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Old 05-04-2015, 09:58 AM   #1 (permalink)
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Need some help with shock valving

I need some suggestions for shock valving. Just for simplicity its a short course truck. The issue is that I have a bunch of un sprung weight, straight axle and huge tires. It is only 3% heavy on the nose. The issue is that it lands nose first every time and no matter what I do I can't get it to launch nose up. The front shocks are 16" travel with .15 comp and .08 rebound. The rear is 16" also but the shocks are angled so it has about 21" of travel. Rear valving is .15 and .12 rebound. What I'm wondering is if the light front valving is causing the front axle to yank the nose down. Compression valving and spring rates are great, it rides awesome. Just every single time I get in the air the front drops like a rock.
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Old 05-04-2015, 09:05 PM   #2 (permalink)
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I'm no expert but I'll still give my opinion.

I believe that you could be too light on the rebound of your front shocks. If your front axle drops out too fast it can pull your nose down like you described. Other areas to examine would be throttle control/technique. Are you causing the front end to drop by letting off the throttle at the wrong time? Is your rear compression too heavy causing it to kick up?

Could you post a video of what's going on?

Good luck.
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Old 05-04-2015, 09:11 PM   #3 (permalink)
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Old 05-04-2015, 09:21 PM   #4 (permalink)
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From my experience the rear does 70-80% of the work. Get some video of the truck, throw some zip ties on the bump stops and shock shafts. Study away...... I bet your rear is not dropping out fast enough and the front is. I would throw some .008" on the rear rebound and try it out. I was thought to go a little more in a direction to make sure its the direction you want to move to (.012 to .008 instead of .012 to .010 etc...) I know we had to pull some trickery to get the rear to drop out all the way (flutter rebound, stiffer spring rate, more preload...)
I'm no expert, shit I barely know what the fuck I'm doing. But we have a big pig that moves pretty good.

With Waynes (All-Tech)help of course....
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Old 05-04-2015, 09:28 PM   #5 (permalink)
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K5, I was hoping you would chime in. Ive read your build and its awesome. I have zip ties on it and the compression valving is awesome. The front eats everything in front of it like its not there, the rear is the issue. I was under the impression that you wanted the front to drop out as fast as possible but the rear to have more rebound valving to get it to launch correctly. Now I'm wondering if on a solid axke rig like mine with a bunch of u sprung weight that it isnt the opposite. If this this would just launch noise up I would launch it into orbit. Staring at the ground is no fun at all.
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Old 05-04-2015, 09:30 PM   #6 (permalink)
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My phone sucks. Sorry for the errors.
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Old 05-04-2015, 10:11 PM   #7 (permalink)
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The problem that we found with ours is that; in the rear when it got close to full extension there was not enough preload or force to extend the shocks. On the front we ended up with 020 comp and 008 rebound IIRC.

Pretty much from what I learned; because of the shocks being mounted to the axles the rates are light. Because there so light the last little bit of extension does not have enough rate behind it. That is why running more preload or stiff rate helps. On top of that a light rebound, that's when you get the axle to drop out.
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Old 05-04-2015, 10:20 PM   #8 (permalink)
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My rates are pretty light. The front is 150/250 and the rear is 150/150. The unsprung weight is more then sprung. If I watch the video it appears that the front hitting the limit straps is what is dragging the nose down.
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Old 05-04-2015, 10:29 PM   #9 (permalink)
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I think another important thing to do/keep in mind is change one thing at a time to see what effect that did.

See if the rear is dropping out.
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Old 05-04-2015, 10:43 PM   #10 (permalink)
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The rear is way slower to drop out then the front.
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Old 05-04-2015, 10:49 PM   #11 (permalink)
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My rates are pretty light. The front is 150/250 and the rear is 150/150. The unsprung weight is more then sprung. If I watch the video it appears that the front hitting the limit straps is what is dragging the nose down.
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