01-07-2009, 10:31
| #62 (permalink) | |
| Pro-tard   Join Date: Dec 2004 Location: three feet away from a tiny little turbo
Posts: 3,648
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01-07-2009, 21:15
| #63 (permalink) | |
| spl dori master  Join Date: Apr 2008 Location: Netherlands, in Maastricht
Posts: 423
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__________________ S13: Turns ordinary men, into expert mechanics! | |
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01-07-2009, 21:19
| #64 (permalink) | |
| spl dori master Join Date: Apr 2008 Location: Netherlands, in Maastricht
Posts: 423
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__________________ S13: Turns ordinary men, into expert mechanics! | |
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01-07-2009, 23:06
| #65 (permalink) | |
| Pro-tard Join Date: Dec 2004 Location: three feet away from a tiny little turbo
Posts: 3,648
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So these cold tyres - narrow ones have less grip, wide ones have more grip or no difference? Vote please. These results will give an indication of whether the equation on the internet is right (wide tyres have no more grip except that due to better heat management) or whether everyone's knee jerk reaction is right. Yes, tyres will warm up, but not immediately, thermal inertia and shit. Or warm the tyres to the same working temperature, then try it. Eliminating the wider tyres better heat management is the key to really getting down to the bottom of the issue, which is that it's entirely counter-intuitive. Let's either validate this theory with practical data or find a new theory. Then we can all join together and write it out in short words for the world to understand and marvel at our scientific methods. In summary - someone send me a pair of 165/70R14 and a pair of 195/60R14 in the same compound, we'll find a nice grippy bit of road, disconnect my turbo and with the tyres cold see if my MX5 can spin up the fat ones in second when pulling away. I'll send the remains of my clutch to the tyre supplier, signed, and a box of chocolates, promise. Last edited by Captain Muppet; 01-07-2009 at 23:20. Reason: a spelling. i'm leaving the rest of the mistakes in | |
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01-07-2009, 23:15
| #66 (permalink) |
| Pro-tard Join Date: Dec 2004 Location: three feet away from a tiny little turbo
Posts: 3,648
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Or we could all agree it's a massively complex subject, and that none of us is really up to ever definitively sorting it out in a rigorous and trustworthy way, and that all the googling in the world just leads to other people who googled stuff, and that the first stage of any study in physics is laughing at the rediculous simplifications made to make the last bit easier to understand, then bugger off down the pub. Pub anyone? No one ever changed anyone's mind on the internet* and I need a beer. *except that time on the CTF forum where I totally made that guy admit squeezy ketchup isn't a shit idea |
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01-07-2009, 23:21
| #67 (permalink) | |
| Do Want  Join Date: Jun 2007 Location: Mid-Wales
Posts: 910
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Leaves people like me, who are trying to learn... up shit creek. I've heard that ET does and doesn't change camber and that it does and doesn't change the scrub radius, and i've been told that adjusting camber does and doesn't change the scrub radius. Basically i'm still as clueless as I was before, I think i'll just do it and see what actually fuckin' happens 
__________________ -96 Impreza WRX Type Ra for the Touge -- Something Ratty and Drifty coming 09 | |
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01-07-2009, 23:51
| #69 (permalink) | |
| =The Guv'nor=  Join Date: Jul 2004 Location: Fresh from Intensive Care Yo !!
Posts: 5,587
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Bollocks !! You spend half an hour typing and tinterweb feckin eats it !!!! I'll do it again tomorrow !! LOL where the threads going at the mo btw !! 
__________________ The future is bright.....................the future is ..........already here !!!! "Bon bon was also famous for another quality, who by the grace of countless activity, could carry unfathomable quantities in the regions(?) of his rectum. Even when given a thorough ass check." Quote:
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02-07-2009, 00:18
| #70 (permalink) | |
| =The Guv'nor= Join Date: Jul 2004 Location: Fresh from Intensive Care Yo !!
Posts: 5,587
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In fairness to Keefe, and his original question, If you imagine that you were looking straight down at the ground where your front wheel was and you turned the wheel left or right with the steering, this would tell you where your turning point is and would therefore tell you your scrub radius. If the wheel literally stayed still and simply angled left or right then you have zero scrub radius, if the tyre is effectively towards the centre of the vehicle then this is negative scrub and as you turned right and the wheel pointed to the right you would also notice the wheel effectively moving backwards to the left (a bit like describing a letter J on the road) and describing a small arc. If you had the opposite effect and the wheel rolled forwards and went to the right (a bit like a letter r on the road) then you have positive scrub radius. Now I hope I havent confused you too much with my poor descriptions, but bear with me for why this is all important !! If you imagined that you actually had hold of the bottom ball joint as this action of steering happened you would quickly realise that a lower value (ie closer to zero) of scrub means that there is less leverage in the system. To picture this, imagine you had some mental bozo wheels sticking out a foot from the edge of your car and you had no bodywork to worry about hitting, it would take alot more effort to turn the wheel through this larger arc than it would if your whel was closer to zero and only had to be moved a smaller distance. This also means that when driving along, any imperfections causing the wheel on one side of the car to "react" have leverage on their side and this effectively makes the steering far more twitchy as the increased grip on one side or the other tries to make the wheel go backwards and therefore steer the car !! Ironically the only downside to having absolutely zero scrub radius is that at parking speeds you have to overcome the grip of the tyre as it doesnt roll in any direction when turning !! Camber has the same effect unless you have adjustable length arms and can bring this turning point back to the original location when accounting for the fact the lower half of the wheel is effectively sticking out further than before (for negative camber application). Again this is a reason for slightly twitchy steering. This is also why positive toe affects steering in a similar way and negative toe "helps the driver" turn in during the first phase of cornering. Sorry if this is all double dutch - its pretty late and Im still feeling the effects of Brands !! J.
__________________ The future is bright.....................the future is ..........already here !!!! "Bon bon was also famous for another quality, who by the grace of countless activity, could carry unfathomable quantities in the regions(?) of his rectum. Even when given a thorough ass check." Quote:
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