OMG &%^&#!@!!! 50/50 always

[bosco]

No, I am right.

 

 

my Granny use to say "if your always talking your always right" bosco

[Beanboy]

You know what, I give up.

 

Remember, my statement is the center diff always is a 50:50 torque split, no matter what.

 

Somebody please with examples/numbers/diagrams like I did with my dyno example, and I will gladly say I am wrong.

 

"Any 4WD system that has some way to lock/almost lock can send almost all (depending on how well the locking mechanism can lock) torque to either front or rear axles, regardless of center diff torque split, or even a center diff (like Haldex)"

 

I've shown an example, and also quoted other web sites. Prove me wrong already! Hehe

[KTM 525]

http://www.stimpco.com/carpix/lol3/billtedwtf.jpg

[Beanboy]

[ineedone]

After 6 pages all I can say is WOW (dumbass)

[-TT-]

After 6 pages all I can say is WOW (dumbass)

 

 

[Beanboy]

Come now ineedone, no need for that. All I'm asking is to show me that I'm wrong.

 

How about this.

 

Let's look at the rear diff on a Subaru then with a viscous limited slip coupler. Would you say the rear diff torque split is 50:50 side to side always, or is it variable up to whatever the holding ability of the viscous coupler is, 90:10 to 10:90 from side to side.

 

If you say variable from side to side, then check out the rear diff on a car with SH-AWD system from Honda:

 

"planetary gear set with two electromagnetic clutch packs to control torque split side-to-side, and it can be continuously varied between zero and 100 percent"

 

What's the difference? To me, the difference is that the Honda system CAN adjust the torque split of the rear diff, while the Subaru can't

[Beanboy]

Seberry, I may harass you about how fast your car is in relation to NA econoboxes in the Rockies/tell you to datalog (have you done it yet?) but thanks, hehe.

 

I just don't know how else to describe it, hehe.

[meier motor sports]

So if you take a truck and it is locked 50/50 in 4WD and lift one set of wheels up and put the other set on a dyno, what % of torque will you see?

50%

You aren't going to see only 50%, the driveshaft is "one piece" You are going to see nearly 100%, even with the torque split in the center diff being physically locked at 50:50. It is variable as well then, sending nearly 100% of torque and any ratio inbetween depending on traction.

 

then the front wheels not on the dyno would be equaly spinning trying to drive you off the dyno. half the power to the front half to the rear

 

Do the same thing to a Subaru, and you will see what, 90% or so since the viscous coupler can't fully lock, but that has nothing to do with the torque split of the center diff.

 

you will see 100% tq quickly dwindel as the front tires or rear or whatever u didnt put on the dyno try to get traction and propell the car forward

 

ANY 4WD system with some type of limited slip device/locker should see close to 100% of torque transfer front or rear depending on which set of axles has most traction and how well the limited slip device holds, it has nothing to do with the set gear ratio of the center diff.

 

the gear ratio part.... how do u think a rock crawler gets more tq to the wheels? low gears. most 4X4 trucks have a low range... this gives you more tq. thats why u can only go 35mph in low gear. just like riding a bike when u shift to the lowest gear and pedal your ass off and go no where. but u can climb a mountain. thats is tq. but it really has nothing to do with tq split

[Beanboy]

So if you take a truck and it is locked 50/50 in 4WD and lift one set of wheels up and put the other set on a dyno, what % of torque will you see?

 

50%

then the front wheels not on the dyno would be equaly spinning trying to drive you off the dyno. half the power to the front half to the rear

 

Sorry, but that is not correct. As I have been saying the torque split is 50:50, power transfer is not, it will be close to 100% to the wheels on the dyno.

 

I posted this earlier:

 

http://www.4x4abc.com/4WD101/awd.html

 

Part time 4WD

Vehicles always distribute torque inside their transfer case 50/50 to front and rear when the shifter is in one of the 4WD positions (Hi or Lo). Most of the time each of the 4 wheels gets 25% of the torque - that minimizes wheel spin. This system is very strong and reliable - unfortunately it can't be used on pavement. Should one of the wheels or one axle lose traction - the other axle will still receive a reliable supply of torque (up to 100%) through the transfer case

 

Hmm, so is this the problem folks are having with this concept?

[Beanboy]

If you don't believe that site, here is another:

 

http://dictionary.laborlawtalk.com/4WD

"Part-time four wheel drive systems are ideal for use in very difficult traction conditions since they allow all of the torque to be sent to the rear or front wheels."

 

This gets to the heart of what I am trying to say, and what many seem to be confused about. The torque split from the engine to the front and rear shafts stays the same, actual power transfer occurs because of the locking mechanism used to limit the slip of the center diff.

[Fly 2.5]

If my Subaru falls in the middle of a forest and no one is around to hear it, does it's torque split?

[Beanboy]

I just noticed something.

 

When I say " lift one set of wheels up" I mean lift them up off the ground completely. Apologize if that wasn't implied. I did mention the fact in a couple of posts though:

 

"Throw one end up in the air and one set on dyno, and you will see nearly 100% of the engine's power output."

 

Meier Motorsports, I take it you agree with that? Again, sorry I wasn't clear about it...

[lookslikeanevo]

i thought AWD and 4WD are different? so whatever info you are pulling from 4WD sites wouldnt really apply?>

[meier motor sports]

Beanboy, I am with you on this one man...

 

The system may not always have a 50/50 torque split, but the Viscous locker's job is to maintain that split.

 

Ok, front wheels on ice, rear wheels both on pavement. When you accelerate, more torque briefly goes to the front because those are the wheels with the least amount of traction. (The viscous locker hasn't heated and locked yet) What the Viscous locking diff does is react to this slippage and limit the amount of torque going to the front wheels that is enabling them to spin and regain a 50:50 split. They will still turn at the same speed as the rear wheels once the car gets rolling.

 

 

 

 

exactly! it trys to be 50/50. it wants it to be even. but its not always 50/50. it can be 90/10 80/20 70/30 60/40 50/50 40/60 30/70 20/80 10/90. bean boy say it ias always 50/50

 

Doesn't matter... the ratio is fixed at 50:50. Replace the diff with a solid driveshaft and gear, the split is 50:50. Throw one end up in the air and one set on dyno, and you will see nearly 100% of the engine's power output.

The center diff gear ratio of 50/50 never changes!

and here he contradicts what he has been saying

Luke, the reason why your front tires spin is because the viscous coupling is reactive and there needs to be a speed difference for it to work.

 

Again, beyond the theoretical, the actual output on the dyno won't be 100% because the viscous coupling can't truely lock... Not sure what the exact figure is, something like 90% locking probably.

 

 

and with that im done. *unsubscribed*

[Beanboy]

No, it does apply. Since there is a viscous coupler attached to our center diff, the concept is the same. Same goes for a Haldex car without a center diff at all, and is part of what I am saying that the center diff ratio has no bearing on torque transfer/no need for center diff at all/power transfer is all about locking mechanism used.

 

The only difference with my examples is that you aren't going to see close to 100% of the torque with a regular 5MT Subaru, since the locking mechanism in our cars doesn't lock fully; just about (an estimated) 90%.

[meier motor sports]

what?

 

see my attachments. they explain how the viscous diff works

 

if u want more works read one of my other posts

[Beanboy]

Light dawns. Thank you Meier Motorsports!

 

Rao and everybody, is that what you meant? If it is, then I apologize x1000 and owe you some money, hehe.

 

To wrap things up:

 

Subaru 5MT:

A 5MT Subaru has a power transfer ability of roughly 10:90 to 90:10 when the viscous coupling is locked. The center diff has a torque split of 50:50. The torque split changes very briefly but is widely variable when slip occurs before the viscous coupling locks. *hmm, can you say the torque split varies slightly even with the viscous coupling is locked since the viscous coupling can't lock fully?*

 

Haldex:

Haldex systems have the same torque split of 50:50 when locked. Power transfer ability might be a bit better since the locking mechanism is clutch-based, say 5:95 to 95:5.

 

Truck:

Center diff torque split is always 50:50. Power transfer ability is nearly 0:100 to 100:0.

 

If you take a vehicle with any of the systems above and lift either set of wheels off the ground and the other set on a dyno, you will see nearly all of the engine's torque through one set of wheels.

[bosco]

what?

 

see my attachments. they explain how the viscous diff works

 

if u want more works read one of my other posts

 

nice job, North Central ftw. wow i'm impressed. bosco

[RockyMtnGT]

Holy Cr@p I farkin made it to the end Fighting with my ADD the whole way...

 

I need a cigarette...and my 15 minutes back:icon_bigg

[Beanboy]

I was saying WTF as well... If I had thought about the center diff. as a plain old open diff the split second before the viscous coupling locked I woulda been fine, hehe.

[bosco]

I was saying WTF as well... If I had thought about the center diff. as a plain old open diff the split second before the viscous coupling locked I woulda been fine, hehe.

 

well at least you where passionate about it bosco

[CasopoliS]

is this thread serious?

RTFM

This is from the 2005 Legacy GT Service manual.

 

Also info on the Viscous LSD

 

If you guys would have read my post it would have saved this thread from a few pages.

[ineedone]

Sorry for the previous dumbass, no harm meant. The Purpose of a viscous differential or coupler, or any other limited slip device, is to vary torque in the direction with the MOST resistance (traction). This action has nothing to do with gearing. So in conclusion, any vehicle with a limited slip device (electronic or mechanical) can vary torque output to whatever axles it is connceted to. (i.e. rear limited slip can vary torque to whatever rear wheel has the most resistance. Or a center limited slip can vary torque towards the front or rear differentials, whichever has the most resistance. From there it is the responsibility of that diff. I really hope this clears this up so we can stop kicking this dead horse in a circle and let it be. If you are just messing around you really had me believe that you were uh..........special.

[ineedone]

You bet everyone right?