XLR8R

Power Wagons naturally have a lower front heim mount, but that's solely due to the auxiliary crossmembers.

Longer bars cause more front end lift, shorter bars push the rear axle down under the frame.

Snapoff

Sorry about my explanation...I'm struggling with 4X4 chassis setup.
I'm concerned a short bar will hit too hard and I thought the longer bar would flex more absorbing some of the shock at the line?

So what bar does a drag racing 1000hp 4X4 QC short box (running street tires) need?

What about the same truck with drag radials?

Do your bars help 60 foot times and/or do they help with consistency?

XLR8R

No - you're thinking of slapper bars - this is different.

Since the bars are only loaded in compression, there is no flexural motion.

Pullers like the long bars more, since it takes more weight off the front (transferring it to the rear tires) to help rollout the sled for higher track speed, and there's little benefit to quick chassis reaction times.

I assume you're running an auto, so no need to soften tire shock like you might need to with a stick (the converter makes a nice cushion). With a long wheelbase, 3-4 ton truck on 5' leafs and 5' traction bars, "hitting too hard" isn't really going to be a problem.
Besides, it's easy enough to tune the rear suspension by weight-jacking the traction bars.

Tire choice won't matter.

Do your bars help 60 foot times and/or do they help with consistency?

Of course!

RowJ

Traction Bars reduce 1/4 mile times by about .2 sec from what I experienced and what others have posted! That 2/10's will show up in the 60" times also.
Consistancy is all in the hands of the driver.... but all other factors being equal, the bars make it easier to do it the same every time.

RJ

Baja

[QUOTE=jrussell;2264788] If/when I decide I need traction bars they will be a triangulated design using a shackle or slip-joint at the frame end. That's the only way they won't bind and make the suspension stiffer.

That is what I did, a shackle in the front, two heim joints in the rear, triangulated bars were 36" long, the rear brackets were welded to the axle tube. Somehow the front shackle bent, twisting about 30 degrees in, toward the center of the truck. I am still wondering how this happened. They were working well until the mount went south.

Snapoff

XLR8R,

Yes, I run an auto.

Please explain in detail both the mechanical and tuning process of what you refer to as "weight jacking"?

I seem to be able to get consistent high 1.60's and if I try for a better number I either get a low (1.60 to high 1.50) or the tires blow off excessively and I get something I don't want to talk about....There seems to be no in between......Do you think your bars can hold me low (1.60-high 150)? Or will I even see some improvement?
I am keenly aware of my input as a driver.

RowJ,
I doubt these bars will get my 7600lbs truck into the 1.30 60 foot bracket.....If so, please send me ten sets!

RowJ

If you can do 1.60 sec w/o bars.... I think they will do a lot. But that's pretty fast already. Only one way to find out?
I know several trucks doing 2.0 that dropped 2/10's. IMHO, the faster you are, the more you need them. Make sense?

RJ

jrussell

A truck running 2.0 60's doesn't have an issue with traction, so how exactly are traction bars going to drop the 60' that much? If the tires weren't spinning before the bars then the truck already had all the traction it could use. I bet the trucks you're talking about were just launched a little harder after the bars were installed.

A member on another Cummins forum reported that he broke his billet input shaft the first time he raced after installing traction bars.

RowJ

One of them was mine, and I never go over 20 psi launches. I never had wheel hop but you could see the axle shift forward over an inch before max grab (just like you can see it on a dyno).
Eliminate the axle movement on launch and you reduce you ET/60'.

RJ

bnold

Seems to me the bars planted the rear end really well then...

jrussell

Yep. Instead of transferring the shock to the leaf springs, it got transferred up through the driveline to his billet input.

bnold

Did it break on launch or on 1 to 2 shift?
Hard to believe it broke on launch as the traction bars limit the shock...

jrussell

He said it broke on the launch about 10' out.

The traction bars don't limit the shock at all, they increase it since the truck is hooking up quicker/harder. Normally the axle would wrap a little and the leaf springs would bend and absorb a lot of the shock. With traction bars the axle can't wrap, the leafs can't bend, and therefore the shock gets spread to other places.

Snapoff

Hooking up quicker and harder is the whole objective of drag racing...
A guy running 2 second 60 footers is going to get much more life out of his driveline than an identical truck running 1.50's...That part is true.

A truck that is running 1.60 sixty footers without something to control the axle wrap will have more driveline wear and abuse than the same setup running 1.60s with a traction device. The first time you experience severe wheel hop you'll know why...perhaps as an added bonus you'll even get to pick up parts off the track!

cquestad

jrussell...

Why so down on bars? In theory they work (but we know that is not enough). In SOT and "feeling" they work (but we also know that is not enought either). Most important yet...hard cold numbers prove they wrok.

Quicker launches and longer pulls.

If they are designed right...there is really NO bind in the twisty's or in up down.

I personally don't support the reduced sag theory or less squat/weight transfer theory...because my truck behaves exactley the same in those areas.

The main difference is ZERO wheel hop...or erratic tire spin.

For aft axle movement is zero...up down stayed the same. The truck drives SO much better.

Tranny is very happy (or it might be just the tranny I have...lol...but I think bouncing causing massive shock loading and funky bending cyclic motion of u-joints in my drivetrain used to be a big no no).

Try some...

I sure you can fab...I spent $75.