shudder in reverse. transmission or what?

[JLitton]

When backing my fifth wheel up any type of incline at all, I get a very noticeable shudder in my truck. I don't know of it is in the transmission or driveline. I have a 47RE with upgraded valve body and Goerend triple disk converter. The camper weighs 12K and the grade is not much at all. A very slight incline that I have to back into my driveway at a 90 degree angle. It is mostly when I begin the turn and throughout the rest of the backing procedure. The only other time I feel anything out of the ordinary is pulling out going forward and turning to the left. At that point I have a shudder that I assume is coming from the rearend. But I'm sure about that either. The last time this happened it actually was not just felt but I heard a slipping noise, like gears chattering.



Can anyone point me in the right direction? Sorry for the long post, but wanted you to know the situation to help me diagnose.

 

[Hoefler]

If it does it going forward and you now it is the rear end doing it, the rear end will do it in reverse as well. Since you are making a sharp turn, I would think it is the anti-spin trying to do its thing.

 

[macdaddy]

Is the truck hunkered down (sitting low),in the back. My 99 would do this on occasion. Your sig doesnt say if you have air bags or not. Drive line angles will cause issues when under load.



I got rid of the problem after I installed the air bags.



Mac

 

[JLitton]

Is the truck hunkered down (sitting low),in the back. My 99 would do this on occasion. Your sig doesnt say if you have air bags or not. Drive line angles will cause issues when under load.



I got rid of the problem after I installed the air bags.



Mac

The hitch weight is around 1900 pounds. The truck is sitting lower than empty, but not squatting. I think I have two issues here. One is the chatter when pulling out that I read so much about on here. The main concern I have is the shudder / lurching when I back up. It used to do it even when empty, but I had the rear bands adjusted and it went away. It doesn't so it empty now, but with the new fifth wheel, it is much worse than before. So much so, that my wife which is amused at my TDR addiction, asked me if I was tearing up my truck. Going to four low to get better gearing is not an option as I am on asphalt and concrete when backing into the driveway.



I spoke to Goerends and they questioned the overdrive clutch in the transmission but alos mentioned the carrier bearing.



I'm hoping to suck out a little of your all's knowledge to help me even more start my quest to fix this without throwing money at it.



Thanks in advance.

 

[Ram4Sam]

I have a small case of this also, when backing my trailer also. In my case, I believe it is a case of "spring wrap" As you back up, the load twists the front of the rear end up, twisting up the leaf springs until tight, then the leafs "unwind" back to a resting position. Then it starts again, and again, and again... a real mild case of wheel hop. If you could duplicate this with somebody on their hands and knees watching the pinion, I'd bet they would see it. With my stick, I can up the rpm and slip the clutch a bit and drive around it.



Sam

 

[RustyJC]

As you back up, the load twists the front of the rear end up... .

It's the other way around. Remember Newton's 3rd Law - the action/reaction one? The rear axle housing is going to rotate OPPOSITE the direction of wheel rotation, so the pinion yoke is trying to rise when the truck's accelerating forward, and it's trying to drop when the truck's accelerating backward. This dropping of the pinion yoke in reverse tends to make the pinion angle worse, thus making the truck more prone to driveline shudder under load.



Rusty

 

[GCroyle]

JLitton,



I like the idea of a trusting volunteer watching the axle, springs, all spring hardware isolators, and wear points, spring bushings, and anything associated with the possible source of spring wrap as suggested above. Might want to try a carefull driving test, same load, same incline, straight back vs. adding turning element. Good time to rule out u-joints and carrier bearing if equipped.



I have ZERO airbag experience, but I am wondering that if you take too much off of the springs and helper springs and put it on the airbag, wouldn't that make it swivel more on the bag points and take stability off of the spring anchor to frame points and increase spring wrap?



Good luck, I'll be watching this one.

 

[Ram4Sam]

It's the other way around. Remember Newton's 3rd Law - the action/reaction one? The rear axle housing is going to rotate OPPOSITE the direction of wheel rotation, so the pinion yoke is trying to rise when the truck's accelerating forward, and it's trying to drop when the truck's accelerating backward. This dropping of the pinion yoke in reverse tends to make the pinion angle worse, thus making the truck more prone to driveline shudder under load.



Rusty

Well, I was close... I knew it was moving around under there, just haven't worried about it for a number of years. I'm well into my CRS years#@$%! I always thought a simple set of traction bars like I used back in the old days would help stop the shudder.



Sam

 

[EricBu12]

my old '01 did that hopping with my 15K 5th wheel trailer. . I ended up getting a front axle air disconnect and using low range. . this help a lot.

 

[fox]

Check and adjust the rear band.