Competition Hopping down the track...

[wildmanben]

I have tried blocking the rear end of my truck when I hook to the sled so it dont squat so bad and both times that I have done that I get some wheel hop. The first time it wasnt very bad at all, but you could hear it in the engine, but the second time I was bouncy like a ball. I am running 4th gear and it pulls good, just bounces. Gotta figure something out here so I dont break an axle. Not enough air in the rears? I have 45 in them. Or should I try 3rd gear instead?



Also, the pulling association got a new sled this year that takes off pretty light but towards the end it stops you pretty quick. I would imagine that momentum will help with this sled right? But when I get to the end of the track and the rear wheels on the sled lift, It will stall the truck out. Do I need more power to pull in 4th or should I stick to 3rd. 3rd doesnt seem to load the truck and it wont build much boost or smoke, just kinda cruises and spins out. 4th pulls hard and uses all the power I got and stalls, but goes 10-20 feet farther. I have a video but a drunk bystander got a few to many f-words in there to show...

 

[DCreed]

rpms/wheel speed/pressure/traction get em spinnin and keep it goin!

 

[wildmanben]

so more air pressure then?

 

[zstroken]

You could drop your hitch height to allow you to spin out in 4th. 4th low is quite a bit of power. The 64 might allow you to do it though since it will stay lit a little lower in rpm.

 

[wildmanben]

The hitch is at 25" I think. The guy at the scale told me that my hitch was 8" too low and that I have to have it up more to pull. I told him that I think it will do fine and drove off. Still got 1st, hopping most of the way. Maybe I should just take the blocks out of the rear, didnt hop then.

 

[bgilbert]

How about running them rock hard like 80psi+ ?

 

[MMiller]

A flat basketball can't bounce. I run little air pressure in the front down to about 14 psi, and sometimes down to 35 psi in the rear. Is the bounce coming from the front end or the rear? Do you have ladder bars? Does your bounce start from the launch, or does is start mid track, and progressivly get worse? Are you running any weight up front?



IMHO, if the sled is light at start and hits hard, its a speed/drag race, use 4th gear and get the bounce under control. If you want to spin out at the end, make some more power.



You can drop you hitch, but then you loose some the advantage of blocking the rear end up.



Michael

 

[zstroken]

A flat basketball can't bounce. I run little air pressure in the front down to about 14 psi, and sometimes down to 35 psi in the rear. Is the bounce coming from the front end or the rear? Do you have ladder bars? Does your bounce start from the launch, or does is start mid track, and progressivly get worse? Are you running any weight up front?



IMHO, if the sled is light at start and hits hard, its a speed/drag race, use 4th gear and get the bounce under control. If you want to spin out at the end, make some more power.



You can drop you hitch, but then you loose some the advantage of blocking the rear end up.



Michael

Yea but 35PSI with all that weight down on it will just shrink the size of the tire and allow the pressure to go up. I would force the pressure up. I would go up in pressure on them, it will let them grab less so once again helping the spin out issue.

 

[MMiller]

Yea but 35PSI with all that weight down on it will just shrink the size of the tire and allow the pressure to go up. I would force the pressure up. I would go up in pressure on them, it will let them grab less so once again helping the spin out issue.

Hmmm, the circumfrence of the tire will not change. Air pressure is air pressure. It does no good trying to make the truck spin out, if its bouncing all the way. I'd rather use full power, and not to have to back pedal because its bouncing. A smooth pull will put you upfront more consistantly, and put the truck back on the trailer with less broken parts.



Ask around to the guys that pull every weekend. Ask the guys that their trucks don't bounce, ask the guys that win most every weekend.



I'm just putting my suggestions on here, the stuff I've tried and worked. I used to run my back tires up to max psi all the time, the truck pulls better at 35-45 depending on track conditions. I used to run 35 psi up front and my truck bounced like a pogo stick, but at 14 not so much. Add 300# to the front bumper and 14 psi, no bounce at all, and full power bonzi. Bouncing is horrible on parts, it needs to get under control.



Michael

 

[zstroken]

Hmmm, the circumfrence of the tire will not change. Air pressure is air pressure. It does no good trying to make the truck spin out, if its bouncing all the way. I'd rather use full power, and not to have to back pedal because its bouncing. A smooth pull will put you upfront more consistantly, and put the truck back on the trailer with less broken parts.

Ask around to the guys that pull every weekend. Ask the guys that their trucks don't bounce, ask the guys that win most every weekend.

I'm just putting my suggestions on here, the stuff I've tried and worked. I used to run my back tires up to max psi all the time, the truck pulls better at 35-45 depending on track conditions. I used to run 35 psi up front and my truck bounced like a pogo stick, but at 14 not so much. Add 300# to the front bumper and 14 psi, no bounce at all, and full power bonzi. Bouncing is horrible on parts, it needs to get under control.

Michael

The circumference of the tire will change, you will flatten it and it will bulge out, actually the center of the will bulge in. The problem is the tire is no longer a circle so you can't say circumference. Now running low air pressure might be doing something else to eliminate the bounce, dropping the hitch height. The tire is gonna compress until the pressure equals the weight pressed on it. Typically airing down increases your contact area, but airing down really low in the rear just sacrifices hitch height.
Drop the pressure in the fronts, fill the rear to 50+, adjust hitch height accordingly. I have zero issue with bounce on my truck, ask our resident 3rd gen manual internet puller about hitch height, he will say start really low and raise it until you get a good feel. I am sure he will have some advice on tire pressure.

Are you pulling with the 38" super swampers? IF so I am sure that the 35 psi isn't as detrimental to hitch height, I think the super swampers have a very strong sidewall.

 

[wildmanben]

I have traction bars and running 45psi all the way around. Will try less in the front and more in the rear and see what happens. Then I will try adjusting hitch height. Will have to make something so I can adjust it... Thanks a bunch for the help. Surprised that no one has told me to get a bigger turbo. Because thats what I think!

 

[zstroken]

You do need a bigger turbo, but I don't think it will help with the bounce, unless your surging alot.

 

[wildmanben]

its not surging... oh and I cant run weights in front in my class.

 

[MMiller]

Heck, get a bigger turbo, and injectors. :-laf That'll fix it all. lol



IMHO the tire will travel roughly the same distance per revolution whether its 35 psi or 80. The I guess the main objective of my first post was this "a flat basketball can't bouce" If the tire is 80psi and starts hopping, then its just going to keep hopping, at 35 is going to have a lot less bounce.



On my particular truck, tires on the soft side work better. Hitch is always maxed at 26"(local rules), and dropping it had no effect on bouncing I fought last year. Tire pressure, springs, and weight location solved the bouncing.



I'm still wondering, does the hopping start at the beginning, from the start, or does it leave pretty smooth, and develop a bounce as it goes down the track, then the farther you push it down the track, the bounce get worse? Is it more in the front or the rear?





Michael

 

[wildmanben]

starts with a little bounce, gets worse and then clears up when the load gets high, about halfway down.

 

[jwilliams3]

I have tried blocking the rear end of my truck when I hook to the sled so it dont squat so bad and both times that I have done that I get some wheel hop. The first time it wasnt very bad at all, but you could hear it in the engine, but the second time I was bouncy like a ball. I am running 4th gear and it pulls good, just bounces. Gotta figure something out here so I dont break an axle. Not enough air in the rears? I have 45 in them. Or should I try 3rd gear instead?



Also, the pulling association got a new sled this year that takes off pretty light but towards the end it stops you pretty quick. I would imagine that momentum will help with this sled right? But when I get to the end of the track and the rear wheels on the sled lift, It will stall the truck out. Do I need more power to pull in 4th or should I stick to 3rd. 3rd doesnt seem to load the truck and it wont build much boost or smoke, just kinda cruises and spins out. 4th pulls hard and uses all the power I got and stalls, but goes 10-20 feet farther. I have a video but a drunk bystander got a few to many f-words in there to show...

Looking at your signature you look to be at or lower than the 500hp mark for sledpulling. You basically answered your own question. You dont have enough power to run 4th. Stick to 3rd low or 2nd gear hi range.

If you cant load the truck in 3rd low or 2nd gear then I would start looking at your truck as the problem not the sled. Could be you dont have the right tire for the dirt you guys run out there.



Oh did I mention you need about at least a 2. 8" or 3. 0" turbo (71mm or 75mm intake wheel). It will probably help eliminate the hop if you can stay on top of it (charger).



If the guy said you can raise it another 8" then you are way low and this could be a reason you can load the truck properly in the rear.

Too many times pullers get lazy and say well I'll just leave it like it is since I am doing ok but this ends up hurting you because the next guy comes in setup right and blows your doors off.



Lowering pressure in the rear: WTF? Keep that pressure in the rear above the max PSI setting. You can adjust tire pressure accordingly but the science is that with the proper hitch, tire pressure and blocks the sled will load your rear end up and make those rock hard tires dig into the ground..... loading your motor and pulling you further (if you have the power).



Just be aware any amount of blocking of the rear can takes its toll if you dont have the power to stay on top of it or if the track is biting hard or a combination there of.

 

[jwilliams3]

Ask around to the guys that pull every weekend. Ask the guys that their trucks don't bounce, ask the guys that win most every weekend.

Miller,

In years past zstroken (Dan) did pull every eekend and even won sometimes.



The guys that do well in the Indiana street class all run blocked and maxed tire pressures.

 

[MMiller]

Miller,

In years past zstroken (Dan) did pull every eekend and even won sometimes.



The guys that do well in the Indiana street class all run blocked and maxed tire pressures.

I wasn't saying he didn't know what he was talking about. I just was meaning to watch the guys that aren't bouncing, and pick their brains. I pulled a bunch last year, and on my truck, it hooked better, and bounced less with less air in the rear tires, hitch maxed, and blocked rear. Then again, I've never pulled in Indiana, just Southern Iowa. What worked on my truck, may work on his, just my experiance.



I'll step out now, and will just watch pulling discussions, I went to 13 pulls last year, hooked in at least two classes each pull and won some too



Michael

 

[DRadzierez]

Leave your rear presure 45 or above. You can ask around on tdr and My trucks almost never bounce without traction bars. Try makeing u bolts and clamp your helper springs to your main leafs. Alot of the time when guys block the rear the take to much load off the springs and they just get axel wrap. And get the hitch up---cant give you an opinion on that ,Ive never tried it that low. in fact Im surprised you did so good.

 

[zstroken]

I wasn't saying anything that you didn't know, I guess I have seen guys on the west coast use boggers!!! Whatever works!