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Discussion Starter · #1 ·
I've searched the threads and have only managed to confuse myself regarding STC. My simple question is that if on a day when the pavement is dry, and the onramp is straight can I maximize my acceleration onto the interstate by turning off STC? Would a curving onramp, in good conditions, slow my onramp speed down if STC was engaged. I'm sure the answer is out there in one of the several threads, but like I said I confused by some of the old threads regarding plain old STC. <p>I also have a teenager who is just getting her license. Will STC assist this newbie driver in rain, ice and snow. I'm coming off of an AWD/4WD Mistubishis Montereo and I'm hoping the Volvo S40Ti won't disappoint this winter. Should have popped for a Volvo AWD I guess.<p>Thanks for listening <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0">
 

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Re: New Volvo S40Ti FWD Driver- Simple STC Question (Jazz2)

The simple answer is don't bother turning off STC in the straights, but turning off in the turns will help (of course making it a bit more dangerous <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">). Also, definitely leave it on for your daughter.<p>You have to remember exactly what STC does - that is, it cuts power to the wheels when there is slippage. If you are accelerating in a straight line and there is tire slippage, it will temporarily cut power until traction (static friction) is regained. If you turned off STC in the same scenario, then your tires would spin, giving you minimal traction (kinetic friction). There is a fine line between when you want kinetic friction and static friction, and STC makes sure you only get static friction, which is much safer (which is why Antilock-Brakes exist).<p>Only when accerating <I>hard</I> from a stand-still is it favorable to turn off STC, but on an on-ramp I can't image there being tire-slippage in the first place, so there is no benifit from turning it off. In the corners, it helps turning it off because STC will just make you coast through the turn. Turning it off allows you to accelarate through a bit harder, even though there is some slipping going on.<p>Hopefully I have somewhat explained it clearly, haha <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">. <p>Take care
 

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Re: New Volvo S40Ti FWD Driver- Simple STC Question (Jazz2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Jazz2</b> »</i></TD></TR><TR><TD CLASS="quote">I've searched the threads and have only managed to confuse myself regarding STC. My simple question is that if on a day when the pavement is dry, and the onramp is straight can I maximize my acceleration onto the interstate by turning off STC? Would a curving onramp, in good conditions, slow my onramp speed down if STC was engaged. I'm sure the answer is out there in one of the several threads, but like I said I confused by some of the old threads regarding plain old STC. <p>I also have a teenager who is just getting her license. Will STC assist this newbie driver in rain, ice and snow. I'm coming off of an AWD/4WD Mistubishis Montereo and I'm hoping the Volvo S40Ti won't disappoint this winter. Should have popped for a Volvo AWD I guess.<p>Thanks for listening <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"> </TD></TR></TABLE><p>STC consists of two components, Tractional Control (TC) and Spin Control (SC). <p>TC (which cannot be switched off at all) transfers power from a slipping wheel to a wheel that has grip.<p>SC (which can be switched off using the switch) tries to reduce wheelspin by reducing torque to the driven wheels.<p>SC can be a little heavy handed in reducing the torque and a little slow in allowing it to advance once the wheelspin has ended so a skilled driver can get a quicker launch by turning SC off and using his skill to minimize wheelspin while keeping the engine in its sweetspot to get the quickest acceleration.<p>I don't think a freeway on-ramp is one of those occasions when you're better off without it.<p>UKMatt
 

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Discussion Starter · #4 ·
Re: New Volvo S40Ti FWD Driver- Simple STC Question (agc525)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>agc525</b> »</i></TD></TR><TR><TD CLASS="quote">The simple answer is don't bother turning off STC in the straights, but turning off in the turns will help (of course making it a bit more dangerous <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">). Also, definitely leave it on for your daughter.<p>You have to remember exactly what STC does - that is, it cuts power to the wheels when there is slippage. If you are accelerating in a straight line and there is tire slippage, it will temporarily cut power until traction (static friction) is regained. If you turned off STC in the same scenario, then your tires would spin, giving you minimal traction (kinetic friction). There is a fine line between when you want kinetic friction and static friction, and STC makes sure you only get static friction, which is much safer.<p>Only when accerating <I>hard</I> from a stand-still is it favorable to turn off STC, but on an on-ramp I can't image there being tire-slippage in the first place, so there is no benifit from turning it off. Hopefully I have somewhat explained it clearly, haha <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">.<p>Take care</TD></TR></TABLE><p>Thanks for the help. I guess maybe I ought to not worry about STC and perfect the manual override shifting on my automatic transmission to wring out some acceleration from the Ti onto the interestate. We've got some pretty short onramps where I live and some folk that will not give merging drivers a break. You turbo Volvo drivers probably don't have onramp acceleration problems <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">
 

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Re: New Volvo S40Ti FWD Driver- Simple STC Question (agc525)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>agc525</b> »</i></TD></TR><TR><TD CLASS="quote">what STC does - that is, it cuts power to the wheels when there is slippage. If you are accelerating in a straight line and there is tire slippage, it will temporarily cut power until traction (static friction) is regained. </TD></TR></TABLE><p>Actually, if one wheel slips, it taps the brake on that side. If both wheels slip, it cuts power.<p>The only time you need to turn off STC (or DSTC, which doesn't really go "off" in this model) is when you're stuck in snow or mud and need to spin or rock the car to get out, or if you decide to enter a drifting contest and want to do silly things. Yeah, you could probably achieve a better takeoff with STC turned off, but you'd need to know what you're doing. And if you were that into it, you'd have replaced the stock tires anyway and wouldn't need to.<p>Bottom line, leave it on and don't worry about it. MHO.<p>Tom.
 

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Discussion Starter · #7 ·
Re: New Volvo S40Ti FWD Driver- Simple STC Question (tmtalpey)

Thanks, this makes sense. I think I got a taste of STC the other day when heavy rains caused some relatively large pools of water. Not dangerously deep. However, when I hit several at about 35 mph I was surprised at the sense that they were slowing the car down slightly, sort of losing a little thrust so to speak. I thought maybe the car was acting like it was light in the front end. This didn't make sense considering this is FWD. I also thought I might have heard ABS like sounds. Maybe these sensations were STC doing its thing? I hope this is the case.<p>The stock tires probably need to be replaced. I've never really liked the feel of All Weather Tires. I do plan to buy winter tires anyway, and once winter is over I'll go in search of better performing tires.<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote"><p>Actually, if one wheel slips, it taps the brake on that side. If both wheels slip, it cuts power.<p>The only time you need to turn off STC (or DSTC, which doesn't really go "off" in this model) is when you're stuck in snow or mud and need to spin or rock the car to get out, or if you decide to enter a drifting contest and want to do silly things. Yeah, you could probably achieve a better takeoff with STC turned off, but you'd need to know what you're doing. And if you were that into it, you'd have replaced the stock tires anyway and wouldn't need to.<p>Bottom line, leave it on and don't worry about it. MHO.<p>Tom.</TD></TR></TABLE><BR><BR>
<i>Modified by Jazz2 at 10:47 AM 5-24-2006</i>
 

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Re: New Volvo S40Ti FWD Driver- Simple STC Question (Jazz2)

Yes, "lightness" due to feathering of the engine output, and ABS sounds are both definitely STC kicking in. If you glance at the instrument, you'll see an orange triangle on the left which blinks when this happens.<p>Occasionally, I get STC when going over speed bumps. I tend to ignore all but the sharpest bumps/humps and just drive at 'em, and occasionally as the front wheels rise up on the bump, the STC system thinks they've started to spin and cuts torque. It's not really annoying because I'm slowing anyway, but sometimes I click off STC just to avoid it. I like that the car is responding, in any case.<p>I recommend Michelin Pilot Sport All Seasons. Expensive, but well worth it.<p>Tom.
 
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