Limited Slip Differentials: LSD Selection, Setup, and Tuning

[@finngurgens3264]

Excellent content, however what is your opinion on gear-type LSDs like Torsen, Eaton Truetrac and Wavetrac units? Surely they won't be as tunable as a proper clutch-type diff, and most of them (other than Wavetrac and the like) have traction issues when one wheel is off the ground, but the question is....Will it rally anywhere close to the level that a clutch-type diff can?

[@matthewstencel8298]

I'd like to add like a Detroit locker to that. I know drag guys like them for the auto-locking and the stoutness, but how are they in rally cars and possibly drift cars?

[@nathanwabre]

Quaife Torsen lsd all day 💪🏻

[@Thundarr995]

I put a used Torsen from a Camaro in my 97 S10 4.3L 2wd. If I had known how much better it would drive,I would have put one in a long time ago. My truck is also a 5sp manual and with the original open diff this truck has gotten stuck on wet grass,a frozen patch of the parking lot at work. I've also was not able to get up the boat ramp at several lakes,and a a few other times that I recall over the years. I always bring a tow strap and some sacrificial old floor mats just in case I get stuck. I've found that If 1 wheel loses traction you can make the other tire turn by using the parking brake. After installing the Torsen the truck does drive a little different. Gotta be extra careful around wet corners or it can spin out fairly easily. Overall I don't have any complaints. I was going to install a G80 gov loc. I decided to go with the Torsen because there's no clutches to wear out and it doesn't loc at speeds over 20mph anyway. Besides that I've seen alot of videos about the Gov Loc failing and the clutches burning out at 30k-80k miles.

[@darkhorse0687]

Love the videos! Can we get a Will it rally- MX-5

[@not12listen]

A quick video on the pros/cons of viscous VS helical diffs VS clutch pack diffs would be nice.

[@ThrottleJerk]

I've been on a team o'neil video marathon and i could witness wyatt's balding

[@Teamoneilrally]

OOooffff you're not wrong. I'm stuck just buzzing it short from here on out

[@ifell3]

I've learned something, never thought they was that adjustable.

[@darius2640]

can you explain why would someone want their diff to lock on deceleration?

[@Calle...]

To improve stability while braking.

[@Ashalmawia]

not at all an expert and not 100% sure, but I think if the differential is locked, then effectively both brakes are applied to both wheels. if the diff is open, then each brake only applies to its own wheel. also, while you're turning, one of those wheels will have a lot more weight on it than the other. if the diff is open, the wheel with less weight might lockup if you're braking. if the diff is locked, then even if one wheel comes off the ground, that wheel won't lock, and both brakes are still working on the remaining wheel. (as far as I know, one wheel locking up but not the other is a bad situation that can cause you to wipe-out or lose control, but I don't know for sure and I don't know the specifics.)

[@Iseenoobpeoples]

I like how you highlight the importance of having a clutch type differential. It is by far the best mod, predictable torque distribution, improved stability, huge gains over gear type.

[@accurian148]

With all of that knowledge, do you have a plan to start a youtube project series like fully rebuild a rally car, or maybe swapping engine, drivetrain, etc

[@Flyingdutchy33]

This. It's real nice and informative to watch bite sized bits about specific topics, but as some of us know by now, it's about the synergy between them. That said, I can imagine the budget not allowing for a complete car build just for youtube. But perhaps other opportunities present themselves, like customer cars or perhaps an instructors personal vehicle.

[@WillMahler]

Great insight on the mechanical workings of an LSD! I always admired the '97 Nissan SE-R and Impreza RS for coming with a mech LSD as an OE set up. It seems like they'd be good for AX/RX back in the day.

[@facepillownap]

Put a truetrac in the rear of my ‘86 4Runner. Is a mild off-road build with SAS and 35s but I live in Alaska and like to daily it and didn’t want a Griz/Detroit/Aussie ratchet style. Absolutely love it, no more peg leg, both wheels spin on snow and ice, and no different from an open diff on dry pavement as a daily. Not very popular in the off-road scene where most folks run a ratchet or selectable, but for me it’s perfect.

[@InitialDIYmods]

Great video! What are your thoughts on helical LSDs? I have been considering one on my AWD car for some time due to the lower maintenance required for a street car that you can also take to the track. Obviously, you will lose a lot of adjustability by not being able to shim or change clutch arrangements, but do they even have a place in racing (realistically speaking)?

[@DashnCars]

Great info Wyatt. I've been learning a lot about this with the Kaaz clutch LSD in my Fiesta ST. I destroyed the first transmission with not shimming it with enough preload, then the second transmission went down and took the diff with it. I'm working with Kaaz to set up the next one with a different engagement profile but it has been a hard road to get here.

[@backupdoughboi6822]

This aint the right lsd video

[@GorgeousGraphs]

Could you explain me/us, why the rally school is using the Quaife differential in their Ford Fiesta’s and not the Wavetrac or the MFactory or the … ?

[@GorgeousGraphs]

Plus, I always wanted to know, what product you guys use to protect the rear under-body of the Fiesta’s ? (like a rear skid plate)

[@semikon9071]

What about just welding the dif, we in Ukraine do that, works perfectly)

[@Iseenoobpeoples]

You say that a differential only has locking effect when ON/OFF throttle, that's not true for many differential, my Cusco Type RS has a coast (preload) setting, the clutches are always working.

[@Itsmike.d]

At 4:30 , did you mis-speak and confuse shallow/steep angle applications for drift/autoX? Maybe not? It seems like people consider steepness/shallowness from different axes.

[@faramund9865]

Good stuff, you're the first I've seen showing one with a cam ramp or whatever that is. Hope I'll understand when the video is done. By the way your lower face looks like an Irishman but the upper like an Iberian, very confusing! I guess that's what being American is like.

[@dennis3954]

What's wrong when it locks up all the times at whatever speed when turning right but left locks only at high torque? It's a Honda civic fd2r.

[@jad21964]

That was the best explanation I have heard about LSD's. That's exactly why I put a selectable locker in my Jeep. I can turn it on and off when I need or dont need it.

[@Kungfujoe1110]

This is a very cool explanation. My experience with diff tuning is strictly virtual (in iRacing, Formula Renault 3.5), and I have access to ramp angle, clutch count, and preload. The car is a handful under throttle, but I further hamstrung myself for half the season by running very low preload and the fewest clutch plates possible, thinking "If it locks up, I'll spin", but once I started playing with the clutch count (moving from 2 to 6), I found the car had significantly more rear grip moving through corners - sure, if I light the tires up, I'm basically a passenger, but that's sort of true of these open-wheel aero cars by nature. It's a shame I didn't find this video sooner, but it's a very cool explanation all the same. Next season I'm moving on to the Formula Williams FW31 F1 car, which has an absurdly configurable diff, almost other-worldly, where preload and locking can be adjusted for all 3 phases of a corner, and can be adjusted on-the-fly from inside the cockpit. Quick question - How do you change ramp angles in real life? Do you have to machine them, or is it a part you can remove and replace? Also, how do you adjust the preload?

[@kester270]

You can just change them . Most diffs come with two different settings as std but there are lots of options. My diff is 35/90 but it also has 35/60 built it to swap to

[@billyjack70]

Little bit of wrong information here in the video. A shallow angle (lower angle) will provide more ultimate locking as it’s a lever. A 90* will provide no additional locking as there is no force pushing the clutches together.

[@seriouslylovingbacon]

Great informative content as usual! Keep it up guys!

[@matejgriac_MGR]

That wooden wall looks great :)

[@annoythedonkey]

Do I want a choose a diff for my work van, I’m going to be hauling heavy loads sometimes in the snow, going over dirt roads.

[@jacobmyler7689]

Are you able to put a limited slip diff in the 5 speed fiestas? Quaife diffs for the ST are easy enough to find, I'm curious if you've tried putting a diff in one of the naturally aspirated fiestas from the fleet at Team O'Neil.

[@Teamoneilrally]

The fiestas at the school mostly all have open diffs, except for the STs and the real competition cars. Of the 4 Fiesta ST school cars, 2 have Quaifes and 2 have clutch type LSDs (Cusco). The Quaife is nice and smooth, no real torque steer to speak of, but will still spin one tire if you get it off the ground. The Cusco is definitely more aggressive, it locks up more overall and is more what you'd want for a rally car, that's similar to what we use in the R2s and competition cars (Sadev sequential transmissions).

[@joelou]

Thank you so much for this. It answered a ton of questions I had.

[@RobHTech]

I believe of every day cars, Torsen is the way to go. In racing, they can change out the diffs. Ya, but this vid isn't really talking about a specific type of diff. Seems kind of mixed up. But great vid, nonetheless.

[@faramund9865]

I kind of get the idea when seeing your images, moreso than I did before, when I hadn't a clue. So if I get it right, the cam moves and pushes the pieces next to it apart, 'locking' the clutches, turning the two seperate axles into one. I'm still left wondering, how come the cam moves under accel or decel, simply G forces? Is that all it takes to generate that much force? Or is it not much force at all that is needed to lock the clutches? Also, what even are these cams? Are they attached to the spiders? Sorry if I have stupid questions, never seen car parts in my life. Trying to figure out how this works so I can understand sim tuning for a GT3 car...

[@ramzial-qassab6260]

Great insight, so far the only one found relevant to me so subscribed :) question, looking for LSD for circuit racing our 2 DC5 RSX FWD NA BHP 230 approx , should go for standard helical or plated ? am concerned a little with the settings of the plated as dont want to make more problems for myself :) what your advise ? how easy is it to adjust after a couple of laps etc..

[@niipheus]

The interesting thing about this topic is that in a clutch-type LSD, you never actually achieve 100% lock. You can get almost 100, but never a full lock. That's because the ramps need to have some resistance from the pins in order to lock the plates. Since the pins are connected via spiders to the drive shafts and thus half of the plates, if the 100% lock would be possible, all the torque would go through plates and nothing would be left for the pins to split the ramps. But you can always get 90+ percent lock by stacking many plates so they wouldn't need much force in order to achieve the locking.

[@DanielP-c9g]

So i have a fwd car with 110hp and i want to go do autocross events, would i be okay with a helical quaife diff? Or would i better off with a clutch pack diff? Ans what ramp angles would be best for me? Thanks

[@kennyhuntsinger2284]

How about transaxles? I'm running a 2000 corolla and there are variants of the transmission that come with an LSD made by Torsen, is there another way to modify these with aftermarket differentials or do you need a purpose built transmission?

[@justicecallander5525]

This was a fantastic video, you talk at such a great speed, the video images where awesome to pause on for a second. Thanks guys.

[@Greg.Bosworth]

love the video! based off your chart and info, looks like i made the right choice going 1.5way for my "multipurpose" street/drift/mtn pass e30 build, but the talk of hp and ramp angles has me curious..the diff was bought is shimmed and built 1.5way e30 diff "capable of holding 900hp and 200mph goals" (according to seller). sounded drag related, so ide imagine higher lock desired especially with the shims (factory is 25% on these, so ide imagine 50%+?)....but with the power he said it would handle, should i be worried that the ramp angles are too shallow for my mainly stock motor 325i e30, or should the extra shims help make up the difference to get good enough lockup for my uses? car will mainly see back road spirited driving and occasional drift events. appreciate the awesome info/content as always!

[@TomBrom323]

Are you guys using the Quaife bc/ib5 lsd in your non ST fiestas?

[@RallyAddict555]

Hello! I'm 14 and am really into rally, do you guys do an under 18s rally experience?

[@JDMdrifterboy7]

What differential would you suggest for a fiesta st? The wavetrac or the quaife?

[@dupajasiu920]

Which diff will be best for a track with tight turns and some occasional drifting ?

[@Zulfburht]

Shoot any recommendations to low maintenance limited slips for daily use on the ice and snow?

[@jazzjokesjalopies]

Hi from nearby! (W.field). Great channel.

[@player-ko3vy]

Finnaly almost 3 years Ive been waiting for dif adjusting tutorial

[@jesss5139]

Not enough rally events around the us might as well all move across the pound

[@bobsanders9500]

Great video Wyatt. Could you explain diff mapping please?

[@vybhavshinde]

Thank you for this video. Please keep 'em coming.

[@snek9353]

I'm curious to get opinions on if it's worth adding a LSD to my car. It's a rear bias AWD with an electronic center differential and traction/stability control system that I have very few complaints about. Would an LSD help or hinder that system? I'd think it would assist in removing the need for the system to act, but would it also remove it's ability to provide a torque vectoring function. Let's say I throw it hard into a corner under throttle, the rear inside lifts and starts to spin and the car starts to over-rotate. The system will then apply the center diff clutches to drive the front axle, apply some inside rear brake, and maybe some outside front brake. When it applies that inside rear brake it's stopping it from spinning which it would have to do less of with a LSD. However it's also by way of the open differential applying more then 50% torque to the outside tire while allowing it to spin faster then the inside, this is a huge advantage to this system and an LSD would work to prevent this.

[@StrangaPsychoPachic]

A rear lsd will make the car more likely to over steer. Since then both wheels would be spinning. I have a subaru with a rear lsd and it kicks the back end out a lot easier then my older non lsd one did. If your wheel is coming off the ground, you are turning to aggressively or need better suspension/tire combo.

[@虎ちゃん-v8t]

How about electronic diff?

[@thegreatfalcon5]

what about milder diffs for street use? do torsen diffs have inherent flaws that would make them worthless in mild racing (AutoX, TimeAttack) situations?

[@Teamoneilrally]

Torsen diffs are basically 1-way LSDs with pretty mild settings. Pros: Smooth engagement, long life, no service required, quiet, minimal torque steer in FWD applications, probably more. They're great diffs for the street and mild track / rally use. Cons: They don't lock up completely, so one tire will usually spin if it's in the air, they're not adjustable, and only work on throttle (TORSEN = TORque SENsing).

[@DWI_Community]

Nice and clear - thanks mate

[@kiweeltyler3586]

Does an Evo 8 have an open diff?

[@ИванНовожилов-э9з]

Great explantation - thanks a lot!

[@gtasomogyi]

"Do your homework" "FF drifting". OK?.... :D As far as I know that is not possible, since the wrong wheels are driven.

[@rollinthesweets6147]

He said autocross and you most definitely want any sort of lsd for ff when racing, some of the most legendary rally cars are fwd, you can still get it to rotate if your knowledgeable about correct driving technique ie; not just ebrake and power over all the time lol

[@gtasomogyi]

@@rollinthesweets6147 I accept your argument with autocross, I forgot that when I wrote my comment. I meant drift as DRIFT, "powerslide", "power oversteer", what is done at a drift event not with fwd cars, or in the Drift Bible. And as far as I know cars like the Fiat 131, Lancia Stratos, Audi Quattro, Subaru Impreza, Lancer, 307, Focus, etc, in WRC are either RWD, or AWD. I know very well that a fwd can be rotated too, without e-brake, "been there, done that", but that is still not drifting, just letting the rear slide, but can't be kept sliding all the time like with rwd/awd. That is how I see it.

[@kermitserpent6298]

i came here to find out about the right set up when it comes to a LSD trip

[@tommyvercetti6035]

I mean, the knowledge in this video can easily apply to both....

[@thor-eivindrnningen9406]

Isn't it the other way around? A shallow angle will make the diff lock more. As the pin moves easier up the shallow ramp and puts more force on the clutches.

[@tomfromthenorth1]

No mate, think about how much of the force actually goes outwards. For argument sake, if you push forward on a 45 degree ramp half of the force goes forwards and hald sideways. If it's really shallow it'll mostly be forwards and if it's steep it'll be mostly sideways. You need the sideways component to ram the clutches together and lock the driveshafts up.

[@thor-eivindrnningen9406]

@@tomfromthenorth1 I am not a native English speaker, so I might be confused by the terms shallow and steep. But this article illustrates what I am trying to say: murmotorsports.eng.unimelb.edu.au/news-and-events/news-and-events/mur-blog-differentialswhats-the-difference-part-two

[@Teamoneilrally]

You're both right, I think you're saying the same thing different ways. A shallow angle in this case means "more flat" or not much angle to the diff ramp. This makes it harder to force apart and lock the diff. A steeper angle is more like a piece of pizza, it's easier for the pin to force the sides apart and lock the diff. Here's another great resource where we found the diagrams: www.cuscousainc.com/downloads/dl/file/id/190/cusco_lsd_guide.pdf

[@lagg-alot8308]

My sti has a torsen rear diff. It always locks

[@Teamoneilrally]

Unless you get one tire in the air, or on a very dissimilar surface (one on ice and the other on pavement) in which case it will function as an open diff.

[@ramzial-qassab6260]

Rambo

[@patonbike]

I was wondering if you guys have ever looked at VAL racing Subaru R160 LSD's on ebay (They are < $400 shipped from Russia). If I bought one, would you want to install/review it on my supercharged Outback? Not too far from you over in VT.

[@sphirit]

Very good video. I’ve never understood the function of blocking diferential under deceleration . ¿Can anybody explain me it?

[@snek9353]

Removing it's(the differential) ability to lock up under deceleration does a lot to prevent lift oversteer. If losing traction decelerating into a corner it allows the inside tire with less traction to slide while the outside still carries the car though the corner. A car with a two-way differential will be MUCH more prone to lift/snap oversteer.

[@tomfromthenorth1]

(proven wrong by Snek!) With an open diff if you trail brake into a corner the unloaded rear wheel can lock up independently of the outside wheel. With just enough lsd tension across the axle you can keep both back wheels working harder for longer as you decelerate.

[@snek9353]

@@tomfromthenorth1 Sorry no, this is false in several ways. First trail braking implies being on both the accelerator and brake, so the differential is loaded in the acceleration direction not deceleration making it moot to the question of the LSDs actions in deceleration. Secondly with any differential for a rear to lock up(not slide but stop) the driveshaft must be disconnected from the drivetrain(clutch in). For an inside wheel to lock with torque still on the driveshaft the outside wheel would have to turn twice as fast. Some forms of differential can help under braking with clutch in or auto transmission coasting but only a type that's pre-loaded to act without any load on the driveline.

[@tomfromthenorth1]

@@snek9353 Oh, sorry. Thanks for helping us understand. When I said trail braking, I just meant braking hard into a corner and not with any form of left foot braking. So some of the loadings you explained I wasn't thinking about. It is possible to start to lock an inside rear wheel with a car in drive though? Without staling the engine? So a rear diff that locks under decelative load would only be to make the car oversteer more? Not to make it more stable under braking?

[@snek9353]

@@tomfromthenorth1 "It is possible to start to lock an inside rear wheel with a car in drive though? Without staling the engine? " - Yes with an automatic as far as it's concerned it's no different then coming to a stop. "So a rear diff that locks under decelative load would only be to make the car oversteer more? Not to make it more stable under braking?" - It would tend to make the car lift oversteer more, but that's certainly not the purpose. The only real reason is to have the LSD work in reverse. You'd never want a 2 way in a street/track car, but you may in a daily driver that'd see snow and such, in a pickup or something that'd go off-road, and maybe in a rally car as oversteer is a desired way to go around a corner anyway.

[@comando293]

First?

[@Pedro5antos_]

Really, really good explanation!! I've been looking for this content but never found one Trying to apply it to SimRacing

[@dissje165]

After a few videos, I still don't think the camera angle changing makes any better. Your videos are educational so camera angle changing makes me fell sudden cut off. Just my opinion.

[@NitroAdventure]

Hi I was wondering how do I practice driving on gravel for rally safety without endangering people

[@testuser564]

They're probably going to recommend you attend their class, which you should.

[@Teamoneilrally]

Rally school! But even then, you'll want to find somewhere safe to practice afterwards... Maybe a gravel pit or a farm or somewhere will give you permission, or usually you can find some dead-end roads where you can do one pass and make sure nobody is on the road and then do a quick pass. If your goal is "safe" it's not too hard as long as you're a little flexible on what's technically legal

[@bobsanders9500]

Hi Justin. I learnt more in four days at the rally school than I learnt in four years of rallying. Finding somewhere to practice is always a challenge (hint: if you're going to use a public road, use a nondescript car that isn't easily identifiable) but trust me, do the school first so you learn basic car control. Getting the daily driver dragged out of a ditch because your speed level exceeded your skill level is embarrassing and expensive.

[@darius2640]

can you explain why would someone want their diff to lock on deceleration?

[@gedas3419]

Stabiliau stabdos, nemėto prieš posūkį šiknos, mažesnė tikimybė, kad užmes ,,gerai sviedžiant" I posūkį. Pastovesnė ir juntamesnė. Lėtėjant prieš posūkį nereik (ble-užmes/neužmes) maldų