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Competition Physics of bouncing while SLED PULLING

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Competition comparable physical size turbo?

I would like to know from the experienced pullers out here, what causes the trucks to bounce going down the track. What is happening with the truck/suspension/tires that is making this happen?

No truck in particular here, just wanting to know what causes it, and better yet, how to fix it.
 
There is tons of things that can cause bounce. As everyone knows the tires are loading and unloading. It can be caused by (but not limited to)tire pressure,hitch,throttle control,clutch control,track,suspesion set up,spring wrap,and a little demon that wont leave. These are just a few things,there just so many things that can go wrong. It is most of the time very hard to find.
 
I agree with the above post, and add two more. Weight, or more the lack there of, and weight location can also be causes of bouncing. Bringing a truck up in weight can(but not always) tame bouncing. This is more evident in gasser classes where a truck can weight 5000# or less empty. Last year moving a mere 300# from the bed of my truck to the front bumper would tame the bouncing of the front end I was fighting. 5800# class was more prone to bouncing then the 6500# class.



Its also interesting to watch a truck that pulls perfectly every time, then the owner adds another 100, 200, 300 hp, and the same truck bounces every time the chain gets tight. Setups can change as the power goes up.



Michael
 
Alot of it is power/rpm/tire vs. tacky track...



Lately I have been a real "bounce bad dodge" causing 1 mainshaft to become 2 and 2 premature shut downs to prevent a catastrophe (happend tonight as a matter of fact).



Like said above though there are alot of things that go into the equation.

The more aggressive one wants to be with their truck/suspension setup the more of a gamble.



My most aggressive setup I run big suspension blocks that raise the rear of the frame up in the air a bit. I also run wheel spacers up front and lower the tire pressure up front (25-30psi area) and run 60psi in the back. Thats with a 26" hitch and MTX tires.



My most non-aggressive track setup would be running suspension blocks with 1. 5" of travel, all terrain tires, 30psi+ up front and 60psi in the rears.



Its all a big puzzle. Sometimes I get it right sometimes I get it wrong.
 
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Justin put it in 4th low range and let it rip. 2. 71 times the torque on the shaft in the high range.



Dan thanks for the advice. I almost did that last night but didnt for some reason (should have though. . )

Next time I am presented with that situation I will.



Clear out your pm box!
 
Cleared out. I have obscure views on lots of things, and sled pulling is no different. The cause of the bounce is usually the tires hooking and unhooking, now there are many different things that could cause that. Like others have said, suspension setup/tire setup. As Dave as said some trucks just bounce. Try an AT tire keep the pressures up high, block the rear, good ladder bars, I think the manual guys has quite a bit to do with clutch release.
 
The reason for the post was, I was watching a local pull where the modified (gas) guys were running (for some reason) an agressive or deep treaded tire, on a very tacky track. Bounced , in and out of the throttle, bounce, etc. I kept thinking to myself that if they were to run a tread that had very little left on the tire, it might have helped.



On the other hand, watching the street diesel division, lightly modified yet street legal, they were running street tires that (most) had good tread on the tires, and none of them bounced, not one. Which leaves me to believe, on this particular night, with a tacky track, maybe the suspension had more to do with it, and maybe the HP level as well. I just didnt understand what was making it do it to some trucks and others not.
 
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