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checking tire pressure
#21

[quote name='flash' date='Sep 7 2005, 07:46 PM']wow - if i let my tires go a pound out the car gets all weird

[right][post="9615"]<{POST_SNAPBACK}>[/post][/right][/quote]



I missed this on the first read.. either you have the most calibrated ass ( butt-o-meter) in town, or your modified alignment / suspension work causes this hyper-sensitivity to tire inflation, or some other cosmic explanation - in terms of ride and handling I need a delta of at least 3 lbs to tell ANY difference, and even that's slight. That being said, I am an "insensitive" driver <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" /> - as these things go, I cannot even sense any change in handling / cornering with the KLA strut bar vs. without it.
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#22

yes, butt-o-meter is highly calibrated



remember, i have a 3 mile canyon i have to go through just to get to a main thoroughfare, so i get to click through and use it as a test track



yes, modifications have made it much touchier



but, it sounds like you aren't pushing the car enough in the corners



i can't feel the difference putting around town or on the freeway - in the twisties though, it becomes very evident very quickly



even when the suspension a tires were stock spec, a 1lb change made a difference, but again, only when you pushed it - it was change in where the car felt solid and where it pushed and which end
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#23

[quote name='flash' date='Sep 10 2005, 09:30 AM']but, it sounds like you aren't pushing the car enough in the corners

[right][post="9727"]<{POST_SNAPBACK}>[/post][/right][/quote]



that's entirely possible.
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#24

lol - well, maybe we'll just have to get you out on the track so you can see what these cars can really do - sure, it's fun to wind it up to 150, but the corners is really where it comes alove - sounds like fun anyway
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#25

the track would probably be the only place I'd feel comfortable testing just how hard the car can corner - I take some pretty fast turns on twisty roads here, but few are without a 300 ft ravine drop on one side, and a telephone or light pole on the other.. <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" /> .. so caution ( and perhaps too much if it ) takes over ..



lol, you know me well... 150mph just getting out of the driveway <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />

given the choice, as great as this car is in turns I'm still a straight run, top end speed freak: love that feeling at 160 ( had it there about 4 times now..). I wish

there was a road ( the only track long enough to do this before you come to a turn is called Nevada I think.. <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> ) where I can test if the speed is sustained for a few minutes just how many more mph can be squeezed out of this baby.. another 5.. may be ? I don't suppose the mods gave it it enough "umph" for 170, is there ?

Like I said before - will gladly give up one second from 0-60 for every 10 mph gain at the top end...sigh, if only there was a mod to give me that... <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" />





ok, now I'm waaay O.T. on the tire pressure thread - sorry.
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#26

My buttometer may not be as sensitive as my hands. The first thing I notice on underinflated tires is turn-in understeer and a sharp rebound jerk to the inside as the tires get back off their edge when they regain their bite, it's very uncomfortable and happens at -2 psi on my Michelins.

On the other end it oversteers way too easy and gets harsh on small bumps at +1 psi.

I find entrance/exit ramps the best playground. No pedestrians, entering or parked cars, John Law. All that said, I've only had motortcycles on a track. IMHO the difference between what you can do on a track and even the craziest street driving is night and day. The track is the only place possible to explore the limits of a fine handling car.
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#27

ok - so after all this talk of tire pressures, i apparantly still wasn't paying attention



i went to the german autofest in ventura over the weekend - nice drive up on PCH - nothing fast - just a nice cruise - thought she felt a bit odd, but i chalked it up to being 6:30 in the morning and not much sleep



on the way back, i got a little happy for a minute and gave it a goose through a corner - got loose - hmmm - odd - down the road a bit more and went through a 45 degree left hand off camber bend that dumped into a similar on camber right hand bend - ooh - opportunity - gave it a little gas from 5k in 3rd - whoa! feels loose! what the heck?



twitched it a couple of times after that - nothing really going on - felt a little weird, but nothing too dramatic - got home and lifted her up - nothing going on - checked the tire pressure



3lbs low across the board since the denver run! that's only 3 weeks



seems the local expert was right - these 30 and 35 series tires lose pressure a lot faster than the taller ones - makes sense when you think about it - the volume loss ratio is probably the same, but given the lower volume of the tire, it results in lower pressure sooner



take note - check your pressures often if you go to lower profile tires
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#28

once a month .... but checked last night and they were down to 30 psi cold all round!



So took the car out to the local station, and pumped the tires to 36 all round. Checked with my trusty dial gauge.



Immediate difference - much smoother ride! A little harsher over road strips, but at least it did not feel like out of round tires when cold anymore! Took the car out on the hwy too and a very noticeable improvement in steering response, etc.



Tires are near new Yoko ES100 225/45/17 and 255/40/17 on boxster twists.
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