Quote:
Originally posted by Thai
Bluto, what car do you have now?? BMW X5??
Anyway, i was using % for torque figures to keep things simple.
Yes, ATRAC does have a limit...that is why i said that ATRAC will not achieve 50/50 split in the real world.
ATRAC is limited by the ABS system. So, that is the limiting factor.
Think of it this way...Hummer H2 can go up a 10% grade incline with one wheel traction. It has ATRAC-like system. Toyota has not published any figures, but i assume that it is probably just as good as Hummer H2's system. With all wheels having traction, a Hummer H2 can go up a 60% grade (compare to 10% with just one wheel). So, as you can see, there are limitation to ATRAC, just like LSD.
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I have an Acura CL-S.
My physics is a bit rusty, but with the Hummer weight & specs, you probably could calculate torque at one wheel needed to move it up a 10% grade. Maybe even the PSI needed at a caliper.
My car has problems getting up my driveway in snow. The system modulates the brakes, but not with enough force to stop the '1 wheel peel' of an open diff. I usually had to walk up the driveway, throw some salt down, and come back later. My brother's 03 4WD Tundra drove up with no problems. I'm sure a 4Runner would do the same.
I was cross shopping with the Nissan Titan. It has an available Active Brake Limited Slip (ABLS) system. Same thing as ATRAC. (Also an optional rear locker but not available with the stability system.) On the Titan forums, owners swore up and down the ABLS system had no limitations and is miraculously better than an LSD. They just did not see the limitations. But Toyota's quality and my urban driving requirements make a 4Runner my only option.
An 04 or 05 is another decision...
From what I've read on the subject, I would choose ATRAC on the front and rear axels, over a single rear LSD. Less maintainance, better traciton up front. Add some great tires, and it's all good.
I just wish manufactures would provided a bit more engineering specs on these systems. The only info available is of 'marketing quality', not for enthusiast.