BEST REAR DIFFERENTIAL FOR 4x2 OR 4x4? - Page 5

louie · 05-06-2011, 09:50 PM

Quote:

Originally Posted by coyotearms

There are no firm specs in the Owner's Manual, but it appears the transfer ratio is significantly better that a standard LSD (with clutches) and in the range of 2.5:1 to 3.5:1. This should mean up to 71% to 88% of the available torque to the wheel that can pull. And lots of talk about good road manners. It should be good for just about any condition except rock crawling, but doable too if you have automatic transmission, which makes brake application to get it to dump torque to the wheel not in the air.

I talked to summit racing today and they were recommending the Detroit TrueTrac as well. Claimed it's more quiet on turns then the Powertrax No-Slip. Please help me understand what is meant by "brake application" to get the wheel not in the air to spin. I am such a newbie with all this stuff...which brings me to my final attempt of understanding how these things work:

A selectable locker or a locker like the lock right always spins both wheels regardless of which wheel has the traction. If one wheel is spinning in the mud and the other wheel is on dry pavement it will send 100% of the torque to both wheels.

A TrueTrac or no-slip does not do this. It will send all the torque to the wheel on dry pavement. If this is the case than wouldn't a TrueTrac or no-slip be a better option?

Or do all lockers - selectable or automatic work the same way once engaged? They send equal torque to both wheels and both wheels spin regardless of traction.

jage · 05-06-2011, 10:52 PM

Quote:

Originally Posted by louie

A selectable locker or a locker like the lock right always spins both wheels regardless of which wheel has the traction. If one wheel is spinning in the mud and the other wheel is on dry pavement it will send 100% of the torque to both wheels.

*If the selectable locker is on. Lock-right is always "on", locked, selected, whatever you call it. Some lockers provide LSD when "off", others are "open" (I think)

Quote:

A TrueTrac or no-slip does not do this. It will send all the torque to the wheel on dry pavement. If this is the case than wouldn't a TrueTrac or no-slip be a better option?

I think some not all of the torque. I think it goes something like this, with TYPE: ICE%/PAVEMENT% for one wheel on ice one on pavement (or air/and dirt etc):

OPEN: 100%/0%
LSD: 75%/25% *
TrueTrac: 40%/60% **
LOCKER: 100%/100% (or 50%/50% if you like, you don't actually get 200% output)

* such that you move forward. Barely but you move. Numbers are for illustration only.

** so the better part in the pavement wheel, meaning you move better which is the name of the game (somebody verify... I'm not sure I recall the marketing correctly)

Quote:

Or do all lockers - selectable or automatic work the same way once engaged? They send equal torque to both wheels and both wheels spin regardless of traction.

Yes.

So...the braking scenerio is something like (same format):
LSD: 75%/25%
LSD+brake: 60%/40%

Increasing your power-to-pavement, thus increasing your ability to move the vehicle. The brake on the free (Ice) wheel acts as resistance and mechanically shifts the %s around, just as Mud/Pavement is different from Ice/Pavement, the brake use "fakes" that there is more traction, ice or the air being illustrative as a "worst case" example.

How come spools and Lincoln Lockers haven't come up yet?

louie · 05-06-2011, 11:43 PM

Jage, Thank you for the explanation. Much appreciated! I'm trying to do a cost basis analysis here and am wondering if there is enough of a benefit to go to the added expense of swapping out my rear axle and paying the higher cost of an elocker or ARB. Elockers sound less complicated thus less likely to fail.

coyotearms · 05-07-2011, 02:07 AM

Quote:

Originally Posted by louie

I talked to summit racing today and they were recommending the Detroit TrueTrac as well. Claimed it's more quiet on turns then the Powertrax No-Slip. Please help me understand what is meant by "brake application" to get the wheel not in the air to spin. I am such a newbie with all this stuff...which brings me to my final attempt of understanding how these things work:

A selectable locker or a locker like the lock right always spins both wheels regardless of which wheel has the traction. If one wheel is spinning in the mud and the other wheel is on dry pavement it will send 100% of the torque to both wheels.

A TrueTrac or no-slip does not do this. It will send all the torque to the wheel on dry pavement. If this is the case than wouldn't a TrueTrac or no-slip be a better option?

Or do all lockers - selectable or automatic work the same way once engaged? They send equal torque to both wheels and both wheels spin regardless of traction.

It might be good to go back to my post and look at the links there

. I think they will answer most of your questions. Please realize that the Truetrac is a limited slip type differential based on gears rather than clutches like "traditional" LSD, but much more capable. The torque ratio improvement seems to be an elusive number, e.g. jage and I seem to have dug up different numbers from our reading. One of the links IS the Truetrac Owner's manual, and even there it is not stated!

No-slip AND lock-right are quite different. When engaged both wheels rotate at exactly the same speed (are locked), but depending on conditions the torque ratio between wheels changes. If one has no traction and the other has perfect traction, 100% of available torque goes to the perfect traction wheel. Obviously, the no traction tire gets no torque---if it did it would start to spin faster, which it cannot do---it just rotates at the speed of the other.

I think one of the best posts has been from Bones_GSXR, who has Truetrac front and rear on his 4x4. Most of us are just giving opinions---he speaks from experience.

jage · 05-07-2011, 09:07 AM

Quote:

Originally Posted by coyotearms

e.g. jage and I seem to have dug up different numbers from our reading.

Bzzt. Nope. I'm just making my numbers up...

think of it as an allegorical form of "more" and "less".

At some point the finer differences of an LSD type pale so much in comparison to the fact that it's an unlifted 2wd van. I feel like we're discussing whether to have the Sterling SVR Reserve 2007 Bordeaux Red or the Dominus Estate 2008 Bordeaux Red with our McDonald's Fillet-o-Fish.

and

Silver350 · 05-07-2011, 09:35 AM

Don't feel bad Jage, you and your Fillet O Fish are welcome to participate.

TwoVans · 05-07-2011, 12:04 PM

Wow. I gotta go with Jage on the one. Your getting way bogged down in the details here.

Both LSD's you are talking about accomplish the same thing in slightly different ways. To the vast majority, you cannot tell a difference from behind the wheel.

What you care about is maintenance requirements and reliability. Both are fire and forget. Slap one in and it just works (you can figure out the break trick later). Long term, the traditional LSD requires an additive in the fluid and the "clutch" will eventually wear causing it to degrade in effectiveness. In my mind, this is why the TrueTrack gets the edge.

I would have the TrueTrack both front and rear if my rear axle didn't have compatibility issues. However, it just works. No issues. AND I can't tell the difference.

Bottom line: If TrueTrack can go in your rear axle, go for it. If not, slap in the other. Either way, it's a nice upgrade that will take care of you in the vast majority of situations you may find yourself in. For the time you come up slightly short, the answer is called a buddy with a tow strap or winch...

coyotearms · 05-07-2011, 01:27 PM

Quote:

Originally Posted by jessenej

Wow. I gotta go with Jage on the one. Your getting way bogged down in the details here.

I could not agree more. And he is a poet to boot. The thread appears by now to have enough nitty gritty stuff to choke a rhino---a great mix of opinion and fact---and really friendly too! Your van was the one that got me thinking about all this stuff in the first place, and I really appreciate what you have done!

TwoVans · 05-07-2011, 05:43 PM

Glad if it helps. Really, TrueTrack is a no-brainer for your van's rear axle unless there is a compatibility issue.

I understand peoples' concerns about LSD's in the front axle. However, based on my personal experience with my van, the TrueTrack hasn't exhibited any drivability issues. Not that I would let my mom drive my van - but if I did, I wouldn't feel like I would need to warn her about the front axle. :-)

louie · 05-07-2011, 06:35 PM

I love this forum! Makes me laugh which I always appreciate. It's true I tend to over analyze everything so apologize for hi-jacking the thread a bit with my redundant questions. Now, and this is going to age me a bit, if I could just figure out if miller lite tastes great or is just less filling...