How a Differential Works and Types of Differentials

[ThaurusFury]

A professional video at last!!!! thank you :)

[bubub56]

now what about a full spool rear end

[snowrocket]

@bubub56 It operates exactly the same as a locked locking diff. Both rear wheels turn exactly the same RPM relative to each other. Great for a dedicated drag car, maybe an ice racer, or possibly a rock crawler. A spool would have way too many drawbacks for any other applications.

[bubub56]

@snowrocket i run one on my pro street c10 i know what you mean by not very streetable lol i spin out around every corner

[89Silhouette]

i wonder if toyota give there customers a years supply of brake pads because of that auto lsd, sorry if ive over-estimated the clamping force it genrates on the rotors but that is something that would definetly stop me from purchasing that specific vehicle, should be called an anti-burnout lsd, spin a wheel and the brake will grab it...sounds more dangerous then anything for wet conditions

[allegroracing]

@89Silhouette Again, the brakes are pulsed via an ABS type system to not stop the wheel from turning but to create some drag to transfer power to the opposite axle. That type of system is a low-speed only system. There seems to be a misunderstanding that the brake "holds" the wheel from turning but it's rapidly pulsed only to the extent needed to transfer power. It has to be manually engaged via a button also.

[89Silhouette]

@allegroracing thats why i wrote "sorry if ive over-estimated the clamping force" so its just enough to transfer power but not enough to cause drag "at low speeds only" as you stated, never assumed it holds onto the wheel just assumed the faster it spins the harder it will grab? wich could be dangerous at speeds if the ass end kicks out, it doesnt seem like that diff has a real purpose amongst others but been cheap, didnt toyota want to use the ol' cone-type lsd? now thats a cheap shit diff lol

[mking9446I]

not to bad. i sat and watched it all. good stuff

[FrenchValleyAirport]

i got a 376:1 ratio... i redline to get to 5 mph

[zela9999]

ALSD's work great for the average driver who seldom goes off road, but for serious off road you need locking front & rear diffs. If you have full time 4WD you also need a locking center diff. Brake activated ALSD systems overheat with continuous usage & waste engine power.

[lukeyblunt]

oooh. ok. so it's on 'locking diff'. ok. no worries guys :) CHEERS ! GREAT VIDEO

[lukeyblunt]

my jimny axles are ALWAYS LOCKED when shes in 4WD. is this good..?

[katongougakyunojutsu]

@lukeyblunt no, if you turn, one of the wheels will slip... and lose traction

[punjabpolice911]

God bless you man. 5 stars for the video.

LOCKING DIFF. are widely used in Tractors.

[jamdc2000]

4 dislikes ha! Prius owners

[Jesus45U]

Too bad the video doesn't look into some of the negative parts of a brake-assisted differential.

Ah well, I guess the marketings people wrote the script for the narrator.

[allegroracing]

@Jesus45U I wrote the script and it was for training sales consultants not for marketing. The primary disadvantage is that it's designed for low speed situations where the vehicle is likely to get stuck. It's not designed for all driving situations like, say, a mechanical LSD.

[Jesus45U]

@allegroracing

Ah well, my bad, didn't want to diss your scripting skills.

As for the main disadvantages to brake assisted differentals is that they are a bit jerky, which can unsettle the car, or even make you loose traction.

They also kill momentum, which is what you are trying to gain. (biggest drawback)

They rely on ABS braking systems, which are heavy and complicated systems, thus adding to complexity and service costs of the car.

Oh, and you wear the brakes a little bit.

[allegroracing]

@Jesus45U Actually it's not a requirement that all passenger cars in the US have skid control...that means they also have ABS as standard so given that all new vehicles have ABS sensors, it's really just software to accomplish this and utilizes existing components. If the diff was being used for high-performance driving (ALSD disengages at low speed) then you would, in fact, tend to cook the brakes as often happens at track days with skid control.

[allegroracing]

@allegroracing Er, I meant it IS a requirement that they have skid control...d'oh!

[Jesus45U]

@allegroracing

Oh I understand why they do it .. after all, if you are going to put ABS brakes on in the first place, might as well use them for other stuff as well.

However, calling them Active LSD's is a misnomer. Brakes are not differentials, and do not behave like it.

The correct wording is Brake Assisted Differentials, but don't like the acronym for that = BAD ! so they come up with a fancy word for it, like Electronic Stability Management, Anti Spin Control .. etc. etc.

[rangerover06sc]

@Jesus45U Actually, its more specifically brake-based traction control. It pretty common two you find on everthing from a decade old ford explorer to a high tech land rover or lexus.

[Jesus45U]

@allegroracing

Also, there are other countries in which ABS *is* mandatory, so if they want to sell them outside of the US .. well, they need it.

Offcourse, this is all just fancy stuff, the real tractive effort in a car comes from it's tires ... bring summer tires to a winter wonderland, and you are buggered no matter what technology you have under the hood.

Tires always comes first.

[metalmessiahmetal]

@Jesus45U i thought it was a pretty good idea

if ur not doing max duoez down lincontom station

[Jesus45U]

@metalmessiahmetal

One has to weigh the advantages and the disadvantages and come to a conclusion based on what you need to do with the vehicle. And as zela9999 mentions, it's a great thing for the average driver who just toodle around in his generic eco box and sometimes run into a small patch of ice on a parking lot.

But for the more serious offroad drivers, or racers, it won't cut it, you will need "the real deal" so to speak.

[agahlot69]

helpful.............:-)

[JOSICO57]

Muy bueno para aprender, esta interesante Mecanica del diferencial.

[EdSuavePerez]

im a huge DRIFT nerd so i need to learn abotu this, nice video =D

[varun9448102800]

Good Explanation...I got it atlast...Thank u

[agricultor2000]

Nice! :) Very usefull! tx!

[mastersduhgree]

In drag racing i dont think this break activated posi is in the least beneficial.WHo on earth would apply a break when your trying to better your time.Whats the matter with a good ole clutch activated posi.? Umm....nothing.Its the best setup there ever was.And trading it in for whats on the rigs now ??? Not in your life.

[allegroracing]

@mastersduhgree First of all, this is in the context of pickup trucks. Drag racing is not a consideration in any way. Secondly, posis are great and have cost and maintenance disadvantages which, in many vehicles. outweighs the benefits when you consider all the features and technologies that are desired by the customer. Vehicles can't have everything. When the Tundra came out, domestics had 4-speed trannies! LOL!

[mastersduhgree]

@allegroracing Right on...Thanks for the note.

[blownutsmyass]

@allegroracing don't let these dip sticks get you all wound up. atlest this brake based LSD idea works much better then cutting the engine back witch does nothing but get you stuck when you was still moving.

[AFROTCbrony]

@mastersduhgree For drag racing, wouldn't you be better off with a locked differential, or no differential at all?

[blownutsmyass]

@mastersduhgree brake activated diffs work just fine on a drag strip but more for steering then traction if/ when the front tires are lifter off the ground or are very close to off the ground and cannot steer the vehicle so you would have to let off the gas to let the front end down to steer witch in the end make you slower then just having a slight brake asist.

[mastersduhgree]

The big big draw back to the break activated LSD differential is that your going to be dragging the wheel with the break on.You will have a tendancy to get the unstuck wheel stuck now.This is a poor poor idea.We used to put the emergency break on when we got stuck to get the power going to the unstuck wheel.SOMETIMES it would work under ideal conditions but;you mostly got the other wheel buried in the process.Not always good.I think on ice this would cause the rear to come around front of you.

[allegroracing]

@mastersduhgree It doesn't "drag" the brake, auto LSD can pulse the brake a fraction of a second or several times per second and stops as soon as the other size gets traction. Trying to do this with the parking brake has a similar effect but is nothing like as sophisticated as the high-speed brake pulsing. It's also the basis of the CRAWL system which allows vehicles like the Lexus 460 to decline incredibly steep hills with both feet on the floor.

[4u250ut]

@mastersduhgree I have a 2005 Toyota 4runner I thought when the LSD is activated it stop the wheel that spins..(like stuck on ice) .and put more torque on the other wheels that not spinning so the car/suv would not be stuck..this video is kinda confusing to me,..if you can explain more that be nice...thanks in advance.

[1990fordf150custom]

thumbs up for a solid straight rear axle

[Pagweb]

This game an idea to make a gear-based computer...

[jnwpse]

Never heard of the Auto LSD till this video. But I just thought about in my head it right before I saw it. Nice job Toyota. Practical simplicity.

[goldenageism]

WOW SO EASY!

[xSykiax]

Diff lock FTW !!!!!

[shad366]

THANK YOU so much. I could not even begin to grasp what the difference between a locking diff and a LSD was, but now I fully understand.

[PayDroification]

Quick question.

I have a 2000 Mustang, & I hate doing burnouts, but I peeled out in the rain & noticed I only get one tire spinning. The rear passenger side. Is my Mustang using one wheel under all driving circumstances for power? Or is ita basic open differential where I get power to both tired until I begin to skid? Am I getting the 2 rear wheels working? Or just one?

[allegroracing]

@PayDroification I'm not a Mustang expert but I know there was a friction-disc LSD on some Mustang rear ends and open diffs on others. If you find out you had an LSD on your particular model of Mustang, it's possible that the friction discs are worn out and it's not providing a limited-slip effect. If you have an open diff, the power tends to always go to the same axle so you would find "1-wheel drive" on the same wheel would be normal.

[mastersduhgree]

@PayDroification TO test if you really have a "limited slip" or a "positrack"(power goes to both wheels); when you turn a corner, step on the gas to lay some rubber.If the outside tire spins too;you have a posi or limited slip.(just look for the fry marks when you go around the block to check out the rubber you layed.

[snowrocket]

@PayDroification You LIKELY have an open diff. There's probably some tag on the diff that would tell your Ford parts guy whether it's open or LSD. Ford used to call their LSD "Traction-Loc", GM called theirs "Positraction" and Chrysler called theirs "Sure Grip". Part of what you're noticing is "driveshaft rotation effect" (my term). DRE with a live axle setup like the shown Tundra or your Mustang tries to pick up the right rear wheel when going forward. This reduces it's traction and it spins.

[snowrocket]

@PayDroification DRE (driveshaft rotation effect) also means that if you attempt to back up quickly, you may spin the left rear wheel more than the right. It's not that only "one wheel drives", it's that your "go traction" is limited by the wheel with the least traction. One of the advantages of independent rear suspensions on rear driven wheels is the elimination of DRE.

[cheapo911]

Just watched all your vids and I must say pretty interesting. Nicely done

[psycotria]

Thanks for the education.

[RxOLLER]

toyota FTW

[WebDevFTW]

I love LSD.

[pnelego]

you can also completely stop your vehicle with a common diff

[evilet1111]

@lokoman, why NOT a Tundra? It's irrelevant..

[thebluecommet]

Toyota must really full of themselves to think that using the brakes to turn an open diff into a crapy version of a limited slip is somehow superior to anything other than an open diff.

[allegroracing]

@thebluecommet Nowhere in that video does it claim that ALSD (which is far from a unique application of that technology in the auto industry) is superior to anything other than an open diff. ALSD has two benefits over other LSDs, it's lighter and it's cheaper to maintain. That is the only statement in the video. The reason so many differential designs exist is that each is suited to a specific need and have advantages and disadvantages depending on how the vehicle is going to be used.

[BerriesMcGOO]

@allegroracing 3:56 "toyota's auto lsd system" then they continue to show it on a tundra

[rangerover06sc]

@thebluecommet The video states that ALSD(aka brake based traction control) does a better job of trasfering torque then other differentials. And it does. Mechanical LSDs can't really change the torque distrabution, they just limit how much of the torque can go to the wheel with the least amout of traction. Brake based traction control can make the wheel with the least amount of resistance the wheel with the most amout of resistance. This why many modern cars use it.

[porknbeans2013]

@thebluecommet im pretty sure that you can do this with any open diff, toyota just felt like telling their customers in case they needed it

[TheGreavette]

@thebluecommet Ya! What he said!

[mout12]

@thebluecommet Uhhhh A limited slip or a clutch works essentially the same way as brakes do...

[lokoman1231]

really? a tundra?

[GTSportsOnline]

Great video! :d

[motoman9477]

Hope you don't mind me asking you a question...I have A ford Explorer(93)..and my rear dif is staying locked...is there any why I can disengage it? Thanks...

[allegroracing]

@motoman9477 Sorry, I don't have any knowledge of that specific diff.

[contentlocked99]

@motoman9477 take your hoghead off and get dirty, thats how youll find out. id be happy if my rearend was locked in an explorer, id never get stuck lol

[RG5EX11]

oh so for drifting what would you use an LSD or a lock differential ???

[allegroracing]

That's a good question. Normally in racing situations, of course, you'd want a limited slip diff. I would think with drifting that you'd still want some differential action but you'd want to really limit it so the amount of "slip" is low so that you can ensure lighting up both rear tires. If the car isn't actually drifted but is driven on curves, a locked differential would not only produce really bad handling but would also potentially damage the diff when turning so my guess is adjustable LSD.

[andrassy888]

Limited slip using braking very clever, thank you.

[allegroracing]

That's a tough question to answer. Remember it's the tires adhesion that ultimately determines if the car moves or the tires just sit there spinning (or skidding if the car is moving). The ability to control wheel slip and distribute power to any of the 4 wheels is very helpful in situations where one or more wheels are slipping but one or more have traction. However, if all 4 tires are on ice and there's no adhesion for any tire, no drive system will get the car moving.

[7150285]

Auto LSD = traction control

[allegroracing]

There are a number of different but related software packages that control wheel slip via use of the brakes but they are actually technically independent. VSC (skid control), TRAC (traction control) ALSD (auto LSD), ABS (anti-lock-brakes), and Brake Assist (BA) all utilize wheel slip/brake control to accomplish a task but they are independent and were not always included as a full set of installed software. Some of the systems reduce engine power, some change brake pressure etc.

[FromThe3PointLine]

Very helpful!

[TheZenPerspective]

How would it reduce maintenance if you are using the brakes more often, it would mean you would have to change the brake pads more than usual, therefore increasing maintenance, but I assume it probably requires less maintenance than the other limited slip differentials out there that do the same job.

[allegroracing]

You answered your own question. Because ALSD only operates at low speeds, the brake friction is low and the brake wear is negligible. Some truck LSDs require frequent oil changes (as frequently as 12 or 20,000 miles) and there are more mechanical components that wear. Changing brake pads is cheaper and easier than differential parts.

[dylf14]

nice tech

[oODubKiwiOo]

awesome vid



[buttmanroad]

Nice!!!