2009 Tacoma "LSD"

[Eagleyed]

I'm still on the fence/comparing Tundra and Tacoma and I'm wondering about Toyota's electronic LSD. Can I really expect it to function like a mechanical LSD, especially in snow?

[demoncleaner]

The 09 Tacoma and 07-09 Tundra both have VSC/TRAC or AUTO-LSD when VSC shut off. From what guys w/ the Tundra say. It does 'act' like a traditional Mech LSD.
However, you stop, push the VSC Button, wait till the Auto-lsd is engaged. It also only works in 2wd (up to 55mph), so if your getting into a low traction or want wheelspin situation, and have 4wd, you'd usally just engage that instead...

[mustang67408]

The 09's no longer offer a mechnical LSD DIFF. It uses the brakes as AUTO LSD.

8. Differential
 The LSD rear differential has been discontinued.
 A low viscosity oil (SAE 75W-85) is used for the front and rear differentials to improve the fuel efficiency.

Briefly pressing the VSC OFF switch in normal mode enters TRAC-OFF
mode, allowing the Auto LSD to operate. The Auto LSD achieves a
function equivalent to that of an LSD system through the use of the TRAC.
The Auto LSD applies brake hydraulic pressure to a slipping wheel to
reduce the difference in rotation speed between the left and right drive
wheels. This causes driving torque to be transmitted to the wheel opposite
the slipping wheel

[demoncleaner]

^Thanks. That 39 page pdf explains it. Quite a difference from 05-08 models.

[Mazatlan]

The 09's no longer offer a mechnical LSD DIFF. It uses the brakes as AUTO LSD.

8. Differential
 The LSD rear differential has been discontinued.
 A low viscosity oil (SAE 75W-85) is used for the front and rear differentials to improve the fuel efficiency.

Briefly pressing the VSC OFF switch in normal mode enters TRAC-OFF
mode, allowing the Auto LSD to operate. The Auto LSD achieves a
function equivalent to that of an LSD system through the use of the TRAC.
The Auto LSD applies brake hydraulic pressure to a slipping wheel to
reduce the difference in rotation speed between the left and right drive
wheels. This causes driving torque to be transmitted to the wheel opposite
the slipping wheel

I'm looking at an 09 or a couple of leftover 08 4X4 Tacoma's and didn't realize there was a difference in the LSD. Can someone offer a "translation" on this issue for the mechanically challenged? It's a little confusing to say the least. Thanks in advance.

[mustang67408]

The mechanical LSD uses a device inside the differential to control wheel slip

The AUTO LSD uses the computer and BRAKE CONTROL (BRAKES) to control wheel slip

[Jason.MZW20]

I'm looking at an 09 or a couple of leftover 08 4X4 Tacoma's and didn't realize there was a difference in the LSD. Can someone offer a "translation" on this issue for the mechanically challenged? It's a little confusing to say the least. Thanks in advance.

It's basically cost-cutting on Toyota's part. A mechanical LSD is a clutch operated device within the rear end (differential assembly) of the Tacoma w/ Sport Package 2005-2008. On an open differential, there isn't such a device, and when a difference in wheel speed between the left and right rear wheels is achieved, power is delivered solely to the spinning wheel since it has the least resistance in a wheelspin situation. With a mechanical LSD, the difference in wheel speed is reduced (not eliminated) because the clutch can partially lockup (hence why it's called limited slip) the differential, thus allowing power to reach the wheel with traction. The amount of differential lock is limited, so LSDs can be overpowered. The threshold is usually dependent on how aggressive the LSD clutch is, and usually, road going production trucks generally don't see very aggressive LSDs from the factory.

Toyota's new Auto-LSD system is completely electronic, eliminating the need for the mechanical LSD. This system uses the rear brakes to limit the amount of wheelspin achieved. Think of the clutch in the mechanical LSD as an internal brake when its activated except it acts on the actual differential and not the wheels. When the Auto-LSD system detects a wheel spinning faster than the other (through the ABS speed sensor), it activates the rear brake on that wheel so the other wheel can get power.

They have the same premise, they just go about it in different ways. An electronically simulated LSD only wears the vehicle's brakes, whereas a vehicle equipped with an LSD wears the clutch/clutches in the LSD itself. An electronic LSD is also programmable.

[Mazatlan]

Thank you jason and mustang...I think I've got the basic idea now. I can see why the Tundra guys with the latest generation model already equiped thusly, would say it's pretty much the same to the driver. In any case it sure doesn't seem like a key to buy or not to buy a 2008 vs. 2009.

[Jason.MZW20]

Yeah, now if Toyota replaced the TRD OR package locker w/ an electronic brake system, that'd be a completely different story. I don't believe a brake system can accomplish the task of keeping power at both wheels precisely even. It'd quickly overheat the rear drums, hydraulic fluid, and glaze the surface areas.