Transmission shudder at takeoff, 2004 48RE

[Superdawg]

Just got back from Yosemite. Nice trip, warmest I have ever been there at about 65 degrees. Had a slight issue with the trans and want to know what you guys think. I had been on the road for about 6 hours, towing 10k with the signature truck with a stock 48RE. We were in the hills at about 5,000 feet elevation. From a stop, starting up a slight grade, was in low 1 or 2, 55 degrees outside and the trans was at 140 degrees measured in the pan. The trans shuddered about 3 times, a couple seconds apart. I really don't think it was a gear shift but maybe??? This was about 5-10 mph. It was the only time I have experienced this and it didn't happen again the rest of the trip.

I have not replaced the gov solenoid or pressure transducer/thingymabob but that is on my to do list.

I change the trans fluid every 30 K. About 15 quarts +/- of ATF $4. Trans always runs 130 to 160 degrees, rarely hotter.

Truck has 120,000 miles.

thanks,

Tom

 

[Wingate]

I would also adjust the bands while the pan is off. .

 

[sag2]

Are you sure it wasn't launch shudder. From 0-10 mph the truck just shudders? Pretty common with lots of weight in the bed or kingpin/hitch weight.

 

[Kry226]

Are you sure it wasn't launch shudder. From 0-10 mph the truck just shudders? Pretty common with lots of weight in the bed or kingpin/hitch weight.

I notice this a lot with our travel trailer in tow. Is it the transmission or rear end?

 

[cerberusiam]

Launch shudder is axle wrap under TQ of launching. The 3rd gen springs have a lot wrap up under heavy TQ and that wrap\release causes the stock drive line with the hanger bearing to ripple. Go to a 1 piece drive shaft and it pretty much disappears.

 

[Superdawg]

I guess that would be okay if it is just launch shudder. It is a lot of weight to start on a hill.
Thank you for the replies.
Tom

 

[Kry226]

Launch shudder is axle wrap under TQ of launching. The 3rd gen springs have a lot wrap up under heavy TQ and that wrap\release causes the stock drive line with the hanger bearing to ripple. Go to a 1 piece drive shaft and it pretty much disappears.

Not wanting to hijack the OP's thread, but I have a 1 piece drive shaft. I get the shudder all the time.

 

[Prairie Dog]

I have only the slightest shudder when launching with the TT in tow. It was way worse with the two piece.

 

[sag2]

Launch shudder is axle wrap under TQ of launching. The 3rd gen springs have a lot wrap up under heavy TQ and that wrap\release causes the stock drive line with the hanger bearing to ripple. Go to a 1 piece drive shaft and it pretty much disappears.

Just to be clear, true launch shudder (a shudder felt from stop up to no more than 10mph) is caused by the drive line angle changing. If it shudders unloaded add center support length, shudders loaded, remove center support length. There are several different length brackets, and the PN for a 1" spacer package that includes longer bolts is 05135709AA.

 

[HBarlow]

Gen III trucks used frequently for heavy towing are known to shudder on launch because the rear leaf springs are weak and sag under load with age. Adding a leaf to the rear springs, adding Timbrens, or installing air bags will often cure it.

 

[cerberusiam]

The 3rd gen springs are not weak and age is not going to effect then much when it comes to a true driveline shudder problem. The drive line angle really has nothing to do with the shudder either. Air bags, timbrens, spacers, and even traction bars are just addressing the symptoms not the source.



A shudder manifests when the drive line goes in and out of normal alignment very fast. This happens either in the center hanger bearing when the surrounding rubber gets weak and it moves too much, or, the axle tilts up an back rapidly from the TQ being applied and releasing when the springs over come the wrap. The 2 piece drive lines are much more susceptible because there are 2 spots an oscillation can occur, at the pinion and hanger bearing. Remove the OE hanger and replace it with a better bearing that doesn't flex as much and shudder all but disappears. Replace the drive line with a 1 piece and the same happens. The lack of stability in the OE drive line is the source of the problem.



Shudder with the 1 piece is simply axle wrap from the springs which is usually a whole lot less noticeable. The springs really do not constribute that much once the drive line is stabilized but the long front section does enable it under certain conditions. There is a LOT of TQ centered on the rear pinion when you pour the coal to it. If most people ever saw how much that pinion really moves when you plant the tires under a load and hammer it they would be surprised. When you see a rear axle that has twited the diff so it is pointing at the bottom of the box you begin to see the forces tyhta are centered on that rather small u-joint.

 

[Prairie Dog]

I recetly saw a video of how much a leaf spring suspension on the back of a car moved under normal driving. It was shocking how much that axle flopped around back there and how pinion angle was changing almost constantly.

 

[Wingate]

Absolutey... . The amounts of torque being exerted into the pinion is really scary if you get to see it happening... or the after affects of a part failure... Not sure if its a viable option on our trucks, but when I used to drag race, I built a homemade pinion snubber to limit the amount of "wind up" the differential was alowed to do. .

Note, do not launch a healthy small block Mopar p/u with your finger on the bottle, while still on the stock rear differential... things get really serious, really quick!!.

 

[HBarlow]

The 3rd gen springs are not weak and age is not going to effect then much when it comes to a true driveline shudder problem. The drive line angle really has nothing to do with the shudder either. Air bags, timbrens, spacers, and even traction bars are just addressing the symptoms not the source.

A shudder manifests when the drive line goes in and out of normal alignment very fast. This happens either in the center hanger bearing when the surrounding rubber gets weak and it moves too much, or, the axle tilts up an back rapidly from the TQ being applied and releasing when the springs over come the wrap. The 2 piece drive lines are much more susceptible because there are 2 spots an oscillation can occur, at the pinion and hanger bearing. Remove the OE hanger and replace it with a better bearing that doesn't flex as much and shudder all but disappears. Replace the drive line with a 1 piece and the same happens. The lack of stability in the OE drive line is the source of the problem.

Shudder with the 1 piece is simply axle wrap from the springs which is usually a whole lot less noticeable. The springs really do not constribute that much once the drive line is stabilized but the long front section does enable it under certain conditions. There is a LOT of TQ centered on the rear pinion when you pour the coal to it. If most people ever saw how much that pinion really moves when you plant the tires under a load and hammer it they would be surprised. When you see a rear axle that has twited the diff so it is pointing at the bottom of the box you begin to see the forces tyhta are centered on that rather small u-joint.

You make that statement based on what - your opinion? Do you tow a heavy fifthwheel? How many miles have you towed one?

Why is it then that the TDR Gen III forum and other forums have so many posts regarding air bags, added springs, wedges, etc. ? You may believe the springs are not weak but you are dead wrong.

I towed heavy with an '06 racking up 135,000 miles in the first year pulling trailers. After the first few months I had to add Timbrens to hold up the rear end. It would sag and rebound so violently over some interstate highway dips the kingpin of fifthwheels I was pulling would raise up to the top of their travel taking the slack out of the kingpin and the kingpin base plate would lift off the hitch. Later I had a spring shop add an additional spring leaf in each rear spring.

Gen III dually rear springs are longer than Gen II springs according to literature I read when the trucks were new. This was a change made to soften the ride. Gen IIIs feel softer than Gen IIs.

 

[Prairie Dog]

Cerb your right about the air bags not changing things - I added them when the truck was new. While they may change the driveline angles somewhat the springs are still wrapping up and letting go.

 

[NIsaacs]

I guess that would be okay if it is just launch shudder. It is a lot of weight to start on a hill.

Thank you for the replies.

Tom

If you have not noticed this launch shudder before you are probably getting a bad u-joint. Usually a binding/dry joint rather than a loose one. This will usually manifest it'self when you are loaded and changing the drive shaft angle from it's normal u-joint wear pattern of being empty.



If you use a front leveling kit or a lift kit, this issue can get worse, or if you unload the springs too much with air bags. As far as the rear axle loading and unloading, this should not happen with a heavy load and the smooth steady torque of an automatic. It's not like you have a loss of traction, the most common cause of loading/unloading.



In the case of a two piece drive shaft, I don't recommend changing the carrier bearing mount to help the drive shaft angle match the pinion angle. The short shaft angle must match the engine/transmission angle. If you change the carrier bearing mount to fix the rear shaft angle you will more than likely cause the short shaft to become misaligned. If there is an alignment issue for whatever reason, then fix the source, the spring perch. Shims are available for this.



Nick

 

[cerberusiam]

Cerb your right about the air bags not changing things - I added them when the truck was new. While they may change the driveline angles somewhat the springs are still wrapping up and letting go.

Yeah, same experience. While Bouncy Barlow is off in the weeds looking for his hitch, air bags are not going to address axle wrap on the long springs. The only thing he did to help it was another spring to stiffen the pack after he overload and over stressed the OE springs. Springs are wear items when they are constantly under a load, doesn't mean launch shudder will appear or disappear. The manual trucks seem to be a lot worse than the autos for the shudder. The smooth application of TQ with the fluid coupling generally stops it unless a u-joint or worn center bearing is the cause. I could make it happen on demand before I put the one piece DS in and it was the center hanger moving around too much in certain conditions causing it. Getting over an inch deflection out of the drive line was not conducive to smooth operation.



Now, the tires just spin which is another story.

 

[HBarlow]

Now you're trying to shift attention by making fun of my comment and changing the subject. There is no doubt you know a lot about automatic transmissions but you're blowing smoke again here.

The RV hauler's complaint usually has nothing to do with axle wrap or spring windup. Most people who tow fifthwheels are using automatic transmissions and making gentle launches. They're not drag racers.

The problem for RV haulers with heavy fifthwheels is binding in a universal joint caused by forcing the joint to work at an extreme angle.

I've seen the launch shudder complaint on RV forums for years made by Furd owners as well as Rams. Don't recall if I've seen the complaint with GM owners. The problem is rare on unloaded trucks but not uncommon on heavily loaded.

I've also seen it cured many times with the use of air bags or other suspension aids to lift the rear of the truck back up closer to its unloaded height.

I'm not denying it also happens with bad u joints but that is usually not the case.

 

[Prairie Dog]

HB? I doubt he ever pulls anything except his own finger. In fact from what I read by him before blocking him, I really doubt he even has a truck and just makes up ramblings and BS as he goes. I think the term for his type is "troll".

 

[sag2]

I don't agree with Harvey all the time, but in this case I think this TSB backs him up. Although the TSB is written for 03-04 trucks, I have used it on dozens of later trucks. In only the last couple of years did the bracket configuration change so these brackets no longer fit.



SUBJECT:

Launch Shudder

OVERVIEW:

This bulletin involves adjusting the propeller shaft working angles.

MODELS:

2003 - 2004 (DR) Ram Truck

NOTE: This bulletin applies to vehicles equipped with a two piece rear driveshaft.

SYMPTOM/CONDITION:

A vehicle may exhibit a drive line shudder or vibrations while accelerating from a stop. The

condition is most noticeable under heavy throttle acceleration and is usually only present a

low speeds (below 25 m. p. h. ).

DIAGNOSIS:

Vehicles equipped with a two piece driveshaft are designed to minimize reaction forces

which result from the universal joint transmitting torque at an angle. These forces can not

be eliminated entirely because of the necessity to compromise joint angle selection

between curb and design loading conditions. When subjected to this vibration, the vehicle

experiences a shudder type disturbance, generally occurring less than 25 mph. This

disturbance will increase as the suspension moves further from its design load (typically

two front passengers). The forces are also torque sensitive, which means the disturbance,

will be highest under wide open throttle.

U-joint angles change depending upon the amount of weight applied to the vehicle bed,

therefore u-joint angle readings may need to be taken with different vehicle loads in order

to obtain a satisfactory compromise. The vehicle should be evaluated under the loaded

condition that produces the objectionable disturbance.

PARTS REQUIRED:

Qty. Part No. Description

AR 52105717AB Bracket - 14. 7 mm

AR 52105587AB Bracket - 19. 8 mm

AR 52105716AB Bracket - 84. 6 mm

AR 52105583AB Bracket - 89. 8 mm

AR 52105714AB Bracket - 113. 1 mm

NUMBER: 03-003-04

GROUP: Differential & Drive

Line

DATE: June 15, 2004

Qty. Part No. Description

AR 52105584AB Bracket - 115. 3 mm

AR 52105715AB Bracket - 132. 0 mm

AR 52105559AB Bracket - 133. 9 mm