"yitznewton" (yitznewton)
10/25/2015 at 11:57 • Filed to: handling, code brown
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"yitznewton" (yitznewton)
10/25/2015 at 11:57 • Filed to: handling, code brown | 1
| 17 |
Yes they can.
I’ve been experimenting with tire pressures in an attempt to change the handling balance of my Jetta. Well, it worked.
Usually coming into this corner, I get understeer on entry, even in the wet. I come in medium hard, and saw my way through using the throttle.
Today in recently-rained wet conditions, I was running 41 psi front, 32 rear, and came in less hard than usual. I noticed on the previous corner that the rear was losing grip more than usual, and felt like the razor’s edge. Say hello to my VW 911!
Thank God I didn’t hit anything. I was happy to have that experience, but I wish it had been on a course and not the road! I really wish I had telemetry on the cam so I could see exactly what inputs yielded this result.
Needless to say I was terrified the rest of my drive, and I’ll be running a more conservative pressure differential next time it rains. And further in the video, apparently someone else was not as lucky.
Opposite Locksmith
> yitznewton
10/25/2015 at 12:03 |
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I'd say that you should leave such level of experimentation for the track, but yeah that's fun as hell. I can tell you let the wheel do what it wanted once it let go, good move. Woulda snapped back
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yitznewton
> Opposite Locksmith
10/25/2015 at 12:15 |
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Agreed, I will definitely dial it back on the street. I never expected that much of a change.
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yitznewton
> yitznewton
10/25/2015 at 12:17 |
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Studying the video, it looks like the rear was on the edge of losing grip, and then I went over a bump which caused it to let go.
SlickMcRick
> yitznewton
10/25/2015 at 12:20 |
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Same happened to me about a week or two ago. My car was in a shop so I borrowed an 03 Corolla from the dealer. Road was damp from a rain that happened more than an hour prior. Back end slipped from behind me and I held on tight for the ride. Car spun 6× merely inches from the concrete barrier. Code Brown was almost in effect. I was doing under speed limit when it happened. Now I see those tire marks everyday on my drive home as a reminder that I hate Corollas and understeer.
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Opposite Locksmith
> yitznewton
10/25/2015 at 12:20 |
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When it's slick out I have a hard time not over inflating the rears of my WRX for the easiest longest most hilarious power slides. Looks like you were on the edge of the rears grip then the road imperfection came...
Rico
> yitznewton
10/25/2015 at 12:21 |
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Whoa be careful there, glad you were okay. What tires are you running? Also why does the door card on the door jamb say the pressures should be at?
Be careful when messing with the PSI besides handling it’ll affect the tire wear and gas mileage.
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yitznewton
> Rico
10/25/2015 at 12:34 |
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Yoko Advan Sport A/S all-seasons
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Rico
> yitznewton
10/25/2015 at 12:53 |
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I noticed my last post said why I actually meant what so I feel like it changed the tone of my post.
My car wants 32/36 but there’s under steer at those levels. I instead put my fronts at 34-36 and the rears at 40. Offers me way better handling, I can take this turn at 60-70 mph as long as no one is in front of me while my passengers scream for dear life:
sm70- why not Duesenberg?
> yitznewton
10/25/2015 at 13:09 |
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Oops
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yitznewton
> Rico
10/25/2015 at 13:59 |
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Wow, I just took a look at that ramp - what are you driving?
Turns out my recommended is 30 front, 28 rear. My Euro mechanic always sets at 40 all around, so I’m working from there. 40/32 worked really well for me in the dry.
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Rico
> yitznewton
10/25/2015 at 16:20 |
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Lol it’s like a slingshot, I drive a 2014 C300. I think the 4Matic combined with grippy tires is what helps the most.
Maybe try lowering the front just a bit? I’m surprised with the type of tires you have you would've spun out that way. Could have also been oil mixed with the damp road and not the car.
Luken10
> yitznewton
10/26/2015 at 03:01 |
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Wouldn’t that PSI set up cause understeer, if anything? I would think the normalish PSI for the rear tires wouldn’t make it prone to snapping like that.
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yitznewton
> Luken10
10/26/2015 at 08:07 |
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The idea of moving from understeer toward oversteer (which was my goal) is to increase grip in the front, or reduce grip in the rear, which can either be through under-inflating, or over-inflating. Or stiffening the rear with e.g. a sway bar. I got good results with under-inflating, just took it a little too far, at least for those conditions. With that much of a differential the balance shot way up to oversteer.
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yitznewton
> yitznewton
10/26/2015 at 08:07 |
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I got the theory from an old issue of Grassroots Motorsports, and it seems to work, though I never tried the overinflating route.
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Luken10
> yitznewton
10/26/2015 at 17:43 |
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Interesting! I’m sure every car/tire setup is different. I figured 41 psi in the front would actually make you lose grip. Good job on not hitting the curb when te unexpected did happen!
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yitznewton
> Luken10
10/26/2015 at 18:17 |
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I assure you it was out of my hands by then :(
Wrong Wheel Drive (41%)
> yitznewton
10/28/2015 at 15:32 |
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Recently rained conditions are guaranteed oversteer for me but my tires are crap. It is kind of fun to put a little oppo in around wet corners but certainly scary. Im in a Miata though so the weight balance really helps things not go completely around.