Drive Shaft needs balancing?

Fredward · April 27, 2010, 08:41:11 PM

Has anyone ever tried having their drive shaft balanced? Reading in my MC-5 manual it says its real important. I have a vibration at about 70-72 mph that can be felt in the floor back over the rear axle. I've had it for years and figured as I moved tires around eventually it would go away but it hasn't. So I removed it tonight and I'm going to take it to Catco and let them check it out.

I wonder if I'll need to tell them rear end gear ratio and tire size? Guess I better check my manual again. I think my MC-5 has 3:43 gears does that sound right?
Fred

JohnEd · April 28, 2010, 12:13:49 AM

Fred,

I am going thru that with a truck at the moment. Turns out my splined shaft is excessively worn. Not a shadow of a doubt that the shop will test that.

Bad shaft will take out the diff and trans bearings and seals. I think the emphasis is on it cause you would not tend to notice it as much in a bus.

John

Sam 4106 · April 28, 2010, 01:49:53 AM

Hi Fredward,
I don't think the rear end ratio is pertinent to balancing. If it is, I would guess that the ratio is either 3.73 or 3.33. The vibration could also be caused by a bad u-joint, but I'm sure you have already checked that.
Good luck, Sam MC8

gumpy · April 28, 2010, 05:40:29 AM

I don't believe gear ratio matters in balancing the shaft.

Might be bent slightly. Saw that once in a work truck. Drove fine till about 40 mph and then started shaking real bad. Turned out
the work crew had high centered the truck in a wash, and bent the driveline ever so slightly. I finally saw a tiny nick on the driveline,
then, with the truck in the air and turning the wheels by hand while watching the driveline turn, I could see the slight bend as it rotated.

Worn splines or u-joints could also be the culprit.

Could also be brake drums being out of round. When did you cut or replace them last?

Fredward · April 28, 2010, 06:01:49 AM

Craig,
I have not torn into the drums yet. Inspection reveals plenty of friction remaining so I have not taken them off. But I plan to do that as well when I replace shocks and rear torsion bushings. Been too busy at work to get to that stuff.

My differential/drop box is leaking somewhere and, strange as it may sound, I can't pinpoint the exact location of the leak. THere's a lot of lube back there and only a little bit appears to be coming from the pinion. ALso it only leaks when under way. If the vibration is caused by the drive shaft then maybe the pinion leaks while the driveshaft vibrates. So I'm hoping to kill two birds with one stone here.
Fred

luvrbus · April 28, 2010, 06:04:09 AM

Fred, a dropbox with too much end play at the input shaft will cause the high speed vibration also most are never checked it should have no more than .005 end play may be bearing time for you and your leak will probably be on the back where the cover for the bearing adjustment is, it has no gaskets only shims

good luck

robertglines1 · April 28, 2010, 06:16:11 AM

I had a 8 with problem...replaced unit and no more problem...checked you tube and didn't find Andy's Keck Gonnerman any more but the 16 hp Huber is on SMOKESTAX I don.t know if the keck is on there yet...Bob a bad shock can set up vibration also.

Fredward · April 28, 2010, 06:33:56 PM

I got the drive shaft balanced today at Catco. They said it was out of balance, but not bad. $55.00. Thats not bad. Don't know if that was bad enough to set up the vibration I'm feeling. Gumpy said maybe the drums are out of round? I've never heard of that. My drop box is leaking maybe there's something about to let loose inside there? Or maybe the vibration caused the pinion seal to leak and the bolts that hold the drop box onto the differential to work loose. There's so much gear lube around there I can't tell what's going on. Probably have to steam clean it before doing anything else.

I will probably take the flange off the input shaft and see if I can see anything wrong there. Maybe replace that pinion seal. Then put it back together and drive it. I've got a trip planned in May.

Fred

luvrbus · April 28, 2010, 07:05:21 PM

Fred, it is your call but if were me and it is not taking the drive shaft out and removing the flange I would remove the dropbox doesn't take that much longer and replace or check the 4 bearings when they vibrate enough for separation my friend you are getting ready to lose a dropbox or a pinion bearing take it from a Eagle owner.
The bearings are nothing special any bearing house will have those.
The problem will be the gasket and new shims if you need those Jefferson in OK City has those in stock never use silicone between the dropbox and differential it will leak.

good luck

David Anderson · April 28, 2010, 08:07:46 PM

Clifford,

Is he needing to replace the same bearings I did on my Eagle last year?

http://www.busconversions.com/bbs/index.php?topic=11625.0

David

Fredward · April 28, 2010, 08:43:53 PM

Clifford,
I'm already this far into it I suppose I might as well do as you say. Is it possible that bearings failing in the drop box will set up vibration noticeable through the floor above? How much does the darn thing weigh? What about adjustments when re-assembling? Is there any gear lash or special micrometer type measurements that have to be performed or is it just dissasemble/reassemble and slide it back on the differential?

I have the manual but have not consulted the drop box rebuild section yet. Its out in the shop and I'm in the house.
Fred

Fredward · April 30, 2010, 11:07:03 AM

After reading David's post, I'm wondering if I can accomplish what I need to accomplish without removing the drop box. If I didn't have to remove it life would be somewhat nicer.

I've got it loosened up and ready to slide off but its going to be heavy and I'm not sure how to handle it from underneath. The MC-5 doesn't have enough room to suspend the gear box from above. Looks like I need to build some kind of jig to mount on my floor jack to slide the drop box off the differential. Any ideas?

Fred

Fredward · May 02, 2010, 05:18:34 AM

Clifford, at your recommendation and the recommendation of some friends, we decided to remove the drop box. (so I renamed the thread) Everything appears to be in order but there is noticeable end play in the input shaft and the seal has definitely been leaking. There must be a lot of oil delivery up there when the coach is rolling.

I'll take it to Steve at C&J bus Monday and let him do the honors of either adjusting end play or replacing bearings and adjusting end play.

It will be interesting to see if this finally gets rid of the vibration we've been experiencing.

I forgot how to get pictures from my iPhone to my computer so I can't post any evidence yet.

Fred