dakotajam

New to the form,
Has any body found a cure for the shudder at take off under
load. some say it's drive shaft angle others say it's axle wrap.
It seems to be wraping, with out the 5er she will break traction.
Any info would be great.

Thanks,
John

pupeperson

Traction bars.

annabelle

Ladder bars. Same animal, different terminalogy, good advise.

jrussell

Those traction/ladder bars won't help with the "launch shudder". It's not cause by axle wrap. It's caused by the carrier bearing on the LWB trucks. You can shim the bearing down and it will help or stop it entirely.

tcr

I've got this shudder on a SWB when I have good traction under heavy exceleration.

jrussell

Yeah, that makes sense. The LWB shudder I think he was referring to still happens even if you take off with an egg under your foot.

pupeperson

Traction bars (the little Tuff Country jobs from JC Whitney) along with relocating the spring spacers on the rear suspension to the top of the spring stack, cured my launch shudder. Used to have it no matter how slow I accelerated pulling my toy hauler or not. Made those changes and the shudder is completely gone no matter how I drive it.

snoyes

Been talked about alot on here, those Tuff Country jobbers only work for the 2500. The 3500 overloads Spring gets in the way. I'm sure my lift and big tries make it worse, but even on stock tires it will shudder on take-off. Been wanting to put a set of traction bars on, but all of them seem to hang too low and interfere with my airbag set-up. I think I may try the carrier bearing trick first, where did you get it done/how did you shim the carrier bearing? Where did you pick up the shims? Thanks for the info...

pupeperson

The OP has a 2500 according to his sig. Anyway, since the Tuff Country bars cure the problem, I think it's safe to say the cause even on the 3500's is axle wrap. Given that, if I had a 3500 I think what I'd try first might be a couple of those plastic wedges that loggers use secured between the bottom overload leaf and the rest of the spring stack in the forward half of the spring. There is someone else on here or the TDR that uses them on the back half of his spring stack to keep his rear suspension from sagging. Used in the front, I think they'd probably control the axle wrap nicely. If it'd work, it'd sure be a cheap fix....

jrussell

Maybe it wasn't (just) the TC bars that fixed your shudder? You said you also relocated the bottom leaf to the top, which probably changed your pinion angle somewhat. A slight change in geometry there could make the difference. When you shim the carrier bearing down you're changing the driveshaft angle at the bearing and also at the pinion. The change is very very slight, but it usually makes all the difference. The launch shudder issue has existed in LWB Dodge CTD's since they started making them in 1989.

I haven't shimmed the one on my '06, but I did shim the '93 I had and it instantly cured the shudder. You can use large washers and stack a few between the bearing and the mount. I would start off with about 3 or 4 and see how it does.

pupeperson

I put the 3 spacers to the top. It lowered the rear of the truck by about 1.5". Since you mention it, it seems like that did help the shudder a bit, even before the traction bars. After the bars, all trace of the shudder was just gone.

XLR8R

U-joint shudder on takeoff is specifically caused by driveline angles forced outside of their designed range of motion by the pinion's torque reaction under thrust (acceleration)... the faster the acceleration, the worse it gets.

A lightly loaded truck is susceptible to this due to the OEM high ride height empty (HD Rams are engineered to regularly carry significant weight) - notably on the 4WD trucks.
If the truck has a 2-piece driveshaft, the carrier bearing can be shimmed down to keep the driveline angles in their ideal ROM.
If the truck's ride height is sufficiently lowered, the takeoff shudder is almost always reduced or eliminated.
For a stock 4WD, I recommend a 1/2" spacer.

Traction bars positively locate the pinion, preventing the leaf pack from deforming from applied engine torque... thus transferring more power to the tire footprint in addition to keeping the U-joints in the "safe zone".
Although it's possible to eliminate takeoff shudder without installing a traction control device, most folks order traction bars for all of their other benefits as well.

I have yet to see a rear leaf-pack truck without an anti-wrap device fail to wrap up the pinion on a dyno... even with stock power, regardless of manufacturer.

jlibert

some people have eliminated shudder problems by using an additive in the rear diff.

snoyes

I think the additive in the rear end was to stop the shudder during turning, not take-off.

XLR8R

I agree that would affect turning not takeoff.