///MDex

Short answer, yes.

In simple terms, your OEM gear ratio (3.23) is optimized for 16s or 17s. You put on bigger and heavier wheels and tires, and the effect is that the gear ratio is effectively lower since the gears are now turning slower.

Insert a taller or steeper (higher) gear ratio, and you effectively offset the larger wheels; more grunt. This is good, and you get the benefit of added traction too.

That’s why if you have the OEM wheels, the 3.76 unit isn’t recommended since you’re apt to hit the rev limiter so easily.

Bigger wheels and tires, in and of themselves, don’t mean you’ll stick like glue; I did a little testing Friday night (install was Sat morn) when the roads were wet or damp, and the open diff still spun my 19x9.5s, and I could drift a little if I wanted. Yeah, I have the TQ, but I don’t care much for breaking traction.



That’s an easy way to think about it; it distributes torque as evenly as possible to both wheels, instead of just one as an open diff does. You break traction with an open diff, and the wheel will continue to spin until you (or VSC) decide to stop it.

When one wheel begins to break traction with an LSD, clutches or gears mesh together and spool the torque to the other axle, thereby allowing the other wheel to move the vehicle.

Here’s a good place for some technical data

Link To Torsen's Website About 3.76 Unit

Also, try using the Search function using “lsd” as your text.
Sorry; its my job to suggest that now.

I think that's pretty accurate - the really smart guys will correct me if mine incorrect.

You’re welcome! Get my email with the tracking number? I boxed them in the same OEM packing material my 01 lights came in – Toyota boxes, bubble wrap and all

Its handle very well IMO; plenty stiff (uhhh huh huh….. stiiiif)

bitkahuna

iTrader: (20)

Does the TRD gearing throw off the speedo?

///MDex

Good question Bit. I don't have a verifiable answer, but the speed is measured via the rear wheels I think; at least when I was at SRT on the lift and hit the gas, the speedo reacted.

I think it is measured by wheel speed, not axle, so I don't think the LSD affects it. This might hold true since the ABS / YAW sensors are at the wheels so they can determine when VSC is needed too.

The speed readings didn't seem out of whack while I was driving the past few days....

2SAVVY

Thanks Dex,

I've just learned so much by this thread!
Wonder if a LSD for the GS430 will work on the SC430.. BTW did your Lexus dealer do the install for you Dex.. If so how much did they ding you for all that work??

Mr Johnson

Good stuff Dex!

You are one of the mod kings and have put together a very sweet overall package.

I'd be curious about the speed readings as previously here it was claimed that the readings were off the wheels.

Also, I'm a bit surprised (pleasantly) about your comments on the changes to the handling in just the LCB. I did the sways and the LCB at the same time and wouldn't have ascribed such a difference in handling from just the LCB.

mumbles

Yes and Yes (hows that for short and sweet?) Long version: by lowering the final drive ratio of the rear end, you can increase your acceleration, but the downside is that you can decrease your top speed. But, the increase in ratio is so small, you'll hit the ECU's top speed limiter before you reach the mechanical limit. Is this increase in ratio enough to overcome the weight of bigger wheels and tires? That would depend on how much heavier they are than stock.
As for the positraction question, pretty much the same thing, it limits power to the slipping wheel via mechanical methods.

///MDex

Thanks for the compliment MJ! That's means an awful lot coming from a SCd GS owner!

My LCB handling comments may be due to my added STB and my 18x8.5s up front too.

Oh yeah, the Blue GSs always handle better.

///MDex

I don't know squat about the SC430 A quick call to the dealer might shed some light. Heck, Lexus is using them in the LX, RX, IS; surely there is an application for the SC.