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Date:         Sun, 2 Oct 2005 21:41:45 -0700
Reply-To:     Jake de Villiers <crescentbeachguitar@TELUS.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jake de Villiers <crescentbeachguitar@TELUS.NET>
Subject:      Re: On weight
Comments: To: Bob Stevens <mtbiker62@hotmail.com>
Content-Type: text/plain; charset="iso-8859-1"

You need to go down to the hairpin turn at your local track and watch an SCCA race. You'll see that the front tires not only initiate the turn, they are all but peeled off the rims all the way through the turn as they provide the lateral acceleration needed to sustain the turn. The rears are much more lightly loaded, except in very well prepared cars or formula/sports racing cars. I think that the rears are that much higher to cause understeer. They put an over-the-top 7+ degrees of caster in the front to create more directional stability, but gave it that extra-solid highway feel by creating understeer with tire pressures. Try it yourself, and you'll see what I mean. Put 50 in the front and 40 in the rear and drive some on-ramps. Put 44 psi in the front of your Accord and 38 in the rear and see how much better it corners. Better still, dial in 1/8" of toe and 1.5 degrees negative camber . I have had two vans aligned to my specs (numbers available on request) and they drive better in every way, especially in corners. Jake ----- Original Message ----- From: "Bob Stevens" <mtbiker62@hotmail.com> To: <vanagon@GERRY.VANAGON.COM>; "Jake de Villiers" <crescentbeachguitar@telus.net> Sent: Sunday, October 02, 2005 9:20 PM Subject: Re: Re: On weight

> My fronts wear faster than my rears too, Jake. The thing that's not being > taken into consideration in your assessment is the effect on the rear tires > of those lateral forces and weight of the van that start all that weight > moving toward the outside of the turn. What does that do to the rear of the > van ... and the tires back there. The fronts only start this momentum. The > rears have to stabilize it. At least that's my reasoning in this. I "think" > the higher inflation in the rear cuts down on effects of dynamic lateral > weight/oversteer forces. > > ... and, back to the question: why are the rears inflated higher than the > fronts if more stress and pressure is applied to the fronts, given that the > static weight of the van is not biased, or biased toward the front when > loaded? wassup wit dat? > bob > ----- Original Message ----- > From: "Jake de Villiers" <crescentbeachguitar@telus.net> > To: "Bob Stevens" <mtbiker62@HOTMAIL.COM>; <vanagon@GERRY.VANAGON.COM> > Sent: Sunday, October 02, 2005 10:03 PM > Subject: Re: Re: On weight > > > > I'm going to have to disagree Bob. The front wheels turn at an angle > > to > > the direction of travel, thereby stressing the front sidewalls to a far > > greater degree than the rears. The fronts are also worked a lot harder > > under > > braking, and especially when braking and turning at the same time. > > Any reasonably powered road race car will use up front tires at a much > > faster rate than rears. It is only live axle V8 sedans that run out of > > rear > > tire first. > > And obviously, on a Vanagon, the rear tires aren't being spun very > > often! :-) Jake > > ----- Original Message ----- > > From: "Bob Stevens" <mtbiker62@HOTMAIL.COM> > > To: <vanagon@GERRY.VANAGON.COM> > > Sent: Sunday, October 02, 2005 8:44 PM > > Subject: Re: On weight > > > > > > > "So why, invariably do the tire inflation specs have higher pressure to > > > the REAR on Vanagons?" > > > > > > my $0.02 > > > It's mostly dynamics because of the effects of momentum and inertia on > > > the > > > weight of the van while moving, along its length. Although the front > > > sidewalls "roll" when the van turns, because of lateral oversteer > > > characteristics inherent in that, the rear sidewalls have more lateral > > force > > > on them than the fronts. Higher air pressure stiffens the sidewall to > > better > > > deal with that force. > > > > > > bob > > > > > > > > > >


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