Forward bite on dirt sportsman

**jnkrb58** · 05-23-2016, 08:13 AM

Need to dirt last year from asphalt. Car handles awesome on entry and through middle can point and turn wherever I want. Problem is no matter how I get back to throttle just blows tires off and never tries hook and go. Just looking general ranges on pinion angles, bar angles, spring split to get this thing to get some traction.
Metric chassis stock mounts on frame for 4 link. 800 lf 900 rf 250 lr 200 rr steel hiem lower bushings rubber uppers, lots of upper bar angle, lr lower down to rear, rr lower level. 52%left 53%rear 56% x 3200 lbs, run e mod Hoosier. All lead is between and above top of coils. Might mention that front is 80" wide and rear 78.5 rr in.
Any help would be appreciated I know there's no magic setup but no one at track will give me any help and just don't know anyone in dirt and have applied all off Asphalt knowledge. Thanks in advance

**WOT114** · 05-23-2016, 02:06 PM

Shorten up your upper linkages on the rear end. Or on mine I put 20lbs above the RR and it made all the difference in the world on traction off the corner

**WOT114** · 05-23-2016, 03:35 PM

If you rob enough HP that it hooks is that not traction. lol

Originally Posted by circletrack

We did experience a slight gain in horsepower due to changes in the pinion angle. We could not change the transmission angle, so all of the changes were to the pinion. We recorded a run at zero pinion angle and then at 10 degrees of pinion angle. We expected a loss in horsepower at the greater pinion angle, but actually experienced a net gain in horsepower. This was very confusing until we thought about what Terry had said. When the pinion was at 10 degrees, the angles at the ends of the driveshaft were opposite and closer to equal. This was a better situation providing less resistance than when the pinion was at zero degrees with the transmission angle at a much different angle.

**jnkrb58** · 05-24-2016, 02:47 PM

Yes I understand phasing and equal angle in shafts save power. Done all that testing myself years ago on asphalt. Just trying to catch what I have missed trying to get it to hook up on dirt. That being said there is a jacking force involved pinion angle present from angular momentum. And I don't need to rob any hp from my little 352. Got my upper arms as short as rules allow.