Rx300 Awd To 2wd

[lexus300rb]

I have a 2000 RX300 AWD that I would like to change to 2WD for the summer months. Any easy way of doing this? Lexus should have made this an option. Anyway, thought this change would increase gas mileage. Any help?

[wwest]

I have a 2000 RX300 AWD that I would like to change to 2WD for the summer months. Any easy way of doing this? Lexus should have made this an option. Anyway, thought this change would increase gas mileage. Any help?

Provided the front driveline torque biasing doesn't interfere you might be able to buy a RV/TOAD kit, RV towing a vehicle, typically 2WD, 4-down. I don't remember the actual source but most any Rv/MH site or magazine will have an ad. Basically you just reach under and uncouple/couple just one of the front halfshafts.

If/once my transaxle fails, as seems to be pre-ordained, I plan to overhaul it myself and at the same time convert it to R/AWD, rear torque biasing, via removing the spider gears and front drive side gear from the center differential and then welding the rear side gear in place. Then the ONLY drive to the front driveline will be via the VC, Viscous coupling.

But while I expect that will add a significant safety factor for me and mine in my 2001 AWD RX300 it is not easily reversiable and therefore likely not much help to you.

On the other hand it might yeild a few extra miles/gallon....

[lexus300rb]

hi wwest...boy, that's quite a reply to my question. I didn't know that removing a drive shaft from between the front and rear would be causing a biasing problem. Really, would a drive shaft removal cause any electronic problem with the computer (or whatever) knowing that the rear wheels aren't driven by the trans axle?

[wwest]

hi wwest...boy, that's quite a reply to my question. I didn't know that removing a drive shaft from between the front and rear would be causing a biasing problem. Really, would a drive shaft removal cause any electronic problem with the computer (or whatever) knowing that the rear wheels aren't driven by the trans axle?

To clarify...

To tow a FWD vehicle 4-down all you have to do is use the kit to disconnect one halfshaft. With a RWD the kit provides a means to disconnect the rear driveline. With an AWD such as yours or mine the rear driveline and one halfshaft would need to be disconnected.

Since yours is a 2000 and therefore doesn't have TC, traction Control, nor VSC, Vehicle Stability Control, nor electronically implemented AWD (braking) there would be no electronics problem with disconnecting the rear driveline. Since the engine torque is so heavily biased to the front I would not advise disconnecting either front halfshaft in order to disable the front driveline.

But keep in mind that MY2000 FWD RX300's did have TC, and north of the snowline often needed it.

[lexus300rb]

hi wwest...boy, that's quite a reply to my question. I didn't know that removing a drive shaft from between the front and rear would be causing a biasing problem. Really, would a drive shaft removal cause any electronic problem with the computer (or whatever) knowing that the rear wheels aren't driven by the trans axle?

To clarify...

To tow a FWD vehicle 4-down all you have to do is use the kit to disconnect one halfshaft. With a RWD the kit provides a means to disconnect the rear driveline. With an AWD such as yours or mine the rear driveline and one halfshaft would need to be disconnected.

Since yours is a 2000 and therefore doesn't have TC, traction Control, nor VSC, Vehicle Stability Control, nor electronically implemented AWD (braking) there would be no electronics problem with disconnecting the rear driveline. Since the engine torque is so heavily biased to the front I would not advise disconnecting either front halfshaft in order to disable the front driveline.

But keep in mind that MY2000 FWD RX300's did have TC, and north of the snowline often needed it.

[lexus300rb]

Hi wwest,

A friend of mine, all around mechanic, says disconnecting rear driveline would screw up the VC(whatever that does?). Better leave well enough alone, he says. I still think there is some thing that's always worth a try, disconnecting rear wheels seems less drag on engine. Have to look up what this VC does or it's purpose.

[wwest]

Hi wwest,

A friend of mine, all around mechanic, says disconnecting rear driveline would screw up the VC(whatever that does?). Better leave well enough alone, he says. I still think there is some thing that's always worth a try, disconnecting rear wheels seems less drag on engine. Have to look up what this VC does or it's purpose.

Your friend, regretably, is correct. Without the VC, Viscous Clutch, your RX does not have TC (nor VSC), so the center differential is simply a standard, OPEN differential. What that means is that the engine torque will go to the WEAKEST "link", front or rear depending on which has the least traction. The VC is sort of like a "wind-up" rubber band, once it is wind-up tightly it will begin to convey engine torque to the opposite end.

In the case you describe, simply dropping the rear driveline/shaft, the LEAST "traction" would now be at the rear. So on depression of the gas pedal the engine would ROAR quickly to HIGH RPM, spinning the center differential output shift RAPIDLY, the VC (rubber band) would wind-up into knots and then finally start conveying torque to the front driveline.

Not exactly the type of CONSTANT duty the VC, VC's viscous fluid was formulated for.

What I propose to do is eliminate the center diff'l altogether by LOCKING the rear driveline into the transaxle output and then use the VC, "rubber band" to drive the front driveline only if it lags the rear driveline.

And by the way it is my firm belief, QUITE FIRM BELIEF, that in the normal case, no wheelspin/slip, the RX's engine torque is heavily biased to the front (95/5 F/R). So your only FE disadvantage, really, for the RX's AWD system, is carrying around the extra weight.

[BudRoy]

I bought 2 225/60/r16 all season tires at a very good price fpr my 2001 RX300 and put them on the front to replace the worn out 225/70/r16.  So far I have not changed the rear tires, but there are warnings about mismatches on tire sizes.  A friend said I could disengage the 4WD (rear axle) by a removing fuse labeled on FDW) I could find no such fuse and the owner's manual does not call out one.  On this car is it a problem if I run the rear wheels larger (70 vs 60) n To disengage the rear wheel differential mechanically sounds dangerous given the function of the VSC (skid control)  That light is on and has been on for quite some time and I have not had a problem with that.

Edited August 1, 2016 by BudRoy
Left out details of car year.