First Generation Firebird-L Mailing List .........................................................................
when power is applied, the drive shaft and rear want to align straight. a downward angle on the rear end would result in almost a pole-vault effect with the drive shaft lifting the front end. a upward angle on the rear end would do the opposite. adding power would rotate the housing down and pull the drive shaft 'out' (it would not come out-out) and pull the front end down... i watched an old video from aslton race cars specifically for this topic and is the same with a ladder bar set up. wherever the instant center point is after the adjustment will determine how your car will react. shorter point will result in a level or nose down reaction on launch a longer point will result it the front end rising, even a wheel stand if you hook sorry you disagree. but physics is physics so, look at this http://en.wikipedia.org/wiki/Instant_center --- On Tue, 2/3/09, Rusty Allison <[email protected]> wrote: > From: Rusty Allison <[email protected]> > Subject: Re: [FGF] Pinion Angle > To: "First Generation Firebird-L" <[email protected]> > Date: Tuesday, February 3, 2009, 9:51 PM > First Generation Firebird-L Mailing List > ......................................................................... > Tilting the rearend down for traction? Who said that. You > tilt the rearend down to make up for traction. > I came from a different school. I had learned that, > especially with leaf spring cars, there was a thing called > axle wrap when the torque that is transmitted through the > driveshaft tries to turn the tires on the ground. > If you use ladder bars or a fixed four link suspension, > there is minimal (depending on how much torque and traction > you have) rotation at the input shaft to the rear end. > If you have leaf springs with new standard rubber bushings > and run traction bars with abouth 1/2" gap to the > rubber snubber, then you stomp on it, do the traction bars > come up against the springs? Sure. Do the springs flex up > during this action, also? Sure. Because of this, you just > added, at minimum, +4 degrees of axle wrap to your input > shaft angle. The higher the torque and the better the > traction, the worse the axle wrap gets. > What does this do when you run -4 degrees on your input > yoke? It makes it zero when you are under full > acceleration. Takes the least horsepower to move the car > and does the least damage to the u-joint. > The problem is most of our driving is on the street, not > the track. There is at least a percentage of time we have > moderate acceleration, then moderate deceleration (using the > engine compression as the brake). The rest of the time is > spent in static, more or less lightly loaded position. > Now, just what angle do you position the input yoke in > relation to the transmission angle when you drive it every > day? > I say, not at zero. I will tilt my rearend down 1.5 > degrees with radials and 2 degrees with street drag tires. > This would give me a tilted up angle of only 2-2.5 degrees > or so. I spend a little time with my foot pushing down and > I don't want to get too much positive axle wrap under > load. I split the difference, so to say. > If I was going to dedicate the car to the track, with leaf > springs, 'stock style' traction bars and slicks, oh > lordy, you can bet I will be setting the down angle at close > to 5 degrees. This would be bad on the street. Most > likely, I would eliminate the flex points with lift bars or > ladder bars and use the springs to just smooth out the ride. > Then I would set the angle at zero for a 13 second car, -1 > for a mid 10 second car and reinforce the housing and be > around -1.5 degree for a upper 9 second car. > Before you zero out every car out there, understand where > the settings should be for the conditions your vehicle will > see. If you really want to run zero difference in the input > shaft to transmission for angle, then run F78 x14" > tires, drive only in the rain or have a turd for an engine > and you will be OK. > > Rusty Allison > > > > > ------------------------------------------------------------------------ > Submissions to Firebird-L: > <[email protected]> > Unsubscribe from Firebird-L: > <[email protected]> > Help: > <http://FirstGenFirebird.org/firebird/Firebird-L.html> > > Classifieds: <http://FirstGenFirebird.org/ubb/> > Owner Pictures: <http://FirstGenFirebird.org/show/> > > Donations: > <http://FirstGenFirebird.org/store/cart.mv?999999> > FGF Merchandise: <http://FirstGenFirebird.org/store> ------------------------------------------------------------------------ Submissions to Firebird-L: <[email protected]> Unsubscribe from Firebird-L: <[email protected]> Help: <http://FirstGenFirebird.org/firebird/Firebird-L.html> Classifieds: <http://FirstGenFirebird.org/ubb/> Owner Pictures: <http://FirstGenFirebird.org/show/> Donations: <http://FirstGenFirebird.org/store/cart.mv?999999> FGF Merchandise: <http://FirstGenFirebird.org/store>
