LSD + Locking Diff options

David K · Apr 1, 2010

Isthatahemi said: ↑

Just put the parking brake on 2 clicks to lock it up when needed....
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I would just love to hear the technical explanation for how that works!

nvdeserted · Apr 1, 2010

David K said: ↑

I would just love to hear the technical explanation for how that works!
Click to expand...

Manual A-Trac

Isthatahemi · Apr 1, 2010

David K said: ↑

I would just love to hear the technical explanation for how that works!
Click to expand...

Do I detect sarcasm? lol
It preloads the limited slip clutch packs, it essentially takes up all the "slack", also known as breakaway torque. It preloads the assembly, so it engages.

BlueT · Apr 2, 2010

Isthatahemi said: ↑

Do I detect sarcasm? lol
It preloads the limited slip clutch packs, it essentially takes up all the "slack", also known as breakaway torque. It preloads the assembly, so it engages.
Click to expand...

That got noting to do with that. This solution is only for the Truetrac. Our LSD's are clutch packs they dont multiply the torque.
In Truetrac which multiples the torque applying brakes allows any wheel to have more torque then zero . So when your wheel is in the air and other side provides no power (anynumber x 0 = 0) you apply brake to provide something for Trutrac to leverage. (anynumber x a = b) where a > 0

EDIT: http://www.4crawler.com/4x4/TrueTrac.shtml

Hydraulic Locker:

As mentioned above, the TrueTrac differential, like all limited slip designs, will only work if there is some load on each axle. If one wheel loses all traction (i.e. a wheel in the air), that wheel will spin and no torque will be transferred to the wheel with traction. This is where brake biasing (or as I like to call it: "hydraulically actuated locker") the spinning wheel in order to transfer that torque to the opposite wheel. It can take a fair amount of brake drag to actually make this work. Let's assume a 3:1 torque bias ratio and one wheel in the air (i.e. no load on it) and the other one on the ground. In order to transfer a given amount of torque to the wheel on the ground (say 100 ft.lb.) you need to apply ~1/2 that amount of brake drag to both wheels on that axle (unless you have custom turning brakes). So now the spinning wheel (and axle) "sees" 50 ft.lb. of drag, allowing up to 150 ft.lb. (3x50) of torque to transfer to the other axle, but it also has 50 ft.lb. of brake drag on it, reducing the net torque to 100 ft.lb. applied to the wheel on the ground.

But the "extra" torque to overcome the brake drag must come from somewhere, namely the engine, so you've got to give it some extra throttle at the same time. So basically, the harder you brake, the more torque you put into the ground. Trust me, it is a totally unique experience. If you have a TrueTrac in your rear axle, the parking brakes are another mechanism for biasing the differential.

In my 4-cylinder Toyota, I find brake biasing only works at crawl ratios of 75:1 or (numerically) greater (since I find I usually need this on a steep hill where the engine is already heavily loaded to begin with). Below that gear ratio, I end up killing the engine before the TrueTrac locks up. At ratios above 200:1, I find my engine can overpower the brakes w/o additional throttle.

The brake biasing technique also works better when used *before* you get stuck rather than after the fact. Learn to recognize terrain that will cause a TrueTrac-driven tire to lift, get in a low enough gear before hand and start riding the brakes *before* you hit the obstacle and you'll crawl right over it like you had a true locker. For photographic evidence of this, check out the 2nd Annual Day After Turkey Day write-up on the ORC web site (below) and notice how the driver's side tire is in the air and is turning just as fast as the other tires as evidenced by the slight motion blur in the photo:
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David K · Apr 2, 2010

Cool...

and Hemi, no sarcasm... I really like to see facts and opinions on all this.

I am glad that our ('09+) limited slip system is clutch free and works the way it does.

Isthatahemi · Apr 2, 2010

BlueT said: ↑

That got noting to do with that. This solution is only for the Truetrac. Our LSD's are clutch packs they dont multiply the torque.
[/quote]

Know your facts......Brake torquing pre-loads the pack, like I said. Thereby engaging it pre-emptively preventing wheelspin.

Powr-Lok (P/L)
This clutch type limited slip is the strongest and most aggressive limited slip differential available from Dana Spicer. It is a clutch type unit using floating cross shafts that ride up on ramps in the case. When power is applied, the shafts ride up the ramps and load the clutches for a positive engagement. A Power-Lok will not lock up 100%, but it is a very durable unit that will hold up fairly well with tall tires. It can be rebuilt, and can be set up smooth or aggressive by changing the clutch design or stacking configuration. Powr-Loks are easily identified by their 2-piece case. They are a very strong unit due to the 4 spider gear design that provides twice as many teeth to carry the load as a 2 spider gear unit does. However, the case bolts can stretch or loosen after severe use over time. (4 pin, 4 tab clutches) (factory)

Toyota Race Development (TRD)
This is a really good Toyota differential. They operate on the same principal as the Powr-Lok. The clutches virtually never wear out. Sometimes this unit chatters and sometimes it does not, depending on the specifications requested by the importer. They are sometimes imported in small quantities by various sources and are now distributed by Auburn Gear. (aftermarket ) 1 yr warranty
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BlueT · Apr 3, 2010

Isthatahemi said: ↑

BlueT said: ↑

That got noting to do with that. This solution is only for the Truetrac. Our LSD's are clutch packs they dont multiply the torque.
Click to expand...

Know your facts......Brake torquing pre-loads the pack, like I said. Thereby engaging it pre-emptively preventing wheelspin.

Powr-Lok (P/L)
This clutch type limited slip is the strongest and most aggressive limited slip differential available from Dana Spicer. It is a clutch type unit using floating cross shafts that ride up on ramps in the case. When power is applied, the shafts ride up the ramps and load the clutches for a positive engagement. A Power-Lok will not lock up 100%, but it is a very durable unit that will hold up fairly well with tall tires. It can be rebuilt, and can be set up smooth or aggressive by changing the clutch design or stacking configuration. Powr-Loks are easily identified by their 2-piece case. They are a very strong unit due to the 4 spider gear design that provides twice as many teeth to carry the load as a 2 spider gear unit does. However, the case bolts can stretch or loosen after severe use over time. (4 pin, 4 tab clutches) (factory)

Toyota Race Development (TRD)
This is a really good Toyota differential. They operate on the same principal as the Powr-Lok. The clutches virtually never wear out. Sometimes this unit chatters and sometimes it does not, depending on the specifications requested by the importer. They are sometimes imported in small quantities by various sources and are now distributed by Auburn Gear. (aftermarket ) 1 yr warranty
Click to expand...

Get my facts straight ??/ I own a truck with LSD
I have truck for 4 years and 4 winters .... Brake preload does nothing and its not needed.

Clutchpacks do take a second to engage afterwards both wheels spin like it is locked. Never ever I had one wheel spinning on my truck, never had to use brakes to "help" lsd.

BlueT · Apr 3, 2010

taco4x4rar said: ↑

It dosn't matter LSD is crap offroad. When trying to get over that rock or off camber turn and that one rear tire lifts off the ground you're done with the LSD. The front will loose traction on at least one tire and you will then be stuck in a position not being able to go forward. The locker prevents this as when that tire inevitebly lifts off the ground there is no loss of power/traction and you continue to roll on down the trail.

This is a good example this seemingly unassuming hill looks rather tame however is impossible to get up without a locker. I've seen all kinds of LSD driven vehicles from jeeps, to tacomas, to z71s, to f150s fail to get up this hill on LSD. Locker or don't bother
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You know whats funny we play on hills like that in winter when they are iced up.
You know what else is funny, first run I had this truck was few months after I bought it. It was snow run and there were two 2gens . Mine with LSD and TRD Offroad. both running stock tires. TRD offroad was the one getting stuck

BlueT · Apr 3, 2010

taco4x4rar said: ↑

Only time you would need the brake thing is if you have one tire completely off the ground.
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Which i had ...
Also believe me having tire in the air and on ice and off camber is almost the same. in both instances there is almost no traction.

luk8272 · Apr 3, 2010

I have the LSD rear would it be as simple as just getting a Tacoma rear end with the locker and swaping them out? I mean are all the electronics ran, just needing me to get a switch?

Love my LSD, no issues yet. Just have to pick a good line.

David K · Apr 3, 2010

taco4x4rar said: ↑

I'm glad you're 09 is electric and only works in 2wd.
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I don't understand this reply... (I have a 2010, and the e-locker works only in L4)... The TRAC LSD works in H2 and H4... ???

David K · Apr 3, 2010

Oh, a Sport? NEVER!! Nothing 'fake' on my Tacoma's hood!

OFF ROAD 4WD (with 9 drive modes) ... How could you miss all that stuff in my signature? LOL

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