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overlander63 · 12-26-2005, 07:13 AM

Quote:

Originally Posted by 74Argosy24MH

Don't get all hung up on the slip joint alignment, the drive shaft has a double spline at the slip joint and can only go together one way.

If you have been having trouble with the tail shaft bolt loosening and leaks there is a good possibility the bushing has wallowed out. You have a lot of rotating weight with the emergency brake drum, that is a good place to start.

John

John, I've been thinking about Steven's problem (a dangerous thing, me thinking) and it could also be from the center support bearing, as well as the bushing in the tailshaft. I am wondering if while he has the shaft out getting the bushing issue taken care of, if he shouldn't replace the support bearing as well. What do you think about it?

swebster · 12-26-2005, 07:41 AM

Terry - I replaced both the forward and rear carrier bearings summer before last. The forward bearing at the time was whining and noticibly sloppy when I hand checked it out of the vehicle. I replaced the rear carrier at the time for good measure and did all of the joints at the same time. This is also when I replaced the output shaft seal, etc.

I have not tried the hammer blow but again....all good things to check. I'm going to check the trans yoke play first. I'll post what I find.

Thanks again for all of the continued "noodle-ing" about this problem.

74Argosy24MH · 12-26-2005, 07:53 AM

I thought he had replaced them. If not they definitely need to be checked, 3 piece drive shafts need quite a bit of attention to detail to run smoothly. The rubber will probably be the cause of the problem, push up, hang on it, push sideways to see how much movement. There is going to be some because it is rubber, but it shouldn't be excessive (like the pinch of salt).

Steve, if you have replaced them (and as long as we are discussing them) check their alignment. The mounting holes are slotted (and pretty oversized), there is a tendency for them to turn slightly from the twisting of the nut (especially if the lockwasher really bites into the thin metal) as it is tightnened; this puts a slight angle in the solid mounted sections of the drive shaft, 2 of them compound the problem. If they are out of alignment loosen, align, tighten one side until it is just starting to touch, do the other, back and forth a couple of times until it is clamped tight enough so their is no more movement as you tighten.

John

driftwood · 12-29-2005, 06:01 PM

Steven,

I stumbled across THIS thread. Maybe Brett has some experience with this problem. You might ask him if he corrected it.

http://www.airforums.com/forums/f159/u-joints-drive-shaft-1087.html

Sorry, I can't make the hyperlink HOT. Copy & past the above.

swebster · 12-29-2005, 08:21 PM

Norm,
Thanks for the link. Actually, I followed Brett's lead on this and replaced all four u joints and both carrier bearings a while back chasing this same vibration. I also figured it was good maintenance since my moho has sooooo many miles on it Only when I tightened the tranny yoke bolt did it stop.

Beginner · 02-11-2006, 08:13 PM

swebster
I had this problem with my GMC van(two piece drive shaft/carrier bearing). After several trips to the commercial driveshaft shop in Chesapeake VA, I got the shop guy to go for a ride with me. He felt the vibration, then looked up under the van when we returned to the shop. He told me that segmented drive shaftsmust be properly phased (ujoints aligned properly) which he marked when I had it in his shop having it balanced and the center bearing replaced. But the vibration continued at initial take off and around 45 mph.
After laying there staring at the transmisson tail shaft for a long time, he said that if you don't give universals something to do they will find something to do and you will not like it. He was trying to remember a previous situation like mine and what eventually solved the problem.
He remembered that if a drive shaft is less that 2 1/2 degrees out of aligment, you will get vibration at that point. Cure, shim the carrier bearing down. After adding a plate to the top of the carrier bearing assembly (1/2 inch thick aluminum 1 inch wide flat bar) to keep the bearing and rubber mount in its place and and another 5/8 inch of shims(fender washers) the vibration went away.
So, study the alignment of the tailshaft of the transmission with the segment of the drive shaft that connects to the Yoke on the transmission and if it looks too straight, it may well be. Shim the carier bearing down, Dont forget to make a flat plate to keep the bearing/rubber shock mount down in the horse shue looking thing that holds the bearing assy.

swebster · 02-17-2006, 07:16 AM

Last weekend I got under there and pulled the drivewshaft off. I was able to push the parking brake/tailshaft assembly up and down maybe a 1/4" with the yoke bolt removed....it did not move at all with the bolt installed.

wanderingeye · 02-17-2006, 05:56 PM

Steve I noticed vibration in the drive shaft after the rear air suspension went flat because the compressor failed. I recieved help from Fred Hinds about filling the air tank at a truck stop. After the coach was in normal attitude the vibration stopped. When the rebuilt compressor arrives and has been installed I will be checking the ride hight/shaft angle for vibration issues. I'll post my findings. Cheers Tom

B25guy · 02-17-2006, 06:52 PM

Here's a long shot...when I read that your mirrors shook...thirty years ago or so I had a 1/2 ton Chevy pickup that at around 45mph the mirrors shook (kinda like my Harley now, but it wasn't a v-twin HD motor doin' the shakin'). Higher or lower in speed and it was fine (sound familiar?). I had a GM shop manual and tore into the rear end, not a full-floater like your moho but similar enough perhaps. Long story short is that I found there was a crushable sleeve between the two pinion shaft bearings that provided a pre-load and kept the bearings snug up against the cups/races. Tightening the yoke bolt more than once or twice rendered this pre-load sleeve used up and required another. When I put a new sleeve in and tightened the yoke to spec, I never had the vibration again. BTW, this truck was a long bed and had a two-piece driveshaft and everybody thought tailshaft and/or hangar bearing....not this time.

good luck

GlenCoombe · 02-20-2006, 06:20 PM

I'm a little behind on my posts so let me catch up.
I took Airstream One into the shop last week to have the U-joints checked. We've been chasing this chassis vibe for quite a while now.
Found earlier after a transmission service that the vibe was about gone after that service but it returned by the time I got to Orlando. The crossmember supporting the tranny had been removed and reinstalled to do the service.
Well they found that the front joint was a bit worn but the remainer where o.k. But what was found was a broken tail shaft mount! I've not been on the road since but am expecting not to have the vibration I've been chasing.

swebster · 02-21-2006, 08:30 AM

Glen,
Intersting that you mention this. I was just pricing new engine and transmission mounts. I'm not sure I think that they are part of the problem....but since I have almost 200K miles on the coach and the mounts are cheap (less than $60 for everything) I thought about replacing all of them for good measure.

I do feel a fair amount of vibration in the steering column even at idle and given the other [lack of maintenance] items I've found on my coach since I bought it I would not be surprised if they've never been replaced.

Of source it looks like it will be a terrible job to do - right up there with the u-joint/carrier bearing replacements.

GlenCoombe · 02-22-2006, 06:33 PM

Steve...et.al. I'm happy to say the road test yesterday had no vibe

time will tell if we got it though as we thought so and it came back after the tranny service. Mounts control so much with the big blocks I'm certain that with the mileage on your rig being as high as it is that new mounts will help to reduce if not remedy your vibrations. The only obstacle is installation. Good luck.