bucking - axle wrap

[TRCM]

I was towing a trailer today, about 11,500 lbs, on a gooseneck.



When I accelerated in almost any gear, if I got on it too hard, it would start bucking like I was letting the clutch in & out. it is really bad if you hit a good bump when accelerating.



see sig for truck.



Any ideas ?



Do I need to redistribute the load ? truck only squatted a few inches.

 

[Diesel Nut]

Sounds like a slipping clutch to me.

 

[McCRam]

The springs on my truck are bad. The rear end starts hopping when I push hard on the pedal. I have no doubt that my problem is axle wrap. If it is the clutch, I would think that it would happen more easily at lower rpms than at higher rpms. Let us know what you figure out.

 

[TRCM]

I highly doubt it is a slipping clutch (hope it ain't anyway). It's a SBC Con OFE that is not even 5 months old yet.

 

[jelag]

We pull with an 04 a trailer that weighs 22K lbs. . we've had this problem a lot and I thought for long time it was the clutch... .



A while back we put on a set of Air Lift brand air bags we bought from Summit racing. (5000 lb kit) We adjust the air, using the air system from the pacbrake and tank... . from 5 psi to 100 psi. . we just measure the back of the truck and bring it back to level... .



This stopped the shudder we had when we drove this truck in 1st - 3rd gear... we now have a smooth acceleration with all this weight... . and the headlights now function well since the truck is level..... I wouldn't have believed that this was the problem but it took care of our issue with 3 trucks... .



Hope this helps...

 

[Grizly]

I too have this same problem but only with 1st and more so with reverse badly, I have so much that I have to stop and get it back together before trying again? I have new SBC con ofe with about 1000 miles on it is this normal? just about have to ride / let slip just to back trailor into Driveway!!!

 

[EricBu12]

I had that problem when manuvering my 36' 5ver... My solution was to get the 2WD low kit which when you put the shifter in 4WD, the front axle does not engage so you have better control on the speed.



I don't have any shudder on normal acceleration and I do have the SBC Con OFE as well.

 

[DIESELMAN]

One of my goosenecks is a 'Big Tex' two axle single wheeler, when loaded heavy and forward, it flexes, bad. This causes it to buck on acceleration and on concrete freeways.

 

[Dieselnerd]

I seem to remember a similar problem from a few years back on the 2nd gen trucks. The fix was heavier throttle springs. As I recall the problem, as soon as the truck "bucked" a little bit, the motion went to your foot and it kept getting worse unless you had a real steady foot. I think there was a TSB for the problem with heavier spring part numbers. I believe it was just for the stick transmission, not the auto.

 

[Bug Out]

Throttle spring

I had a 97 1-ton 5 speed that did the same thing. I put on a heavy throttle spring and that fixed the problem.





I could have bet money at the time that it would not be the problem, but it went away after that.



Its a lot cheaper then clutches etc.

 

[TRCM]

Well, I have some other minor issues we are gonna look at, and in the process, I'll look into some heavier springs for the throttle.



I know one or two of the times it did it, it was probably my foot, but my throttle is so sensitive, you can't hold any constant rpm in neutral above idle.



I learned how to drive around it. Only did it in 3rd of 4th, and only with significant weight on the trailer. I could barely get it to do it unloaded, and I'm not sure unloaded was not the road. Just made for some slow take offs, and hence some worse than normal mpg - got 11 mpg with ~ 19,000 lbs total weight - both trucks & trailer)



I did notice, even tho the truck dropped about 2-3", the overloads were barely touching, or so it seemed, but I know the weight was farther forward than I normally put it with my gasser on the trailer.



Doubt it is the clutch. I said before it was less than 5 months old... heck, it was put in in early February, so it's less than 3 months old. It does not show any signs of slippage, and with the load, you can definitely tell when it grabs.



The air lift bags probably smoothed out the ride enough to get rid of the bouncing that causes your foot to move the pedal. I've been thinking about the kelderman air rear suspension (the cheaper one) some, but I'd like to make sure it isn't something else first.



And I've gotten so used to 35 psi in the rears unloaded, that when I drive it with 55-60 in them, even with the empty trailer on it, dang, I feel like I need to go see the dentist to fix my teeth from the jarring it gives me -- don't know how yall do it all the time.



Well, I'll keep things updated as I find out.