TechyInAZ

I'm moving to a new city soon where it snows and I've been doing a lot of research into my 1999 RX 300s AWD system. But it is so hard to find any solid info on the nitty gritty stuff. Hope you guys can help.

Questions I have (again my model is an AWD 1999):

1. Can I tell if my vehicle has an LSD thru the VIN?
2. If it is an LSD is it a torsen?
3. Is it easy to overheat the Viscous diff driving both axles?
4. If one side (left or right side) has zero traction, I cannot pull the car out under it's own power correct?
5. I'm assuming the front differential is open right?
6. Does my vehicle come with VSC or TC? I'm assuming not.

Sorry for all the questions, hope somebody can answer even just one of them. I like to know EXACTLY what my vehicle is capable of in unconventional situations.

salimshah

You can try finding the details by contacting Lexus of USA.

Now a bit of reality check ..
Back then the AWD system used by Lexus in RX was coupling to the rear through viscous fluid. So the slipping wheel at the back will take all the rotational force from the engine, same is true for the front.

So the only model that could work its way out was the FWD with traction control [traction control was not standard]. This is because the slipping wheel will have the brakes applied to it.

Salim

ukrkoz

I know everyone is trying to be helpful, but this is how it really works.

The transmission in the 2001 four-wheel drive RX 300 features an integrated transfer case and a viscous center differential that provides a 50/50 front-to-rear power split. The system requires no activation by the driver. If slippage occurs at the front or the rear, the viscous center differential automatically and transparently directs power to the wheels with the most traction.

The traction control provides further "fine tuning" by sensing individual wheel rotation speeds and braking the appropiate wheel when necessary.

The fact that the 4wd system on the Rex is supplying torque to both axels all the time gives it superior handling characteristics to other so-called AWD systems where only one axel has torque until slipagge occurs. These are "reactive" systems, the Rex is a "proactive" system.

Hope this helps,
TC

https://www.clublexus.com/forums/rx-...k-exactly.html



sold with front wheel drive or full-time all wheel drive. Viscous coupling locking center differential, normally 50/50 torque distribution and up to 95% either axle when slipping occurs. Rear limited slip is optional. No low gearing.
http://www.awdwiki.com/en/Viscous+coupling/

automatic all wheel drive

This is an "on-demand" all wheel drive system. Under normal driving conditions, only one axle is powered. When wheel slipping occurs (the driving driveshaft rotates faster than the driven driveshaft), a multiplate hydraulic clutch, viscous coupling, or other similar traction control device locks and engages another axle. Torque gets transferred to another axle. As soon as difference in front and rear axle speeds is eliminated, the device unlocks and the vehicle goes back into two-wheel drive mode.The difference between the traction devices that are used in full-time all wheel drive and automatic all wheel drive systems is that the device used in automatic all wheel drive system replaces the center differential.Advanced electronically controlled all wheel drive systems can be proactive and lock the traction control device even before wheels start to slip - the need for all wheel drive is determined in real time, based on the information that is collected from various sensors http://www.awdwiki.com/en/all+wheel+...ll_wheel_drive

carguy07

He has a 1999, no traction control, has LSD in the rear.

sktn77a

iTrader: (2)

The '99 AWD had a Torsen (torque sensing) LSD, if equipped - it was an option. You can get this information from the VIN if you have a friendly dealer. The torque distribution (on the '99, at least) was 75% front, 25% rear. It's not the best in snow and ice but better than the FWD