|
Computer viking posted:Oh wow, it's like a jacuzzi on wheels. I was on the bike, so slightly above driver's shoulder level and it looked like the dude was in one of those kiddie pedal cars with no roof.
|
#
?
Oct 13, 2016 20:44
|
|
|
|
| # ? May 11, 2024 12:22 |
|
|
Uthor posted:So, it's set up like a drift car? If the X5 is on McStruts in the rear (BMW loves McStruts, for much the same reason that Subaru does - and they get boned just as hard by the SCCA for it) you definitely want all the negative camber you can muster back there. The big downside with Macpherson struts from a performance driving perspective is that as you compress them, the arc forced by the single control arm forces them to gain camber (jack up your car and watch the wheel trace an arc instead of going straight up and down). So if you want a lot of negative camber when the car is turning and the suspension is fully compressed, you have to start with even more negative camber when the car is at rest. The reason why you want a lot of negative camber when the suspension is compressed is because as the car rolls onto the tread of the tire and 'flattens' it against the ground such that the tire is now perpendicular to the ground, you get much more resistance to sliding laterally. Grab a pencil eraser and push it against a desk. First, push the very tip across a desk and try to push it along the tip like a sliding tire. Now, rotate the eraser so an entire face is in contact with the desk and try the same thing. It's much harder to push the eraser sideways. Since generally you want to go forward instead of sideways, this behaviour is desirable in a tire. Cars without McStruts but with independent suspension (e.g. short-long arm or double wishbone) will also gain camber under bump but usually the difference is not quite as dramatic. Depending on how the chassis is tuned from the factory you'll see a variety of choices for OEM camber - Mazda loves a lot of negative camber in the rear on the Mazda 3, for instance. There's a lot of variables to all this and "more negative = faster than" is not true at all in many cases. The downside of this for your average BMW X3 owner is that excessive negative camber wears tires when driving in a straight line, due to some property of radial tires that I haven't bothered to look into because tires are for driving on, not for looking at. Seat Safety Switch fucked around with this message at 03:43 on Oct 14, 2016 |
|
#
?
Oct 14, 2016 03:37
|
|
|
Computer viking posted:Oh wow, it's like a jacuzzi on wheels. lomarf 
|
|
#
?
Oct 14, 2016 03:57
|
|
|
Seat Safety Switch posted:I'm no doctor, but... It's not. But yeah camber in itself will not cause too much extra wear, it's when you have some toe that is dragging the tire when any camber causes really quick wear on one side. Anyhow, the x5 is big and tall and heavy so a little rear camber keeps the handling on the understeer side and probably keeps tire wear more even unless all you ever do is drive in a straight line.
|
|
#
?
Oct 14, 2016 06:21
|
|
|
Sagebrush posted:lomarf Catering to people that really liked the look of the Murano CrossCabriolet but also considered Japanese levels of reliability to be far too boring.
|
|
#
?
Oct 14, 2016 14:07
|
|
|
Help, I fell down the e-bike hole last night while looking at how to make an electric Geo Metro and now all I can do is look at pictures of fried Chinese hub motors. metaxus posted:Catering to people that really liked the look of the Murano CrossCabriolet but also considered Japanese levels of reliability to be far too boring. Every time I look at the convertibles I just can't stop thinking about the trunk.  There's not a lot of cars with pretty trunks out there, but this has to be one of the worst, other than that Buick/Opel with the hidden secret double set of tail lights inside the trunk. Seat Safety Switch fucked around with this message at 14:12 on Oct 14, 2016 |
|
#
?
Oct 14, 2016 14:08
|
|
|
Seat Safety Switch posted:other than that Buick/Opel with the hidden secret double set of tail lights inside the trunk.
|
|
#
?
Oct 14, 2016 14:15
|
|
|
slidebite posted:OK so I am curious now, what is that? It's the Opel/Buick/Holden/Vauxhall Cascada of course. 
|
|
#
?
Oct 14, 2016 14:16
|
|
|
So what is the deal with the hidden tail lights? 
|
|
#
?
Oct 14, 2016 14:25
|
|
|
slidebite posted:So what is the deal with the hidden tail lights? Most places now require that tails lights be visible when the trunk open. Those are just a different way of meeting that requirement.
|
|
#
?
Oct 14, 2016 14:29
|
|
|
We're never going to get another straightforward simple car are we?
|
|
#
?
Oct 14, 2016 14:32
|
|
|
Seat Safety Switch posted:The big downside with Macpherson struts from a performance driving perspective is that as you compress them, the arc forced by the single control arm forces them to gain camber (jack up your car and watch the wheel trace an arc instead of going straight up and down). Most of what you wrote is right, but on this it's the other way around, actually. Macphereson struts, the angle of the tire relative to the chassis doesn't change much compared to wishbones - so when the body rolls during cornering, the outside tire, which is doing most of the work, heels over onto the outside edge unless you put a bunch of static negative camber on it. Wishbones you can tune so that the camber changes as the body rolls, keeping the tire in the orientation you want under cornering while not having to sit on the inside edges of the tire while going straight.
|
|
#
?
Oct 14, 2016 14:33
|
|
|
mekilljoydammit posted:Most of what you wrote is right, but on this it's the other way around, actually. Macphereson struts, the angle of the tire relative to the chassis doesn't change much compared to wishbones - so when the body rolls during cornering, the outside tire, which is doing most of the work, heels over onto the outside edge unless you put a bunch of static negative camber on it. Wishbones you can tune so that the camber changes as the body rolls, keeping the tire in the orientation you want under cornering while not having to sit on the inside edges of the tire while going straight. The fact that I thought the camber curve worked more in the inside tire explains so much about my autocross career.
|
|
#
?
Oct 14, 2016 14:39
|
|
|
Cindy Shitbird posted:Most places now require that tails lights be visible when the trunk open. Those are just a different way of meeting that requirement. Makes a lot of sense if you imagine having a flat tire on the side of the road at night. I don't think I've seen that on European cars, but they do have reflectors on the underside of the trunk lid.
|
|
#
?
Oct 14, 2016 14:43
|
|
|
Yeah, I was gonna post something snarky, but then I remembered all the times I've had to drive home from Home Depot with 2x4s sticking out of my trunk or whatever.
|
|
#
?
Oct 14, 2016 14:45
|
|
|
1500quidporsche posted:We're never going to get another straightforward simple car are we? It's all Ralph Nader's fault I tell you.
|
|
#
?
Oct 14, 2016 15:21
|
|
|
I can see the reason for it. They wanted those kickin rad tail lights that go almost all the way to the middle. that would require a smaller trunk opening if the lights weren't part of the trunk lid. So now they get a bigger trunk opening and their lights.
|
|
#
?
Oct 14, 2016 15:30
|
|
|
Data Graham posted:Yeah, I was gonna post something snarky, but then I remembered all the times I've had to drive home from Home Depot with 2x4s sticking out of my trunk or whatever. The requirement is fine, but the Cascada’s way of meeting it is not. Why does the whole back panel need to lift? The inner tail lights preclude you from using the full width for cargo anyway.
|
|
#
?
Oct 14, 2016 15:35
|
|
|
Yeah the issue is more that GM is seeking a solution to an issue that never existed in the first place.
|
|
#
?
Oct 14, 2016 16:18
|
|
|
Form over function in an automobile? That never happens!
|
|
#
?
Oct 14, 2016 16:26
|
|
|
|
|
#
?
Oct 14, 2016 16:29
|
|
|
It looks like it's swallowing a smaller car.
|
|
#
?
Oct 14, 2016 16:42
|
|
|
Seat Safety Switch posted:It's the Opel/Buick/Holden/Vauxhall Cascada of course. 
|
|
#
?
Oct 14, 2016 16:51
|
|
|
It's been done before
|
|
#
?
Oct 15, 2016 00:37
|
|
|
 http://www.miningreview.com.au/news/drill-offsider-run-tracked-vehicle/ quote:A drill offsider escaped with minor injuries after being run over by a tracked vehicle, according to a Department of Mines and Petroleum significant incident report.
|
|
#
?
Oct 15, 2016 14:00
|
|
|
Reminder that the whole point of a tracked vehicle is that it reduces ground pressure. An 80 ton Abrams tank only puts about 15 psi on the ground, compared to 30 or 40 for a passenger car. Of course a tank can run over your entire body with that weight, while the car can only run over a small section of it.
|
|
#
?
Oct 15, 2016 17:33
|
|
|
Correct, but if you are on soil that isn't significantly softer than you, you will conform to the tracks until you're flat and then support 15psi. The soft ground is what saved him. Cars have drat near the same ground pressure as the air pressure in their tires. This is why large commercial vehicles do substantially more road damage than cars, they have to run a much higher tire pressure than cars to support the load in them. A tracked vehicle has no real limit on ground pressure over a non-flat surface since the tracks are steel - if one runs over a concrete block or a skull on flat solid ground for instance, the whole load will be supported on that point until it crushes and the rest of the track hits the ground again.
|
|
#
?
Oct 15, 2016 17:57
|
|
|
kastein posted:Correct, but if you are on soil that isn't significantly softer than you, you will conform to the tracks until you're flat and then support 15psi. The soft ground is what saved him. Are tracked vehicles allowed on public roads? Because I see a possible solution for a lot of infrastructure problems
|
|
#
?
Oct 15, 2016 19:26
|
|
|
The Door Frame posted:Are tracked vehicles allowed on public roads? Because I see a possible solution for a lot of infrastructure problems Tracks are devastating to pavement.
|
|
#
?
Oct 15, 2016 19:30
|
|
|
Yes, with street treads. The Abrams' are rubber, made by vibram. That said, even rubber treads can cause damage by turning, because they drag sideways and can delaminate the road surface with shear forces.
|
|
#
?
Oct 15, 2016 19:30
|
|
|
Dang, I was thinking of half-tracks; just put rubber treads on the trailer and also the two rear tractor wheels, but keep the front wheels with tires. Then you don't have to alter steering systems too much and only require minimal training for truckers to use the new system
|
|
#
?
Oct 15, 2016 20:35
|
|
|
tactlessbastard posted:Tracks are devastating to pavement. Also, tracked vehicles just aren't that fast. A balanced wheel can spin a hell of a lot faster than a heavy linked belt can run over rollers. I think the world record speed for a tracked vehicle is under 100mph. So, probably not all that useful for long-haul interstate trucking.
|
|
#
?
Oct 15, 2016 20:38
|
|
|
tactlessbastard posted:Tracks are devastating to pavement. But you don't need pavement if you have tracks :P
|
|
#
?
Oct 15, 2016 20:49
|
|
|
Sagebrush posted:I think the world record speed for a tracked vehicle is under 100mph. Hmmm. If AI ever decides to set a land speed record, this might be easy pickings. Battery Electric Tracked Speeder. All BETS are on.
|
|
#
?
Oct 15, 2016 20:51
|
|
|
I don't know about the US, but you can legally drive tracked vehicles (with road-type tracks) on the road here. Which leads to things like this: https://www.youtube.com/watch?v=lY8WTWAw6XM
|
|
#
?
Oct 15, 2016 20:53
|
|
|
There's a guy in Mesa with an APC.
|
|
#
?
Oct 15, 2016 21:14
|
|
|
A guy down the street from my old house has an APC that he'd occasionally take out up and down the (dirt) road. The road's now been paved so I'm not sure if he still does it.The Door Frame posted:Dang, I was thinking of half-tracks; just put rubber treads on the trailer and also the two rear tractor wheels, but keep the front wheels with tires. Then you don't have to alter steering systems too much and only require minimal training for truckers to use the new system I have to imagine that half-tracks are just understeer nightmares unless you add in some individual braking, in which case now you're altering the steering, braking, and handling (especially during emergency maneuvers. That said what you're describing sounds a lot like the track option for a John Deere Gator 6x4, though my experience with that vehicle definitely returns us to the point about understeer. That thing loved to go in a straight line.
|
|
#
?
Oct 15, 2016 21:55
|
|
|
Tracks wear out super fast miles wise, cost a lot, are loud, don't ride or corner worth a poo poo, and beat the hell out of the road when going fast and/or turning.
|
|
#
?
Oct 16, 2016 00:20
|
|
|
I did my mandatory military stint (Germany) in a town that housed one of Germany's tank driving schools and a few self-propelled artillery units. All of the road-going training tanks had glass turrets, looks kind of cute. I never saw anything but rubber tracks on any of them (this included Leo2's, M113's, and eventually the PzH2000), probably because they absolutely had to use public roads to get into and out of the base compounds. One Leo2 flattened 1/2 of an early 90's Golf while the driver was half-pulled off the road, showing ID to the guard station to get in. I am not sure how the Leo driver didn't see him. I heard from the guard shack that the passenger was pretty shaken up afterwards. TotalLossBrain fucked around with this message at 00:31 on Oct 16, 2016 |
|
#
?
Oct 16, 2016 00:29
|
|
|
|
| # ? May 11, 2024 12:22 |
|
|
Sorry to distract from tank chat but we had some fun failures at the track this weekend. Yesterday was a practice day so each of our five drivers did two 15-20 minute sessions to relearn the track (Road America) and feel out the car. The brakes were bad before lunch when we bled out a couple bubbles but I still wasn't happy with them after. End of the day we went to put on new pads for the race today and found this... With that fixed we had a 7 hour race today, about 15 minutes from the end of the race the car lost power. Our driver pulled over and got towed in. Engine didn't want to start and when it did it sounded terrible. Pulled the valve cover then noticed one of our valves had went missing.   
|
|
#
?
Oct 16, 2016 01:15
|
|
