# AWD will reduce wheelspin



## Bowser330 (Jun 15, 2008)

Wouldn't having AWD decrease the wheelspin from these torquey EVs?

It would help to stick better 60ft. times as well as better 0-60 times...

Ofcourse it would put a lot of stress on the gears so getting some hardened gears and a good cryo-treatment would be advised...

Also, how much inefficiency would the AWD add?


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## ww321q (Mar 28, 2008)

I'm not sure that it would be an advantage . When you first take off a lot (almost all)of weight transfers to the rear . So any extra traction would be limited . If hooking up good most cars weather EV or ICE will almost or do pull the front wheels off the track . J.W.


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## Qer (May 7, 2008)

ww321q said:


> I'm not sure that it would be an advantage . When you first take off a lot (almost all)of weight transfers to the rear . So any extra traction would be limited . If hooking up good most cars weather EV or ICE will almost or do pull the front wheels off the track . J.W.


Where I live we spend several months per year driving in that white stuff that now and then turns into brown slushy and extremely slippery stuff. To add insult to pain (or whatever you usually call it) our government hate us and spread salt over the brown slush, turning it to steel eater that ruin the cars in the long run (mental note: make sure brown slushy stuff don't reach the motor).

In that situation rear wheel drive isn't a big hit, really. Most of the time it works going rear drive (although the car occationally wags it's tail), but some days are so bad you'll be grateful if you're driving front wheel drive and thank the powers that be if you drive a 4WD.

So even if I agree that a lead sled will do great as rear wheel drive in the summer and that I will choose that path for my (hopefully first but not only) EV since it seems easier to do, I believe that there will be several days winter time when I will go by ICE instead. Later I would, however, love to convert a 4WD Jeep or similar and one thought for that is direct drive with two motors, one rear and one front.

That will take some money, skill and time though, so it doesn't feel like a good newbie project.


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## noclutch (Jul 13, 2008)

For drag racing it goes RWD>AWD>FWD. A well set up rear wheel drive car should out-60' a well set up AWD car.


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## Bowser330 (Jun 15, 2008)

no clutch, I think you are neglecting to mention the fact that a huge part of making a RWD better at the dragstrip is the slicks it wears....

Comparable tires all around, AWD>RWD at the drag strip....

It used to be there were drag cars and regular cars, then automotive engineers were able to merge the two, so mercedes sedans with v12 engines can smoke drag prepped mustangs...

EVs will go through the same growth phase...right now most of the DIY EVs are drag OR drive...not both...

However if one was to build an AWD DIY EV with a Warp 11" and some juice from a nice sized pack...It could be a drag & drive...


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## noclutch (Jul 13, 2008)

Personally I would say a properly set up RWD solid rear axle car should murder a comparably set up AWD car, tires being the same. 

I'm not biased either, I have an AWD eclipse that 60's in the 1.45 range on DR's, A solid axle RWD car with the same credentials should go ~low 1.4's high 1.3's.


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## Bowser330 (Jun 15, 2008)

I dont really think many people can murder an eclipse with a 1.45 thats pretty damn good dude! I love the gsx just for that! impressive.

However also keep in mind that the torque rush from an electric motor is different than a gas motor....Its more instant and at 0 rpm...

Im sorry but I cannot understand how 4 wheels will spin more than 2 tires...essentially thats what you are saying, that the 2 wheelers will hookup before the 4 wheeler will, thus enabling it to move 60ft before the other. your expeirence with fast gas cars surpasses mine and I do not argue that...but 0 rpm dude?...thats a TON of torque, enough the break loose the fattiest of tires...

I dont know...i guess im just being stubborn on this one...I cant understand, even though i know the car lurches back, in an awd, the front wheels almost help to keep the car grounded dont they..


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## ww321q (Mar 28, 2008)

Bowser330 said:


> Im sorry but I cannot understand how 4 wheels will spin more than 2 tires.....



"When you first take off a lot (almost all)of weight transfers to the rear"

your extra weight of the front wheel drive ,transfer case ,ect.(that is doing almost nothing ) makes the difference . J.W.


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## Bowser330 (Jun 15, 2008)

Its not that i dont trust the board, it just would be great to see some real life EV examples...I guess in years to come there is bound to be someone who will do it...I guess i will just wait...

Since we were talking about gas comparisons before, maybe you could explain why the skyline gtr with less hp and tq than the C6 Z06 has a 0-60 of 3.3 and the Z06 only has one of 3.7?


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## Ioku (Sep 27, 2007)

well the skyline is likely lighter than the z06 so that will help with its 0 to 60. But I do know what you mean about an awd should be better in the 0 to 60 than a rwd, I'm into Subaru's and know a bit about them I know that when they take off they don't spin there wheels like a rwd car dose. People do use them as drag cars, but there not the best for it and one reason why is the transmission its not supper efficient I think you lose about 30% of your power by the time it gets to the wheels. 

I do plan on covering my Subaru but I think I am going to use two motors one for the front one for the rear, I'm interested to see how this dose for wheel spin.


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## Bowser330 (Jun 15, 2008)

Nissan GTR = 3814 lbs.

Chevy C6 ZO6 = 3132 lbs.

Almost 700lbs. difference, with slightly less (yet comparable) power and still does 3.3, compared to ZO6 3.7...With ZO6 having wider rear tires...

I think your idea for double motors is really cool...ive thought the same!


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## noclutch (Jul 13, 2008)

Bowser330 said:


> Nissan GTR = 3814 lbs.
> 
> Chevy C6 ZO6 = 3132 lbs.
> 
> Almost 700lbs. difference, with slightly less (yet comparable) power and still does 3.3, compared to ZO6 3.7...With ZO6 having wider rear tires...


Neither of those cars were built to drag. The difference in 'magazine' times is likely due to the rear mounted paddle shifted auto trans, almost perfect weight distribution and better tires from the factory on the Nissan. Start throwing more torque and stickier tires at both cars and the Vette will get off the line far better. 

For a low power, improperly setup street car with garbage tires and suspension, yes, a RWD car will spin before an AWD.


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## Bowser330 (Jun 15, 2008)

noclutch said:


> For a low power, improperly setup street car with garbage tires and suspension, yes, a RWD car will spin before an AWD.


I would say most EVs that people would DIY would be...

Lower Power than pro-draggers
90-100% steet driven
Slimmer tires/over-inflated, for less friction drag

So i guess we are in agreement that, barring inefficiencies (dont really know how much...) it would help acceleration and reduce wheelspin if the EV was awd.


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## noclutch (Jul 13, 2008)

Bowser330 said:


> I would say most EVs that people would DIY would be...
> 
> Lower Power than pro-draggers
> 90-100% steet driven
> ...



I would agree with that, the only problem comes with the couple hundred pounds that the rear driveline adds


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## Shocked! (Jun 30, 2008)

AWD is not an advantage drag racing. Front end lifts losing traction - if you weigh the front end down you've lost another advantage - lighter weight. There are no awd cars doing good in drag racing for that reason. 

Other than a car with limited traction due to lousy tires.......would you see some advantage. But a purpose built racer? No.

Tommy Ivo found that out in 1961 when they built the 4 engine "Showboat." I've talked with him several times about it. It was a loser from the get-go - but a crowd pleaser back then when tons of tire smoke and eight second ET's were ....cool. 

Google Tommy Ivo - Showboat. Wild man. 

Mickey Thompson actually built one before Ivo (2 engine) and quickly learned the same thing. Pitch rotation. I have pics of that car. They're hard to find cause Thompson didn't run it for long.


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## skullbearer (Jul 9, 2008)

30% is pretty damn efficient for a RWD or FWD tranny. All in all, between a tranny and diff for a single axle the avg. town car loses 25-40% of its power, and that's in a fully engaged manual or locked overdrive. Torque converters can eat 15-30% more, based on their design (accelleration or comfort, and most are comfort designed).

The trouble in an AWD with tranny efficiency is you have TWO diffs, and you also have a set of transfer gears... considering a high efficiency tranny may lose 20%, that is through the input gear to the first set, the first set to the second set, and the second set back to the first shaft but onto the drive half of it... in other words, 20% spread out onto 4 power transfers is ~ 5% per transfer (in h.e. non-linear tranny). Add that transfer for the front axle onto an otherwise RWD tranny to make your AWD (which is how most AWD trannies are) and you add AT LEAST another 5%.

So our older model (late 90's) WRX STi might be pushing out 75% of the engine power into the diffs, and now our limited slip diffs (best combo for cornering and accel, solid axle has very high accel efficiency) sap another 8-15% from the numbers my old friend who used to mod and drag these Imprezas used to tell me... that means we just split the 75% power into two and then sapped each by up to 15%... an additional 30% loss!

75 x 0.30 = 22.5% and so 75%-22.5% means only 52.5% of original engine output is getting to the wheels. This has to overcome a heavier weight for the same class of car running an extra drive axle, which is a small detriment...

HOWEVER!!! All in all, to say that an AWD vehicle DOES NOT HAVE THE GRIP of a RWD vehicle is absolutely insane. Of course and obviously 4 like tires have more grip, and YES, in heavy acceleration the bulk of the weight is shifting to the rear tires, but balancing (for a drag vehicle) and proper suspension setup allow the front tires to add an impressive amount of grip, and thus power.

SO: In the situation, as in an EV, where you can't even grip with your fatty drag slicks, technically with all your vehicle weight shifted forward, a long throw suspension several inches higher in the back to allow a more horizontal angle when compressed, and a good control (usually 75% rear 25% front on the power transfer... which you can control in some of the best AWD vehicles electronically) you can transfer more power to the road than a similar RWD vehicle.

I've seen videos of AWD vehicles popping wheelies alongside RWD ones... its about matching your setup to your power, because your setup will only ever allow a certain amount of power to the wheels. Where EV dragsters will destroy top fuel cars won't be in the start (except the first 60'), it will be the massive torque and smooth power maintained down the track, power that even top fuel dragsters can't deliver in a constant level.

Otherwise, if you're already popping wheelies, you might as well leave it RWD, cause the fronts ain't even touchin.


EDIT!!!!: I just noticed I had a massive brain fart in the description of power transfer in a manual gearbox. The input gear in the boxes I've worked in is sometimes ON the first shaft, and I've heard that some types of racing boxes can get it to 3 transfers, and I don't even know about linear gearboxes... never met someone that could properly explain how they work to me. I ought to just find a junk bike gearbox and tear it apart...


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## noclutch (Jul 13, 2008)

skullbearer said:


> 30% is pretty damn efficient for a RWD or FWD tranny. All in all, between a tranny and diff for a single axle the avg. town car loses 25-40% of its power, and that's in a fully engaged manual or locked overdrive. Torque converters can eat 15-30% more, based on their design (accelleration or comfort, and most are comfort designed).
> 
> The trouble in an AWD with tranny efficiency is you have TWO diffs, and you also have a set of transfer gears... considering a high efficiency tranny may lose 20%, that is through the input gear to the first set, the first set to the second set, and the second set back to the first shaft but onto the drive half of it... in other words, 20% spread out onto 4 power transfers is ~ 5% per transfer (in h.e. non-linear tranny). Add that transfer for the front axle onto an otherwise RWD tranny to make your AWD (which is how most AWD trannies are) and you add AT LEAST another 5%.
> 
> ...



Dynoing the same setup essentially back-to-back changing only from FWD to AWD I saw nowhere near the additional 20% loss that most people claim. More like 10% loss from FWD to AWD. This was on a very well dialed in ~400whp setup.

And again, to say that an AWD drag car will out 60' a RWD drag car is nuts.


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## skullbearer (Jul 9, 2008)

I still stand that it is situational. If the two cars are pulling their noses high or nearly so, then the additional front wheel drive does not matter!

But any additional drive, ASSUMING you have the appropriate additional engine torque, WILL improve acceleration. Maybe if you took two identically powered and weighted vehicles and one was rear and the other all-wheel... then yes, the RWD would win due to better engine-to-road efficiency and less torque requirements for the initial wheel startup.

Not to mention in drag racing... how many AWD cars do you see doing burnouts to heat their tires? The crank and tranny strain is up to double a single axle! Some electronically controlled tranny/diff setups can do one axle and then the other... but in general the RWD car can heat his tires better than the AWD, which may be another factor involved in your experience with RWD vs AWD at the strip.

Also, in regards to the power loss... it all depends on the quality and type of the components involved in the tranny back. Good drag tranny and quality performance or drag axles will totally whip the numbers I spit out, which are oriented around basic sport or non-sport vehicles, since most people don't own race built vehicles.


I'm no expert though, these are just my deductions from discussions with my boys who run the strip, and from my classes in physics and automotive service, as well as my experience as a mechanic (not terribly significant given my 22 years)


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## Shocked! (Jun 30, 2008)

Well, it matters cause of the penalty of the front drive assys weight isn''t returning a performance advantage. 

Now hit the dirt and everything changes eh?


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## noclutch (Jul 13, 2008)

skullbearer said:


> I still stand that it is situational. If the two cars are pulling their noses high or nearly so, then the additional front wheel drive does not matter!
> 
> But any additional drive, ASSUMING you have the appropriate additional engine torque, WILL improve acceleration. Maybe if you took two identically powered and weighted vehicles and one was rear and the other all-wheel... then yes, the RWD would win due to better engine-to-road efficiency and less torque requirements for the initial wheel startup.


Even throwing efficiency out the window, just talking sheer traction, RWD is king. Especially when you have 4000lbs+ of weight transfer loading the rear wheels. 2 slicks and a decent solid rear axle suspension setup. Even with a very stiff rear suspension and Slicks, it's extremely difficult to match that amount of traction in an AWD platform.


skullbearer said:


> Not to mention in drag racing... how many AWD cars do you see doing burnouts to heat their tires?


 I do! Along with everyone I know with AWD drag cars who race competitively.


skullbearer said:


> The crank and tranny strain is up to double a single axle! Some electronically controlled tranny/diff setups can do one axle and then the other... but in general the RWD car can heat his tires better than the AWD, which may be another factor involved in your experience with RWD vs AWD at the strip.


 I'm not sure where your going with that point? Are you saying the reason an AWD car can't hook as well as a RWD is due to not getting heat in the tires? There are tires out there now that need very little heat to get them up to ideal temp for racing


skullbearer said:


> Also, in regards to the power loss... it all depends on the quality and type of the components involved in the tranny back. Good drag tranny and quality performance or drag axles will totally whip the numbers I spit out, which are oriented around basic sport or non-sport vehicles, since most people don't own race built vehicles.


I could see that, my case just shows one example of what could happen. Mine consisted of removing a 3 piece driveshaft, transfer case and small rear diff with CV's to realize a 10% loss.



skullbearer said:


> I'm no expert though, these are just my deductions from discussions with my boys who run the strip, and from my classes in physics and automotive service, as well as my experience as a mechanic (not terribly significant given my 22 years)


Well you've been a mechanic almost as long as I've been alive..


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## skullbearer (Jul 9, 2008)

noclutch said:


> Well you've been a mechanic almost as long as I've been alive..


I'm afraid you are horribly mistaken, unless you've only been alive for 4 years.

I'm 22 years OLD not 22 years a mechanic. Been working on my home cars since about 14 and always been interested in mechanics...

Aside from helping with tuning and such though, I've only done real mechanical work for a little more than 3 years, and the bulk of that was part swapping and electrical, rather than nitty gritty rebuilds and such.

I've rebuilt a couple manual trans from the same 94 Ford Ranger POS pickup, complete with a 4 cylinder reliable beyond anything Ford has actually made in my lifetime (I found out in an automotive course that the engine was actually built by Mazda and designed by the same group as Toyota's legendarily reliable 4ae motor)

I've torn apart a descent number of valve covers and a couple assemblies, and I've seen more than a few diffs and auto-trannies, but never worked on them.

As for electrical, be it audio, security, or basic issues I've probably seen or done at least one of everything aside from major custom, and I started that with an AC/Cooling System course (which taught me 90% of actual AC problems are relays, and so it turned out to be in 9 out of 10 buddy/family vehicles I've done AC service on)

Other than that... I just keep my ears open, my eyes bloodshot from reading, and my brain perpetually fried from excess of information.


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## Shocked! (Jun 30, 2008)

skullbearer said:


> I'm afraid you are horribly mistaken, unless you've only been alive for 4 years.
> 
> I'm 22 years OLD not 22 years a mechanic. Been working on my home cars since about 14 and always been interested in mechanics...
> 
> ...


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