I need help to stop this. The rear is where the problem is. I'm going to remove the traction bars I have. They have poly bushings on both ends. I'm replacing them with solid adjustable lower bars using the original front mount on the frame and the mount I added below the axle. Another bar will be added to the upper axle mount and forward to the frame. Basicaly a four link. Any other ideas? This is what I have now.

 

i was thinking of this too when you posted to Scott last night about your intercooler, you mentioned bounce.

a trianglulated three link to the top of the pumpkin and traction bars should do the same as a four link. however a three link triangulated will prevent side to side movement. are you having problems with axle wrap causing the hop, or is it the fact that the rear end of the truck is bouncing because of the axial torque on the axle is pushing the frame up and down on the springs. my suggestion if this is it is to add a heavy duty air bag system on top of your springs to the framerail. it will help bring up your back end a bit, to give more traction to the front wheels, so the rear wheels dont have to do most of the propelling (less sprung weight on the rear wheels, less hop, correct?) however it will squish the rear tires down more. but the only thing wrong with what i can see with pulling, these bags are designed for towing 15000 pounds, not dragging 45000 pounds. maybe an overbuilt air bag system from the big rigs (Firestone)could be the ticket. however i may be completely off the handle here about what i said above.

if you know, tell me what YOU think is causing the bounce. i still want to see that video where you bounced and almost stopped but kept going and got 24xsomething

 

Last night we had the overload springs clamped to the pack. This pulled the rear down solid on the pump stops. I don't know if the tires are balling up or if it's still axle wrap. This was in pro street class so it's legal. For street you have to keep two inches of rear travel. I'm stumped and disgusted!

 

i have another idea. before when you had (still have) bounce, is it from a two link traction bar setup? is it from the top or bottom of the axle? or both? my hypothesis is that if the traction bar is from the top of the axle, when it torques up, the front of the pinion of the axle raises up. so that means if you are looking at the left of the truck, the axle torques up to the clockwise way. a true four link going to the frame for both top and bottom links (cannot be equal length) will eliminate the hop. since you will be torquing the axle up some on takeoff, and then when you let off the clutch pedal you are putting all the torque down, the truck goes down even more in the rear becuase of more load. i believe that when the traction bars are above the axle, torquing the axle will pull the springs down and when mounted below near the shock mount, putting power thru the axle will push up on the truck. finding the right balance is the hard part. is any of this making sense and am i correct here?

 

The original bars mount between the spring block and axle housing. The problem started when we added more power with the turbo. I then added the lower adustable bar to the setup. It's the gold bar in the pic. I think your on the right track with a bar above and below the axle. Going to the front from the top is tough with limited space. I thought about adding the top bar and going the the rear and mounting it here.
http://community.webshots.com/photo/...80528090MUQExV

 

yes i do think that would be a good idea. great in fact. you would just have to figure out a way so it would not clock the axle around while not putting a load on the truck. for example if you are pulling, you are squatting the truck and if done right, the top link which is triangulated (read later) is in a neutral position. but once you stop (and since this is a daily driver) the axle should also be in a neutral position(the position it is in when it is not under power).... so it would have to be a triangulated link, defanitely with heim ends. i would also convert your poly bushings to heim ends if possible. take all slop out.

anyway to the link, i think you should add a perch on both sides of the third member(on the axle tube relatively close to the third member). make the perches the height needed to make the triangulated link vertical or near vertical when pulling. this way it will give alot more leverage to the link to keep the axle more "neutral", instead of just welding a heim joint on the top of the axle tube, and not getting much leverage. and then not utilize the setup where the traction bars are now, they are not getting you any traction. it would be easier to have two more perches on the bottom of the axle right below the leaf spring pads, again with the same amount of perch height as the triangulated link at the top. all in all it should come out good, and good luck.

when figuring out all of this, wouldn't you want the measurements to be taken at pulling height? by this i mean stress the truck by putting weight on it until it sits at the normal ride height.

edit-- ooh yeah 4000 posts babyy.

 

I'm just reading this from an amateur's perspective, but would a pinion snubber be of any value for testing purposes? Easy and quick to do.

 

Snubbers would help at the dragstrip, but the load from the sled would likely just crush them.

Doubling up on the mounts for the traction bars should help...but I fear it will make it impossibly stiff on the street. If you used heim joints on both ends of the upper bars s that it could be removed on the street and allow the axle to do it's thing.

Another option would be to remove the rear blocks and mount the springs directly to the axlepad. The blocks are compuonding the stress on the springs and contribute greatly to the axlewrap IMO.

 

Here's a pic from last night before the bounce. Got a ball game to go to now.

 

aww man that is 'effin sweet. that is so cool, you can still throw that smoke pretty damn high with those 6" stacks do you have a bigger version of that, for possibly a new computer background?

 

in the rockcrawling world, one solution is these traction bars here, they keep the pinion from rotating, while allowing normal suspension cycling, so you could still bring down the rear, on top of the bump stops, and the pinion shouldnt rotate if built properly. With this much torque going to both wheels you may want to be sure you weld your axle tubes to the differential also, to prevent spinning your axle tube inside the housing. just my .02

 

Check the web shots link at the bottom.

 

yes that is right where i went after that post, and damn all of them are awesome.

 

The frame is flexing. Here's the vid.

 

yeah you beat me to it about the frame flexing you can see the misalignment in the bed. sounds like its time for some more steel back there, if you can and still run in the class you want i would 4 link the rear end, use hiems at the track and use another set of bars with poly ends for the street. since your lifted you can use a firestone 1t14c3 bag above the axle without having to notch the frame, if you went behind the axle you could run the poly bushings all the time since its gonna keep the axle loaded to the back all the time. suicidedoors.com can make the bars however you want but i dont even know if there 2" .25 wall DOM bars would hold up to pulling. you might be able to do that bar with some bracing in them. might want to see what some of the high mod classes are using to hold the rear in place..... you would have to 4 link with panard if you wanted to keep your fuel tank where its at the triangulated wont work with the stock tank location.