trying different suspension combos... ECSB
#81
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Join Date: Apr 2004
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Here's a screen shot of a sketch I did of an ECSB truck. Everything is labeled and the dimensions were taken from my truck. All CG dimensions are estimates since I've never had actually figured out where it is. It'd proababy pretty easy though. They're educated guesses though.
Also these dimensions will be different for every truck. If you would like to pm me YOUR dimensions, then I can figure the IC location and antisquat value for your truck. I need your front leaf height, tire height, front AND rear caltrac location and how much its lowered front/rear. It's an estimate, but at least we can compare why other's trucks hook better.
So my truck has an IC behind the CG, which is probably not ideal for a nose heavy vehicle, and it's at 35" where it crosses the front wheel centerline. 35/28=1.25 or 125% anti-squat. I'm not sure if that's too much but....?
Also these dimensions will be different for every truck. If you would like to pm me YOUR dimensions, then I can figure the IC location and antisquat value for your truck. I need your front leaf height, tire height, front AND rear caltrac location and how much its lowered front/rear. It's an estimate, but at least we can compare why other's trucks hook better.
So my truck has an IC behind the CG, which is probably not ideal for a nose heavy vehicle, and it's at 35" where it crosses the front wheel centerline. 35/28=1.25 or 125% anti-squat. I'm not sure if that's too much but....?
#82
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So I went and bought an angle finder today and realized my angles really aren't that horrible.
Keep in mine my rear tires were on ramps so the angles may seem a bit screwy.
These are in relation to the ground
Transmission angle-180*
Front driveshaft angle-180-181*
Rear driveshaft angle-179(angling down from back to front)
Pinion angle-178(angling down from back to front)
Hopefully that makes sense. I also tightened the hell out of my long bars, but I'm worried if what the consequences of that might be for a daily driver. I don't want there to be no articulation in the rear suspension and rip off a mount.
I also picked up some v6/m5 front coil springs. I've heard they should help with weight transfer so we shall see.
Keep in mine my rear tires were on ramps so the angles may seem a bit screwy.
These are in relation to the ground
Transmission angle-180*
Front driveshaft angle-180-181*
Rear driveshaft angle-179(angling down from back to front)
Pinion angle-178(angling down from back to front)
Hopefully that makes sense. I also tightened the hell out of my long bars, but I'm worried if what the consequences of that might be for a daily driver. I don't want there to be no articulation in the rear suspension and rip off a mount.
I also picked up some v6/m5 front coil springs. I've heard they should help with weight transfer so we shall see.
#83
Your long bars will suffer the same fate as mine, loosen them up... Since all they are is for anti-wrap, they only need a small amount of preload. Just enough so they don't rattle so bad. Mine were so tight they actually shoved the mount forward off the frame... Just FYI.
#84
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Your long bars will suffer the same fate as mine, loosen them up... Since all they are is for anti-wrap, they only need a small amount of preload. Just enough so they don't rattle so bad. Mine were so tight they actually shoved the mount forward off the frame... Just FYI.
I looked around a bit online but didn't come up with much.
#86
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Thanks Ben for the help. Now I just need some drag radials to see if I can ever drop into the 1.xx 60' times.
#87
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1) You get a vibration(launch shudder).
2) Your leaf spring rebounds from the spring wrap, and unloads your tires. Traction is lost.
Your longbars may be helping to prevent wheelhop, but this is where Cal-tracs are superior. They work to prevent the spring wrap when launching.
I'm gonna suggest that you add shims, target 3-4 degrees of pinion angle. You want the pinion yoke pointing more towards the ground.
#88
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Okay, so if I'm reading this correctly, your pinion angle (relationship of the rear half of driveline to the pinion yoke) is only 1 degree. So when you accelerate hard from a stop, and the pinion gear climbs the ring gear, and you get a little bit of spring wrap, your pinion angle goes negative. Two things happen now.
1) You get a vibration(launch shudder).
2) Your leaf spring rebounds from the spring wrap, and unloads your tires. Traction is lost.
Your longbars may be helping to prevent wheelhop, but this is where Cal-tracs are superior. They work to prevent the spring wrap when launching.
I'm gonna suggest that you add shims, target 3-4 degrees of pinion angle. You want the pinion yoke pointing more towards the ground.
1) You get a vibration(launch shudder).
2) Your leaf spring rebounds from the spring wrap, and unloads your tires. Traction is lost.
Your longbars may be helping to prevent wheelhop, but this is where Cal-tracs are superior. They work to prevent the spring wrap when launching.
I'm gonna suggest that you add shims, target 3-4 degrees of pinion angle. You want the pinion yoke pointing more towards the ground.
I've been able to all but completely eliminate the vibration. I messed around with tightening the bars up last night and there is almost nothing. I'm running 4* shims right now, but I think I'm going to try and run some 6* shims and see where that puts me.
One thing I will say is that these longbars don't have the articulation that caltracs do. With them tightened up I can hear a few moans and groans when daily driving it, that are scaring me. I'll probably back them off a turn or two until I don't have to worry about them ripping the mounts off. I will say the guy who did them did a fantastic job with the welds though so I'm more worried about the frame twisting than I am tearing the mounts off.
#89
11 Second Hall Moniter
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It would be smart to run those bars looser. Especially daily driving. Cranking them tight is probably adding pinion angle, which is helping your vibration. However, it is bending(loading) your springs. That stored energy is constantly being pushed through those longbars. Something will give. I would guess that it is also hurting your traction rather than helping it (too much preload).
#90
TECH Veteran
iTrader: (24)
It would be smart to run those bars looser. Especially daily driving. Cranking them tight is probably adding pinion angle, which is helping your vibration. However, it is bending(loading) your springs. That stored energy is constantly being pushed through those longbars. Something will give. I would guess that it is also hurting your traction rather than helping it (too much preload).