In-Car Comparison - Open Differential vs WaveTrac Limited Slip Differential 

I agree, excellent video.

Thanks! In my experience in other cars, the Wavetrac and Quaife diffs perform very similarly and feel almost the same. In theory the Wavetrac should have an advantage in situations where the inside wheel lifts completely off the ground, but we don't really lift the inside driven wheel that much on the tracks in our area.

Thank you for watching! Installing a helical LSD will typically not reduce or induce oversteer in a FWD car. It will make the car more eager to turn in when you apply the throttle with the steering wheel turned, however, so the car will feel like it has less understeer in the middle of and exit of corners. I hope that makes sense!

I would say the effects of the LSD are much more pronounced in slick / wet conditions. You get a lot more inside front wheelspin through slow corners when the track is wet, and the LSD helps keep that under control. It would be difficult to do a direct comparison on a wet track (because it's difficult to replicate the same amount of rain), but I suspect the difference in lap times would be much greater if the track was wet.

@@StudioVRM so your saying a helical LSD is much better in rain than a open, correct? (I'd imagine a clutch lsd is also but not sure). Okay so with a helical LSD like you used in the video.....when the inside tire loses traction in the rain, is all the power shifted to the outside tire or does it try to 'lock' and send power to both? BTW....this was a great video!

@@stephenwhite5444 That's right. A clutch pack LSD can be faster than a helical LSD or an open diff, but it depends on how it's set up. Some 2-way clutch pack LSD setups are so aggressive that they'll prevent the car from turning in under deceleration. The wavetrac (and pretty much every other helical LSD out there) tries to shift the power to the outside wheel. The wave gears in the wavetrac would make you think it works like a locker, but in practice it behaves like any other helical LSD. The only difference between it and the others is that the Wavetrac is designed to work when one wheel is in the air. And thanks! I'm hoping to restart video production soon. Just as soon as the coronavirus situation calms down a little bit.

@@StudioVRM do you feel like a clutch style would work just as good as the Wavetrac in dry and rain but just picked the Wavetrac based on maintenance concerns? And with one wheel up? I think the clutch style do fine with one wheel up. I have a factory Ford 8.8 LSD in my garage and had been looking at a Eaton Truetrac for it (slightly used for $200), but if theres no benifit besides maintenance then I may just rebuild the clutches tight and be done with it. My main concerns are wheel up and rain. I know itll be fine on dry. It's also street driven so dont want a auto locker, and cant afford a selectable locker.

@@stephenwhite5444 A Wavetrac or similar helical LSD will feel smoother on the street due to the naturally progressive way that they engage. However, if you are worried about traction when you have one wheel in the air, a clutch pack LSD will generally give you better traction than a Wavetrac. It will also outperform an Eaton Trutrac too, since teh Eaton design is more of a standard helical LSD (without the wave gears that allow the Wavetrac to work when there's one wheel in the air.

Definitely. I don't think you'll have to change your approach either. These helical diffs drive very naturally compared to a clutch pack or locking diff.

It depends on the car and the cost of the diff itself. On Honda cars like ours, the diff can be purchased for anywhere between $500 and $1200 US, depending on whether it is a torsen (like this one) or a clutch pack. Installation can also run anywhere between $500 and $1200 depending on the car and how difficult it is to remove the transmission.

That's the beauty of helical LSDs like the Wavetrac. Because they behave the same way as an open diff most of the time, you don't have to change your driving style at all. Once you get used to it you'll notice that you can get on the throttle earlier and that you don't have to lift as much to get the car to turn. But that's really it. You can keep driving the car the same way you do today.

@@StudioVRM thank you for the answer! So basically i can enjoy corners without being afraid to understeer like i usually do. Other than that that s no downside to it. Am i correct?

@@FilipCosminM Yes that's basically true for most cases. Helical LSDs are nice that way. Good, noticeable changes in the right situations, no bad behaviors to worry about.

@@StudioVRM thank you for the answers!

@@FilipCosminM No problem! Hope it helps.

If you like to drive aggressively, you will notice it. Especially when you turn the wheel and apply the throttle at the same time. The car will feel like it wants to pull itself into corners.

@@StudioVRM That's the reason I bought my GTI 😁 It's a restoration project, since older cars are kinda rusty in Finland. And of course the engine is being modded & tuned, so I think Wavetrac would compliment the build perfectly then 🤔

It's because the tyres aren't on the lateral limit of grip when the inside front wheel starts to spin. Even with the open diff there's still plenty of grip on the outside front tyre. But because the inside front has no traction I have to lift off the throttle, and that causes me to lose time. With the LSD, I can keep applying some throttle so I don't lose any time. That said if I floored the throttle at the apex, the car would try to understeer off the track.

Thank you so much for the explanation! So basically LSD can reduce inner front tire’s wheel spin when light throttle is applied, so more time on the throttle so it’s faster. LSD enables the possibility to apply more throttle in a turn than a open diff, is that right? When off throttle, LSD(except 2 way) and open diff should have same character? Thanks!

Yes, that's correct. The WaveTrac (and other helical LSDs that I've driven on) behave like an open diff most of the time so it feels very natural coming from a regular car with an open diff. I found it to be a very easy transition, with very little mental re-training involved.

StudioVRM I see. I drive a Subaru WRX with front and rear open diff. So the strategy for cars with open diff should be entering the corner with a tighter line and straighten steering earlier, then apply full throttle? Is it possible to catch up the car with front and rear helical LSD in theory? Thank you so much for the insights!

Hmm. In theory entering corners with a tighter line and doing an aggressive rotation of the car will put more work on your center diff and less on your open front and rear diffs. However, based on my own limited experience with my WRX and watching the behavior of various WRX's at track days, I suspect that the amount of cornering speed that you lose from driving a tight line would outweigh any gains that you get from working the diffs harder. I think it might be faster just to drive a more traditional line on entry. If corner exit understeer is an issue, you can take a slightly later apex through slow turns to help straighten the car.

That's right. It works pretty well for a low-maintenance LSD.

The LSD was worth an average of 1.1 seconds a lap on NJMP Lightning, and about 1.3 seconds a lap on NJMP Thunderbolt. Both tracks at NJMP have weird turns where an LSD makes a big difference. I would expect the difference to be greater at a stop-and-go type track (like Summit Point) and less at a flowing high-speed track (like Lime Rock).

do you think that the open diff will be faster at high speed curves with 100% throttle ? @@StudioVRM

@@astrios9259 I don't think the helical diff and open diff will be all that different through high-speed corners, as long as the drive wheels aren't traction limited. An aggressive clutch pack diff can hurt the car's turn-in through high-speed corners though, so an open diff can be faster in those situations.

weird to me. i hate open dif. one wheel burnouts suck and lsd handles alot better when you know how to maneuver it

Yes my friend it is:)