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psychoazn | Posted: Oct 24 2013, 08:31 PM | ||
IDW Special Member Group: Members Posts: 295 Member No.: 1,617 Joined: Apr 11th 2004 Location: Update Profile |
I do suspension tuning professionally | ||
Banken | Posted: Oct 25 2013, 01:24 AM |
IDW Goldmember Group: Advanced Members Posts: 1,110 Member No.: 22,465 Joined: Dec 17th 2006 Location: Japan | psychoazn, If you don't have wheelspin/traction problems you aren't driving fast enough, or already have an LSD. Damper settings are extremely important, but he was talking about the 1-way click adjustable settings on off-the-shelf coilovers, not talking about revalving bump/rebound settings. The range of adjustments on off-the-shell street shocks is so small that it will never make any difference except for slight changes to response, stability, and comfort. To make any real setting changes you have to revalve the shocks. Yes, I understand you have to change damper settings for spring rate, but I was trying to keep the discussion as simple as possible. Spring rate (and bars, to an extent) are more overall is more important than shocks, assuming your shocks are sufficient enough to dampen the springs and for stability/transition purposes. The front/rear balance of roll rate is what determine handling balance more than shocks. Anyone who thinks fiddling with the knobs on (Tein, no less) one-way adjustable shock will make any significant difference is an amateur. Generally speaking there is a fairly strong correlation between lock-to-lock turns and steering ratio. Unless you're talking about two different kinds of cars. We're talking about typical passenger cars. As long as the total steering angles are about the same, there is a strong correlation. The Evo 8 I drove had very quick steering, with it's 2.5 turns. My MR2 has 3.2 turns, even with power steering (manual is worse: 3.5), so in street driving I have to do a lot of passing of the wheel, and occasionally turn the wheel a lot during track driving. Formula cars can have more than one turn lock to lock, they simply never have to use more than half a turn on a full circuit. On a small circuit or a skid pad, or simply while moving the car around, you can end up using a lot more steering angle. The formula car I drove had at least full turn of the wheel. Karts on the other hand only have half a turn because they don't have steering racks, they have a direct linkage. Of course, a kart usually only needs a few degrees of steering because of that, unless you're countersteering for a spin. If you are doing near 1.0 G in a corner, you will not be able to achieve a full range of steering (compared to sitting still) by using the crossed arms technique, at least not with a stock seat and seatbelt. It simply isn't going to happen. That technique only works in low-speed corners with low cornering force, which is why I suggested switching hand position before the corner. If you are in a racing car with a custom molded seat and six-point belts, sure, the technique can work. But for crash safety reasons I wouldn't suggest it, nor would you need it (because racecar). If you have a ton of grip on a car, you can use more steering angle in a given corner. It's common sense. The more steering angle you use, the more cornering forces. It's the same reason why a bike with better tires can lean more. You might not go any faster in a given corner, but you can still use more angle than you could with a car that doesn't have enough grip. Part of this simply comes from bushing compliance. The outside tire wants to turn away from the direction you're steering. Part of it is tire compliance. On a race car with solid suspension joints and slick tires that use tiny slip angles, the matter is different of course. And of course, the less angle you use the faster you go. Kiroshino, Steering techniques (and heel and toe, and shifting) can be practiced all day every day during normal driving. You can also try jacking up the front of your car slightly and practice going from lock to lock, but you'll probably get bored with that really fast. I used to think about the same stuff you are now, but then I realized it's just a matter of muscle memory and seat time. The hardest part about track driving is keeping yourself in your seat, which is why a seat upgrade, harness belts, and steering wheel mods (distance to driver) are important. |
psychoazn | Posted: Oct 25 2013, 07:34 AM |
IDW Special Member Group: Members Posts: 295 Member No.: 1,617 Joined: Apr 11th 2004 Location: Update Profile | I'm aware of more than a few 1-way adjustable dampers that have significant changes per click. If you're talking about $1000 OTS junk, then yes, the adjustments don't do much individually. Revalving would cost more than the shock MSRPs brand new. The BRZ video I posted is with a stock steering wheel, stock seat belt, and stock seat. It's doing about 1.5G sustained in corners. Peak steering angle is nearly 270 degrees, per SAS. You can see it in turn 5. More grip = faster cornering, not more cornering. Small, but important distiction. Optimum slip angle is highly tire dependent. I'm curious what/where you drive, since you clearly have done a lot of reading. |
Spaz | Posted: Oct 25 2013, 01:58 PM | ||
Just a guy towing a car across the country to chase a dream. Group: FORUM MODERATOR Posts: 9,272 Member No.: 30,193 Joined: Jul 25th 2008 Location: Plymouth, MN |
Duly noted. I'll throw you on that list, as I don't have a pro suspension guy on there yet. You're in the company of a certified racing instructor and a pro driver, both of whom are heavily invested in Evos. It shouldn't take much digging to figure out who the driver is, either. | ||
psychoazn | Posted: Oct 25 2013, 02:11 PM | ||
IDW Special Member Group: Members Posts: 295 Member No.: 1,617 Joined: Apr 11th 2004 Location: Update Profile |
I think I have an idea... Have you considered coming out to SLB? | ||
Banken | Posted: Oct 25 2013, 06:30 PM | ||
IDW Goldmember Group: Advanced Members Posts: 1,110 Member No.: 22,465 Joined: Dec 17th 2006 Location: Japan |
Most coilovers in the $1000 range can't be rebuilt or revalved. But you're thinking about it the wrong way. If you already have a set of cheap* Tein coilovers (which can be rebuilt/revalved like all Teins), you can them have them refreshed and set to whatever damping you want (and of course, rebuilt) for $1000-$1500 (depending on the condition they're in). To get order-made coilovers would usually cost you $2500-3000. So you've now got fresh shocks with the damping levels you want for $1000-2000 less than it would have otherwise cost. Add $200 or so for new springs. That said, a non-adjustable damper that has been set the proper settings for the spring rate that the car needs will always be better than adjustable off-the-shelf coilovers, especially those designed for the street. Which is why I suggest that spring rates and spring rate balance are more important. As is alignment, and to a lesser extent, anti-roll bars. Shock adjustments get you tenths, roll rates and balance get you seconds. As do LSDs. 1.5G sustained with street tires with bolt-on aero parts and no significant weight reduction? I find that claim...dubious. No offense. Peak, sure. If you had DOT race tires, sure. Or if you were in a very highly banked corner. But maybe those JRZ coilovers work on magic. Hehe. As far as I can see you aren't crossing your arms to any significant extent, and you're only countersteering to just past 90 degrees right of center, which can easily be done with both at 9 and 3. I was talking more about steering closer to 180 degrees from center by crossing arms, which I don't believe is possible while cornering at any significant speed (because your torso will shift away the direction you're trying to steer). On a car like the 86/BRZ with it's relatively fast steering, you'd be fine leaving your hands at 9 and 3 on pretty much every corner of a circuit. I will concede that in most cases, more grip will allow you to go faster rather than simply corner more, but that more grip will allow you to use more steering in corners where you are not going as fast as you could. For the same reason why most motorcycle riders will never go anywhere near their bank ankle limit (on purpose, at least). I drive and race (wheel to wheel) on circuits all over northeast Japan. I have an MR2 turbo. *Tein doesn't actually any $1000 coilovers (excluding the Street Basis which I don't count since they don't use straight-wound springs and it reuses stock top mounts). Also the price is irrelevant if you already have them. | ||
psychoazn | Posted: Oct 25 2013, 07:39 PM | ||
IDW Special Member Group: Members Posts: 295 Member No.: 1,617 Joined: Apr 11th 2004 Location: Update Profile |
I've yet to drive any cars that gain seconds with a clutch type LSD over a gear type; any LSD is seconds over an open diff if you have the power to spin the inside tire. The track surfaces in Japan are vastly different to the surfaces here... My s2k will hold 1.5G on a skidpad; 255 RS3. Fresh of course. In the video, the car is only holding about 1.35. Theyre day 6 ZII (roughly the 40th deep heat cycle or so), and the lack of grip is pretty evident. I"m... very familiar with Tein. I've developed specs for SRD/SRC/N1, and they hold a few records in the states Also, select data from the lap. The accelerometer isn't calibrated, since only the relative reading matters. Also, the track surface really IS that bumpy. Image size reduced, original size: 1920 x 1080. Click here to view the image in its original dimension. | ||
Banken | Posted: Oct 25 2013, 08:01 PM |
IDW Goldmember Group: Advanced Members Posts: 1,110 Member No.: 22,465 Joined: Dec 17th 2006 Location: Japan | I was comparing to an open diff. A helical LSD is fine. But viscous is just vicious. I'm not sure what I'm suppose to be looking here, but you can't do 1.5 g sustained on street tires on a skidpad, no matter what you're driving. The tires simply don't have enough friction coefficient for it. Even a formula car or race kart will only do a little over 1.3 or so, and that's with slicks. 1.05 is a more realistic number, and even that's really high. |
Spaz | Posted: Oct 26 2013, 06:32 AM | ||
Just a guy towing a car across the country to chase a dream. Group: FORUM MODERATOR Posts: 9,272 Member No.: 30,193 Joined: Jul 25th 2008 Location: Plymouth, MN |
I had, but with needing to acquire and prep another car I don't think the money will be there. | ||
Vortrex | Posted: Oct 26 2013, 12:45 PM | ||
1988 Toyota MR2 AW11, My Go-Kart AE86 Group: Advanced Members Posts: 559 Member No.: 38,745 Joined: Jul 2nd 2012 Location: Huizen, The Netherlands |
3.25? God, i am looking forward to daily a AW11! It's fun to get pain in the muscles every day! | ||
Cyinide | Posted: Oct 26 2013, 03:37 PM |
Request Title - PM Mods Group: Members Posts: 381 Member No.: 39,054 Joined: Oct 7th 2012 Location: Modesto, CA | I've always wondered this, but is there EVER a time where drifting is the fastest, or just as fast as grip, way to get around a corner? Is there any particular situation where drifting is the most ideal way to do something when driving? |
Vile | Posted: Oct 26 2013, 07:28 PM |
IDW's Furfag Group: Members Posts: 393 Member No.: 30,586 Joined: Sep 7th 2008 Location: Update Profile | I also would like to add Cyinide's question, when is drifting really the ideal way to getting around a corner? Also Is threshold braking and then trail braking to get the car's momentum to turn more considered drifting? [ Post made via Mobile Device ] |
Banken | Posted: Oct 26 2013, 08:50 PM | ||
IDW Goldmember Group: Advanced Members Posts: 1,110 Member No.: 22,465 Joined: Dec 17th 2006 Location: Japan |
To answer y'alls question, A tight corner with a car that doesn't like to rotate. A tight corner on a low-friction surface (rally). Here's a little ditty from Mr. Tsuchiya... http://www.youtube.com/watch?v=xZw4xaWbJiw | ||
Cyinide | Posted: Oct 26 2013, 08:58 PM | ||
Request Title - PM Mods Group: Members Posts: 381 Member No.: 39,054 Joined: Oct 7th 2012 Location: Modesto, CA |
I have no idea what is being said in that video, but so far it is interesting to watch. | ||
Banken | Posted: Oct 26 2013, 09:59 PM |
IDW Goldmember Group: Advanced Members Posts: 1,110 Member No.: 22,465 Joined: Dec 17th 2006 Location: Japan | the FD was just barely slower when drifted and the R32 was just slightly faster if memory serves. [ Post made via Mobile Device ] |
psychoazn | Posted: Oct 28 2013, 07:11 AM | ||||||
IDW Special Member Group: Members Posts: 295 Member No.: 1,617 Joined: Apr 11th 2004 Location: Update Profile |
The G forces are on a relative scale; the purple line is lateral G, and shows a sustained 1.3+ G. Formula cars can corner at 3.5+G, and Karts on sticker slicks easily do 1.8+G Stock high performance street cars do over 1.05 (think Viper, Corvette, etc.)
Yes, as previously answered, in a car that absolutely will not rotate, it CAN be faster. However, fixing the lack of rotation will yield FAR better results. Drifting will cook your rear tires, and ultimately result in slower corners elsewhere, unless its a very short run. Also, with the advent of dataloggers, even rally drivers have reduced their slip angles substantially. It's proven to be FAR faster. Sliding/drifting will be slower 100% of the time in a car that is prepared, and slower 99% of the time in street cars (and result in more wear for less time). This post has been edited by psychoazn on Oct 28 2013, 07:14 AM | ||||||
Lonely_Driver | Posted: Oct 28 2013, 09:02 AM |
IDW Supremo Member Group: Advanced Members Posts: 870 Member No.: 38,019 Joined: Oct 24th 2011 Location: Update Profile | What are your thoughts on tire scrub radius and steering angle inclination? Based on those 2 things is what made my decision to use factory upgraded bilstein shocks and SpecB rims even though they only allow me to run a 215 wide tire. Edit: Should clarify that "SpecB" is what STi is too the impreza line, although I can get STi parts that are made for the Legacy, I just beleive that the engineers at Subaru have put more thought and testing into there parts then other cheaper aftermarket parts companies have. This post has been edited by Lonely_Driver on Oct 28 2013, 09:04 AM |
TranceKitsune | Posted: Oct 28 2013, 12:33 PM |
IDW God Member Group: Members Posts: 176 Member No.: 42,103 Joined: Sep 24th 2013 Location: Bakersfield, CA | I hope my question is relevant to the subject topic. I want to ask what can happen if an engine that was freshly and fully rebuilt is being driven with pulls from 4000-6000 RPM's straight out the box. I was told that the engine needs to be broken in for quite a while with sooner than usual oil changes and that I should be shifting it at about 3000 RPM's to be safe and help break the engine in the right way.. Yet my mechanic seems to be driving the living hell out of it and says it's still not ready since we have been having idling issues. He's the one who originally gave me the advice on earlier than usual oil changes and the 3000 RPM limit so I'm scratching my head wondering what the hell is going on. The idling issues have yet to be fixed and I know even when they are "fixed" it's just going to be driven the same way again for "testing". Boost is being planned to be upped already before I even get the car back and I'm really worried about the internals being compromised by increased boost and high RPM's so soon after the first start-up. I haven't driven the car since it's been put back together, it is two hours away from where I live. Please give me your insight on what I should look out for and what I should be worried about. I don't want to receive a broken/crippled engine that I paid a lot of money to have rebuilt. This post has been edited by TranceKitsune on Oct 28 2013, 12:34 PM |
psychoazn | Posted: Oct 28 2013, 03:39 PM | ||||
IDW Special Member Group: Members Posts: 295 Member No.: 1,617 Joined: Apr 11th 2004 Location: Update Profile |
Break-in is a highly debated topic. I've done hard and soft break-ins, and have seen no real difference. With modern factory engines, the tolerances are so tight that it often takes 15k miles to finish breakin in per used oil analysis. When it comes to aftermarket built/rebuilt engines, it's HIGHLY dependent on your engine builder; I would go with their recommendation, since you already chose them by your experience with them and/or reviews/recommendations.
Scrub radius isn't a real concern that I've had to worry about, so my knowledge on that is minimal. At my level of motorsport, either maximizing tire, or balancing tire vs power has always far outweighed geometry (as far as scrub radius is concerned), so I haven't really studied that. Sorry, I'm unable to really answer your question. OE parts are generally not made for maximum performance. I own a S2000 CR, which is "factory tuned", but I can easily upgrade the suspension. In fact, I've developed a suspension that FAR outperforms the CR suspension, albeit, with a harsher ride. OEM and their in-house tuning depts design parts keeping in mind that the vast majority of their markets will not track. Examples: AMG ///M STI TRD Car examples: GT3RS ZR1 430 Scuderia Your parts will be extremely durable and have a long life, but is still a compromise between comfort and performance. They're designed to be noticeably stiffer and "sportier", but determinig what balance of comfort and performance is best for you is... best determined by you. | ||||
Lonely_Driver | Posted: Oct 28 2013, 04:02 PM | ||
IDW Supremo Member Group: Advanced Members Posts: 870 Member No.: 38,019 Joined: Oct 24th 2011 Location: Update Profile |
So in what ways could you maximize a tire? | ||
kyonpalm | Posted: Oct 28 2013, 04:08 PM | ||
Professional Amateur Group: ADMINISTRATOR Posts: 10,568 Member No.: 30,882 Joined: Oct 16th 2008 Location: Laniakea |
Inflate it until just before it explodes. | ||
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MetalMan777 | Posted: Oct 28 2013, 05:27 PM | ||
Snooping as usual Group: Advanced Members Posts: 1,780 Member No.: 32,588 Joined: Apr 13th 2009 Location: what are you doing in my swamp? |
No, that's not what he means. I have no idea what he means, but it's not that. Geometry is pretty important. You can get a lot of things wrong with it and still be fast (look at all the race cars that use a live axle and still turn decent times), but I've noticed an improvement in grip from adding scrub radius. Makes steering feel heavier, but I don't care much for feel, I care about results. | ||
kyonpalm | Posted: Oct 28 2013, 05:41 PM | ||
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Image size reduced, original size: 853 x 480. Click here to view the image in its original dimension. | ||
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WillDearborn | Posted: Oct 28 2013, 05:53 PM | ||
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Image size reduced, original size: 937 x 612. Click here to view the image in its original dimension. Stock C5 (non Z06 but with FE3) Corvette on street tires and r compounds. 1.05 is what they get on a very bad day. 1.4 lateral sustained is what they can get normally. Longitudinally, 1.5 is easy. I have seen friction circles of up to, and over 2g (transitional) on Vettes. *Data is from traqmate This post has been edited by WillDearborn on Oct 28 2013, 05:55 PM | ||
psychoazn | Posted: Oct 28 2013, 06:18 PM | ||
IDW Special Member Group: Members Posts: 295 Member No.: 1,617 Joined: Apr 11th 2004 Location: Update Profile |
Fit as much tire as you can, without getting too much that straightline speed is compromised. | ||
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