Rule of thumb for girder and hydraulic frontend
Posted: Tue Feb 19, 2013 10:26 am
Rule of thumb for setting trail of hydraulic and girder frontends:
First use the tire width formula (T=(((rear tire width/front tire width)*100)-100)*0.01) to find the needed adjustment trail.
I.E.: 90/90/21 front tire and 250/35/18 rear tire
T=(((250/90)*100)-100)*0.01
T=(((2.778)*100)-100)*0.01
T=((277.778)-100)0.01
T=(177.778)*0.01
T=1.778" of trail adjustment needed
* remember this equation results in American Standard Measuring not metric so you would have to do one more little conversion for metric: simply multiply answer by 25.4 to get mm answer
* i try to round to three decimal places as that is a common amount when machining.
So now using a baseline trail of 2" I will add the trail adjustment to the 2" baseline and come up with my needed trail.
I.E.: 2" + 1.778"= 3.778" of needed trail or round to nearest 1/8" so 3.75" of trail.
- I do not concentrate on wheel flop for these front ends as they respond better to the trail numbers rather than the wheel flop numbers. Frontends with a rocker system at the axle, I use my wheel flop equation and shoot for .125" of trail as the axle travels in an arc about the fulcrum point.
First use the tire width formula (T=(((rear tire width/front tire width)*100)-100)*0.01) to find the needed adjustment trail.
I.E.: 90/90/21 front tire and 250/35/18 rear tire
T=(((250/90)*100)-100)*0.01
T=(((2.778)*100)-100)*0.01
T=((277.778)-100)0.01
T=(177.778)*0.01
T=1.778" of trail adjustment needed
* remember this equation results in American Standard Measuring not metric so you would have to do one more little conversion for metric: simply multiply answer by 25.4 to get mm answer
* i try to round to three decimal places as that is a common amount when machining.
So now using a baseline trail of 2" I will add the trail adjustment to the 2" baseline and come up with my needed trail.
I.E.: 2" + 1.778"= 3.778" of needed trail or round to nearest 1/8" so 3.75" of trail.
- I do not concentrate on wheel flop for these front ends as they respond better to the trail numbers rather than the wheel flop numbers. Frontends with a rocker system at the axle, I use my wheel flop equation and shoot for .125" of trail as the axle travels in an arc about the fulcrum point.
