Everybody’s heard the acronym YOLO by now: You Only Live Once. Well, for car enthusiasts, it takes on a different, less positive meaning. YOLO, for us, means “You Only Leave One”, referring to a one-wheel burnout. This is caused by having an open differential in the rear, which sends all the engine’s power to the wheel with the least grip. It’s also extremely embarrassing! How can we save you the shame of performing a one-tire fire?
There are an abundance of different differential types. Some completely lock the axles together, such as welded, spool, and locking differentials. Others allow for some slip under low pressure, including vLSDs, Clutch-type LSD, and Torsen/Helical differentials. Finally, some differentials are computer-controlled, actively sending torque where needed, called Torque Vectoring differentials.
Each type of differential has its own pros and cons, including the lockers causing premature tire and drivetrain wear, LSDs wearing out, and TVDs being unpredictable. Let’s dive into each category, find out how they work, and which differential is best for drifting.
Can I Drift An Open Differential?
The open differential is one of the most simple, economical, and practical differentials for a commuter car. With no restrictions on turning, a simple design, and few moving parts, this is a fairly reliable design too. If you looked at the street right now, odds are that over ninety percent of the cars you see have open differentials. Unless you’re reading this from a motorsports complex, or a Ferrari dealership, I suppose.
The biggest drawback of the open differential is that.. well, they’re open. Force tends to go through the path of least resistance. So when torque is applied through the differential, whichever wheel has less grip gets more power. In daily driving scenarios, that’s OK, due to there rarely being a need for both wheels to power down. On the track, drag strip, or drift circuit, however, your chances of putting significant power down are gone. If one of your wheels starts to slip, then all the power goes away from the wheel with grip, you lose all acceleration force. Needless to say, this is a massive detriment to any car looking to go quickly.
I’m sure you can see where this presents an issue for drifting. I’ve tried it, and it ended with a month-long repair and a couple grand in the hole. Starting a drift is incredibly difficult, and keeping it is near impossible. If by some miracle you get sideways, then the next issue arises. While you’re drifting, a lot of your weight is on the leading tires, and shifts frequently when you’re transitioning between corners. Each time you transition, or stay in a bend with that weight distribution, is another chance for the differential to quit putting power to both wheels.
Should I Drift With A Limited Slip Differential?
This type of differential is your most practical option for a track or drift car that you drive on the street. With the ability to lock up under power while not sacrificing turning ability, this is your low-tech middle ground. However, for those willing to make comfort sacrifices in order to drift better, pass these up. There’s a few different ways that LSDs lock up, using clutches, gears, or hydraulic-esque fluids. Each one has its own quirks, lets go into them.
Clutch-type Limited Slip Differential, Spring-based
Opening up with the most common type, we have the clutch-based LSD. Featuring one clutch pack per axle, this differential relies on axial force and friction in order to lock up. When you’re going straight on the road, the power goes through the diff housing and right to the wheels, same as in an open differential. When one wheel loses traction, however, is when things get interesting. The wheel that’s still got grip receives higher torque, trying to turn the wheels at the same rate. That produces an axial load on the gears, pushing that side’s gear out a little. The clutch pack for that axle then compresses, locking its rotation to that of the housing. This force is accentuated by a spring in the center of the differential that constantly presses outwards on the axles. This results in both wheels getting nearly equal power.
This is the highest-maintenance differential of those used in drifting. Due to the nature of the clutches slipping past one another while not locked, they wear rather quickly. Eventually, the clutches will wear to a point where they won’t lock together, and you’ll need to replace them. During daily driving, this occurs as well, making it rather impractical. While it may be a quick-wearing differential, it’s also one of the cheapest, being nearly the same as an open differential, with some clutches added to the housing.
Clutch-type Limited Slip Differential, Compression Ring-based
This type of differential is incredibly similar to its spring-based brother, with the primary difference being the lack of a spring. Instead, there are items called “pressure rings” around the edges of the housing, with small cutouts for the spider gears to slide into. Whenever a torque is applied to the differential (acceleration or deceleration), the spider gears push against those pressure rings. The angled surface turns that force into axial force, compressing the clutches, locking the differential.
The angles of those cuts for the spider gears is what determines whether your differential is “1-way, 1.5-way, or 2-way”. A 1-way differential only locks under acceleration, a 1.5-way locks fully under acceleration but half-locks under deceleration, and a 2-way locks under both acceleration and deceleration. No matter which of these you choose, the biggest benefit of these differentials is how they don’t lock unless pressure is applied. This is how I daily drove my ’95 240sx, I would accelerate straight, then put the clutch in and make the turn, then apply power once I was going straight again.
While I was under power, the differential would lock up, and I didn’t want to be dragging a wheel through the whole corner. When I’d put in the clutch, that’d release all pressure on the differential, unlocking the clutches. I’d just coast through the corner with the diff under no load, then once I was straight again, start accelerating. I drove like this for a long time, and although I got a few weird looks, it was nothing compared to when I pumped gas into the trunk! (That car had a rear-mount fuel cell, and my town is chock-full of non-car people, who don’t know what that is.)
Viscous Limited Slip Differential
Second only to the open differential, the VLSD is one of the worst differentials for drifting. Relying on nearly the same principles as a torque converter, they have two large fans inside thick liquid. When one wheel starts to spin, the fan turns the liquid, which attempts to turn the other wheel. This type of differential, at best, works like a broken 2-way LSD. It’s a great differential for street use, where you don’t need an immediate response. When you need both wheels to be turning at the same rate in a drift, or at the track, this isn’t your differential.
TorSen and Helical Differentials
These differentials are my ideal choice for limited slip differentials. They don’t have any wear items such as hydraulic fluids or clutches, nor do they have complicated electrical designs. These are operated simply by the laws of physics, require few moving parts, and reliably lock both wheels when desired. I grouped these together due to their incredibly similar methods of working, basing their designs on worm and spur gears. To put it simply, a work gear can turn a spur, but a spur cannot drive a worm gear.
Thus, when power is applied to the differential, the gears cannot be turned separately by the engine, and move as one. However, when taking a turn, the wheel is forced to spin faster. This force is applied by the ground onto the tire, and since the worm gear is attached to the axle, it can drive the spur gear, allowing for different wheel speeds. This results in a reliable, predictable lock when you want it, and a smooth drive when you don’t.
The primary difference between the two differentials is that the Torsen differential has gears on the end of its longitudinally-mounted spur gears that connect the two axles. The helical differential, on the other hand, has the spur gears mounted horizontally, and they mesh together. While this doesn’t affect performance, this does slightly change the size proportions of each diff. The Torsen differential is a much taller one, while the helical differential is wider (and slightly weaker per pound).
Are Locking and Locked Differentials Best For Drifting?
Having a differential that can lock itself is good, but can also lead to unwanted locking. If you’re prepared for the differential to be constantly locked, however, it’s extremely predictable. That’s what almost did in my S13 though, so be careful! Being able to lock and unlock your differential on command isn’t a new technology, but one that started in the off-roading community. Having one of your Jeep’s wheels in the air and an open differential is a recipe for disaster. Locking up that differential allows you to avoid the issue, putting power where it can be used.
Why would you use a locking differential in drifting though? While you’re sliding, there’s no reason for you to unlock your differential. If the car is a road car too, or even if your drift event has a tight parking lot, unlocking can help a lot. Daily driving with a locked differential isn’t the most convenient, nor is low-speed maneuvering with one. If you had the option to unlock the differential, though, you could daily it like a normal car, and lock it up when you’re ready to drift.
If you aren’t ready to shell out a decent chunk of change for a differential, however, you could go with a locked differential. Namely, a Spool differential. This type of differential’s purpose is solely to provide equal power to both wheels, permanently. While most commonly used in drag racing, a spool differential can easily be used in drifting, acting the same as a welded differential. A spool’s purpose is to remove the spider gears from your differential entirely, instead replacing them with one solid piece. This lets you bolt your ring gear to the face of the spool, and slot both axles into either end of it. Thus, constant power to both wheels.
Here we go, the main event! Welding your diff solid is a cheap, easy way to get power to both wheels equally. This is both the upside and the downside, as it locks your axles together. While drifting, this is extremely useful, as it’s the most predictable differential. On the street, and in low-speed maneuvering, this puts incredible amounts of stress on the vehicle. I almost trashed my ’91 240sx by underestimating the effects of a welded differential.
As long as you’re on top of your maintenance, and consistently inspect your vehicle, you should be OK with a welded diff on the street. For drifting, as long as the welding job is quality, you shouldn’t ever have issues with it.
Torque Vectoring Differentials
The technology behind Torque Vectoring Differentials has been out for a long time. From skid steers to tanks, we’re surrounded by it. However, use in automobiles is fairly new, with the first patented design coming in 2006, and first being seen in the Lancer Evolution. As seen in the video, when the white Evo lifts a wheel at 1:54, it’s still able to pull itself out of the ditch. The torque vectoring differentials put all the engine’s power to the wheels on the ground, shoving the car forwards. In low-grip scenarios, this is incredibly useful, as well as for off-road motorsports.
For drifting, however, this technology is not idea. If one wheel is receiving more torque than the other, that could lead to a very unstable or imbalanced drift. You’d be much better off with a welded differential or a mechanical LSD.