wrap/ trac bar (1 Viewer)

[dustin]

I need some lessons on anti-squat.. Is there a best of both worlds, or compromised solution?

-Dustin

 

[rusty_tlc]

I personaly do not like the tube design, an interferrence fit is not going to work so you have to have a certain amount of slop in the "twisty" portion. Which will only get worse over time. Also, you are putting the most stress on the weakest portion of the A arm..


There are prople that have made that sort of bar work tho..

Isn't that true of any of these designs?

 

[Mace]

Not always if the bar is built right.

But it can be the weakest point. Which is why I don't see the reason to build that single point weaker than the rest of the unit (i.e. bigger tubing to smaller tubing at the furthest point from the axle..)

Am I actually making any sense?

 

[Mace]

Another thing to ponder. Bu reducing the size of the tubing at the apex and then sleeving it you are incorporating a stress point.

Consider breaking a stick by just grabbing it at both ends and bending..
Then place a central point in it (your knee for instance) Much easier, right?

The slip design causes a stress riser at the point where the small piece meets the bigger piece.

 

[bad_religion_au]

hmm good point re, stress riser...

2 reasons i like the slip idea.

1, no heims... their expensive over here, hard to get, and department of transport frowns apon them, fair enough if i keep breaking the slip design, i'd probably convert to heims, but if i can get away with avoiding them i'd prefer it

2, i would like some adjustibility, as the rig will be dual purpose... as spring oversare frowned apon, it'll run spring over for hardcore s***zniz, and spring under on the street/ on the sand/ where travel is less important than stiff springs. i'd like the wrap bar to work in both situations, and can't see myself getting enough adjustability in a heim setup. i am always open to being proved wrong

 

[Radd Cruisers]

I liked the slip idea also, of course as I mentioned after welding it was impossible to get the bar inside the tube due to the heat created when welding.

Maybe weld in stitchs and cool or even get a ream and ream it once all the welding is done.

Could get fancy and put a zerk on the top of the tube.


I like simple and cheap, this does seam to be both.

 

[busiboy]

hmm good point re, stress riser...

2 reasons i like the slip idea.

1, no heims... their expensive over here, hard to get, and department of transport frowns apon them, fair enough if i keep breaking the slip design, i'd probably convert to heims, but if i can get away with avoiding them i'd prefer it

2, i would like some adjustibility, as the rig will be dual purpose... as spring oversare frowned apon, it'll run spring over for hardcore s***zniz, and spring under on the street/ on the sand/ where travel is less important than stiff springs. i'd like the wrap bar to work in both situations, and can't see myself getting enough adjustability in a heim setup. i am always open to being proved wrong

If you use the leaf shackle option of connecting to the chassis, this is where you adjustment should be. SOA and SUA differences would be in heigh relation to the chassis unless you are changing wheelbase at the same time.

therefore you shouldbe able to use the same wrap bar and just have std and extended shackles for chassis connection(?)

 

[CaliCruiser]

great post, im glad i didnt make mine this weekend. i stiil need to build one for my 60. thanks for the great info.

 

[JDay]

Another thing to ponder. Bu reducing the size of the tubing at the apex and then sleeving it you are incorporating a stress point.

Consider breaking a stick by just grabbing it at both ends and bending..
Then place a central point in it (your knee for instance) Much easier, right?

The slip design causes a stress riser at the point where the small piece meets the bigger piece.

The motion is actually a moment applied at the axle end, the resistance at the x-member side is like a point load. Whoa... I thought about actually making some shear and bending moment diagrams for this, then though better. Unless you're a weight meiser, build it stronger than you need at the expense of weight.

I'll see how this lasts: 1.5" Sch 40 black pipe with a heim and shackle at the crossmember and 0.25 plate gussets for the ladder effect.

 

[Sputnik40]

Damn, that's funny. I've been running one of those TSW bars as a single non-shackled bar with my my SUA for 3 years and it's worked decent with a similar top tower on the axle. Getting ready to add a ladder type as I'm going SOA - I'm not at home to check, but I thought the housing was aluminum - did you mig with gas to put the 2 together?

lol yes. BUt hey it works and I know where I can get replacements for only 29 dollars to fix any problem. Not pretty but it works. No more axlewrap under braking or climbing. Makes a big difference when slaming on the brakes when trying to stop at a yellow light because a cop is on the other side. A cop could give a rats ass about axle wrap and the reason you were all the way out in the intersection.

 

[Mace]

No you are right John, The tip of the wrap bar only sees resistance forces, the axle end generates the forces (sort of)

Engineering geek

 

[sixty]

here a pic of my bar I just built.. its not nearly as long as it looks.

I have no gussets since the forces on the bars are compression & tension & all major bending will be near the shackle.

Hopefully I'll get it offroad in the next few weeks to put it thru its paces.

 

[FLYINGLOW]

here a pic of my bar I just built.. its not nearly as long as it looks.

I have no gussets since the forces on the bars are compression & tension & all major bending will be near the shackle.

Hopefully I'll get it offroad in the next few weeks to put it thru its paces.

I think the end of the lower tube will be a major stress riser for the top bar. Let us know if it bends like JDay's did. I personally like Woody's design, and thats what I used.

Edit: if you are worried about AS, mount the bar to the shackle as low as posible to reduce it. That is prolly why some people experience wheel hop after intalling a wrap bar.

 

[sixty]

the reason I bent the bottom bar & ran it parallel to the top bar was to hopefull spread the load evenly over the length of the top bar & keep stress points to a min. Its all made from 1.25" sched. 40 (1.7" od.) so I think it will be ok.

John says his is made from 1.5" sched 40 (1.9" o.d.) but to me it looks more like 1".

I can detect no AS in my bar.

 

[FLYINGLOW]

the reason I bent the bottom bar & ran it parallel to the top bar was to hopefull spread the load evenly over the length of the top bar & keep stress points to a min. Its all made from 1.25" sched. 40 (1.7" od.) so I think it will be ok.

John says his is made from 1.5" sched 40 (1.9" o.d.) but to me it looks more like 1".

I can detect no AS in my bar.

The AS comment was thrown in for the people talking about it in earlier posts.

 

[Radd Cruisers]

here a pic of my bar I just built.. its not nearly as long as it looks.

I have no gussets since the forces on the bars are compression & tension & all major bending will be near the shackle.

Hopefully I'll get it offroad in the next few weeks to put it thru its paces.

Are yur drive shafts on backwards?

 

[Mace]

Are yur drive shafts on backwards?

No..

The CV is at the tcase end

 

[green73]

Since we are on the wrap/trac bar topic. Will having one a little off the centerline of the axel make a big difference? Nothing drastic, but 1-2"

 

[Mace]

Not an issue
centered is better but nothing is perfect..

 

[bad_religion_au]

Edit: if you are worried about AS, mount the bar to the shackle as low as posible to reduce it. That is prolly why some people experience wheel hop after intalling a wrap bar.

so if you can mount the shackle under the xmember, would this be better for AS?