Baptizo

I was researching some options for my FSB and came across a company called Wavetrac Differentials. I've been considering Truetrac's or Aussie's for it, front and rear, but some guys mentioned the Wavetrac's as another option.



http://www.wavetrac.net/technical.htm

After looking at their applications list I found this under Porsche:

http://www.wavetrac.net/application.htm#

944 incl turbo 1986, 40.309.170WK, $1,295.00

Note: "944 turbo and turbo S models with OEM LSD and
trans oil cooler option must convert to open-diff style drive gear, part number 016.155.165A and rollpin N.100.792.01"

Has anyone tried one in a 951? Mine is an open diff with a OEM trans oil cooler.

Droops83

Depends on what you are doing with the car.

If it is primarily a street car or used autocross, then the wavetrack might be a good option. It only locks up during acceleration, so is good for traction out of tight turns.

If you do a lot of track events, might want to try a clutch-type diff like the factory unit or one from Guard. These also lock up during deceleration, which is great for stability during hard braking before/into a turn, but can cause some mid-corner understeer, depending on how aggressive of a lockup ratio you are running. This would not be desirable for autoX.

If you do serious track work, do not get a Wavetrack. If not, it should be fine.

sig_a

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You seem to have a good understanding of the Wavetrac diff. Have you ever driven a Wavetrac equipped car on a road course?

Here is what Wavetrac says about their torsen type diff in deceleration mode.

"In the case where both wheels are on the ground during zero axle load, such as during a transition to deceleration, the Wavetrac® device is able to prepare the drivetrain for when the zero torque condition stops, eliminating the delay seen with ordinary gear diffs.

What this means for you as a driver is that power is delivered to the gripping wheels for more time and in a more constant manner – making you faster and improving stability."

Baptizo

I'm still seriously considering getting one for my 951 since it's primarily street driven and will only see occasional DE's @ Mid-Ohio with the PCA.

gruhsy

LR sell that Diff

gruhsy

sells

Baptizo

That's good to know, I'll head over there and see if I can find it!!!

sig_a

derekc23:

Yes. I'm having the Wavetrac installed in my 911 G50 at BMC&G by Brian Copans in Athens, Ohio next week. Salisbury clutch type LSD can be tuned to chassis, suspension and road course, but is much more expensive to tune, setup and maintain. Wavetrac or Quaife is "install and drive" using commonly available synthetic gear oil. My installer talked me out of clutch type and recommended Wavetrac.

Baptizo

It's good to know that word is spreading about the Wavetrac, it seems like a lot of bang for the buck as far as LSD's go.

ninefiveone

Not to be pedantic but by definition, an LSD is a clutch based diff. Wavetracs, quaiffes and the like are torsen diffs.

The differences only matter to a few but for those few, the differences are important.

What wavetrac says about their diff under braking is like saying "our lightbulb doesn't work when there's no electricity but it's quicker to light than a fire when there is electricty. "

s14kev

Torque sensing differentials are excellent if you drive your car at 8/10ths which is the majority of us street and occassional DE types like myself. Amateurs like myself never drive at 10/10ths. I would never risk my self built/funded car.

If you are a serious track type they are unpredictable. Especially running slicks/track tires with high levels of adhesion you are more likely to lift a wheel while cornering. As soon as this happens, torque sensing differentials effectively become open diff's.

Personally. I prefer clutch pack style LSD's. A good clunky 2-way is awesome.

sig_a

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You are mistaken.

Torsen style Quaife, Wavetrac are mechanical devices that limit wheel slip. They are automatic torque bias type LSD, not clutch type.

ninefiveone

This is such an old misconception.

See, you're letting the terminology trip you up. You're operating under the misconception that there are open diff's and there are limited slip diffs. And that within limited slip diffs there are clutch type and torque biasing type.

Actually there are open diffs, torque biasing diffs, and there are limited slip diffs.

It's all about how the work. Google LSD's and torque biasing diff's and you'll better understand the differences, as well as why an LSD and a torque biasing diff are not the same thing.

As I said before, the differences only matter to a few but they are very real. As someone else noted, for 90% of people they do the same thing.

sig_a

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Well, if you're sure you're correct, perhaps its time you edit out the misinformation at Wikipedia -- Limited Slip Differential. You would be doing the motorsport world a great favor. I doubt I'll see your "correction" posted.

"Types

Two main types of LSD are commonly used on passenger cars; torque sensitive (geared or clutch-based or cone-based as shown in figure at top of page) and speed sensitive (viscous/pump and clutch pack). The latter is gaining popularity especially in modern all-wheel drive vehicles, and generally requires less maintenance than the mechanical type.
[edit]Torque-sensitive

The use of the word mechanical implies that the limited slip differential is engaged by interaction between two (or more) mechanical parts. This category includes clutch and cone and helical gear limited slip differentials. For road racing, many prefer a limited slip differential, because it does not lock the two output shafts to spin at the same rate, but rather biases torque to the wheel with more grip by up to 80%."
[edit]

ninefiveone

Ah! You're basing all this on wikipedia. Yes, the entry is incorrect in a lot of substantial ways. What's interesting about wikipedia is that as misinformation or incorrect terms get propagated there, they become "truth." The world would be simpler if we all stuck to proper definitions rather than convoluted ones.

Here's a simple version of the original definition:

http://www.guardtransmission.com/tech_faq.html

It seems like you're getting very upset by all this, but you really don't know how these things work. Here's the thing, that's ok. If the differences don't matter to you, then they don't and you can use whatever term you like!