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SUVs Acura RDX Acura RDX vs Infiniti EX35
49 messages, Last post on Mar 02, 2009 at 9:00 AM
You are in the Acura RDX Forum. Your Hosts are steve_ & tidester
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Replying to: garandman (Nov 15, 2008 3:48 am) According to the Wiki on SH AWD, "SH-AWD in the Acura RDX and Acura MDX use a default power split of 90% to the front and 10% to the rear. Like the unit in the RL, both can power the rear wheels with up to 70% of the engine torque. With this variant of SH-AWD, there is no acceleration device. Instead, the rear differential is constantly overdriven by 1.7 percent. During straight line performance, that difference is scrubbed off by the clutch packs. When cornering, the difference is used to overdrive the outside rear wheel." This is similar to the AWD system used on automatic shift Subarus in the 90's, with the addition of the clutch packs on each side. It might be more accurate to call it a "three wheel drive and temporary four wheel drive system." The Acura RL system uses a planetary gear set and is likely far more durable as well as being more efficient and capable. Compared to Subarus VTD system or the DCCD system in the WRX STi, it's tractor technology.
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Replying to: garandman (Nov 15, 2008 1:53 pm) |
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Replying to: garandman (Nov 15, 2008 3:48 am) I think that any AWD system that results in the BRAKING effects of engine compression being primarily at the rear upon throttle lift or "clutch" downshifting will add some level of safety factor in low traction conditions. I also think that any FWD or F/AWD can too easily lend a false sense of security to a driver not fully knowledgeable or experienced in the dynamics of handling these on a low traction surface. Sorry if I have come across as a fan of Honda, my position is, has been, that the SH-AWD system is the best of the best for vehicles with a sideways mounted engine, or any "base" FWD converted to F/AWD.
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Replying to: wwest (Nov 21, 2008 8:19 am) "I also think that any FWD or F/AWD can too easily lend a false sense of security to a driver not fully knowledgeable or experienced in the dynamics of handling these on a low traction surface. " As that represents the vast majority of cars and crossovers sold in the Us today, I hope not......
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Replying to: garandman (Nov 22, 2008 5:37 pm) Not what I said, NOT nearly what I said. There are LOTS of advantages of AWD... But all of those advantages will be easily overcome if engine compresssion braking is primarily at the front wheels, as it is in most F/AWD systems. The new Acura TL is getting a manual transmission, that would NOT be a viable option except for the ability to have rear torque biasing upon a downshift, or severe throttle lift, on a low traction surface. That's why there are very few stick shift FWD vehicles in the marketplace, and getting fewer every year. In the hands of an inexperienced driver they are PATENTLY UNSAFE in wintertime conditions. Even with FWD automatic transmissions the AAA is recommending that owners practice quickly shifting into neutral in preparation for doing that safely should the need arise, severe "plowing", understearing, on a low traction surface. Personally I would add my suggestion, gained from real life experience. In those same circumstances the use of rear implemented e-brake, judiciously/slightly, can be a tremendous aid in both holding the "line" and slowing the vehicle to gain more "bite" for those front wheels. |
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Replying to: garandman (Nov 22, 2008 5:37 pm) Yes, first an '85 Jeep Cherokee Limited, then a '92, both with RWD/AWD/4X4hi/lo modes. The '92 has been retired to a north central MT cattle and wheat ranch and is still doing stellar duty. A '94 AWD Ford Aerostar, "donated" to son. A '00 AWD Chrysler T&C, "donated" to daughter. An AWD '00 RX300, traded. Currently... A '94 AWD Ford Aerostar. 2001 Porsche 911/996 C4 2001 AWD RX300. The '00 Lexus RX was primarily FWD using a VC, Viscous Clutch, to apportion torque to the rear if the front wheels slipped consistently, for a prolonged period. The '01 primarily uses TC braking to apportion torque and has a more flaccid VC for backup. The VC in my '01 has failed completely, ~80,000 miles, so I only have TC for AWD fucntionality. |
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Your experience with modern AWD systems could use some updating.
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Replying to: garandman (Nov 26, 2008 12:20 am) Currently looking closely at the CX-7, RDX, and Ridgeline. I Like the RDX's SH-AWD system, the CX-7's DISI engine, and the Ridgeline's utility. But I would settle, quickly, for a CX-7 with the FEH/MMH/Tribute's hybrid drive. Suggestions...?? But expect knowledgeable rebuttals. But for the moment I'm awaiting the details of the 2010 RX350 AWD system. Otherwise I will probably be converting my F/AWD '01 RX300 to R/AWD. |
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Replying to: garandman (Nov 15, 2008 1:53 pm) Hmm.. I can't see how this can possibly help on fuel economy.. I look forward to the 2010 RDX rumoured with FWD as a powertrain option.
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Replying to: 645e3a (Mar 01, 2009 11:30 am) In this case the only time the rear clutch packs are seriously engaged is during moderate to heavy acceleration, and you can't accelerate forever. The RDX already has a FWD mode, all you need do is install a DPST switch to interrupt the flow of electricity to the rear clutch packs. Since they have positional feedback you would probably get a "don't care" failure code. |
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