Front anti-wrap bar and anti-dive

[Hogback Fabrication]

I will be putting an antiwrap bar on the front end this winter to tie me over until I (someday ) am able to link the front. Its a cheap and easy solution and the 52's flex well enough.

Anyway, depending on how I setup the antiwrap bar I will have some amount of antidive especially with my ridiculously soft front springs. I think I know enough about link calculations to determine roughly how much antidive I would be dealing with.

Here's my question:

It seems that I might want the front to suck down under throttle. My truck basically sits on the front bumpstops at ride height so it won't suck down much and it seems like that might keep the front end sucked down on climbs.

Thoughts?

 

[iwaxmyjimmy]

I don't see how you could build a traction bar to keep the front from "rising" on a hill. Your springs will always unload at the same point unless you use something attaching the frame to the axle (ie. limiting strap). A traction bar is just gonna keep the axle from pivoting on the springs. Never heard of having to find the anti squat for the front suspension, if your gonna link it, either. And, from some reason i got a laws of physics going off on my head, that theres no way to make the front "suck" down under acceleration. Unless you put your center of gravity way forward, IE move the motor to have the bell housing on your front bumper.

 

[Hogback Fabrication]

Here's a picture I drew to help visualize what's going on:

While the axle drives the tires forward there is an opposing torque trying to force the pinion to point at the ground. The antiwrap bar prevents the axle from twisting (axle wrap) and instead pull down on the front suspension. That's called anti-dive (a strange sounding term I know). At least I'm pretty sure its called anti-dive.

Anyway, the intensity of this "anti-dive" is controlled by the vertical seperation of the two mounts on the axle side and by the length of the bar.

 

[iwaxmyjimmy]

In order for you to get the effect you want...... your gonna have mounts by the rear spring hangers. You'll never get enough leverage to pull the front end down. And, the only way I can see to even remotely do what your talking about would be to have the lower link mounted to the frame, and the upper link providing pressure to it to push the link down.

 

[iwaxmyjimmy]

or where the lower mount for on the axle would have to be super long,hang down really bad, and the upper would have to be like mid axle.

 

[Hogback Fabrication]

Your thinking of it backwards. The closer the vertical seperation on the axle (the closer together the axle mounts are) and the shorter the anti-wrap bar the less effective it becomes, making the frame mount "work harder" because of leverage (thereby making the truck pull down more).

Besides, it won't take much to pull my 175 lb/in springs down 1"

 

[iwaxmyjimmy]

um dude .. you can try it, but I just don't see it happening. You have, no leverage with out using the rotational force of the axle. Unless I can put my hands and witness it, I think your theories are crap. I've never seen a front end squat under acceleration.

 

[B_to_C]

i think your theorys are crap.

On a side note, I think your spelling is...

 

[iwaxmyjimmy]

On a side note, I think your spelling is...

better?

 

[iwaxmyjimmy]

can anyone else explain this better?

 

[B_to_C]

When conjugating a word that ends in "y" to plural you change the "y" to "ie" and add "s".

Thus, you should have typed "theories".

The only time you would have "theory's" (notice the apostrophe) would be if you had a sentence such as... "The theory's basic assumptions are not based in reality."

This conlcudes this lesson of English 101 for CK5'ers

 

[iwaxmyjimmy]

When conjugating a word that ends in "y" to plural you change the "y" to "ie" and add "s".

Thus, you should have typed "theories".

The only time you would have "theory's" (notice the apostrophe) would be if you had a sentence such as... "The theory's basic assumptions are not based in reality."

This conlcudes this lesson of English 101 for CK5'ers

i just hit spell check real quick so yeah ive got like 3 things goin on at once but ill clean it up for you.

 

[Blazr77400]

Anyway, the intensity of this "anti-dive" is controlled by the vertical seperation of the two mounts on the axle side and by the length of the bar.

The vertical seperation will have no effect on the anti dive with a ladder bar type traction bar. Only the length and the angle of the bar will effect that. Mostly the length. The more seperation you have, the more leverage you have on the axle easing some of the stress on the mounts.

The traction bar I had on my blue truck was a ladder bar with a shackle on the end. It was on the front of the axle and worked fairly good. It did cause the front end to lift when torqued.

Another option is to add some leaves to the front of the spring. The front of the spring is what controls the axle, the rear of the spring controls the ride.

 

[Hogback Fabrication]

The traction bar I had on my blue truck was a ladder bar with a shackle on the end. It was on the front of the axle and worked fairly good. It did cause the front end to lift when torqued.

Blazr77400's anti-wrap bar caused his truck to lift because its pointing forward of the front axle. The fact that his truck noticeably rose under power proves that there is significant vertical force caused by the anti-wrap bar, which I already knew.

Mine would be pointed rearward of the front axle causing the front of the truck to squat.

Back to the original question, I'm thinking that having the front firmly pressed against the bump stops would be good for climbs. Thoughts? Would the anti-dive ever be a disadvantage?

 

[Blue85]

Yes, a traction bar like you describe would pull the front end down. How much depends on the amount of traction the front tires have. Does anybody notice the rear of their truck lifting from the rear traction bars? It doesn't seem like anti-dive can be the right term for this effect though (maybe "dive" or "squat"?). It's a matter of how much force it takes to compress the springs vs. twist them and the length of the lever

The disadvantage I can think of is in a situation where the frame or T-case is hung up on something. As you try to climb forward, you make the hang-up worse. If you were really high centered under the right conditions, you might bounce the front tires up and down off the ground.

 

[Hogback Fabrication]

It doesn't seem like anti-dive can be the right term for this effect though (maybe "dive" or "squat"?).

I double checked and its referred to as both anti-dive and anti-lift. Anti lift certainly makes more sense to me but I think anti-dive is the more common term and that's what popped into my head yesterday

The disadvantage I can think of is in a situation where the frame or T-case is hung up on something. As you try to climb forward, you make the hang-up worse. If you were really high centered under the right conditions, you might bounce the front tires up and down off the ground.

I really hope the t-case isn't hung up on anything (easy way to break adapters)

A good point and thanks for the input

 

[cybrfire]

Blazr77400's anti-wrap bar caused his truck to lift because its pointing forward of the front axle. The fact that his truck noticeably rose under power proves that there is significant vertical force caused by the anti-wrap bar, which I already knew.
quote]

His blazer also rose in the front due to weight transfer from acceleration. How much was one and not the other, only he can know.