it is quite a brain teaser... lol ive had some guys in the bigger classes tell me to fully box the frame all the way to just buildin a new one.

and i'm not sure bout the snuber. I haven't seen any other trucks with them but yet i haven't seen any with this particular problem. I'm sure i can try it. Whats the worst theyr'e gonna say? take it out? lol

 

Looks like the frame is flexing a lot to me. Try the new shocks and if they don't work you might have to box the frame.

 

I really wouldn't recommend the pinion snubber. For one, I don't think they would allow it, but also I think it is a bad idea. I know you said you have a huge spring pack in the back that is clamps, but watch the rear suspension when it unloads, it still comes up 2-3 inches. If you have a snubber on there, all of the axle movement would be transfered to the pinion, which would not be a good idea. It is the same as using short ladder bars like drag cars use, truck pullers have found over and over again that short bars don't work well, they only contribute more to wheel hop.

The extremely soft front suspension isn't helping you at all, since it is allowing the front to move quite a bit. I'd recommend getting a set of leaf springs from a 78-79 F250 (or even an 80s-90s truck). They are flat 2-leaf packs which will drop your front end to about the point it is now, but they have a much higher spring rate. The higher spring rate will take some of the travel out and stiffen the front up.

The shocks will also be key. Get the stiffest, heaviest shocks you can, on the front and the rear. Like I said, even with the heavy rear springs you still have some movement in the rear suspension, and you want to dampen that movement out.

Another thought. You mentioned that you built the rear packs from multiple stock packs. A better route to go would be to build a pack from a heavy-duty truck leaf spring, like a 90s model F-450, or something similar. These trucks have very thick leafs with a very high spring rate. Stacking and clamping these leafs will cut down on travel in the rear packs. Thicker leaves are always better than multiple thin leaves.

I'm also surprised at how easily it broke. Are you using a stock shaft with larger ends? Maybe going with a heavier slip joint? Again, think F450-550 for parts to scavenge. I've seen a lot of trucks bounce, but yours didn't take much hit to break the shaft.

Just for kicks, here's a video of my truck. I have considerably less power than you, but mine also tries to bounce at the end. It has done that a lot, but it has never broke. I have bone stock front suspension (it's a 79), and the rear suspension is bone stock with 2 additional leaves in each pack (even the blocks are still there). Tire pressure is around 35-40psi all around (drove 1.5 hours to the pull, pulled, drove home after).

Eric 1st pull 10.08.11.AVI - YouTube

 

would completely locking out the rear suspention be a viable idea? and would it be legal? i was a couple trucks here in the local pulls last year that had a setup with removeable pins to lock it out in the rear

 

If his class is like ours, you are not allowed to run solid suspension. We have to maintain at least 2" of travel between the axle and the bumpstops. But with the right rear spring combo, you can essentially eliminate all of the suspension travel.

 

to answer some questions... the driveshaft slip shaft is the same size as ones off a 79 half ton with 1410 joints. I got them from a gentleman that runs in a bigger class. thats what he is using. I looked this morning after work and noticed my rear perch on the pass side is crushed and i have less than 6 degrees in the driveshaft angle at the pinion. plans for building some new perchs that wont give way are already in the making.

The rear springs were made out of packs i had laying around. I've been looking for thicker heavier springs to make a new pack and have come up with a set of 2.5s off a one ton chevy so far. still lookin. front springs are hard to come by around here as our "junk" yards have a crappy selection. but again i've been looking. the adjustable front shocks arrived this morning so that will help. Would it be a good idea to try and run a quad shock set up?

We have to maintain "some" sort of rear suspension. the class i plan on running next year allows us to lock them completely out and run ladder bars but i would like to figure this problem out before i do move up.

Again thanks everyone for the help and great ideas

 

I have a set of front springs I just took out of my 79 F350 4x4. They are in great shape. The truck only has 89K on it.

Mike 1 530 927 9827

 

Havnt used one but what about a longer anti wrap spring perch

Outdoor Logic - Anti-wrap Spring Perches

Or maybe if you can get away with it a bam bar

BamBar - Ultimate Anti-Wrap Solution - Jeepaholics Anonymous

 

i'm actually using the bigger anti wrap perches. and it appears the one on the pass side rear is toast. flatter than a pancake. but the bam bar might be something to try.

 

The flattened perch is from axle wrap. You need to cap the front and back open ends with some 1/4-1/2" plate and weld it in.
That happened to me too!

 

ok after much deliberation i found someone with front springs out of a 89 or 90 1 ton dump. I'm sure this has been discussed before but they should bolt in right? If i have to fab a little thats not a problem.

These front springs should be better than the half of a stock pack i have now right?

 

its a 4x4 dump. don't know if that matters

 

pulled the truck a couple times this weekend. Friday night on a really dry clay track the truck thought it was a jack rabbit right at the start. So for sunday i took some weight out of the front and moved it mid ship. Moved 2 clamps on the rear leafs around as well. The truck came out of the hole beautifully and hooked awesome!!! Took it a few feet shy of 300 and just started digging in... No noticable hop bounce or buck like i was experiencing. It just flat ran great!! Between the adjustable shocks in the front and pinion angle set right I think we have most the bugs worked out. Just need to remember to put the rear bed bolts in before the next one. Lol

Thanks for all the help I will post a video up when i get a couple extra minutes.