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To D or not to D

paulp

Active Member
Jul 23, 2015
3,072
1,509
Adelaide, Australia
Which you absolutely get on the way out of a corner in a AWD. Particularly in the wet.

On the way in, you absolutely do not. It is impossible.
according to googie on 24.12.15 @ 5.44pm, "awd does not improve the cornering ability of the car"
So which is it googie? AWD does or does not improve cornering as you are conflicting your own opinion. A one sentence answer to avoid further confusion would be appropriate.
 

googie

Member
Dec 23, 2015
11
0
Sydney
according to googie on 24.12.15 @ 5.44pm, "awd does not improve the cornering ability of the car"
So which is it googie? AWD does or does not improve cornering as you are conflicting your own opinion. A one sentence answer to avoid further confusion would be appropriate.

It can improve one part of the cornering ability.

I must have said this about five times now:

AWD does not improve braking, corner turn in or mid corner speeds. The extra weight reduces the speed.

AWD does allow for earlier and faster acceleration (but not necessarily a faster speed as it's coming from a lower base) out of corners. This being dependent on the vehicle having sufficient power to overwhelm the chassis grip to start with - eg our old 2300kg Toyota Landcruiser Troopy with only 96KW is hardly going to be fishtailing out of corners in RWD on dry tarmac from excess power so no benefit for AWD there.

So:

AWD = slower on the brakes in all conditions
AWD - slower on turn in in all conditions
AWD = slower at the apex in all conditions.
AWD = variable on the exit depending on vehicle and surface condition:
- on dry tarmac for low powered vehicles = slower
- on dry tarmac for high powered vehicles = about equal (acceleration out be faster than RWD however it's coming from a slower apex speed so "trap" speed out about equal)
- on wet tarmac/loose surface for high powered vehicle = faster (still slower on entry and apex but significantly better acceleration enough to overcome this)
 

omniwolf

eNizl
Aug 27, 2014
125
8
Neutral Bay, Sydney
this is getting silly. everyone on their respective sides of the fence is arguing the points they know are correct, but there is very little intersection between these arguments.

Googie: yes, simple physics will tell you that more weight means less braking power, everything else equal. I haven't seen anyone refute this specific claim, but you continue to argue it

everyone else: yes the D will corner* better - the proof is in the pudding. a lot more fluff has been thrown around that is mostly irrelevant.


Googie: you are arguing a hypothetical scenario against people who drive the thing every day. this is theoretical physics vs applied. Your argument has boiled down to "the D cannot corner better for the first half of a corner, assuming no throttle is used". As i said above, i don't think anyone is really denying this. However, real world driving would suggest that the combination of throttle actually being used in the first half of this corner, and your admission that the second half of the corner can (is) be better in a D, means that the overall corner(*) is OFTEN better in the D.

Therefore, by your own argument, and some real world injection, the cornering on a D is better than the non D.



ps i applaud you attempting to temper the (what can be seen as) blind assertion of 4WD being better in every way, because being technically correct is the best form of correct :wink: but there are other factors involved, i guess.
 

paulp

Active Member
Jul 23, 2015
3,072
1,509
Adelaide, Australia
So googie, in making your opinion heard I assume you researched all the facts. Can you advise please the mass of an 85 against an 85D? (Or 70 against 70D). Clearly without that information you wouldnt be saying the D is heavier.....or have you assumed it is?
 

Blue heaven

Fair Dinkum Tesla
Nov 25, 2014
1,152
1,397
South West Australia
From various sources : P85D weighs 4936 pounds, 291 (132Kg) more than the P85, the weight distribution is 50/50 for the D compared to 52 rear/48 front on the P85, putting about 100Kg extra over the front.

At the end of the day regardless of purchasing dual or rear only their both superb vehicles.
 

Dennis87

Member
Nov 15, 2014
364
202
Norway
The 3 fastest normal productions car on Nurburgring are all 4wd. Nissan gtr 35, Porsche 918 and lamborghini Aventator. So 4wd is the way most are going. Even the next Bmw M5 will have 4wd.

The Model S is far from a track car but the P85D have better lap times and faster corner speeds than the P85+ in tests I have seen done by the same driver on the same track.

I have driven both the P85+ and P85D on the track and the P85D with the pre april 30 suspension feels better in the turns. And the power fade happens a little bit later.
If you look at the Motortrend test the max g in turns is a little higher on the P85D compared to the P85. So the 4wd extra weight is no handicap.

If you look in the parts catalog the D models have ticker anti roll bars and many other differences from the earlier rwd cars including the +.

All the D models 70D,85D, P85D and P90D have the exact same suspension parts now. But P85D build before april 30 have stiffer dampers. Everything else is the same and is improved from the P85+.
its not like the boat feeling the earlier 85 rwd without + suspension has.
 
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Dennis87

Member
Nov 15, 2014
364
202
Norway
From motortrend:

"Replacing the now-discontinued P85+ as the apex Model S, the P85 Dual Motor gains 197 pounds, tipping the car’s weight distribution from 47/53 (f/r) to 51/49. Anti-roll bars and shock valving are suitably thicker and firmer, but the Michelin Pilot Sport PS2 tires are the same, as is the car’s 0.91 g of lateral grip."


So the extra weight on the D model is not a problem. Still have the same g of lateral grip as the P85+ even with more weight.
 

Keiron

Member
Dec 9, 2014
229
17
Melbourne,australia
Gudday Googie

I cant say that I entirely agree with the logic applied to AWD vs RWD. Being an engineer having built rebuilt blowup crashed rolled and generally destroyed alot of V8 ICE's and having spent alot of time racing both rear wheel drives and 4WD I would have to say my preference on regular bitumen would lay with 4WD given same power to weight and F/R weight distribution. I agree 4WD is claimed not to enhance braking but this is traditional foot on brake systems not 4WD engaged regen plus Foot assisted. I agree 4WD regen does have an interesting weight skip as its varies within a corner line. I describe as akin to the fixed rear axle skip you get in small bubble cars when you reach slip point on rear tyre traction combination.

Again totally dependent on the experience and skill of a given driver I would back 4WD to claw lateral torque at corner apex vs traction oversteer from forward momentum vectors. It gives you capacity to get redirection torque across the front axle with a much more predictable outgoing line. Mind you we are discussing the very apex of perforkmance characteristics that the majority of Model S simply wont push that close to the edge. Personally I find it a bit of fun to get the adrenaline rush and as Clint Eastwood put it "Mans gotta know his limitations" including the wheels under him.....:biggrin:
 

Juanmax

Member
Sep 30, 2014
54
1
Germany
AWD engineer here, based in Germany but with plenty of driving experience in northern Sweden and New Zealand roads. I would take the D with no doubt.
 
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Oli C

Member
Oct 8, 2015
28
12
Bondi,Sydney, Australia
Nick, the best thing for you to do is take both for a drive and see what makes you happy, I am in Sydney next time you are up here I am happy for you take mine for a spin, in regards to cornering tyres will make more difference as the tyres Tesla give us are the best compromise for sound, traction and comfort. Mine is a D on 19s as this was best for us as our local roads are shocking. 21s look awesome but our old ICE car was lighter had 19s and the tyres and rims kept getting destroyed so 19s were chosen
 

Jude

Member
Sep 16, 2015
63
11
I've had a 70D for three months and due to a repair, I'm now driving a 70. I like cars that are tight and responsive to drive, and the 70D is so much better than the 70. Traction feels better as well. I'm not an engineer so won't join that discussion, just adding my two cents as a driver who has spent time with both.
 

Nickdp

Member
Feb 7, 2015
156
105
Melbourne, Victoria, Australia
<snip> ... the 70D is so much better than the 70. Traction feels better as well ...

Thanks Jude - 'qualitative' comments such as yours help de-mistify the issue of D or not D, of course there is the whole engineering narrative going on in the background (as googie has illustrated) but in the final analysis it is about how the car feels.
 

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