I'm stumped. My driveline vibration is back in force. I'm begining to suspect the transmission output shaft/bearing/bushing and could use some advice from my good friends on the forum once again.
First some background; the issue centers around a growing vibration in the coach itself between 35 - 45 mph. It feels like a lower volume version of driving your wheel over the rumble strip on the shoulder of the highway, not nearly as bad, but you notice it. The difference is that it's not just in the steering, it's everywhere - the entire coach is vibrating. In fact, recently the mirrors have begun to vibrate so much when this happens that I've considered changing the safety placard to say "objects may appear blurrier than the actual are"
The vibrations goes away above 45. It returns again above 65 but it's more like a high pitched whine. No real vibrations. Since I don't spend too much time between 34 and 45 it's not a big issue but since it's getting more noticable I would like to deal with it.
I have "repaired" this vibration in the past by tightening up the bolt that holds the transmission yoke into the tailshaft. Every 1000 miles or so it would start to vibrate again, I would tighten it and it would stop. After my last trip (2400 miles) it happened again and got noticably worse. Since the trip was so long I figured it was just "more looser" (as my five year old would say) so I grabbed my tools, shimmy'd under the motorhome, dropped the driveshaft but when I tried to tighten the bolt - it was already tight.
So now I'm thinking bearing/bushing/yoke, etc.
Related to the driveline and for the sake of having the "rest of the story" here is a list of what has been replaced on the the chassis to date: replaced all four driveshaft u-joints, replaced both driveshaft carrier bearings, replaced front shocks and steering stabilizer with bilsteins, replaced rear shocks, replaced tag axle shocks, replace front air bags, replaced rear transmission seal. Keep in mind that my 345 has 175,000 miles on it so many of these parts were replaced along the way to ensure safe and reliable operation. The transmission fluid is changed and checked regularly (ever other fuel stop). It always is clear red and smells clean.
Now I can handle a lot of repairs on the 345 myself but transmissions are like black magic to me so I have a few questions:
When I replaced the rear seal (two years ago) no real fluid came out of the tailshaft (it just sort of weeped). Is there supposed to be a lot of fluid back there? If there isn't should I be budgeting for a tranny?. I assume the tailshaft is fed from the transmission itself and not it's own gear oil? I have no leaks as far as I know and I've never needed to add fluid in operation over almost 30,000 miles. Again, the fuild is alway picture perfect.
I've been reading on other forums that many driveline vibrations with descriptions that match mine have been repaired by replacing the rear bushing or bearing on the transmission. Some mention driveshaft runout, but because I have "cured" mine in the past in the trans/yoke area I have not reconsidered a driveshaft balance issue. Any thoughts on this?
NAPA lists the rear bearing on their site. I've seen a few posts about it being a driveway replacement but unforetunately I can't find many details on the procedure. Any thoughts/recommendations on replacing the bearing (or bushing). What about the yoke? Is it wiser to just replace the entire tailshaft assembly? What would be involved?
Steve. It sounds as if you may have been repairing problems caused by a misalingned drive shaft.The yokes must be aligned correctly. One spline off will cause a vibration in the drive train you might not feel in the cab.The more splines out of alignment, the heavier the wibration. This is just a thought. Hope it will help.
I don't mean to state the obvious - but - have the drive shafts checked, by a professional, for balance and straightness. Most likely this cannot be done at home!
Henry is on target for one of the most common problems.
In the manufacturer of 1000's of rear drive limousines, 80% of our vibrations were cured by proper straightness and balance of the drive shaft.
Other problems we encountered were sometimes related to worn or failed transmission/pillow block mounts or failed engine mounts. When the torque increased, the alignment of the drive train would temporarily change.
Another can be related to excessive angle at the union of a two-piece shaft.
Have you listened to the trans for 'chatter' when in a specific gear?
__________________ NORM #3305
"... there is nothing you can't fix yourself ...
... if you're handy ...
... with a check book! ..."
I don't mean to state the obvious - but - have the drive shafts checked, by a professional, for balance and straightness. Most likely this cannot be done at home!
My two cents,
Henry
I'll second this. It may be obvious, but its also very commonly overlooked. "KISS", remember? (keep it simple...).
My brother-in-law specializes in this kind of work. I've watched him build/repair/balance driveshafts a hundred times. It is very specialized work, requiring very expensive specialized tools, so it may not be easy to find someone in your area. But its also cheap, fast, and easy, for those that do it. definately start there before ripping apart your tranny. You went right by us last summer...should have stopped in!
Henry, yes driveshaft balancing is not for the driveway. I had been thinking about the rear tailshaft bearing replacement as a shade tree repair.
No chatter as far as I can tell. Also, this vibration occurs even when I place the transmisison in neutral and coast with the engine at idle. So, I haven't been thinking about a torque, flexplate, mount, etc. related issue.
Sounds like you are all thinking my yoke issue is really a symptom of a driveshaft issue.
Chuck - We'll be in Connecticut next week and back through MA/NH again this summer.
Norm,
Right, I understand that. My point was that there was no positive loading or torque against the driveshaft when in neutral from the engine/tranny combination, just the opposite in that the diff is now turning the driveshaft.
Anyone else have experience with the tailshaft housing and rear bearing? I can have the shafts checked locally but since I've had "issues" in this area of the drivtrain I would like to ensure that even if it is a symptom of an inbalance that I'm checking/repairing any possible failures in the driveway instead of on the highway.
Have you tried the trick with the hose clamps to change the weight balance on the driveshaft? I wouldn't recommend it as a fix, but as a diagnostic tool.
Steven, a quick couple of things to check. Someone has already mentioned this, but maybe it weasn't clear. Check the driveshaft to make sure all the U-joints are aligned with each other, all the way from front to back. If U-joint #1 is in a position that looks like "+", all the U-joints have to be oriented the same way, all caps pointing straight up and down, and side-to-side.
If that is all good, you can try pushing up on the u-joint and yoke coming out of the transmission. If it lifts up more than a smidgen, you probably have a worn output bushing. the tailshaft housing usually needs to be removed in order to replace the bushing, if it is bad.
__________________
Terry Change is inevitable, except from a vending machine
AIR#2611
Hi Steve,
Have you checked the differential yoke?
I've seen them spread so to speak, so that although the U joint is good, and it is tight in the straps, the yoke is too wide, allowing the U joint to have play in it, in other words it slides in the "cups"
this will cause vibrations as the shaft is off to one side or the other.
Also a tire with a bad/ broken belt, altho looking good visually, will also cause a vibration that will literally shake the whole coach.
It seems like you have never really stopped this problem in the past.
does this trans have the parking brake on the rear of the it? could be a problem with the drum out of balance or loose.
is there noticable play in the slip yoke(s) on the drive shaft.
If it were mine, and I have done this, I would jack it up and put sturdy jack stands, VERY STURDY!! under the rear axle and have a TRUSTED helper slowely increase the speed to the trouble range and then the culpret will show itself .
Oh, on the trans yoke, usually very little trans oil will leak out when you remove it, unless you have the coach jacked up REALLY high in the front.
The pan on the trans is full to the top normally,but not up into the case and the output shaft is above that, so little leaks out.
You are correct in dismissing flywheel/torque converter problem as they are turning only at idle rpm's when you have it in netural while coasting, or not at all if you were to turn the engine off (not recomended as you loose power assist brake/steering)
Steve. Rather than try to explain the line-up of yokes, just slide under any truck with a two piece drive shaft that has no problems and make a diagram of the alignment. It doesn't have to be a P30 chassis but it might be easier. Make sure the U joints are pressed in exactly where they should be. Sometimes a roller will fall into the cup and won't let it be pressed all the way in. Good luck.
Thanks for the continued advice and items to check out. I now have a solid checklist and will go through each item.
Terry - when I replaced the U-Joints I made sure to mark all of the shaft orientations so maybe I'm confused on the "line up" thing. Am I looking for a twist in the shaft with this check?
Tinsel - nice try!
George - yes my P30 chassis has the driveshaft mounted parking brake (manual). It's definately on my suspect list since it's so close to the yoke. I'll check the diff joint and thanks for the info on the tranny.
Again - thanks for the conitued toubleshooting advice. Everyone's collective input is very helpful. I'm still very suspicious of the output bushing so I might drop the first shaft (the 345 has THREE!) and check for lateral play in the yole first. I won't dismiss the other possibilities but something has been talking to me in this area of the drivetrain for a while.
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so I grabbed my tools, shimmy'd under the motorhome, dropped the driveshaft but when I tried to tighten the bolt - it was already tight.
Check the shafts
You went right by us last summer...should have stopped in!
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