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Acura RL



  • markcincinnatimarkcincinnati Posts: 5,343
    I have now enjoyed for some 11,000+ miles 18" wheels with 245 x 45 tires mounted. I had, in my previous car, 255 x 40 x 17" wheels/tires. The aspect ratio, of the tire, is -- broadly speaking -- more important than the number of inches in diameter of the wheel. There is, I'll grant and agree, the law of diminishing returns in play in this regard, however.

    The 20" wheels with the 35% (aspect ratio) tires that I think were in the show Acura, probably handle well and look great. And, if DESIGNED specifically for these wheels and tires, I suspect the ride qualities could be mitigated (by that I mean the poor ride characteristics could be smoothed with the suspension's engineering).

    However, my guess is that the Acura will be marketed with 17 or 18 inch wheels -- and it may well be optimized for such wheel size.

    Generally plus zero or plus one sizing will provide about all the plusses (no pun intended) that can be extracted from a given tire, wheel and suspension set up.

    So, if the new car comes standard with 225 x 55 x 17" tires/wheels, it will most likely achieve its maximum performance NOT from 20" or even 19" wheels (and appropriate tires), but from plus zero'd tires or a plus one set up.

    If this is the case, the performance will improve with little degradation in ride quality and unsprung weight (the nemesis of the suspension and wheel tire system is, after all, unsprung weight) if they are upsized to 245 x 50 x 17" or 245 x 45 x 18" -- plus two sizing to a 19" wheel with a 35 series tire would most certainly increase the unsprung weight, increase (probably, but not absolutely) the stopping distance, degrade the ride quality, be more susceptible to pot holes and perhaps even accelerate more slowly and possibly be slower through a slalom.

    My hope, for "balance" is 18" wheels and tires with a profile that does not go below 45.

    My wife's car has 40 series tires on 18" wheels, sometimes it looks like the thing is wearing rubber bands instead of tires. Potholes under these circumstances are NOT your friend.
  • ksomanksoman Posts: 593
    the low profile more than the wheel size is the make or not make life hell thing. sometimes. i'd like to see 18" with 45 size tires.

    i've to say again, even though the link shotgun posted had a modded accord to show off the SH-AWD, which seemed to have stock tires, i was quite impressed with the presentation and video...
  • shotgunshotgun Posts: 184
    Mark's case for 18" wheels is indeed compelling and, quite frankly, very logical! That being said...I will graciously accept, or if optional, order 18" wheels for my new 05 RL.
  • steveaccordsteveaccord Posts: 108
    Kudos everyone!

    As always as I return to this post I am treated to a feast of very interesting points.
    I'd like to thank shotgun for the opportunity given to view the exiting footage of the SH-AWD equipped Accord.

    I believe it confirms many of the previous comments that were made including some considerations on how this new transmission may change (revolutionize) various aspects we have considered in so far to predict how great a vehicle will drive.

    I admit my last contribution may have been a little foggy (I guess consequence of spending a nice evening with good friends and excellent wine!! lol) but in summary I am prone to believe that because the SH-AWD is so much more efficient in translating engine specs in 'tyres' work we cannot truly compare the new RL Hp for HP with competing models.
    I dare predict that the RL 300 HP (I sideline the torque arguments since we do not know much in that direction), will not only match but surpass Jaguar V8 (and the like) in real world performance. Of course I do not expect the RL will take all trophies, 0-60 and any other straight line spec will rank accordingly to displacement figures!
    I also think that all of the above is immediately concerned by the recent tyres discussion.
    I am interested more in establish if a new type of tyre is really needed to use fully the potential availed by the SH-AWD. My brain went on immediate overdrive when the Michelin story was brought up in this post. As other have commented I do not believe that was necessary to have custom made 20" for an autoshow prototype but I think makes a lot of sense to study prototype of radically designed new tyres. My reasoning being that beside the tyre/wheel ratio having direct reflection on the ride qualities additional demands are put by the SH-AWD on the width specs of matched tyres. I assume that, although less relevant than for other aspects of the axle/differential, as you widen the area of tyre contacting the pavement you increase the difference in the distance the inner and the outer edge of the tyre have to cover while steering/cornering (this type of steer problem is not really avilable to be corrected by differntails etc and will ultimately cause increased friction, heat generation and loss of efficiency). I cannot really quantitate that contribution but I see this area as one of reasonable interest to fully capacitate the SH-AWD and I would place my bet that the Michelin rumor has something to do with this rather than the 20" size (and btw It would make sense to see some tyre adustments folowing the developmental work Michelin does for F1 racing since it requires just such an incredible optimization to give full traction under all conditions)!
    Hope to find more comments in regard!

  • lexusguylexusguy Posts: 6,419
    Jaguar? Why Jaguar? The Ford sourced 4.2L Jaguar V8 is one of the weakest in the segment, and makes less HP than Honda's new 3.5L V6 for the RL. The M-B 5.0L, BMW 4.5L, Audi 4.2L, and Lexus 4.3L are all significantly more powerful and superior to the Jag engine, and coupled with the infamous J-gate, the RL should have no trouble besting the mediocre S-Type 4.2
  • lexusguylexusguy Posts: 6,419
    Can you be a little more descriptive with the experience? I've driven more than a few cars with 4-speed autoboxes, and there have been occasions where I would be accelerating quickly in first gear, and instead of a smooth shift at say 6,000rpm, for whatever reason I would need to lift off the throttle before the upshift and the transmission would get "confused" for a second, and then make a rather "hard" or "abrupt" shift at say 5300rpm. Is this the kind of thing your talking about?
  • csgmancsgman Posts: 5
    Well, yes. . .and no. It is a hard shift, and it sounds like it "slips" from 1-2. The rest of the gears shift nice and strong, albeit a little abrupt by todays standards (and 5 sp autos).

    I have known this particular car for its whole life and it has always done it, so it is not that big of a deal to me -except that I am trying to sell it, so I want to represent the condition should it come up in conversation. I had a '92 Legend before this, and it did the same thing all the way up until I sold it. I have read some things that state that "this the way this particular gearbox was made", etc. but I wanted to get some feedback from other owners of this car. . . I did get the tranny looked at and there seems to be nothing inherently wrong with it. . .

    Sorry I can't be more specific on the nature of the shift; it is unlike anything I have experienced in any other kind of car.
  • shotgunshotgun Posts: 184
    This device really intrigues me! According to Honda "...During straight-ahead driving, the twin-pinion planetary carrier spins in synchronization with the propeller shaft, causing the front and rear wheels to turn at the same speed. When the vehicle enters a curve, however, the planetary carrier is locked to the case, releasing the device from synchronization with the propeller shaft and accelerating the rotation speed of the rear wheels..." It seems to me that with a little tweaking this acceleration device could also be invoked without the car necessarily entering a curve - potentially giving the car a substantial "pseudo turbo-boost" in straight line acceleration! Do I have less than a firm grip on reality to think of this possibility?
  • lexusguylexusguy Posts: 6,419
    Interesting. I havent really spent much time behind the wheel of a Legend or the current RL, so I dont really know what to tell you. Most likely, its not a problem.
  • varmintvarmint Posts: 6,326
    I think what you'll find is that it accelerates the rear wheels at the expense of power to the front wheels. So, no, I kinda doubt it.
  • steveaccordsteveaccord Posts: 108
    Exactly my point of stressing that V8 per se can have very little relevance when comparing vehicles. I also think it is a relevant comparison because Jag has recovered quite a bit of credibility duirng this past year (according to JD Power initial quality report) and it is often looked at as an established ultra luxury segment vehicle (at list XJ8 high end trim).
    I Agree with you on the fact that there are V8 that are in a league of their own yet I made my view clear before, with the current gasoline pricing (in excess of 2.25 a gallon in the Chicago metropolitan area) I would stick to a V6 anyhow!
  • steveaccordsteveaccord Posts: 108
    I concur,
    the only gain woudl be achieved if you provided the accelerator with extra power (hybrid tranny using the ~ 100HP for that purpose?). But that would trow us back in asessing if this type of technology would be prime time ready or too experimental for mass-marketing!
  • cericceric Posts: 1,092
    From the explanation and looking at the device, I think the planetary gear set acts as a transmission(in term of gear change) while entering a curve. This is my understanding of what they mean by "accelerating". i.e. spin faster than it originally is. There is no extra power available. The power is channeled from the inner rear corner to the outer rear corner. With planetary gear change, the outer wheel is able to spin faster than w/o the planetary gear. In normal driving (straight-line), spinning is synch up with the drive shaft.

    Correct me if I am wrong. But this is what is unique about SH-AWD to provide "active yaw control".
  • markcincinnatimarkcincinnati Posts: 5,343
    Yes, active yaw control from side to side rather than ONLY front to rear. Moreover, the way the write up could be interpreted, it is possible to conclude that as the car enters a right curve that the left rear wheel is able to provide some additional accelerative force (a 5% increase) over, for example, an Audi quattro or Mercedes 4Matic in the same circumstances.

    I am wondering, with all the recent talk about rear-biased AWD, if the SH-AWD will provide FWD, neutral or RWD bias? BMW and Mercedes provide something on the order (depending on who you talk to) of 40% F and 60% R torque split (BMW sales reps claim 32% F and 68% R, Mercedes and the new Chryco 300C claim 38% F and 62% R, as I recall) -- and Audi, in point of reference claims an intial 50-50% split, while Volvo's AWD claims 95% F and 5% R, even in the S60 Type R.

    Do we know the design goal of SH-AWD with respect to "initial torque split?" It would seem that a minimum of 50-50 would be desirable from an ad-copy writer's perspective and that perhaps 40-60 would be even more "stylish" (to quote Clint Eastwood).
  • robertsmxrobertsmx Posts: 5,525
    We do know SH-AWD can split the torque 30% (front) and 70% (rear), and is continuously variable (unlike other systems). And that may be the torque split (30-70) to “start” the car. I don’t think it would really matter if the car has 70-30, 50-50 or 30-70 split as the default as long as the system works seamlessly.
  • lexusguylexusguy Posts: 6,419
    Yes, I believe that the whole idea of SH-AWD is it will give the optimal torque distribution based on the needs at hand. So, perhaps if you floor the car, most of the torque will hit the rear wheels, and in stop and go traffic, perhaps more torque is given to the fronts.
  • markcincinnatimarkcincinnati Posts: 5,343
    The "argument" used by BMW and Mercedes (generally against rival Audi, by the way) is that a REAR biased start torque split is "best."

    I don't think that Volvo's 95 - 5 split makes much sense, but once you get to 50 50 I am less than convinced of a big wow difference.

    I doubt that the SH AWD will start at 30 70 however.

    And, although I agree that your suggested possible splits probably don't make much difference with a seamless system, the argument for rear biased AWD is growing louder and louder.

    We test drove a Merc and a Bimmer recently and when we came in in an Audi they nearly fell over themselves to tell me that "Audi don't know how to do AWD!" I couldn't believe it. Now, the BMW and the DM offerings were very nice yet, I could not with a straight face claim that Audi's AWD is an after thought and that "really Audi is a pretender in the AWD sweepstakes."

    You may have your biases but that one just doesn't stand up to scrutiny.

    I hope, for Marketing Purposes only that Acrua thumbs its nose at the rest of them and offers AT LEAST 50 50 and perhaps maybe even 40 60 or someother rearward bias. So that other issues can be discussed intelligently.
  • lexusguylexusguy Posts: 6,419
    95\5 is basically FWD. What is even the point of that?
  • saugataksaugatak Posts: 488
    95-5 is so that Volvo can market an AWD.
  • cericceric Posts: 1,092
    After researching Nissan ATTESA-ETS on the net (figures, articles), I don't seem to find any major differences between Acura's SH-AWD and Nissan's ATTESA-ETS Pro, other than
    - SH-AWD split F/R 30/70 to 0/30: ATTESA 50/50 to 0/100.
    - SH-AWD varies rear L/R 0-100 to 100-0. ATTESA can also do the same thru similar clutches or so called "Active LSD".

    Other than the mentioned "acceleration device" in video of SH-AWD, I cannot find other substantial differences between the two. Any comments? Why Acura claim SH-AWD is "world's first!"?
  • pg48477pg48477 Posts: 309
    Attesa-ets moves torque to the wheels with no traction to wheels with more traction, which is the same as any other AWD system. SH-AWD measures G forces and moves torque according to a need for better handling, this system can accelerate on wheel if needed. Nissan's AWD does not make a care handle better in dry weather, and Hondas AWD does. No other awd can do it, at least for now.
  • pg48477pg48477 Posts: 309
    The point is, that the best set up for cruising on the highway or normal driving in the city is FWD. According to Volvo if you want to experience performance of the vehicle system shifts to 50/50, but if you just driving around 95/5 is more than enof.
  • markcincinnatimarkcincinnati Posts: 5,343
    So SH AWD will indeed be rearward biased at 30F 70R? Color me, from a marketing perspective, impressed that Acura decided on this approach.

    Where, praytell, can we find out information, now, about the torque at RPM of the engine?
  • shotgunshotgun Posts: 184
    RPM and Torque data has not yet been released - It appears to be TOP SECRET information.
  • jrock65jrock65 Posts: 1,371
    The main difference between the RL AWD system and other AWD systems is that it distributes up to 100% of available rear torque to one or the other wheel, depending on circumstances.

    We'll see how it translates in the rear world, but it does sound promising.
  • lexusguylexusguy Posts: 6,419
    FWD is not the best at anything. It has absolutely zero performance advantages over RWD or AWD, and several significant disadvantages. The only reason its used at all is because, combined with a foward weight bias of most pedestrian passenger cars, it provides better foul weather traction than RWD. A supposed "performance" car sending maximum torque to the front wheels is rather rediculous. Ever driven the old 93 Viggen? FWD and fast dont mix.
  • cericceric Posts: 1,092
    There are many generations and versions of ATTESA-ETS. The one I was talking about was used on GT-R R34, which has ATTESA-ETS Pro. It comes with dual clutches to control torque split between left and right wheels. They call it "Active LSD". Other than the fact that SH-AWD can accelerate 5% on the outer rear wheel, I failed to see the difference.

    The ATTESA used on G35x is an inferior, or simplified system, which does not come with the Active LSD.
  • jrock65jrock65 Posts: 1,371
    I had no idea that the GTR had an AWD system like that. That does sound a lot like SH-AWD.

    Well, the GTR isn't here, yet. Maybe they'll adopt that AWD system in the G35 and M35 somewhere down the line.
  • pg48477pg48477 Posts: 309
    According to Honda and Volvo. FWD set up is better for highway cruising, I have much more trust in them than you. I was not talking about performance, but just everyday driving, if you want to experience performance, Volvo AWD can give you perfect 50/50.
  • pg48477pg48477 Posts: 309
    I was wondering if system like that can be used with MT. Do you know if GT-R with ATTESA-ETS comes with MT?
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