Re: Best SUVs - Consumer Reports
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Re: Best SUVs - Consumer Reports
| Steve | 16 Nov 2006 21:51 |
> Steve <no@spam.thanks> wrote in article > <5pSdna5Wbc9fz8bYnZ2dnUVZ_v-dnZ2d@texas.net>... [quoted text clipped - 17 lines] > Straight axles actually have a HIGHER RC than most IFS and IRS > setups.....producing the "better rollover resistance" to which you refer. Yep, I said it bassackwards, but the effect is the same. Solid axles result in a lesser rolling moment for a given lateral G force.
> The whole problem is that most solid-axle vehicles have such a high CoG > that they actually have a longer moment arm than the Independent > suspensions, ergo, apply the CoG mass with more force. Well, if you talk "fleet wide" where all vehicles are lumped together, I agree, because then you're throwing the Dodge Durango in the mix with a Miata and Corvette.
But I don't agree if you compare solid-axle SUVs to IRS SUVs (EG, Dodge Durango to Ford Expedition). The COG is about the same for each. And if you take the few remaining solid-axle cars being made (Mustang, for example) and compare it to a similar hight IRS car, the COGs there are about the same.
> So now we're talking a 14-inch CoG applied to a two-inch RC giving us a > 12-inch moment arm in a passenger car...... [quoted text clipped - 3 lines] > > Which vehicle will have the greater tendency to roll over???? Zis is ze time on Shprockets where ve say "duh." :-)
But that is ALL THE MORE reason that all SUVs should be solid axle.
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| * | 15 Nov 2006 22:03 |
Steve <no@spam.thanks> wrote in article <5pSdna5Wbc9fz8bYnZ2dnUVZ_v-dnZ2d@texas.net>...
> >>Not good for off road either. > > [quoted text clipped - 8 lines] > center, meaning they have better rollover resistance without massive > sway-bars The lower the roll center, the MORE leverage the Center of Gravity has on it.
Straight axles actually have a HIGHER RC than most IFS and IRS setups.....producing the "better rollover resistance" to which you refer.
Many of today's RWD, IFS cars actually have RC located below ground while the rear IRS RCs are considerably lower than the solid axle's RC.
A 14-inch CoG acting on a 10-inch RC (solid axle) is going to roll the car less than the same CoG acting on a RC that is two-inches below ground (IFS)......A four-inch moment arm (solid axle) versus a 16-inch moment arm (IFS) applying the CoG mass......but, the SUV CoG is much higher than the passenger car's CoG.
The whole problem is that most solid-axle vehicles have such a high CoG that they actually have a longer moment arm than the Independent suspensions, ergo, apply the CoG mass with more force.
CoG of a 1978-1985 mid-sized GM car that we build for oval track use is at approximately 14-inches above ground by the time I am done putzing with it. The RC ends up at approximately two-inches above the ground.
CoG for a SUV is often at least a foot higher.....approximately at camshaft height.
So now we're talking a 14-inch CoG applied to a two-inch RC giving us a 12-inch moment arm in a passenger car......
....versus a 26-inch CoG applying a heavier mass to a 10-inch RC in the SUV - giving us a 16-inch moment arm.
Which vehicle will have the greater tendency to roll over????
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| Steve | 15 Nov 2006 17:47 |
>>Not good for off road either. > > Why would you say that? Because its true....
>Only idiots who want to "lift" a truck are bothered > by IRS. Wrong, wrong, wrong. Lift is irrelevant. Solid axles have a lower roll center, meaning they have better rollover resistance without massive sway-bars (this is troe ON highway, not just offroad!) Solid axles also articulate better when offroad with sway-bars disconnected, allowing each wheel to have a better contact patch (the "high" wheel actually helps plant the "low" wheel to the ground).
As far as IRs and towing, the differences are less dramatic than with offroading and rollover resistance. But all those added bushings and CV joints will *never* hold up to towing as well as a solid axle.
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| C. E. White | 15 Nov 2006 16:36 |
> What's the point of calling it an SUV if you cannot tow with it, > or take it off road? I don't know. Probably a marketing advantage. Calling something a mini-van or a station wagon makes it undesirable to a large portion of US consumers. Whether it makes sense of not, names do matter to many consumers. Do you think Toyota would sell as many RAV4s or Highlanders if they called them Camry Wagons (which is what they are)? If Ford renamed the Freestyle "Five Hundred Station Wagon," how well would it sell? Or worse yet, suppose they revived the Country Squire name and slapped on some vinyl wood trim on a Freestyle?
> Ever try towing with independent rear suspension? Yes, I towed often with my 2003 Expedition with IRS. It towed just as well as my 1997 with a solid rear axle.
> Not good for off road either. Why would you say that? Only idiots who want to "lift" a truck are bothered by IRS. Doing a suspension lift on an IRS vehicle is very difficult in comparison to lifting a truck with solid axles. Unless you are doing some really weird rock crawling, or tying to drive across a swamp, highly lifted vehicles are ridiculous. For any sort of mundane off roading, IRS is better than stick axles.
> Did I forget to mention how small they are. Compared to?
> People who buy these would be better off with a station wagon. Probably true for most people. And several of these really are station wagons.
 Signature Regards,
Ed White http://home.mindspring.com/~ed_white/ - my automotive opinions http://home.mindspring.com/~ed_white/id7.html - my oil filter comparison
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| me at | 15 Nov 2006 13:56 |
What's the point of calling it an SUV if you cannot tow with it, or take it off road? Ever try towing with independent rear suspension? Not good for off road either. Did I forget to mention how small they are. People who buy these would be better off with a station wagon.
 Signature Vic
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| Ted Mittelstaedt | 15 Nov 2006 08:52 |
> The new Mercedes-Benz GL- and R-Class luxury sport utility vehicles > outpointed competitors from Volvo, Audi, and Cadillac in tests for the > November issue of Consumer Reports. Just another evidence that CR is a stupid useless magazine for evaulating cars.
People are dumping their gas-guzzling SUV's right and left and buying economy cars, due to the gas prices, yet CR is still bothering to review SUVs. Yeah, right, real intelligent there.
Ted
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| Joe | 15 Nov 2006 05:21 |
The new Mercedes-Benz GL- and R-Class luxury sport utility vehicles outpointed competitors from Volvo, Audi, and Cadillac in tests for the November issue of Consumer Reports. The GL- and R-Class posted "Very Good" overall scores in tests against the Volvo XC90, Audi Q7, and new 2007 Cadillac Escalade. Though the Volvo, Audi, and Cadillac finished lower in the scoring, those three vehicles still posted "Very Good" scores.
To read the full text, please go to: http://www.contactomagazine.com/bestluxurycars1106.htm
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