Crimedog

I had another hook yesterday at the Wright County Fair, I got 6th out of 15 or 16 trucks. I stripped down to make weight in the 6200 class (200 lb grace, so I pulled @ 6380). I noticed that all of the lighter classess of trucks, 5500 and 6200 had a lot of bounce but the 8,200 class which was mostly diesels, had no hop. Las year when I pulled here I had no hop, but more wheel speed because I only had 33's. I hopped pretty good, but was able to keep into it enough to go 263 feet (1st - 303, 2nd - 295, 3rd - 289). Two weeks before this I hooked at a Elk River that was a pretty similar surface of mostly hard clay. It pulled like a Cadillac there, but hopped yesterday. My theory is that I still didn't give it enough wheel spin, because I could have spooled the turbo longer, and if the wheels are spinning fast they'll eat through the bumps. Maybe it has something to do with tire pressure, I put about 17 lbs in the front and leave the back at 55, maybe going less in the rear would help absorb some shock? What are you folks doing to cure this? There was one truck that was all over the track and hopping really bad but stayed on it so the hops kept getting bigger, he made it 250 ft before he snapped a front axle shaft. Any input on this is appreciated, I'm hoping I can pull again on thursday, otherwise it'll be next weekend.

joefarmer

ladder bars.



(did I mention ladder bars? )

brandon.

Crimedog

So you're saying I should get ladder bars

When I blocked the axle once earlier this year I got a lot of hop, but I didn't think I could get much spring wrap, but I guess I do? I don't block up anymore, but I must be getting a little bit of spring wrap when I hit the bumps, then let off and some weight comes off and the springs straighten out, then I get traction and more spring wrap, and it keeps cylcling? It makes plenty of sense to me...

As far as fabbing some up, is there a certain angle I should follow so they don't bind with the suspension? I would assume at the same angle as the driveshaft, right?


Thanks brandon... BTW, I finally built a rear loop just like the one in your pics Just gotta get going on the others

FrdRdnk

When you say hop do you mean springwrap or bouncing over bumps? Lots of things can cause SW,but like was said ladder bars should take care of it. The main cause I've experienced is too much traction, i.e. not enough wheel speed. My best advice to you to prevent it without spending alot of money, I don't know if you're trying to be competive or just have fun, would be to keep it wound up and keep the tires at street pressure. The sidewalls will ?amplify? the hopping with their flexing and greater traction at lower pressures. It's sort of like a trampoline effect.

joefarmer

When reviewing my videos last year, I believe I would have placed much better if axle wrap would have been minimized. When on the dyno, you could see the rear u-joint wrap down about 4" lower than normal. There could have been some flex from the side walls as well.

I would think that either the same length or longer than the drive shaft should work for ladder bars. Most of the pulling trucks have the traction bar bolted to the frame where the frame is still boxed for more strength. I never got around to building a set, but I will need some on the new truck as well.

hth,
brandon.

Crimedog

Do you think building a setup with one link on the frame side and two on the axle, connected by trianglulated tubing would be ideal? It seems that this would be much more rigid than just running a straight bar with only one link on each end. Just to be sure, 5/8" rod ends should be stout enough, right? They have something like a 9500# static load capacity...

As far as tubing I'm thinking 1.5" dia. with .125" wall, should be stought enough...

JoshPeters

Matt,
After watching yours hop like a bunny.....I think it was axle wrap. The Ladder bars will help considerably.

Check out BBD's bars on Diesel-Central, or his web site. I think he used 1/2'' wall tubing.

Josh

Crimedog

You could have at least called it a rabbit

After watching the video a few times I noticed that the hops accompanied upshifts on the tranny, so we've got some heim joints coming tomorrow and hopefully we'll have them built by Sunday, it's a bit of a drive for you Josh, but Litchfield has one. Tomorrow is Benton County truck pull, I'm up against the Heartland Truck Pullers boys so we'll see what happens. I'm pulling 6500 again.

bwillard

Ladder bars as others have mentioned are a must. As far as tire pressure, this is a general rule of thumb...more air makes the tire taller and skinny which equals tire slippage or spin, because there is less tread contact with the ground. Less air makes the tire lower and fatter which equals more contact on the ground and a tire that forms around the ground which equals less spin or slippage. Good Luck!

joefarmer

Oops, missed that question.

I think triangulated or 'ladder' bars would appear more stable, but I don't think you'll have a noticable advantage over single or 'traction' bars. Something else to consider is that ladder bars will need more math to keep the rear end from binding up. The traction bars will allow you to have a single flex point as opposed to 2 points on the rear axle. Again, my opinion only.

brandon.

PourinDiesel

I have single bars and they haved worked well so far sled pulling.

JoshPeters

Matt...Andy pulled out there...said the sled was set VERY tight. Did you get your bars built?

Josh

Crimedog

Didn't get the bars built. For some reason things never go as planned, things such as... losing reverse Dave's sending me up a new 3rd gear clutch and valve body so it's alright. I hopped at Benton county (shifted while power braking=bad start), but yesterday I put it in 4HI 1st and it pulled nice and smooth and got a little bit of spin out of the big mudders, but I didn't spool the turbo off the line otherwise I would have gotten more wheel speed. If I get my bars built by next weekend (either Willmar or Carver county) I'll pull in 4lo, if not it'll be 4HI.

On a side note, it's kinda funny that I used to pull 6500 street legal because I thought that they wouldn't let me pull heavy. I didn't change a thing and pulled 8,000 lb stock heavy class on Sunday That'll give an idea on how loose the pulling rules are around here

durasmack

Ive seen people pull in multiple classes before in the same night.... strip the truck down, pull 6500, load it up, pull again in 8000....

cumminsdriver635

As long as you arent over the weight limit you can pull a 3k lb nissan i the 8k class.

Eric