Drivetrain Vibration Issue

[StanCrock]

Purchased new last Jan my Jayco 24B class C motorhome with the new 7.3L Ford V8. I have noticed a significant vibration that feels like either the driveline or the transmission. I'm a 20 year RVr, and have never run into this before. Done the legwork listed below, but no luck so far. Anyone out there that has suggestions as to diagnosis for this issue would be much appreciated before I run into a failure.

The issue appears to have 2 components - a shudder and a medium frequency vibration. The shudder starts at about 45mph and continues on up through 80 mph when driving in Idaho ad Utah. The vibration starts from 2400 rpm to 2700 rpm in 6th; 2900 to 3100 rpm in 5th and 4000 rpm in 4th.

Jayco has put me onto my local drive line shop where they've balanced it and changed support shims twice. The shop doesn't like the drive line angles.

L&W Engineering, Jayco's chassis engineering firm says a shudder is normal, no comment on the virbation.

Ford says its not them, as their chassis was lengthened 23" by Jayco.

[Florida Ranger]

Why don’t they change the drive line angle , this can be done if they know how.. Delivery trucks (Uhaul, Beer Trucks, moving trucks ) have this done when thier frame rails are extended our delivery trucks are extended by the box body manufacturer. We have No shudder or vibration. Same thing is done when they build a Jayco Super “C” motorhome, frame rails are extended. Find another frame shop and ask them…..

[JbarJ]

Originally Posted by StanCrock

Purchased new last Jan my Jayco 24B class C motorhome with the new 7.3L Ford V8. I have noticed a significant vibration that feels like either the driveline or the transmission. I'm a 20 year RVr, and have never run into this before. Done the legwork listed below, but no luck so far. Anyone out there that has suggestions as to diagnosis for this issue would be much appreciated before I run into a failure.

The issue appears to have 2 components - a shudder and a medium frequency vibration. The shudder starts at about 45mph and continues on up through 80 mph when driving in Idaho ad Utah. The vibration starts from 2400 rpm to 2700 rpm in 6th; 2900 to 3100 rpm in 5th and 4000 rpm in 4th.

Jayco has put me onto my local drive line shop where they've balanced it and changed support shims twice. The shop doesn't like the drive line angles.

L&W Engineering, Jayco's chassis engineering firm says a shudder is normal, no comment on the virbation.

Ford says its not them, as their chassis was lengthened 23" by Jayco.

Hello Stan! I’m a 30 plus year driveshaft builder in Houston! That being said I have built and balanced everything under the sun! Heavy duty truck industry is our bread and butter but cars and trucks as well as rv’s are our specialty! How many miles on your unit? How many driveshaft sections are there? Why size tubes are on each shaft? Can you get a picture of each u joint where it connects to each shaft? Shudder usually comes from slack from wear usually in the rear shaft of a multi shaft unit in the slip yoke and stub shaft! You can test it by pushing up and down on the female piece and feel for slack. A lot of times the rear of a unit is stretched and balanced individually . In order to truly balance the shafts should be connected and balanced as one piece as it runs in the truck, car , motorhome etc.

[Lake Huron]

Quick story kind of related. A few years back my Yukon xl had a u joint go bad. I tried to hammer it out but wasnt having much luck so I pressed it out. Bad idea. I got it out but bent the ears. I had a driveline shop make me a new one. A year later it developed a vibration at highway speeds. I took it back and had it rebalanced. Joints were good. Vibration came back a short time later. I had two shops work on it over the course of the next two years, playing with different angles on it, checking out the rear diff and axle bearings, etc... the vibration always came back shortly after. I ended up ordering a new complete Percision brand driveshaft from my local auto parts store, installed it and the vibration is gone. Completely. (knock on wood)... this is the longest its lasted. Only thing I can think of is the previous made shaft may not have been a thick enough wall and starting to flex too much at highway speeds??

[StanCrock]

Thanks for the comments/tips.

My local driveline shop has already made changes. They are now recommending they remove the center bearing support for the 3 piece drive shaft that L&W Engineering installed with the 23" chassis stretch. Their extra bearing support takes the driveshaft down another 1.5" over the Ford bearing support its welded to. Tried to up load pics, but not able to with my Chrome PC.

The coach is only 6 months old and still under warranty so I'm reluctant to make changes to something that Jayco has welded in place until I'm clear it will be the solution.

Also I'm wondering if anyone has comments on the transmission. I get the vibration in the top 3 gears. It is the standard 6 speed tranny that has been installed in these units for several years. My local Ford dealer is booked with RVs for at least the next several weeks.

Appreciate it.

[JbarJ]

Sounds like a Friday at 5:30 going on vacation at 6:00! The faster you turn anything that is out of round or off center, the greater the vibration gets! We compare it to a jump rope as it goes around it grows! Try to Email me some pics and I’ll look at them. I would like to see the bracket and angle. By removing the cb bracket are they modifying your rear shaft or adjusting the height of the bracket? I say if it was happening since new I would send it back to Jayco ! If someone local is doing the work I would be tempted to ask to see the shop and look at how the straighten and balance driveshafts! We have a group down here that say they balance but only heat and straighten and calling it balance! If it isn’t getting a good spin and weights added it isn’t getting balanced!

[Florida Ranger]

XXX 2. With what jbarj recommends,,that is what I would do if one of my trucks was having problems. A pair of Experienced eyes will spot the problem. Remember the person that installed your driveshaft at the factory could have left thier glasses at home that day….

[JbarJ]

Pm me a phone number and I will be happy to talk you thru some things if you want!

[Happy wife / happy life]

Just curious, has anyone looked to see if one of the wheels threw a wheel weight ( wheel out of balance)?

[don_kleinschnitz]

Stancrock,

I don't know if this has anything to do with your problem but take a look.
I have a new bearing on the way and will install it in a few weeks.

https://www.jaycoowners.com/forums/f...tml#post981900

[StanCrock]

Thanks for the comments everyone. I have made a few long trips with my coach, now one year old.

I have also found a commercial Ford truck dealer who has sent the complete 3-piece driveline into the regional balancing shop where they balanced it all as one assembly re-installed and re-shimmed.

There is no shudder at 30 to 60 mph now, but still the same concerning vibration at 65 to 75 mph on the Interstate highways.

Any suggestion now for next steps? I feel I really need to stay on this issue, or will run into a failure down the road.
Appreciate it.

[1950]

1950 here. i have a 2021 24 B Redhawk and had the same problem the driveline seems to be out of allignment mine had a bad viberation and hum at 64 up to 72 MPH what i did was remove the two shims from the rear carrier and pushed the driveline up some now it is more in line and noise and viberation are all but gone. not sayin it was the right thing to do BUT it helped me

[JbarJ]

I think the shims are a great place to start as 1950 stated! It could be just enough to throw it out!

[StanCrock]

Thanks for the suggestion guys. Will try that this weekend and test.
What did you do wit the front bearing hanger shims? Leave both of them installed?

[drmike961]

Originally Posted by 1950

1950 here. i have a 2021 24 B Redhawk and had the same problem the driveline seems to be out of allignment mine had a bad viberation and hum at 64 up to 72 MPH what i did was remove the two shims from the rear carrier and pushed the driveline up some now it is more in line and noise and viberation are all but gone. not sayin it was the right thing to do BUT it helped me

Exactly my experience.

[StanCrock]

Thanks Mike. What did you do wit the shims on the front bearing carrier? Just leave the 2 shims installed?

[drmike961]

Originally Posted by StanCrock

Thanks Mike. What did you do wit the shims on the front bearing carrier? Just leave the 2 shims installed?

I left the front alone. I just used the eyeball test and raised the other carrier bearing that looked too low to make the driveshaft more straight. Hardly scientific I know. Alazear tried it first with success, and he was right. Had to pull both of them to completely eliminate the noise.

[StanCrock]

OK thanks Mike. Have tried several combinations, but not that one. I'll make the change on the weekend and report back to the group.
Appreciate it - Stan

[1950]

1950 here. i did not remove the shims from the front carrier, seemed to be in proper allignment by FORD. just remove the two quarter inch shims from rear carrier and push it up. you will see the driveline will look much better as there will be less angle at the carrier . if it doesnt help ,, yopu can always put them back !!!

[Randy]

Hi Stan- Just to elimanate, I would have all of your tires balanced... many a people have been fooled thinking a driveline issue was actually tire balance and vice vercy--