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Traction Bars

Christopher

NAXJA Forum User
Location
Bakersfield, CA
Well, I've got some considerable axle wrap and was wonder if any one knows or has an opinion on the best traction bar out there, and the best / most reasonable place to pick one up?
 
JC Whitney had some traction bars for XJs that mounted on the rear u-bolts. The front end looked like a ball joint and mounted to the cross member in front of the rear axle. The whole assemble is threaded so you could adjust it for different heights. It requires you to drill holes in the cross member for the mounting bracket. I remember that they were cheap (less than $90), but I have no idea how well they work.

Terry
 
Re: Traction Bars Cal Tracs

CalTracs makes a bolt on traction bar setup for XJ/MJ. Just put one on my MJ.
661-948-1490
 
Sam's Offroad sells one, and I'm sure it can be adapted to an XJ. The issue will be the length and the front mounting point. I'm sure others are available, but I don't know where they are.

Sam's Offroad traction bar

The other traction bars, like the JC Whitney unit, will bind up when articulating and aren't good for off roading. The traction bar needs to move around and pivot at the front mount for our application.
 
Re: Traction Bars Cal Tracs

rsalemi said:
CalTracs makes a bolt on traction bar setup for XJ/MJ. Just put one on my MJ.
661-948-1490


Do you have any pics of this traction bar? Does it work well and not bind when flexed? How much did it cost?

I am planning on building mine but theres some geometry that I dont understand how the traction bar will effect. Do a search with my name and its all listed there.

AARON
 
MrShoeBoy, I've chatted with you before about the geometry over on JU I think. I started mine a few weeks ago, but then had to go back to school. I will be finishing it up in about 2 weeks or so when I go back home. What I have found by reading and talking to others (no personnal experience yet):

-Traction bars cause anti-squat, you know that already.

Long bars
-The longer it is (say up to the crossmember) will give less antisquat than having a shorter one.
-If the pivot's at your T-case driveshaft u-joint and the bar is the same length as the driveshaft, you will completely get rid of u-joint bind.
-Since it reduces driveline bind, you get suspension bind since the t-bar and the springs are not moving in relation to each other.

Short bars
-The shorter the bar (say front leaf spring eye) will give more antisquat than a longer bar.
-If the pivot is lined up with your front spring eyes, this should get rid of suspension bind, but will not stop u-joint bind under extreme flex (but who cares, most u-joints are broken from spring wrap, which you've stoped, right)

I made mine pivoting with my leaf springs to reduce suspension bind through it's travel, with the shackle pointing up for ground clearance. (not sure what pointing it up or down will do to it) I had to cut into my floor quite a bit for this to work, I've still got some more cutting to do, then welding it all up. The bracket is 1.25" .120 wall cromoly.

170272_38_full.jpg


170272_37_full.jpg


One thing I'm never doign again is welding to my axle with it under the truck. I'm not good at that contortionist welding. My axle bracket is the most disgusting thing I've ever seen. :) I'm going to pull it and redo it all.
 
I don't get the thing about suspension bind.....in fact I totally disagree. The idea with a single link traction bar that allows movement at the front pivot point is so that there will be no suspension bind. As the axle articulates, the traction bar can pivot (twist) at the front joint. As the axle moves slightly fore and aft as the suspension cycles, the front mount allows for this movement so there is no bind. It makes little, actually no difference if the front traction bar mount is even with the spring eye or even with the driveline u-joint, since the shackle/heim joint/whatever front traction bar mount allows the bar to move fore and aft with the axle. The combination of the front mount and bushings on the axle mount also allow for some sideways movement, so still no binding.

The concept is a single traction bar with a front mount that allows movement in all directions except up and down. The suspension is free to move, but the axle cannot rotate up or down with the force of torque.

Also, there's nothing wrong with a little anti-squat on an XJ, which many times is loaded down with gear. I'm going to re-design my current bar to increase the anti-squat, since I liked my old one better that had more.

standard.jpg

standard.jpg


I did mine with two heim joints because it allows for better side to side movement and it fit better in the limited space we have under our XJ's.
 
the twist and the shackle movement is not what binds. It is the twist of the axle as it travels. As the axle droops, the axle twists a bit pointing the pinion up (traction bar or not), therefore also forceing the traction bar to point up at a more extreme angle, that's what causes the anti-squat, but that's what also causes the bind if I'm correct. With the longer bar, the end of the traction bar will want to move to a hgiher height than the springs will allow. I hope my thinking is clear. Search pirate, there are some good posts about it. _nicko_
 
Gearwhine thats a hot setup :cool: What does the inside of the cab look like with the traction bar coming up through the floor? What space did it kill?

So whats not to like the contortionist welding thing?:) Dont tell me you cant handle the splatter falling down on you from above burning through your clothing then sitting on your skin. Its not THAT hot :laugh3: :D :D

When talking about antisquat, just to clairify, thats the force that compresses the springs when power is applied? Like you hit the gas and the rear squats.

So Goatman, you are going to build a shorter traction bar to reduce the amount of antisquat? Will that have any effect on the ledge climbing ability of the Jeep? Then does this effect the street handling when carrying a load?

AARON
 
When talking about antisquat, just to clairify, thats the force that compresses the springs when power is applied? Like you hit the gas and the rear squats.

The higher the percentage of ANTI-squat, the more the rear end RISES under acceleration. General Rule: 100% is neutral, anything less, the rear quats. Anything more, it rises.

CRASH
 
MrShoeBoy said:
Gearwhine thats a hot setup :cool: What does the inside of the cab look like with the traction bar coming up through the floor? What space did it kill?

The box to cover it all will stick out of the floor about 6" high. It goes about 5" or so into the rear seat foot space, and all the way back under the seat. I can say there is no useful lost space whatsoever. I can still fit all my goodies that I had under the seat back under there.

MrShoeBoy said:
So whats not to like the contortionist welding thing?:) Dont tell me you cant handle the splatter falling down on you from above burning through your clothing then sitting on your skin. Its not THAT hot :laugh3: :D :D

Ha, I don't mind the splatter, I've got a pretty welding jacket. The worst part is it burning through your shoes right to your toes, that's not a fun one. It's even worse when it gets inbetween your toes. Time for boots for me.

MrShoeBoy said:
When talking about antisquat, just to clairify, thats the force that compresses the springs when power is applied? Like you hit the gas and the rear squats.

Anti-squat is the force resisting the squat, so you are right. When powers is applied, the rear wants to lower to the ground (squat), but the traction bar will resist that and raise it away from the ground causing anti-squat.
 
CRASH said:
The higher the percentage of ANTI-squat, the more the rear end RISES under acceleration. General Rule: 100% is neutral, anything less, the rear quats. Anything more, it rises.
CRASH

I understand the term of antisquat, now for the fun question: How do you determine antisquat with the traction bar?:D

Is it the same as you would calculate antisquat for a 4 link?

My goal is for the traction bar to be transparent in the way the suspension functions, keeping all the current specs or characteristics but resisting axle wrap. Man, talk about demanding! :wave:

Ha, I don't mind the splatter, I've got a pretty welding jacket. The worst part is it burning through your shoes right to your toes, that's not a fun one. It's even worse when it gets inbetween your toes. Time for boots for me.
I got something better :D Hot Metal on Nuts! Instead of the splatter burning through your shoe, its the crotch of your pants..... I never had this experiance but I know a friend who has, sorry Andy.

AARON
 
gearwhine said:
the twist and the shackle movement is not what binds. It is the twist of the axle as it travels. As the axle droops, the axle twists a bit pointing the pinion up (traction bar or not), therefore also forceing the traction bar to point up at a more extreme angle, that's what causes the anti-squat, but that's what also causes the bind if I'm correct. With the longer bar, the end of the traction bar will want to move to a hgiher height than the springs will allow. I hope my thinking is clear. Search pirate, there are some good posts about it. _nicko_

Well, nicko, let's talk about this. :)

Any binding of the suspension would be a concern when articulating, and I don't see any motion when articulating that will bind the suspension against this type of traction bar. There would be a very slight force sideways on the bar as one wheel is up and the other down (very slight rear steer), but this will easily be absorbed by the bushings or shackle, or very easily in the double heim mount that I use.

As far as the pinion pointing up as the whole axle drops, this is marginally true depending on the springs, but it won't happen much, if at all, in a leaf spring suspension. Even if it did, it makes no difference since the traction bar angle moves as the axle moves and would go with any pinion angle change. To any degree that the twist of the axle and the traction bar would work against each other (if it did at all), it would be absorbed by an extremely slight movement of the leaf springs, which would affect nothing. So, I don't see any situation where a properly built traction bar of this design would bind the suspension. Also, I've read threads on POR about this, and I have seen a few talk about some suspension bind, but I don't agree with them.

Anti-squat isn't from any suspension movement trying to force the bar up, it's from engine torgue trying to twist the pinion up and that force working against the bar, pushing up on the vehicle. That is what the bar is supposed to counter-act, holding the pinion steady while torgue is applied so the pinion doesn't raise and bend the springs into an S shape, which is spring wrap.
 
MrShoeBoy said:
So Goatman, you are going to build a shorter traction bar to reduce the amount of antisquat? Will that have any effect on the ledge climbing ability of the Jeep? Then does this effect the street handling when carrying a load?

AARON

A shorter bar will increase the anti-squat, since it allows more leverage/torque to be applied to the bottom of the vehicle. Longer bars are used to decrease anti-squat. I want a little more anti-squat, but I'm not going to shorten the bar, I'm going to increase it's angle. The more the traction bar points up, the more anti-squat there will be, so I want to lower the bar on the axle. Mine is a little bit of a weird setup because I tried to use the mounting pad on the top of my Tera60R for my traction bar mount, which hasn't worked very well. I'm going to have to give in and weld a mount to my axle tubes.

Limiting all axle wrap, and slightly increasing anti-squat will help on big ledges. Street handling won't be affected at all, with or without a load.
 
So do you just take a crap shoot on how long you want the traction bar to be? Contineous experimentation with different designs interfears with the whole broke college student lifestyle I happen to live in now.

Thanks guys,

AARON
 
I thoguht about it some more, and drew up why a longer bar binds the suspension, I hope this makes sense.

170272_39_full.jpg


There are 3 sets ups here. Long t-bar, mid traction bar, short traction bar in relation to the spring length. They all meet at the axle tube at approximately the same height. Apply force to where the arrow is. Which one is going to move freely? The two top set-ups will not move freely at all. Of course there is a LITTLE bit of play for it to move, but all that other flex has got to be by bind in the spring with extra bending. The bar mounted at the leaf spring eye is the only way to get a relatively bind free traction bar set-up from what I can see. Hope you can see it. _nicko_
 
Its my understanding that by running a shackle and a JJ or heim joint at the frame end of the traction bar, the bind which you describe is taken care of. The shackle takes care of the changing arc of the springs and the JJ takes care of the axle rotation(articulation).

You do have a valid argument but I think what Goatman is saying is that the JJ and shackle will keep the bar from binding.

AARON
 
In practice, Goatman is probably correct in that there is very minimal bind with a long traction bar. However, theorhetically, I feel that the diagram is correct. Even with the forward end of the traction bar allowed to float for and aft, the radius of the axle movement with a traction bar is changed from how it would move with no traction bar. The difference is taken up in the springs and various bushings, but the difference MUST cause SOME bind. If the traction bar forward end is in line with the front leaf spring hanger, there should be very minimal difference in axle movement between having and not having the traction bar there. However, there will still be some as without the traction bar, the axle will more or less move straight down since the rear of the spring plays into this. The axle will not rotate in an exact arc from the front spring hanger without a traction bar, but it will with a traction bar. I can see it, but it is hard to explain it via words. Jeff
 
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