LLY: Traction Bars recommendation for heavy towing

[NevadaLLY]

Curious if anyone has used traction bars in heavy towing conditions? I don't want to have to adjust the pre-load every time I hook up my 40ft toy hauler. I gross in around 27K Pin weight is about 3K. Air Bags help keep truck level but I do experience some bucking from axle wrap that I'd like to eliminate. I also want to ensure I'm not binding when loaded vs unloaded. Conditions for use are mostly highway and some light off road (usually towing trailer through sand/trails to the camp spot).

Also - I have a pretty good setup with EFI live tunes and Mike L's transmission so get a bit of wrap when i use the go pedal on the HOT tune. :driving:

 

[Chevy1925]

I’ve ran my own bars for years. I tow heavy as well with 37s on my truck and tow tune in the 500rwhp range for summer/600rwhp range for winter. Gross around 26k (need to weight it because I’m pretty sure I’m heavier)

I never preload them. They have 0 in them and never had an issue. No axle wrap on the road, sand or dirt. It either keeps traction or blows them off with a white cloud behind me.

 

[NevadaLLY]

What is your setup? Maybe a few photos? I could build some but timing is playing against me. Are you running 60” or 72”? Also, what is the best geometry you found?

 

[Chevy1925]

just standard ones with tabs welded to the bottom of my u-bolt buckets and tabs welded to the frame right at the bend. truck is a long bed so my bars are 64" eye to eye. i dont build them anymore, too many other whores in the industry or people who dont understand why mine are simple but extremely strong.

the best geometry is a triangulated axle wrap bar with a shackle at the frame side but the bar and the shackle needs to be mounted on the same plane the springs are mounted which can be difficult to do.

the longer the bar for the typical two bar setup, the less pinion angle change. its best to have them at the same angle as the driveshaft as well.

the truck will ride stiffer as well unloaded as there wont be as much spring deflection now and doesnt allow the springs to move as smoothly.

 

[Bdsankey]

Like James, I've built my own bars. I made my brackets out of 3/8" plate and through bolted them on the frame side just ahead of the bend (I should have gone to the bend) and welded them to the axle tubes. I used 2" OD/1.5" ID (0.25" wall) A513 DOM that I got for $0.30 per lb.


I used ballistic fab 2.63" bushings on one end and ballistic fab 2.63" joints on the other with 1" shafts. If I haven't broken them in 3 years of sled pulling and taking some pretty nasty hops I don't think they will break.

https://www.ballisticfabrication.co...products/forged-chromoly-2-63-ballistic-joint

https://www.ballisticfabrication.co...s/products/ballistic-forged-poly-bushing-2-63

 

[N2BRK]

I banged out a few of these for myself and friends. I used rod ends with bushings and my ride didn't suffer. Maybe this will help you:

https://www.duramaxforum.com/forum/...mple-effective-traction-bars-diyable-guy.html

 

[NevadaLLY]

I guess I’m just curious about the geometry when unloaded vs fully loaded. It seems like adjustable rod ends are necessary? I could be completely wrong.

 

[Bdsankey]

I guess I’m just curious about the geometry when unloaded vs fully loaded. It seems like adjustable rod ends are necessary? I could be completely wrong.

Adjustable are nice as it can help you dial it in how you want as well as adjust incase any of your measurements are off. Also allows you to add preload if you so desire.

 

[gmduramax]

3k pin weight on a GMT800
With the airbags they should be keeping the same height loaded or unloaded so I wouldn’t think you don’t need to worry about binding.

 

[NevadaLLY]

Truck sits about 2.5-3” lower (level) as the rake is taken out when the load is on the truck.

 

[NevadaLLY]

Thanks BDSANKEY I’ll go that route first. Why should you have gone to the bend instead of where you mounted? Most I’ve seen are where you mounted.

 

[Bdsankey]

Thanks BDSANKEY I’ll go that route first. Why should you have gone to the bend instead of where you mounted? Most I’ve seen are where you mounted.

My bars angle upward, i.e. the front mount of the bar is lower than the rear. When the rear of my truck is jacked up for sled pulling my bars are perfectly level to the ground which was the intent.

Mounting them to the bend not only makes it somewhat easier as the bracket doesn't need to be as robust, it also puts the bars at a better angle in relation to the driveshaft.

 

[sneaky98gt]

I'll be honest: after a good amount of time spent drawing up my own traction bars to build (triangulated bar with a shackle at the front, like Chevy1925 described), I bought a set of Caltracs on the cheap. I've read all about the noise and stiffness issues with them, but they were too good of a deal to pass up, and I figured I could easily offload them if I didn't like them.

Well, several months with them so far in a very wide variety of conditions, and I don't have a single bad thing to say about them. The length of the bar very closely matches the length from the front of the leaf to the axle centerline, and runs relatively parallel also. This basically makes it a 4-link without very little (if any) binding through the axle travel.

I have noticed absolutely no decrease in ride quality, can't tell they're there at all. And that's on-road, basic off-road, and light/medium towing (6500 pound camper + 2 dirt bikes and gear in bed). I also have air bags to help with the squatting (I'm also lowered a little bit).

Driving at very low speeds, with the radio off, with the windows down, I can just barely hear some squeaking as they move around. But normal driving situations? No, never once heard a peep.

I should also add that I'm a fairly particular person when it comes to stuff like this, not one of those types that just passes off compromises in NVH as necessary for performance.

I think most people's problems with the Caltracs is that they set them up with preload. That's correct for a drag car with a transbrake, but a diesel truck is a little different. You don't want any preload at all. I've got mine backed off 2 full turns from contact, and I've had no issues with wheel hop or axle wrap, yet still retain ride comfort.

Standard traction bars are great, simple, and effective. But don't be under any illusion that you won't sacrifice ride comfort with them. I've never ridden in a truck with them, that I couldn't immediately tell they were there. The simple math of the situation is that you have a single point (the axle) trying to move in two different arcs (the leaf spring arc, and the traction bar arc). In a perfectly rigid setup, this triangulated setup couldn't move at all. In the real world, the bushings in the traction bar flex for some deflection needed to allow the axle to travel. But this bushing deflection will add to the effective spring rate (significantly if not set up correctly), which will decrease ride quality. The more the axle moves (like a large difference from unloaded to loaded heavy), the more apparent this will be.

Nothing wrong with any of this, just be aware of it.

 

[Chevy1925]

I'll be honest: after a good amount of time spent drawing up my own traction bars to build (triangulated bar with a shackle at the front, like Chevy1925 described), I bought a set of Caltracs on the cheap. I've read all about the noise and stiffness issues with them, but they were too good of a deal to pass up, and I figured I could easily offload them if I didn't like them.

Well, several months with them so far in a very wide variety of conditions, and I don't have a single bad thing to say about them. The length of the bar very closely matches the length from the front of the leaf to the axle centerline, and runs relatively parallel also. This basically makes it a 4-link without very little (if any) binding through the axle travel.

I have noticed absolutely no decrease in ride quality, can't tell they're there at all. And that's on-road, basic off-road, and light/medium towing (6500 pound camper + 2 dirt bikes and gear in bed). I also have air bags to help with the squatting (I'm also lowered a little bit).

Driving at very low speeds, with the radio off, with the windows down, I can just barely hear some squeaking as they move around. But normal driving situations? No, never once heard a peep.

I should also add that I'm a fairly particular person when it comes to stuff like this, not one of those types that just passes off compromises in NVH as necessary for performance.

I think most people's problems with the Caltracs is that they set them up with preload. That's correct for a drag car with a transbrake, but a diesel truck is a little different. You don't want any preload at all. I've got mine backed off 2 full turns from contact, and I've had no issues with wheel hop or axle wrap, yet still retain ride comfort.

Standard traction bars are great, simple, and effective. But don't be under any illusion that you won't sacrifice ride comfort with them. I've never ridden in a truck with them, that I couldn't immediately tell they were there. The simple math of the situation is that you have a single point (the axle) trying to move in two different arcs (the leaf spring arc, and the traction bar arc). In a perfectly rigid setup, this triangulated setup couldn't move at all. In the real world, the bushings in the traction bar flex for some deflection needed to allow the axle to travel. But this bushing deflection will add to the effective spring rate (significantly if not set up correctly), which will decrease ride quality. The more the axle moves (like a large difference from unloaded to loaded heavy), the more apparent this will be.

Nothing wrong with any of this, just be aware of it.

BS. its all dependent on the setup of the truck.

if you have a gap in your cal-tracs, they aint doing a thing for you unless you have significant suspension movement at which point, you loose their purpose. a tiny gap on a full spring truck might be ok depending on bar location in the pivot and tire/traction.

the aluminum spacer in the front of the spring puts a SHIT ton of stress on the spring in the even there is any articulation from the suspension. good way to stress and crack a main leaf you venture off road while fully loaded. Thats assuming you dont wallow out the aluminum first.

 

[N2BRK]

I'm 5 turns off from contact and in the second hole. I feel them every day and they are great on a boosted launch. I have confirmed with go-pro that they are touching the pack as soon as I touch the throttle in my neighborhood.

FWIW, I got this idea from an article in CompD years ago.

 

[Chevy1925]

and i have an 8 sec 4wd truck running with 8 turns into the leaf pack.

i dont care what you run, there is NO specific cal-trac setup for all trucks. they will ALL take work.

5 turns off the springs is not giving the cal-tracs much to do because of the amount of spring you have or weight transfer happening or lack of traction.

 

[N2BRK]

like you said - no one setup I guess. Mine hits the tires hard and pushes the front down in 4wd launches. In 2wd I get no hop and great traction and manners.

The post I was referring to says 3x off (about 1/2" off the spring), so maybe my memory is off and I am not set as far away as I thought.

 

[sneaky98gt]

BS. its all dependent on the setup of the truck.

if you have a gap in your cal-tracs, they aint doing a thing for you unless you have significant suspension movement at which point, you loose their purpose. a tiny gap on a full spring truck might be ok depending on bar location in the pivot and tire/traction.

the aluminum spacer in the front of the spring puts a SHIT ton of stress on the spring in the even there is any articulation from the suspension. good way to stress and crack a main leaf you venture off road while fully loaded. Thats assuming you dont wallow out the aluminum first.

Of course, every setup is going to need something a little different. I'm generalizing a bit relative to the OPs situation.

That said, the audience I'm addressing are the mildly modified street truck owners. The guys who drive them all the time, maybe tow some, have a hot tune on it, and want to fix the axle wrap. Caltracs backed off a couple-few turns will meet all of their needs, and not make the suspension unnecessarily stiff in the process like traction bars frequently will. They're also cheaper than virtually any off-the-shelf traction bars, and not significantly more expensive than just the materials needed to fab your own (not counting your time).

You're speculating on how much movement is allowed in the axle by backing off the spring a couple turns. I did the math when I put mine on, and it's well less than a degree before the spacer contacts the leaf spring. Hardly enough to worry about in a street truck (I'd argue the binding from a traditional traction bar forces the axle to wrap more than that just from normal articulation). I've been meaning to grab a Go-Pro video like N2BRK mentioned, but just haven't gotten around to it. I was under the truck a couple nights ago, and you can CLEARLY tell that the spacer is making contact with the leaf (i.e., they're working).

Is it the perfect set up for an 8-second drag truck? A 1500 horsepower pulling truck? Other extremes? Probably not. But that's clearly not what the OP is using his truck for. My truck is a simple 500 horsepower tune/trans/bolt-on LB7, that I drive and tow with frequently (20k+ miles a year). I'm usually running a sticky street tire, and before the Caltracs, it wheel-hopped like a son-of-a-b.... any time the tires broke lose, even in snow. With the Caltracs, it either hooks up perfectly, or it boils the tires off (usually hooks up). So they're working awfully well for me without any preload, AND there's no decrease in ride quality. Win-win.

I'm 5 turns off from contact and in the second hole. I feel them every day and they are great on a boosted launch. I have confirmed with go-pro that they are touching the pack as soon as I touch the throttle in my neighborhood.

FWIW, I got this idea from an article in CompD years ago.

I found the same info in my research beforehand. It makes perfect sense, and like I mentioned earlier: when you do the math on it, the axle is allowed very little movement before the Caltracs stop it.

 

[sneaky98gt]

like you said - no one setup I guess. Mine hits the tires hard and pushes the front down in 4wd launches. In 2wd I get no hop and great traction and manners.

The post I was referring to says 3x off (about 1/2" off the spring), so maybe my memory is off and I am not set as far away as I thought.

Yup, 3 turns is the number I recall as well. But with my truck being lowered, I was only able to get about 2 turns before running out of thread, so I left it there. Nowhere near 0.5" off the spring though. I'll check next time I work on the truck, but from memory, I'd say 0.100"-0.125" TOPS. I think it was more like 1/16".

 

[Bdsankey]

I didn't notice a ride quality decrease with my traction bars. Either I am not in-tune enough to notice or if the high quality joints allow enough movement to make it not a problem. My truck doesn't "off-road", mainly just roads be it gravel or pavement. The ballistic joints (like Johnny Joints) have poly races which I believe helps them in terms of movement.