Tesla Model S Suspension Walkaround
edmunds.com
edmunds.com
I believe Lotus does a lot of engineering consulting helping other manufacturers dial in suspensions. I wouldn't be surprised if Tesla had them consult.
Even some of the big car companies have trouble dialing in suspension on their own (I'm looking at you underdamped Japanese cars). European brands tend to be really good at this, and can take the same raw materials that everyone else is working with and create superior setups. Porsche somehow manages to start with the 911 where they stick the engine way out behind the rear axle (high polar moment of inertia, poor front/rear weight distribution) and make it handle beautifully. VW cars also tend to have great suspension tuning. Being able to keep the weight low to the ground in the Tesla contributes to a low center of gravity and I imagine must really help enormously.
Also the body under-tray is beautiful, like something you'd expect to see on a purpose built race car, probably helps a lot with the aerodynamics. I imagine more and more cars will get similar under-trays to improve aerodynamics and fuel efficiency.
It's interesting there is strong anti-dive geometry built into the car, probably to avoid problems with throttle lift oversteer caused by inexperienced drivers. I wonder if the current Model S handling leaves anything to be desired when driven to it's absolute limits and how the car would handle with some of the anti-dive geometry removed. Removing this geometry is a common mod on some cars.
Actually there are some benefits to the arrangement. The high polar moment of inertia actually should make any spin slower to start and easier to catch than a mid engine arrangement. Under hard braking the weight shifts forwards so the weight distribution changes to more balanced than with other arrangements. Under power the weight is over the rear wheels for power out of the corner.
A 911 behaves differently to other cars but I'm not sure the arrangement is actually worse in most dynamic scenarios. Understeer into the corners is the main dynamic weakness when pushed really hard and can be compensated for by trail braking into the corners. I guess you can get into trouble if you go into a corner too fast, panic brake and lose the rear end but if you are used to the set up you can make use of it.
[I've only driven a 1980's 911 so maybe I'm over extrapolating to all rear engined cars and I've never tried a mid engined car. This book is really good at explaining how do get the most out of different weight distributions and has some fun stories (I've got the first edition but it probably isn't much different): http://www.amazon.co.uk/Porsche-High-performance-Driving-Han...]
911 grips harder as you turn harder, very strange to get used to but once you 'get it' it feels great. obviously there is a limit but you are not going to hit it on the street in a car like a 911.
i haven't driven any modern mid-engine cars like the R8 or boxster though, i'm sure it's vastly improved from the NSX, which was basically designed in the 80s, so no fault to it. it was a great car. can't wait to see the new one.
right now i drive a performance sedan but my next car will be a "regular" 911, probably a 991 S.
as for the tesla... eh. doesn't give me that "gotta have it" feeling. i still want gasoline and a clutch. call me old fashioned.
i would be interested to know the % of current tesla owners that have ever owned "real" sports cars, not just "sporty" cars. it doesn't strike me as the same crowd.
and the roadster just absolutely does not appeal to me. i don't like roadsters in general but it's just too feminine and it looks hideous with the top on.
It's actually really easy to test drive Model S. Click big red button on the website, they call you, and boom - test driving Model S Performance.
While I don't think it's time to buy EV yet, I highly recommend test driving Model S Perf - it feels, accelerates and handles beyond amazing for car of it's size.
if you've never actually driven a fast car, i'm sure it's very impressive, but objectively, it's not fast compared to its competition.
it appeals to a different crowd, the kind that wants EVs. i bet most people who considered/bought the S perf have never seriously considered an M5, E63, RS, or even Cadillac V (since we're talking American cars here). all of those handily beat the S in every benchmark.
have you test driven a BMW M5 or AMG E63? or does driving a giant, turbocharged, gas guzzling V8 not interest you?
well that's what interests me. not a battery pack.
It's really something you need to experience before you criticize it.
"instant" torque is cool and all, but no match for "more" torque. which also happens to be "instant" when you move beyond a cheapass 3-series M or base 911 with no balls (try a GT2, when you start wearing big boy pants) or V10 in that price range.
All I'm saying is that in my opinion based on driving the cars is that I prefer the Model S Performance over the supercharged M3, 911S because of superior handling, torque and feel.
Just my two cents, no need to get offended that a battery car can give a decent ride.
Also, I know there are people who have traded in the M5's for a Model S Performance and have been quite happy.
maybe for bay area millionaires automotive performance is less important than social progressivism when you drop 100k but not for me.
Personally, I don't feel a tenth of a second makes much difference, but it's wrong to say that the Tesla is handily beat in every benchmark.
References: http://www.edmunds.com/bmw/m5/2013/road-test-specs.html http://www.edmunds.com/car-reviews/track-tests/2013-tesla-mo...
I suspect they engineered the throttle lift oversteer and such specifically for the wider market they were looking to hit. Not just car aficionados, but also people who were EV or green or geeks and such.
Considering the Williams F1 active system was developed for the 1992 season, I'm kinda disappointed that no fully active system has ever hit a production car. The best we've seen is active damping on several cars. Bose had a pretty cool prototype [4], but never hit prod. The neat thing about electromagnetic damper/springs is that they can regen for a EV.
If your unfamiliar with car mechanics, then this is a good serious of short video tutorials [5].
[1] http://www.edmunds.com/car-reviews/track-tests/2012-mclaren-...
[3] http://scarbsf1.com/williams_active/WilliamsF1_ACTIVE_SUSPEN...
[4] http://www.bose.com/controller?url=/automotive/bose_suspensi...
1: http://www.amazon.com/Bosch-Automotive-Handbook-Robert-GmbH/...
Mercedes and BMW have their own active suspension systems that are standard in the high-end models, not sure if they look as magic as Bose's.
Some have variable strength roll bars, but roll bars are really just a 'hack' anyway. Very few have used a variable springing system (Merc ABC). An air suspension can change springing and ride height, but's it's slow.
In addition to low latency damping/springing adjustments/ride height, a fully active system in able to apply force into the suspension so the attitude of each corner is under complete software control, milli by milli. You can have a perfectly smooth ride, but no roll. All current non-active designs are a compromise between sporty and confort (high vs low springing/damping constants, and movements in attitude due to accelerating/braking/downforce/cornering/road surface.
The main problem with fully active is that it uses quite a bit of power and is very complex. Here's some more info http://www.autozine.org/technical_school/suspension/tech_sus...
http://www.edmunds.com/car-technology/suspension-iii-active-...
TL;DR Tesla Model S suspension is pretty neato.
I think untog's comment is spot on. There are lots of stories that seem to get upvoted for reasons other than their own merit.
Pointing that out in this case is probably appropriate.
Edit: Oh wait sorry no... I suck!
The part that impresses me though is the steering knuckle (they comment on it towards the beginning), and its aluminum hollow construction. We build modified steering knuckles for trucks that provide additional lift height, but out of ductile iron in a cast mold, same as OEM specs/mfg process. So i'm kind of at a loss how they would make it hollowed out, while maintaining stability. Definitely expensive, i know billet aluminum knuckles for corvettes run about $1500/piece.
Basically welding using a combination of joining pressure with a very high speed spinning steel bit that heats the aluminum joint via the friction created by it spinning on its surface. That spinning bit travels along the seam heating, and then it's pushed together when it's no longer quite solid, and spun together by the bit. Some interesting discussion of the crystal structure formed and the associated mechanical properties, as well.
Both SpaceX and Tesla are largely built on skimming the superstars out of the entrenched players. There are plenty of people that are really really good at their jobs at Boeing, Lockheed, Ford, General Dynamicsm, etc. They are generally underpaid, undervalued, and given little freedom relative to their skillset. But they stick around in those companies because that's where you have to be in order to work on really cool stuff like the Ford GT 40 or a space rocket.
Tesla and SpaceX offer the same cool stuff to work on, without the crappy low-value coworkers that never get fired, legacy systems holding you back, and the opportunity to do things as you believe they should be done.
This is part of why the old companies will have a hard time noncompeting. Not only are SpaceX and Tesla disrupting their business, but Elon Musk is stealing from their top tier talent pool that could defend against disruption.
1) Spend 6 years at an insanely high burn rate with zero revenue for research and development to create a marketable car
2) Have enough brand loyalty to delay delivery to your high-earning clientele multiple times
3) Hustle Daimler into investing to do payroll at the height of the financial crisis, with Daimler themselves having no money
4) Hustle the DOE into funding your fully electric sedan while having only a taped together basic model to show for it, with your competition (Toyota) being granted billions just to refit a factory
Step 2: Remove all barriers stopping them from being awesome at what they do. Pay them well. Appreciate them.
Step 3: Profit
I wish them well, but the "profit" part still remains to be seen for both SpaceX and Tesla Motors.
When I worked for Ford, I would overhear conversations like this:
Manager: Customers are complaining, the pedal is to hard to press on the Town Car.
Engineer: The pedal is too fucking soft as is. If we make it any softer, people won't know if they are even pressing it.
Manager: Just make it softer. It is showing up as a problem on the TGW report.
Or Sindelfingen, hopefully.
Maybe when 3D printers get better...
What you see in the hobbyist 3d printing world is about 10-15 years behind the commercial world.
I suppose this must be what owning a car in California is like.
[1] http://en.wikipedia.org/wiki/Inerter_(mechanical_networks)
A niche benefit: I live in the mountains and it handles going down much better than gas cars, where you have to downshift and use engine braking to avoid burning the brakes. It uses 12 miles of range going up, and gains 4 back going down so the average is close to a flat road of the same distance.
The brakes you see in the photos are for breaking, hard (full stop, quick stop, racing).
2. Don't get rear-ended
Wait, it seats 7?
http://news.consumerreports.org/cars/2013/03/our-tesla-model...
It can seat 7 at once???
They won't be able to sit back there forever. My daughter probably has 2 years and my son maybe 4 or 5. When they are both done with the seats, we can have them removed and get even more trunk space.
One thing that I ding Tesla a bit about... They don't tint the hatchback window the way they do the panoramic roof glass. This was a mistake as the back seats get hot in the direct sunlight and there isn't currently air conditioning vents back there.
Enough owners have raised these concerns that I believe they will likely correct one or both of them in future revisions of the car, and we'll see if they make it one of the proposed hardware retrofits.
In the interim, we had the back windows after-market tinted and the kids have no complaints.
The slide-out brake pads are a neat idea, but I'm wondering why, as the caliper still has to be removed during a brake change to pull off the rotor.
Those aluminum pieces can't be cheap. Neither can the 4-piston brake calipers. Nor the armored underbelly. It's definitely performance-oriented.
Every car I've ever worked on with calipers has slide out pads just like that...
> as the caliper still has to be removed during a brake change to pull off the rotor
Although pad changes are much more frequent than rotor changes, so it makes sense.
Even if you don't replace the rotor, you still have to remove have it turned (grinding the contact surfaces flat again), so the new pads make good contact, instead of being pressed against the ridges and valleys left in the rotor from the worn-out pad.
It just seems like a bit of over-engineering.
On a regular car you might have to have your rotors turned, but on something like this the rotors are more heavy duty and I think resist warping. Plus, on something like this you could run a lot softer pad (for track days) and need to change them out after a single weekend of use. It is still a good idea to sand the rotor surface, by hand, just so the pads will seat correctly.
Edit: And I do agree, I've never seen a "normal" car with the slide out pads... although they always look like you can do that until you get close and realize it is going to be a little more work than you thought. :)
Rotors don't have to be changed as frequently as pads. It's probably a lot easier this way vs dismantling the whole thing.
If you do not replace the rotor when you replace the pads, a machine shop has to grind the rotor, so its surface will be flat to work effectively with the new pads. If you don't, the pads won't make full contact with the rotor, and maintaining the brakes would make them operate worse until they wore in.
Actually, when I first read this doc a couple of weeks back, it showed me the reason for something I had noticed. If I have my foot on the brake while changing the suspension level, I've noticed that when I let off the brakes, the wheels shift a bit. Turns out that for the front tires, it doesn't lift and lower straight up and down. There is a bit of horizontal motion as well.
No. The force provided by regenerative braking is proportional to your speed. Without friction, it would be impossible to reach 0 speed.