Engine/Transmission (1998.5 - 2002) High HP, Heavy towing and spring wrap

[plongson]

I frequently read about many folks here pulling HEAVY trailers with their trucks with lots of hp/torque.



Do you folks have a problem with spring wrap?? I dyno'ed at 330 and around 700 and cannot use it all when towing conditions are good (Low Ambient, Low Altitude, EGT in check etc. ) because I get spring wrap. If this sounds unusual, do a search for "spring wrap" and there is lots of info.



Anyway, do you guys get the "bump'n and hump'n" from the spring torquing up and then realeasing under extreme loading??

 

[MRose]

I pull 18k and never had a issue with it. Popped my t-case into neutral once at a light once, oh that scared me! But never axle wrap issues.

 

[KKlingbeil]

I have grossed at 32,000 with truck and trailer, and haven't ever had it. When empty and spinning in the snow or gravel, yeah, but not with a trailer on. . Are you seeing it when starting off, accelerating, or crusing?? I know there are a few people that make and sell traction bars... That would correct your problem. I plan on building my own set once it gets a little bit nicer outside... .

 

[RustyJC]

The only time I have it is if I'm on the accelerator pedal at takeoff. There's a technique to starting one of these trucks when towing heavy. Don't touch the accelerator but smoothly release the clutch at idle - the ECM won't let the engine stall. Once the clutch is fully engaged, smoothly roll into the throttle - no snap loading either accelerating or decelerating.



It works like a charm for me. Of course, YMMV!



Rusty

 

[TGibbs]

Some of the spring flex will also depend on where your hitch is placed in relation to the axle. The farther forward of the axle, the smoother the ride and the less flex you will get.

 

[plongson]

My spring wrap problem occurs when I am fully loaded at around 18k GCW, and on a grade or with a headwind, and I am nearly maxxed out power wise. It seems a little bit worse when the air bags are inflated to help with the load. This is expected because the bags are carrying more of the weight and the springs are less loaded and more flexable, but still... if I let the bags way down to say about 5psi. and the springs are fully loaded, I still get that weird "Hump and Bump" as I describe it. Originally I thought it was the clutch slipping but I swapped to a NV5600 and a SBC CON-OFE, it is still there. I was also considering adding an extra leaf to see if it would help.



I am not too jazzed about adding traction bars because it seems to me that with the full travel that the these spring see, there might be an issue with binding. I hear that 4-link is really the way to go but I refuse to start redeisigning the rear suspension.



If I am one of the chosen few to suffer this problem, it may just be my springs have fatigued and need some help. I don't want to chase this problem by just throwing parts at it... cost way too much$$$

 

[KKlingbeil]

As long as you make your traction bars plenty long, like 6-8 feet, the curveature (spelling??) of the arc will be almost flat, and beings they are adjustable, you can change them so there is the least amount of binding at where you are spending most of your time on the road. Good luck. . I hope you figure out something to make it better!!

 

[Todd T]

The only time I feel anything is when I get on it hard around a turn with the trailer on back. And mine is not spring wrap its the sidewall flexing on the tire.



with your airbags are you still using the bump stops for the overloads? maybe you've caused this problem by not dispursing the weight over the spring properly... . you're lifting from the center of the axle housing above the spring instead of the spring mounts out at the ends.



if you allowed the overloads to hit the stops you've effectively added two more mounts to the frame closer together toward the centerline and increasing the leverage needed to cause spring wrap. With the weight tetering over the axle housing (air bag) and being steadied by the spring ends it would be easier to wrap the spring up. wouldnt it?

 

[mattg]

For those of us who are lacking in fabricating equipment, who makes a decent set of traction bars for a reasonable price?

thanks

 

[TSBrown]

i think im also in need of ladder bars im looking for them now after what i did yesterday. look under drive shaft problems for pics

 

[Forrest]

For those of us who are lacking in fabricating equipment, who makes a decent set of traction bars for a reasonable price?

thanks

Ck my pics ... they work excellent!!!!!



https://www.turbodieselregister.com/forums/showthread.php?t=126217

 

[plongson]

Forrest:

So with all the HP and Torque on your truck, were you seeing spring wrap??



Is that why you installed the ladder bars?? Did they cure it?? They look nice, are they well built for the $$?? Would you recommend them??



LOTS of questions... Thanks, Paul...

 

[Forrest]

Hey Paul.



I'm guessing it was spring wrap. As the mods & torque went up, the worse it got. The indicator was when you romp on it & you have a hard time staying in the same lane. This is assuming the rear end isn't breaking loose ... too much. Also, hitting "irregularities" in the road under lots of power caused directional stability issues. :-laf



Anywho, all that went away. Stays straight now. Absolutely recommend them. Very well made, tough stuff. The cost was low too.

 

[plongson]

THANKS!!! I am going to give them serious consideration...



Paul...

 

[plongson]

What the heck... I ordered a set. THANKS for the input. I will let you all know if they cure my "Hump and Bump"... $300 and change delivered is not too bad... but there goes my OT check

 

[KKlingbeil]

Yeah, that is a pretty good price... . Hope they work out for you!!

 

[Rman]

I've got airbags, which I think makes the spring wrap worse. I get it pretty bad when I try and accelerate with heavy loads. I've found a good technique to minimize it, but no matter what if I accelerate hard with a load hooked on, it'll do it. My goose is located right above the axle, maybe next time I'll move it forward a little and see if that helps.

 

[Forrest]

... but there goes my OT check

Yea ... but everytime you walk up to your truck

 

[plongson]

Forrest...

Do the bars have adjustable Heim or ball ends on them??

 

[Forrest]

No.



When you're mounting them, you put on the rear brackets 1st & leave them just snug enough to move under the axle & put on the bars. Then put the front/frame brackets on the bar & lift the front of the bar up to mark the spots to drill on the frame. That way, the rear brackets "pivot" into alignment. Pretty much takes the need for swiveling outa there.



The frame is 1 tough customer. I used a long 2x4 as a lever against the drill motor. Made it faster & easier to drill the bf holes.