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SUVs 4WD & AWD systems explained
1221 messages, Last post on May 11, 2008 at 3:09 PM
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Replying to: chelentano (May 09, 2008 11:41 am) Correction the last few posts are about the 80/20/80 split, which hasn't changed lately. Except I'm guessing in the 2009 Forester, based on the latest video, one wheel possibly could drive the car.
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Replying to: kdshapiro (May 09, 2008 1:53 pm) No evidence of that, unless you could post some credible links. Quite contrary: all sources I posted suggest 90/10 - 50/50 split since nineties.
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Replying to: ateixeira (May 09, 2008 11:51 am) Well, untill they revise it, we not going to make stuff up and we use the available info. >> Traction control does not affect Front/Rear power split ratio >> Not true. In fact, Toyota uses open diffs and relies on traction control primarily to shift power. Are you sure or you it's your guess? Forget Toyota, does the Subaru traction control affect the Front/Rear power split ratio? |
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Replying to: ateixeira (May 09, 2008 11:54 am) It's hard to have an intelligent conversation about AWD if you say that VDC is AWD.
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Replying to: chelentano (May 09, 2008 9:19 pm) |
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Replying to: chelentano (May 09, 2008 9:35 pm) Did you review the video posted? Here is a short course on AWD. AWD is an acryonym for all wheel drive. There are many variations of AWD, but it refers to the ability to have any or all wheels powered at the same time. How many wheels are powered at the same time and under what conditions are all implementation details and there are many different ways of accomplishing the end of keeping a vehicle moving. However, some ways are better than others. The terms for this are on-demand and part-time. In addition some systems give the ability to lock the f/r ratio. However the use of this is very limited and usually results in system damage if used on a non-slippery surface. In addition, some systems can vary the f/r ratio based on acceleration and deacceleration. Other systems can vary the f/r ration based on accelerator position. Some systems assist with LSD (limited slip differential), others assist with the anti-lock braking mechanism. BMW for example, does both. Having said that Subaru has multiple types of AWD systems. The ones we are debating are the one attached to the automatic. 2009 has a different system than 2008 and earlier. 2008 and earlier always power 4 wheels. According to the information presented there is always fluctation between front and rear from 80/20 to 20/80. Mitsubishi as Subaru is not very forthcoming with information about their AWD system. But much of that functionality seems to be based on accelerator position or slippage. 2006 Outlander models and earlier seems to be at the level of the RAV4/Highlander, which incidentally call their systems 4WD. I'm not 100% clear on 2009 Subie system yet, except that I'm guessing any one wheel can power the vehicle. I hope this short explanation helps with some of the terminolgy and concepts. Feel free to ask additional questions. |
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Replying to: kdshapiro (May 10, 2008 5:39 am) This is my final post on this subject. However the statement from Subaru that Bob referenced was actually from a marketing guy who may or may not know the engineering behind his statement. -mike
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Replying to: paisan (May 10, 2008 8:11 pm) Just to set the record straight, I have been following these forums for a bit and by your posts I know you know what you are talking about. It's not me who is questioning the veracity on the information given on the Subie f/r split.
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Replying to: kdshapiro (May 10, 2008 8:42 pm) I know, just was responding to the thread in general. It's sad that I am here to help folks, yet some refuse to believe me. Frustrating at times actually.  -mike |
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Replying to: paisan (May 10, 2008 8:11 pm) More than marketing; Mike McHale, being the Corporate Communications Director, is ultimately responsible for anything that SOA sends out to the public in terms of product and corporate information. I'm sure anyone in that position will make sure they have their facts straight before making pronouncements. Could he be wrong? Of course. He's human after all. Still, knowing how important AWD is to the brand, I'd put my money is on him being correct on this point. Bob |
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