Pay attention to that "strange" vibration...

[skihor]

Yesterday I noticed more than the usual vibration. The rear duals have flat spots due to a panic stop and I'm used to a certain amount of vibration from that. Anyway it seemed more than normal and I noticed the mirrors had a view like when riding an old Harley. I commented to the wife that it seemed like more than last time we went out, and more than the day before. I tried backing off to a neutral throttle, full throttle, and decel with no noticeable change in the vibration. That led me to believe that it was not ujoint related. After some of the roads we traveled this week I chaulked it up to poor roads. About 3 miles after I came to that conclusion...
BANG and the driveline was no longer attached to the Trans. It sheared all 8 bolts from the Trans side and three of the eight on the diff side were gone, with the remaining 5 loose. Coach Net came thru with a Service truck who got us up and running again. The full extent of possible damage has yet to be determined, but we should be able to make it home where I can fix things in the comfort of our shop.
A better Pre-Trip may have preventive this, hard to see the driveline without going under the bus. More importantly If something seems out of the ordinary CHECK IT OUT. We had just gone up from Durango, Co. to Ouray on SR 550. For those of you who have never done that road IT'S SCARY, steep, narrow, no guard railing, (corners so tight that several times had the wheels turned full lock), lots of traffic. If this had happened up there We might not be here to tell the story.

Don & Sheila

[luvrbus]

You need to check the up and down play in the drive line at the drop box if you have a bunch you are not going to make it, those 2 bearings and seal can be changed with the drop box in the bus and with the seal leaking it's not a good sign ? did your guy check the nut on the drop box flange.
If you catch it now you can save the drop box let it go it will cost big time and you MCI guys have worked on me so hard lately I don't have any drop boxes to give  LOL   

good luck

[skihor]

Clifford you spend entirely to much time on this board... I told my wife that there is "this guy" on here and I bet he not only answers first, but will in prolly minutes. I, for 1, am glad to have someone of your caliber on this board. You should set up a "pay for answer" website. I bow to your knowlege and dedication to this community. THANKS MUCH
No discernible play in the driveline @ the "T" box and the nut seems tight. Can't move it either way. I think the seal has had a small seep for some time, and as such I think the damage is minimal @ the "T" box.
Being who I am it will get new bearings and seal before it rolls again.


Don & Sheila
Don & Sheila

[luvrbus]

LOL I know Don with getting old and health problems not much else to do but I am getting better each day even cleaning the shop today I have stuff in there I haven't seen in 2 or 3 years  , wise choice to pull the box and install all new bearings doesn't cost that much and not a rocket science either just work 

good luck

[eddiepotts]

I wanted to add that those bolts are grade 8 and fine thread. Make sure you find the fine thread to replace them. It has to do with the shear factor. Course thread bolts have deeper threads and not as much shear strength.

[John316]

Can somebody explain the best way to check the driveshaft? Simply check for play?

I grease our U-joints pretty much every 5K, with the rest of the chassis.

Thanks,

John

[rcbeam]

What is a "drop box" in an MCI?  In my MC8 it looks like the driveshaft comes out of the trans and into the diff.  Am I confused again?

[Barn Owl]

If you lock your rears and burn a flat spot across them, rotate one rear tire on the dual set with the flat spot 180 degrees from the other flat spot until you can fix it. That way only one flat spot is on the ground at a time 180 degrees out of phase with the other and you wont shake yourself to pieces.

The San Juan Skyway is incredible and should not be missed. If you screw up on it you wont get a chance to tell your story, that's for sure!

[skihor]

Made it home with all pieces intact... Well, we do have some nerves yet to recover.

Don & Sheila

[skihor]

I wanted to add that those bolts are grade 8 and fine thread. Make sure you find the fine thread to replace them. It has to do with the shear factor. Course thread bolts have deeper threads and not as much shear strength.

I was told by the service tech that Grade 5 bolts are better. The reasoning behind that is: In my situation the "more brittle" quality of the Grade 8 bolts caused them to "snap" where as the Grade 5 bolts will bend some before failing. Of course I should have caught this problem before it was an issue...

Don & Sheila

[JackConrad]

What is a "drop box" in an MCI?  In my MC8 it looks like the driveshaft comes out of the trans and into the diff.  Am I confused again?

Drop box was used in 35' MC-5s. due to shorter overall length, the driveshadft could not go directly into the differential like they do on the 40' (tag axle) models.  Jack