had my first proper racing start tonight, i though 'ill show him in his calibra' s:twisted: :twisted: s:twisted: Took it upto 5k revs, dumped the clutch......nothing but wheel spin! it was like i was just sitting there on the line and me thinking ' so are we gonna start moving forward then?'
I thought rear wheel drive cars had lots more traction? whats the best way for a good launch?
So I gather you got p155ed on s:( :( s:(
Check out:
m http://www.mr2roc.org/forum/viewtopic.p ... =technique (http://www.mr2roc.org/forum/viewtopic.php?t=3139&highlight=technique) m
I think that a lot depends on tyres though
well not really, it was just my mate and he was behind me. i was just expecting to power off the line, and leaving him for dead - his being FWD. it has been raining today so the road was probably cold and damp.
Oh well, have to try fewer revs next time s:? :? s:?
I wouldn't have expected wheelspin at that RPM unless the surface was poor/wet. I've just been out messing about with my GTECH I dialled in a few more revs this time, even at about 5800 sidestepping the clutch the car hooked up very well. Infact the results were massively impressive
0-60 feet 2.085
0-60mph 6.270
0-100mph 15.346
0-120mph 22.204
0-130mph 26.319
1/4mile 14.2 @ 98.41mph
These were all taken on a quarry road, (private). I know the speed things pretty contentious, but thought i'd share anyways. Plus despite my car having those awfull engine problems before, it seems back to rudest health.
0-60 in 6.2?!?! - you're avin a larf! s:lol: :lol: s:lol: and a quarter mile in 14.2 secs, nah, cant believe that.
As for my wheel spinning, think i might put some different boots on, think ive got some shitty bridgestones on at the mo s:( :( s:(
It is admittedly quite fast....but the Gtech doesn't lie (much!) and it's prooved very acurate in tests. This was pretty much the perfect start I hasten to add..no wheelspin..lost hardly any revs when leaving the line. I don't think i'll ever beat that again. The times are only a bit faster than those on Monkeywrench for a stock car..
The car had no perol in it, and has been lightened by a marginal amount also - spare/toolkit/engine tray
does the gtech work by the user inputting the weight of the vehicle ect or does it just sense the g-forces and rpm via the fag lighter?
The gtech works by doing all those things s:lol: :lol: s:lol:
Well technically it only senses the RPM through the cigarette lighter.. the G's it calculates from the 3 inbuilt accelerometers, and the power calculation is calculated from the inputted weight.
so how do you know the precise weight of the vehicle? have you had it weighed? did you account for yourself in the car?
Well firstly I approximated the weight, using m http://www.kumosport.com/component_weight_zzw30.asp (http://www.kumosport.com/component_weight_zzw30.asp) m
Had it on the weigh bridge last week though as i've had a new stereo since so made sure the weight was correct
what was the weight excluding tool kit and spare etc.. do you have it in kilos? i think the stock weight is 975kg without the driver
I've only ever measured with the driver in on the weigh bridge, so won't be much help sorry. If you take the base 975 then take away the weights on the previous weblink and add your weight you won't be far off
Manufactuers weights can be in Caterkilos. Basically as it's in their interests as figures (sadly) sell cars.
Caterkilos are legendary as they sell their cars on their light weight. So the figures are massaged a little. For example take the R500. According to the manufacturer they're 460kgs and 230bhp, giving exactly 500 bhp/ton. How handy. Except in the trim required to actually use the car (bearing in mind this is sold as a track car), and with fuel this actually rises to 499 kilos. This is weighed on proper cornerwieghting scales by the way. The net result is that an R500 is actually a R460. See how less impressive that seems.
What I am saying is take all figures you read with a pinch of salt, especially when it comes to weight. Firstly make sure we are talking kerb weights. Basically the car with all fluids. It's common for people to quote dry weights that are no use to man or beast, given that cars don't work without oil, water and fuel in them.
The only way to be absolutely sure is to weigh it yourself or have it weighed. Preferably on proper scales and with you in it.
More figures to be taken with a pinch of salt that in the scheme of things, really don't mean anything: http://www.juansolo.demon.co.uk/P2W/P2W.html
Perfect example, just noticed I have the weight of the Mr2 as 950 (which will have come from the interweb somewhere). Not right of course. Arses, I'll change that now.
Just because you read it on the internet, doesn't make it true s:wink: :wink: s:wink:
As I understand it though, MRMike's figure for 0-60 is derived from his GTECH jobby measuring start time and time at 60 (which it interpolates from acceleration over time), and so shouldn't need the weight of the car input at all. While it's true that weighing it is the only way to get a true value, he'd only need that for a BHP figure.
It needs the weight to accurately figure out when it's doing 60. A guestimate of this will give you a guestimate reading.
oh yeah, f=ma. Ooops, sorry.
edit (it's early in the morning, gimme a chance):
surely you only need to know the weight of the "masses" in the forcemeters in the gtech unit. That way, when you measure the force on them, as you know their mass, you can work out their acceleration... over time you can then work out the speed. So you wouldn't need to know the mass of the vehicle at all?
Right we're getting properly beardy here and it's beyond my very limited knowledge on the subject. These mini-dataloggers, they're not reading anything directly apart from maybe revs from the pulses going through the electrical system. Therefore any readings it takes must be coming from G-forces read from the accelerometers. This of course relates directly the the mass that's being propelled.
I'm wishing I payed more attention in Physics now...
Anyhow, this is only ever going to give you an approximation. The proper test gear they use either has a wheel on it that runs along the road and is calibrated. Or it has some sort of electronic gizmo that does the same.
Quote from: "juansolo"Perfect example, just noticed I have the weight of the Mr2 as 950 (which will have come from the interweb somewhere). Not right of course. Arses, I'll change that now.
Just because you read it on the internet, doesn't make it true s:wink: :wink: s:wink:
Well like I said I have subsequently weighed it on a weigh bridge...does that make the weight true? s:wink: :wink: s:wink:
Close enough s:D :D s:D
Quote from: "phil4"oh yeah, f=ma. Ooops, sorry.
edit (it's early in the morning, gimme a chance):
surely you only need to know the weight of the "masses" in the forcemeters in the gtech unit. That way, when you measure the force on them, as you know their mass, you can work out their acceleration... over time you can then work out the speed. So you wouldn't need to know the mass of the vehicle at all?
You need to know the mass of the vehicle, so that you can work out how much oomph (or BHP for the technically minded s:D :D s:D ) it takes to achieve that acceleration.
I have a copy of one of the first reviews of the Roadster in March 2000 Autocar.
They did their own 0-60 test and weighed it. According to them it came in 101kg over weight at 1076kg (no driver) but still made a 0-60 of 7.5 seconds.
This may not help much but confirms what Juansolo said. s:wink: :wink: s:wink:
Air conditioning is one item which makes a considerable difference..i'm not sure whether that would have been included on the original 975kg Toyota claims..what i mean to say is that you could have a manual car, no air con, and have an SMT, with air con, and HT. There is a considerable difference in weight between the two. As has been said ultimately you won't know unless you weigh the car.
I am clueless with the gtech, never seen or used one, my question is how does it know when you reach 60mph?
From GTECH..
The G-Tech measures your speed and distance travelled by integrating forward (the forward direction is chosen automatically) acceleration over time. Basically, if you know how fast you are accelerating for a certain time period you'll know how much your speed changed after that time period. So if you start off from zero speed then you'll know what your speed is after every time period. These time periods are very small (a few thousandths of a second) and that's how G-Tech maintains its accuracy. However, if you don't start from zero speed your measurement won't be correct because you won't have a good reference point. Consequently, it's very important to start all of your measurements from an absolute standstill.
Hmmmm...it needs the weight only for calculating hp.
Think about it...it knows the time internally and it knows the acceleration all the time. That's all you need to calculate speed and distance s;) ;) s;)
I'm not sure about the Competition model, but the basic model doesn't even ask the weight, unless you're doing hp run...
And 6.2 is easy to believe. Those of you who don't believe it, get a GTech or similar to yourself and notice how your time improves by second with a lil training s8) 8) s8) I was able to get 6.48 with a worn clutch myself...but it you miss the launch, it's easily near 8s...
Quote from: "mr-s_turbo"I am clueless with the gtech, never seen or used one, my question is how does it know when you reach 60mph?
It's basic physics...
v=at (speed=acceleration*time)
Of course the acceleration changes all the time, but you get the idea...
Also s=0.5at^2 (distance=0.5*acceleration*time^2) and that's how you can do 1/4mile runs...
Quote from: "Tem"Hmmmm...it needs the weight only for calculating hp.
That's what I was thinking Tem, so it ain't just me then s:) :) s:)
I sit corrected.
would an LSD improve your 0-60? mines a j-spec 2000 so probably doesnt have one. Maybe this is why i have trouble putting the power down?
I thought they all came with LSD s:?: :?: s:?:
i beleive its only UK and a few later imports came with LSD as standard. ive heard it metioned that some jap 2's dont have it
True, lower spec Jap cars and none of the US model cars came with LSD (although the US get it on the '04 model as an option).
Quote from: "Tomr2"would an LSD improve your 0-60? mines a j-spec 2000 so probably doesnt have one. Maybe this is why i have trouble putting the power down?
Not really. Traction out of corners yes, from a standstill you really haven't the power to spin one wheel up and not the other. Most likely it's spin both. To be perfectly honest, the Mr2 doesn't really need an LSD.
Quote from: "Slacey"True, lower spec Jap cars and none of the US model cars came with LSD
According to some brochures I have, LSD was an option to all four models in Japan (for year 2000).
Quote from: "Tomr2"0-60 in 6.2?!?! - you're avin a larf! s:lol: :lol: s:lol: and a quarter mile in 14.2 secs, nah, cant believe that.
As for my wheel spinning, think i might put some different boots on, think ive got some shitty bridgestones on at the mo s:( :( s:(
Finally got round to uploading that 1/4 mile run..again conducted on
private quarry road m http://www.SpyderMagazine.com/files/speed.jpg (http://www.spydermagazine.com/files/speed.jpg) m
Also a rev graph..notice how smooth it leaves the line (no flare in Rpm) even launched at 6500rpm!
m http://www.SpyderMagazine.com/files/revs1.jpg (http://www.spydermagazine.com/files/revs1.jpg) m
Quote from: "MRMike"Finally got round to uploading that 1/4 mile run..again conducted on private quarry road
m http://www.SpyderMagazine.com/files/speed.jpg (http://www.spydermagazine.com/files/speed.jpg) m
Looks like you're already doing 5mph at 0.0s? s:? :? s:?
Or am I reading those wrong..?
I can't see it Tem..the 0 line is the first line on the vertical grid. Speed reads 0 then. There is the 'rollout' distance (0.5 of a second) as you probably know..are you referring to that?
Quote from: "MRMike"I can't see it Tem..the 0 line is the first line on the vertical grid. Speed reads 0 then. There is the 'rollout' distance (0.5 of a second) as you probably know..are you referring to that?
Ah, now I get it...I didn't notice the "rollout" s:oops: :oops: s:oops:
I've done that before, on the graphs they tend to be 'bunched up'
bloody hell, you get 95mph out of 3rd?? i get 80-82 tops! s:( :( s:(
Quote from: "Tomr2"bloody hell, you get 95mph out of 3rd?? i get 80-82 tops! s:( :( s:(
I beleive that Jspecs have lower gear ratios - hence your lower speed in 3rd.
mph @ 6500rpm for a pre '03 Mr2 on standard tyres
1st - 35.6 mph
2nd - 59.1 mph
3rd - 85.9 mph
4th - 116.2 mph
5th - 138.1 mph
(posted by Juan Solo on an earlier thread)
If the above are correct, then it seems to me that there is an issue with the quoted accelleration data. The speed graph seems to show reaching 40, 66 and 95 in 1st, 2nd and third, which according to JS's numbers, is not possible.
Have I missed something?
Andy
Quote from: "Andy S"mph @ 6500rpm for a pre '03 Mr2 on standard tyres
1st - 35.6 mph
2nd - 59.1 mph
3rd - 85.9 mph
Have I missed something?
Yeah, you missed that the values above are for 6500rpm, not for rev limit s;) ;) s;)
Quote from: "Tem"Quote from: "Andy S"mph @ 6500rpm for a pre '03 Mr2 on standard tyres
1st - 35.6 mph
2nd - 59.1 mph
3rd - 85.9 mph
Have I missed something?
Yeah, you missed that the values above are for 6500rpm, not for rev limit s;) ;) s;)
Ah, so I had!
Later in that same thread I posted them at 6750rpm which is the marked red line (though not where the limiter is which is around 7000rpm).
Quote from: "juansolo"Quote from: "Tomr2"would an LSD improve your 0-60? mines a j-spec 2000 so probably doesnt have one. Maybe this is why i have trouble putting the power down?
Not really. Traction out of corners yes, from a standstill you really haven't the power to spin one wheel up and not the other. Most likely it's spin both. To be perfectly honest, the Mr2 doesn't really need an LSD.
it might not need an LSD if you are driving on your perfect road, around the city here i can hear and feel LSD grippin if i am turning at traffic light, and no I am not driving like an maniac, just the roads are extremly worn off and pretty slick... add a bit of water or extreme sun, stock rubber will slip easily and thank god for LSD or i would have to be feather footed...
This is what might have happened to him, on some bad roads, i can loose traction in 2nd gear (or even 3rd), with not hard push at the pedal, of course, as you wrote, LSD wont engage if I am going straight
btw - all euro spec with 6speed (03 model) came with LSD from factory...
LSD is Torsen stylie which is geared. It works by directing the torque to the wheel with the most grip on up to a certain ratio (usually around 5:1). Once this ratio is exceeded the diff goes 'open'. Therefore they don't work on snow and ice.
It's not an LSD as such, it's what is known as a torque biasing differential. The beauty of them is that they're great for road cars as they are seemless, quiet/silent and require no more maintenence than a standard open differential.
Essentially it means that putting on a lot of lock and dropping the clutch doesn't spin up your inside wheel, it spins both. But do that violently enough with a non-LSD car and the results are the same.
Same goes for getting off the line. The stock Mr2 simply doesn't have the power to give you any issues. Don't get me wrong, it helps in certain circumstances, powering out of exceptionally tight corners for example. But it's nothing a bit of throttle control couldn't compensate for. Great and probably getting to the point of being essential for the turbo boys though.
This is the same reason that the Lotus Elise has never had an LSD, as it simply doesn't need it.
as i said, it works fine in extreme worn off streets here (turning from traffic light), but you are absolutly correct about straight line, i never notice it - so clear it up for technologically impaired, will our stock LSD help putting down power on straight whith turbo'd car? i eventually do plan getting an TTE turbo (if ever released),...
It will be more useful on a turbo'd car yes. Won't make much, if any difference in getting off the line though. Unless one of your wheels is on a patch of oil and the other isn't that is.
sureley it makes a difference when pulling away in the wet?
If you've got a turbo'd 2 then pulling away in the wet is a wheel spin frenzy. Doesn't matter if you've got LSD or spikes in your tyres. If you think the LSD is your answers then i'm afraid your going to be dissapointed. It takes no time time at all to get used to the different conditions and it can actually be quite amusing to floor the throttle in 3rd and feel the wheels spinning trying to gain traction. But basically it's in your control, you just need to try it to appreciate it.
This Sunday is a good time to try it, i believe, if you can make it to MK.
Juansolo your proving to be quite a guru in the mechanical workings, i like reading your posts cause they actually talk sense. I take my hat off to you. s:wink: :wink: s:wink:
Quote from: "juansolo"It will be more useful on a turbo'd car yes. Won't make much, if any difference in getting off the line though. Unless one of your wheels is on a patch of oil and the other isn't that is.
figured... featherweight foot around the city will be! s:) :) s:)
or I will look like some kid in '89 blacked-out (and peeled off) 3 series, doing slides from the traffic lights
Quote from: "Tomr2"sureley it makes a difference when pulling away in the wet?
If you think about it you are feeding the same drive to both wheels. If the weight on both wheels is the same and the surface under the wheels is the same (thus having the same traction properties), then there is no reason that one of the wheels will spin faster than the other, which is what an LSD is there to combat.
Now imagine you are on a track and going around a tight corner. All of the weight of the car is on the outside of the vehicle. With a standard open diff (and a lot of power), flooring the throttle on exit with the car loaded up this way will cause the torque to go to the place of least resistance, which is the unloaded wheel. Once that starts spining you'll just spin all the torque away.
What an ATB diff does (see here: http://auto.howstuffworks.com/differential.htm and here for an the Torsen (ATB) white paper: http://www.sonic.net/garyg/zonc/TechnicalInformation/TorsenDifferential.html) in this situation is direct the torque to the outside wheel that has the traction, allowing you to power out of the corner more effectively. It can only do this to a point though. Most are a ratio of 5:1. But in reality once you exceed that both wheels are spinning anyhow and your already catching an armfull of oversteer.
This is also why it's more difficult to donut a car without an LSD. The priciple is the same. You need to get both wheels spinning but as you're essentially trying to turn a very tight corner, the inside one instantly unloads and spins up. What the ATB does is exactly what's mentioned above and gets both wheels spining.
However as I've mentioned before, ATB's
don't work in extremely low traction situations. You try driving on ice and you'll find that the ratio is exceeded instantly, the diff goes open and one wheel will spin up. This is why in the days before electronic diffs, rally cars all used plate differentials as an ATB would be useless on the loose surfaces.
A plate LSD is far more brutal than most diff's that you'll find on a road car. It's a proper LSD for a start. What they do is allow a certain amount of slip (set up when it is built) before essentially locking the diff. Drive is then directed 50/50 to both driven wheels regardless of traction. One of them could be in the air for all it would care.
The problem with plate diffs is that they are incredibly noisy. I have one in the Westy and the looks I get sometimes are comical as it sounds like the back of the car is about to fall off at any time when trundling around the paddock as even the slightest amound of steering lock starts the diff 'winding up'. Basically they bang and clunk in a very loud way. They also need new oil every year and require rebuilding when they wear out.
There are others; Viscous diffs work (very simply speaking) on the resistance of special oil within it. Worm diffs just freak me out and I don't understand them at all.
The main rule of thumb is that if it's a road car or a road / occasional track day car: fit an ATB/Torsen. If it's a pure track vehicle, fit a plate.
Quote from: "mr-s_turbo"Juansolo your proving to be quite a guru in the mechanical workings, i like reading your posts cause they actually talk sense. I take my hat off to you. s:wink: :wink: s:wink:
s:oops: :oops: s:oops: Why thank you. s:oops: :oops: s:oops: It all comes from buying a kit car that was utterly unsuitable for the purpose I wanted it for and the resulting very expensive rebuild after I blew the engine and decided to sort it all out in one fell swoop.
It also helps to know people who really know there stuff. I have a friend up the road who prepares race and sprint cars for a living (and re-built a lot of mine). My mate who stores my car used to restore classic vehicles (almost scratch built one!). Finally I have my rallying friend who lives and breathes very silly cars. Their knowledge and help has been invaluable.
Before the kit I had little real knowledge of how any of this stuff worked. I just had to pick up a lot of this stuff really rapidly as there was little that didn't need sorting in the car.
FWIW, when I get around to it, I'll be doing write ups on both the kits on my site. I used to have a running diary for both on Pistonheads but the spiraling costs depressed me so I deleted them. I will get around to it as both are insights into the reality of preparing a strong enough kit for track use. Which is not as straight forward as you might think.
Quote from: "juansolo"Quote from: "Tomr2"sureley it makes a difference when pulling away in the wet?
If you think about it you are feeding the same drive to both wheels. If the weight on both wheels is the same and the surface under the wheels is the same (thus having the same traction properties), then there is no reason that one of the wheels will spin faster than the other, which is what an LSD is there to combat.
my mate has a celica (old shape - jap ST202) and he did a stationary burnout infront of me once, and when he pulled away there was only tire marks from one wheel? now for this car to do this, it most definately wont have an LSD, BUT the traction on both wheels and suface was the same so how come only one wheel spun??
So surely an LSD would get you off the line quicker if both wheels are spinning (as you have twice the grip)
QuoteSo surely an LSD would get you off the line quicker if both wheels are spinning (as you have twice the grip)
You'll get off the line quicker if neither of your wheels are spinning s:wink: :wink: s:wink:
Also you don't have twice the grip, the grip level is the same regardless of whether you have an LSD or not. All an LSD does is redirect torque either proportional to grip (Torsen/ATB) or by locking drive to both wheels (plate).
For one wheel to spin up and not the other there is a difference in traction for some reason. Maybe, being FWD, he had a little bit of lock on (doesn't need to be much), or the tyre pressures were different, or many other factors that can effect this.
Quote from: "juansolo"Quote from: "Tomr2"sureley it makes a difference when pulling away in the wet?
If you think about it you are feeding the same drive to both wheels. If the weight on both wheels is the same and the surface under the wheels is the same (thus having the same traction properties), then there is no reason that one of the wheels will spin faster than the other, which is what an LSD is there to combat.
Sorry to be picky .. . but won't unequal length drive shafts have some effect on this? I think a longer drive shaft will 'absorb' the energy destined for the wheel by twisting more than a shorter one. Therefore everything at each wheel is not quite the same - the wheel at the end of the longer shaft will have less energy sent to it because the longer shaft used some up (less torque?). The '2 has different length shafts 'cos it's a cheap ex-FWD engine stuffed in the back.
I believe that Honda did a lot of work on their engine bays to make drive shaft lengths as equal as possible to reduce torque steer for the FWD cars - ISTR the old CRXs had equal length drive shafts. Not sure if this was carried forward to the mental Integra-R, as that had a worm LSD fitted. Now why doesn't MrT do some of that?
Quote from: "juansolo"If you think about it you are feeding the same drive to both wheels.
May I disagree? s:oops: :oops: s:oops:
In basic theory, you are...but once you go deeper into it (and real life is as deep as it gets), I don't think you are. The right side wheel gets more torque than the left side wheel. It's not a major difference, but it is there. And I'm afraid I don't have enough knowledge to specifically explain the reason...it's a weird mixture of differential internals and axle movements. I'm still working on understanding it s:oops: :oops: s:oops:
You can easily try it with non-LSD car that has enough power to spin the wheels on given surface. Major power easily spins both wheels, but if you try to balance on the limit between traction/spin, you'll just spin the right wheel. And it's always the right wheel, never the left one (assuming they have the same grip).
It was a real issue with my Mk1 MR2, which didn't have LSD s:? :? s:? It wasn't an issue with stock engine on dry roads though, there's plenty of grip for both wheels once you're moving. I did notice it in tight corners though, but nothing I couldn't live with. It was an issue on winter though, nothing that would make normal driving too hard, but an issue when you really wanted to go fast. With some extra power and wider tires, it became on issue on summer as well...again, nothing that would stop me getting the groceries though s:twisted: :twisted: s:twisted:
Quote from: "Tem"May I disagree? s:oops: :oops: s:oops:
By all means s:wink: :wink: s:wink:
FWIW traction is always going to be more of an issue with a FWD car than a RWD one. As you don't need a whole lot of power to require an LSD (Honda ITR/Focus RS), or traction control via ABS (pretty much everything else) to try and keep this in check.
As for an LSD getting you quicker of the line; it doesn't. If you are spinning your wheels you are already not getting off the line as quickly as you could and are wasting fractions of a second as your tyres scrabble for grip. If however you're doing it properly the wheels are not spinning and there is therefore no work for the LSD to do in the fist place.
You youself mentioned that you didn't have an issue with the standard car and it was only when you increased the power that the problems started. That was my point exactly. It's when the power starts to more easily overcome the grip available that an LSD really starts to make it's presence felt. The turbo people in particular with their non-linear power delivery will appreciate it more than most.
Quote from: "juansolo"As for an LSD getting you quicker of the line; it doesn't. If you are spinning your wheels you are already not getting off the line as quickly as you could and are wasting fractions of a second as your tyres scrabble for grip.
This is splitting hair, but I think it does help. s8) 8) s8) Let's say the torque is distributed 51% to right and 49% to left. That means you can only use 98% of grip that is theoretically available, or you will lose traction and end up spinning one wheel. Not really a major difference and surely nothing to worry about in real life (unless you're racing).
Then again, when you go above that and spin the wheel, first you'll lose major power on the spinning wheel and only some end up to the wheel with grip (=less acceleration). Also, you'll have to raise the throttle a lot without LSD go gain grip on the spinning wheel again, while with LSD you can get away with a lot smaller throttle decrease. And this is what actually makes it help in real life, cause no human can make a perfect launch again and again. It's easy to make a non-spin launch every time, but then you're not trying enough s:lol: :lol: s:lol:
Also, the fastest acceleration comes when you're spinning the rear wheels at about 107% (meaning 7% faster than fronts/real speed). More or less impossible to do with driver controlling the throttle, but that's why God invented electronics for us s:twisted: :twisted: s:twisted: Obviously you can't do that without LSD.
But you're right that the stock '2 doesn't really need that in real life s8) 8) s8)
Quote from: "Tem"This is splitting hair, but I think it does help. s8) 8) s8) Let's say the torque is distributed 51% to right and 49% to left. That means you can only use 98% of grip that is theoretically available, or you will lose traction and end up spinning one wheel. Not really a major difference and surely nothing to worry about in real life (unless you're racing).
When both wheels are driving the car then 100% of the grip is being utilised. Only when a wheel(s) is spinning does this reduce. Grip is down to the tyres and road surface, not the LSD. When it comes to torque distribution, again as long as both wheels are not spining, 100% of the available torque is being utilised.
Diffs vary where torque goes all the time, an ATB certainly. Other than welding a diff up or fitting a plate LSD, you'll never get a true 50/50 split. But then that's not always desireable as the ATB (up to 5:1 or whatever) will actually make better use of the available torque out of corners than a plate diff given that it can give more than 50% of the torque to the loaded wheel.
It's all swings and roundabouts and there is no right or wrong answer.
May I join in? I think the issue now is whether or not we are getting a 50/50 torque split between both rear wheels, which ideally we should be. If we are not, as TEM is saying, then an LSD will help because it will in effect redistribute the torque to both wheels.
If there is already an equal torque split then juansolo is right because as long as there is equal traction on both tyres then the perfect start will be acheived when the tyres are on the verge of spinning and the torque is divided equally between the two.
The only exception is if there is differeing levels of traction across the rear axle, in which case the LSD will help to juggle the torque between both sides of the axle to avoid spinning it away.
Hope that lot makes sense
Quote from: "RUSTY"I think the issue now is whether or not we are getting a 50/50 torque split between both rear wheels, which ideally we should be.
Like I said above, I'm afraid I can't explain it nor provide any proof s:oops: :oops: s:oops:
Still trying to understand this stuff myself, it's pretty dman complex s:? :? s:?
But I'm sure everyone has access to a car without any kind of LSD...make the wheel(s) spin and note how it's always the right side wheel that spins (or both). You just can't make the left wheel spin alone, assuming you're going straight and have even grip for both wheels.
Just to throw a couple of ideas in:
Unequal length driveshafts - I seem to remember other cars I've owned (don't know about the '2) used different diameter shafts and made use of both hollow and solid shafts to try and match the distortion properties and weights of both shafts. I'm sure it's not ideal, but I bet they get pretty close.
Right wheel always spinning - is this going to be down to weight distribution? All things being equal, I would expect RHD cars to spin up the left wheel first due to the weight of the driver.
Quote from: "mrbarney"Right wheel always spinning - is this going to be down to weight distribution?
Well, try it on RHD cars. I'll still bet for the right wheel s8) 8) s8)
Most RWD cars have equal lenght shafts for rear wheels, the '2 is just an exception to that, so it can't be that.