there is ‘no-load’ applied through the drivetrain, when one drive wheel is nearly or completely lifted (often in aggressive cornering). It also occurs during the transition from engine driving a vehicle to engine braking and back, even with both drive wheels firmly on the ground.
Here’s how that loss of drive hurts you:
1) If you lift a wheel, all gear diffs except Wavetrac®, will NOT power the other wheel."

So I speak spanish and maybe my english is not good enough to understand what ZERO LOAD or LIFT A WHEEL means since people at Wavetracs are telling me everything is OK with my Wavetracs diff after watching attached Video .

After Wavetracs claims, isn´t supposed that power from lifted wheel shall be transfered to other wheel (grounded)?

The Video:
1. At the beggining Right Rear wheel grounded.
2. Then first gear, clutch out accelerating.
3. As Right Rear lifts the ground it starts to spin as it looses grip.
4. No power to left rear, right rear lifted = no advance.

http://www.youtube.com/watch?v=jyjjJSIjKqg&feature=youtu.be

 

[Will at RSI]

Your left rear wheels should be spinning. If it is not then something is wrong with the installation.

 

[Allan]

That is not working right at all.

 

[SRT101969]

Your left rear wheels should be spinning. If it is not then something is wrong with the installation.

Thanks Will.
The installation was done by Unitrax. So I bought the whole Diff with installed WV already, I just replaced the whole diff.
This is part of what they replied:
" The Wavetrac is unique and exclusive in that if a wheel does become elevated it tries to still send power to that wheel. "

This is what I think:
1. I don't have a Wavetracs diff.
2. I have a Wavetracs diff that is not working properly.
3. Wavetracs claims are completely untrue.

 

[Will at RSI]

Remove the cover and post a photo of the unit.

 

[Viktimize]

Thanks Will.
The installation was done by Unitrax. So I bought the whole Diff with installed WV already, I just replaced the whole diff.
This is part of what they replied:
" The Wavetrac is unique and exclusive in that if a wheel does become elevated it tries to still send power to that wheel. "

This is what I think:
1. I don't have a Wavetracs diff.
2. I have a Wavetracs diff that is not working properly.
3. Wavetracs claims are completely untrue.

I don't know if you typed this differently, or I'm just reading it wrong? But if a wheel becomes lifted or has a no traction situation, than an LSD diff like the WaveTrac should be transfering power to the wheel with traction. That is the whole point of a LSD. It may continue to send power to the spinning wheel, but it should reach a 50/50 torque bias between the wheels once the clutches engage. So the wheel with no traction would only be able to spin as fast as the wheel with traction.

What you typed out there would only make the wavetrac unique in the fact that it is a non functioning LSD.

 

[SRT101969]

Remove the cover and post a photo of the unit.

OK, do I have to take the whole Diff down to remove cover?

 

[Fatboy 18]

Yes you do. You will also be removing the straps that hold the UJs and drive shafts. It is recommended that you always replace these straps and Bolts. The bolts should have a Loctite patch on them. If they have been replaced recently, you may have Cap bolts (Allen head).

Good luck, not a 5 min job

 

[dester243]

I wonder if he can drain the fluid then get in there with a video inspection camera scope?

 

[WDW MKR]

Yes you do. You will also be removing the straps that hold the UJs and drive shafts. It is recommended that you always replace these straps and Bolts. The bolts should have a Loctite patch on them. If they have been replaced recently, you may have Cap bolts (Allen head).

Good luck, not a 5 min job

No u-joints/straps on his CV axles.

 

[Fatboy 18]

No u-joints/straps on his CV axles.

Really? How's that work then, do you have a pic? Thanks. Interested to see the set up

 

[palindrome]

I could be wrong as I am not a mechanic but aren't most modern high performance LSDs' speed sensing? I would assume that if it doesn't sense speed it will act abnormally or not work properly? I could be wrong.

 

[Viper Specialty]

That is absolutely not working right at all. Curious to see pictures of what is actually installed, or what happened to it...

 

[SRT09]

You should not beable to spin the car in one spot like that!

 

[C-Note]

I just installed one, haven't been into it hard yet as it is still in break in. I am also curious to see what you find.

 

[SRT101969]

I wonder if he can drain the fluid then get in there with a video inspection camera scope?

William, Dan and others with diffs. knowledge, Videoscope with fluid out can work? what to look at?

 

[Will at RSI]

There is clearly something wrong. Even if you could identify the issue with a video scope, you won't be able to fix it without pulling the unit.

 

[SRT09]

There is clearly something wrong. Even if you could identify the issue with a video scope, you won't be able to fix it without pulling the unit.

Exactlly pull the diff and take a look, but before you do that call unitrax and talk to them in case they want more testing etc...

 

[SRT101969]

So this is the main issue, Wavetracs thru Unitrax replied diff is OK!!!!
WAVETRACS SPECIALIST:
"Some customers trying this test can make their car move, while others cannot.", so this is a flip coin game or what!!!!
No further indications or testing requested from Unitrax or WAVETRACS.
So I am on my own thru with all of your help to find out if this is Wavetracs traditional OK diff or there's something really wrong here.

 

[JAY]

WOW ! They are suppose to have a lifetime warranty . Just surprised they would take that approach .
Keep us posted

 

[TrackAire]

So this is the main issue, Wavetracs thru Unitrax replied diff is OK!!!!
WAVETRACS SPECIALIST:
"Some customers trying this test can make their car move, while others cannot.", so this is a flip coin game or what!!!!
No further indications or testing requested from Unitrax or WAVETRACS.
So I am on my own thru with all of your help to find out if this is Wavetracs traditional OK diff or there's something really wrong here.

At first I was going to suggest that the inside tire needs "some" resistance to allow the gears set to climb and start to make the torque transfer. Then I saw this on wavetracs website:


"To best understand how the Wavetrac® is truly different from the other gear differentials on the market, you first have to understand the primary problem that the Wavetrac® solves.
The problem: Loss of drive during zero or near-zero axle-load conditions.
Zero axle-load is a condition that occurs during normal driving, but creates the most noticeable problems when driving in extreme conditions. Zero or near-zero axle-load is the condition that exists when there is ‘no-load’ applied through the drivetrain, when one drive wheel is nearly or completely lifted (often in aggressive cornering). It also occurs during the transition from engine driving a vehicle to engine braking and back, even with both drive wheels firmly on the ground.
Here’s how that loss of drive hurts you:
1) If you lift a wheel, all gear diffs except Wavetrac®, will NOT power the other wheel.
2) During the transition from accel to decel, all gear diffs except Wavetrac®, do nothing.
Why does this happen?
All gear LSDs (including Torsen®, Truetrac®, Quaife®, Peloquin, OBX, etc.) work in basically the same manner: they divide the drive torque between the two axles, applying drive to each side, up to the available grip of each tire. The amount of drive torque one wheel can get over the other is described as the bias ratio, a measure of the torque split across the axle.
Standard, open differentials have a bias ratio of 1:1. They can only apply as much drive torque as there is available traction at one wheel. When one wheel loses grip, the total available drive is lost as well (at a 1:1 ratio). All your power goes out the slipping wheel - along the path of least resistance.
Torque biasing differentials offer increased bias ratios over open differentials. For example, if a diff has a bias ratio of 2.5:1, then it can apply drive torque to the wheel with the most traction (gripping wheel) at 2.5 times the traction limit of the wheel with the least traction (slipping wheel). This is a significant improvement over an open diff… most of the time.
The problem is that when one tire has LITTLE or NO grip (zero axle-load), the other wheel gets ZERO DRIVE, because (basic math here): 2.5 x 0 = 0.
Lift a wheel (or substantially unload a wheel) and you get zero axle-load on that side - that means that during the time the wheel is unloaded, the typical diff will NOT power the wheel that’s still on the ground. No matter how high the bias ratio, you get no power to the ground.
During the transition from accel to decel, where you have near zero torque on the axle, even if the wheels are on the ground, the typical diff is unable to begin applying drive torque until AFTER the zero torque condition is over. While this condition is generally short-lived, the fact that most diffs can do nothing during that time means that there will be a delay once the zero torque condition stops - creating a reaction time in the driveline."



You can view the entire explanation at http://wavetrac.net/different/

Apparently the Wavetrac is adjustable with changeable bias plates to allow for fine tuning. They claim they have enhanced No-Load bias ratio via "special wave mechanism"....whatever that means. I read it to mean you will not have one tire spinning if it has zero traction, the exact opposite of what is happening to you.

Have you tried finding dry clean piece of road way and doing a burn out launch where you are trying to leave rubber on the road?.....if you end up with only one black line instead of two equal tire marks, that would lead me to believe there is a serious issue.

Good luck,
Geoge

 

[MoparMap]

I think the Wavetrac is supposed to be a combo of a Quaife/Torsen and the old Mopar SureGrip (aka Powr-Lok for the clutch type apparently). I have the old SureGrip in my 67 Dart and it works by putting the cross shaft for the spider gears in a notch in the carrier. When the wheels try to turn at different speeds, the spider gears try to rotate in the case which forces the cross shaft to try to climb the notches. This tries to split the carrier apart, thereby adding more load to the clutches (so the more the tires spin, the harder it squeezes the clutches to try to lock the wheels together).

The WaveTrac appears to be a combo of this in that it uses helical gears like a Quaife/Torsen for the normal biasing (which it nice because it sends power to the wheel with better grip as opposed to just trying to lock them together), but when one wheel gets unloaded, which the helical gears can't handle, the "wave" part of the WaveTrac takes effect similar to the SureGrip in my old diff to try to keep power going to both wheels (there's an animation on their website if you look up how the WaveTrac works).

I suppose this might preload the spinning wheel enough that the helical gear set can take over again and bias the power to the wheel on the ground, but I'd just be guessing at that. Regardless, it sounds like the wave part of your Wavetrac isn't putting enough pressure on the other wheel to keep it moving. That or you aren't spinning it hard enough for the wave part to climb the ramps (which sounds like it might be tunable with different springs).

 

[StyVip]

Its looks right to me. As you add more power, the diff should start to lock up. Slow speed/no speed testing doesn't work. What you are actually trying to do is (Rock Crawl) and to do that you need full locking diffs. If they locked up under the conditions you are testing you would get full lock up on any turn at any speed causing a serious traction issues on your rear tires in a corner. The opposite tire (onroad) needs to be turning to cause the diff to start to lock up. If you had a partner start to push your car you would see the diff start to enguage and transfer power over causing the car to start moving forward.

 

[SRT101969]

I want to thank everyone here for their posts. Again: I live in Mexico and without your help it would be imposible to move on and improving my Snake.

Now, I can see that maybe the diff works OK and the lift wheel scenario sometimes will transfer power to the other wheel sometimes NOT. But going to the basic WV claim "If you lift a wheel, all gear diffs except Wavetrac®, will NOT power the other wheel." This is the same as: WV diff is the only that will power the other wheel when you lift it.

I am waiting for my new TRANZILLA tranny + BBG dual clutch kit to arrive (hopefully this week), so when replacing I will do the scope thing or take down the whole Diff to open it and take some pics to try find out what is happening.