Bus Conversions dot Com Bulletin Board
October 25, 2014, 04:33:12 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you had an Online Subscription: It will not be stolen by your mailman or your neighbor who also may be into buses.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: 1 2 [All]   Go Down
  Print  
Author Topic: Odd Vibration MC8 45-55mph  (Read 2768 times)
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« on: August 21, 2011, 08:04:15 PM »

I get an odd vibration when accelerating from about 40 to 50 or so.  I was thinking it might be front wheel bearings but it doesn't show up consistently so I am a little lost.

I haven't noticed it at all when coasting or maintaining a constant speed just when I'm accelerating and then only in the speed range mentioned.

I would rather fix something when I'm home than when I'm on the road -- called good judgement I think.

Any opinions (I know I'm taking a chance with that) YES ANY opinions appreciated.

Thanks

Melbo

P.S. I am hitting the road again soon  Grin
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
eddiepotts
Sr. Member
****
Offline Offline

Posts: 446





Ignore
« Reply #1 on: August 21, 2011, 08:24:04 PM »

I am sure it could be 100 differant things but the only vibration I ever had like that was my drive shaft bolts were coming loose. give us more info. do you fell it in tour steering wheel, seat or in the structure of the whole bus.
Logged
Ed Hackenbruch
Hero Member
*****
Offline Offline

Posts: 2433




Ignore
« Reply #2 on: August 21, 2011, 08:39:05 PM »

My first thought was also u joints. Smiley
Logged

1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« Reply #3 on: August 21, 2011, 08:44:09 PM »

The driveline is fine --- Was just lubed and checked before the last road trip and nothing was amiss --- it really isn't something that a passenger would notice -- I can feel it in the steering wheel -- the front wheels were balanced when I put the new tires on somewhere less than 7 thousand miles ago.

The drives all have balancing powder

I hope this helps --- I also freshly lubed all the suspension about 2500 miles ago

Melbo
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
Ed Brenner
Sr. Member
****
Offline Offline

Posts: 253





Ignore
« Reply #4 on: August 21, 2011, 08:54:24 PM »

Check to see if you thru off a front balance weight, steering wheel vibration especially at that speed usually indicates a front wheel or
loose front end part.(at least in the automotive world). Same difference just bigger stuff !!
THanks ED
Logged

Ed Brenner
77 Eagle 05  Murrells inlet, SC
 " While We're At It " A Busnut's most costly Phrase !!
luvrbus
Hero Member
*****
Offline Offline

Posts: 12771




Ignore
« Reply #5 on: August 21, 2011, 09:24:37 PM »

 happens only when accelerating at certain speed diffidently something in the power train,Jim had that problem and his was caused by the ring gear bolts coming loose on the cage hope that is not your problem

good luck
Logged

Life is short drink the good wine first
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« Reply #6 on: August 21, 2011, 09:31:54 PM »

The bus was parked for over six months before this last trip --- is it possible that the tire or tires developed a flat spot??

Something loose in the diff does not sound good --- how would that be checked??

Melbo
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
Lin
Hero Member
*****
Offline Offline

Posts: 4570

1965 MC-5a




Ignore
« Reply #7 on: August 21, 2011, 10:22:30 PM »

Does it do it also after you have been driving a while?  Tires can get out of round just sitting for long periods, but recover when they get hot again.  Anyway, after giving everything a good shake, re-balancing may be worth a try.
Logged

You don't have to believe everything you think.
Rick 74 MC-8
Full Member
***
Offline Offline

Posts: 214





Ignore
« Reply #8 on: August 22, 2011, 05:29:14 AM »

can you feel the speed of the vibration? example wheel speed, drive shaft speed, engine speed. can you change gears?  Does that change the speed of vibration



      Rick 74 Mc-8
Logged

About 20 Miles West Of Chicago
luvrbus
Hero Member
*****
Offline Offline

Posts: 12771




Ignore
« Reply #9 on: August 22, 2011, 06:26:15 AM »

Mel, if you think it might be the tires up the pressure to close to max and see if that changes the range of the vibration but doing only on acceleration sounds to me like something does not like that torque range could be a rear wheel bearing going bad,and about the only way you can really check the U joints on 1 is pull the shaft and remove the caps they will be tight as a drum and be wore out   

good luck
« Last Edit: August 22, 2011, 06:35:09 AM by luvrbus » Logged

Life is short drink the good wine first
lostagain
Hero Member
*****
Offline Offline

Posts: 1567


MC5C




Ignore
« Reply #10 on: August 22, 2011, 06:38:25 AM »

After driving for a while, feel the wheel bearings with your hand. A bad bearing will be hotter than the others.

JC
Logged

JC
Invermere, BC
1977 MC5C, 6V92/HT740
Lee Bradley
Hero Member
*****
Offline Offline

Posts: 714




Ignore
« Reply #11 on: August 22, 2011, 10:23:14 AM »

How did you check the u-joints? The only way I trust is to disconnect the u-joint and work it through it's full range of movement. I'm guessing you have a seized u-joint that you can feel when the acceleration torque changes the drive train alignment; below 40 mph its not turning fast enough for you to feel and above 50 mph you don't have the torque to cause enough misalignment.
Logged
Chopper Scott
Hero Member
*****
Offline Offline

Posts: 1301


MCI 7




Ignore
« Reply #12 on: August 22, 2011, 10:54:26 AM »

Two things come to mind also. Definately check those u joints disconnected but also check your rear housing pinion bushing and also the tranny bushing for looseness. I had a similar problem in a pickup and it turned out to be the tranny bushing. later
Logged

Seven Heaven.... I pray a lot every time I head down the road!!
Bad decisions make good stories.
wal1809
Hero Member
*****
Offline Offline

Posts: 1339




Ignore
« Reply #13 on: August 22, 2011, 01:53:42 PM »

The bus was parked for over six months before this last trip --- is it possible that the tire or tires developed a flat spot??

Something loose in the diff does not sound good --- how would that be checked??

Melbo

I am replacing to tires right now as a result of flatspots.  I only felt the vibration at medium range speeds.  When I got up to 60 I couldn't feel it.  45 to 50 I could feel it.  Especially on the first black top road leaving home.  It was as if the tired heated up and it calmed it down a little.
Logged

1984 Silver Eagle Model 10 6V92 Allison auto tranny
www.snakebreaker.com
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« Reply #14 on: August 22, 2011, 07:50:02 PM »

Ok I looked up the invoice for the drive line and the slip yoke was built and balanced 8/28/2008

It has been lubed five times since it was installed --- I'm wondering if the heat gun would tell me if there is a problem.

I will be adjusting brakes and lubing it up before I hit the road so here is my plan.

I am going to air up the tires (per Clifford) --- Adjust the brakes and lube it up.  Check the oil level in the front hubs and tags.  The bolts that hold the driveline in place are one use bolts so I don't really want to drop it but if the consensus is that it must be done I will do it.

Then when I am on the road I will check the temps of the hubs on the steers and  tags the drive hubs and the temps of the universal joints in the drive line when I get about 50 or 60 miles down the road.

This has bugged me for a long time --- I have jacked the bus up and run each side off the ground to see if it was wheel bearings. I have replaced the tires with michelins. I have had the diff gear set replaced. I have replaced the driveline TWICE the second time is referenced above. The bus is MUCH better than when I started. It is quiet and pleasant to drive but I don't want problems on the road so this odd vibration means something and I would like to find and fix it.

Melbo
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
chev49
Hero Member
*****
Offline Offline

Posts: 763




Ignore
« Reply #15 on: August 23, 2011, 11:40:13 AM »

Hope you checked the pinion  torque as mentioned above when you checked the u joints. I fixed one about 10 yrs ago that had a similar vibration and that was the problem, after disconnecting drive shaft to check the u joints.
Logged

If you want someone to hold your hand, join a union.
Union with Christ is the best one...
txjeff
Full Member
***
Offline Offline

Posts: 115





Ignore
« Reply #16 on: August 23, 2011, 02:53:33 PM »

You mentioned that the drive line was repaired twice. One easy thing to check would be if the drive shaft is in time. Make sure both ends of the drive shaft are aligned in the same position.

jeff
Logged

73 MC-7combo
Brenham, Texas
Len Silva
Hero Member
*****
Offline Offline

Posts: 4086


Angle Parked in a Parallel Universe


WWW

Ignore
« Reply #17 on: August 23, 2011, 03:08:48 PM »

Any chance you can get it up on a chassis dyno?  That would seem well worth a couple hundred bucks rather that having to road test after every thing you try.
Logged


Hand Made Gifts

Ignorance is only bliss to the ignorant.
lostagain
Hero Member
*****
Offline Offline

Posts: 1567


MC5C




Ignore
« Reply #18 on: August 23, 2011, 04:41:41 PM »

Txjeff makes a good point I had forgotten about. It happened to me on the D3 2 or 3 years ago when I installed a new drive shaft and Ujoints not properly. I had a vibration. It was pointed out on this board how it should be timed in line. I fixed it by aligning both Ujoints the same and the vibration went away.

JC
Logged

JC
Invermere, BC
1977 MC5C, 6V92/HT740
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« Reply #19 on: August 23, 2011, 06:41:13 PM »

I do not know how to check the pinion torque --- That information would be helpful.

It seems like the consensus is to remove the driveline to check the universal joints.

I will drop the driveline tomorrow and check the to be sure there is nothing amiss.

I was also told to check that the flanges mate solidly and smoothly to each other so I will also check that.

Rocky Mountain Cummins has a shop with a dyno about 6 blocks from my bus I may also check with them first to see what the procedure and cost is.

Thanks for all the ideas and opinions.

Melbo
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« Reply #20 on: August 24, 2011, 08:23:31 AM »

I spoke with the service manager at Cummins -- His thoughts were that it would be one of two things (neither of which he was sure he could duplicate on the dyno).

1. Transmission shudder (he was not sure a ZF would do it) he said it was not uncommon for an Allison to do it at that speed.

2. A subtle misalignment of the driveline caused by the torque, air suspension, and weight of the coach under acceleration.

He said that typically bad u joints vibrate more under deceleration -- he discounted the idea of tires being a problem.

He told me to remove all the pressure from the driveline and check it while in place when I lube it up  -- be sure everything is secure and in place.

Once again I appreciate all the thoughts and ideas of how to procede on this.

Melbo
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
bevans6
Hero Member
*****
Offline Offline

Posts: 4764


1980 MCI MC-5C




Ignore
« Reply #21 on: August 24, 2011, 01:29:52 PM »

FWIW and probably not relevant to this particular bus - not all driveshafts are properly timed with the u-joints in phase.  My MC-5 driveshaft has the U-joints about 30 degrees out of phase, the the splines are such that you cannot put it together any other way.

Brian
Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
Oregonconversion
Sr. Member
****
Offline Offline

Posts: 300



WWW

Ignore
« Reply #22 on: August 25, 2011, 11:58:51 AM »

Sounds to me like it might be a wheel bearing?
Logged

1977 MC8
8V92 HT740
luvrbus
Hero Member
*****
Offline Offline

Posts: 12771




Ignore
« Reply #23 on: August 25, 2011, 04:11:50 PM »

Mel, I was talking to Bill at Southern Plains Cummins and was telling him about your problem he said when you check all drive train components and still have the problem he suggested you change the harmonic balancer  if hasn't been changed in the last 100,000 miles he told me those need replacing on a L 10 every 100,000 miles they do it more often on the CNG engines or they shake apart 

good luck
Logged

Life is short drink the good wine first
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« Reply #24 on: August 26, 2011, 08:49:52 PM »

Well I think I found the problem on the inside drive tire.

Here is a picture of it -- looks like it could cause some subtle vibration --

Don't have the time to do anything with it before we are on the road

I would have not noticed it but I spun the tires getting up on the blocks and it showed the irregular pattern because it was polished up a bit.

The drive line is good (glad I checked it --- thanks for the encouragement) -- Adjusted the brakes -- lubed things up and changed the fuel filters -- so I guess I am ready for the second road trip of the year.

Going to spend some serious time in the bus this trip so I am looking forward to it.

Thanks again for all the input --- good to feel confident as we hit the road.

Melbo
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
luvrbus
Hero Member
*****
Offline Offline

Posts: 12771




Ignore
« Reply #25 on: August 26, 2011, 08:54:52 PM »

Keep the right air pressure in those tires and they won't cup  Melbo I found that out the hard way lol

good luck
Logged

Life is short drink the good wine first
Melbo
Hero Member
*****
Offline Offline

Posts: 1070


MC8 under construction




Ignore
« Reply #26 on: August 26, 2011, 08:56:33 PM »

Will do Clifford I will air them all and check my monitors to be sure that they are working properly.

Melbo
Logged

If it won't go FORCE it ---- if it breaks it needed to be replaced anyway
Albuquerque, NM   MC8 L10 Cummins ZF
luvrbus
Hero Member
*****
Offline Offline

Posts: 12771




Ignore
« Reply #27 on: August 27, 2011, 10:18:58 AM »

Yep Mel that is the reason I air tires to max 1st when looking for a vibration if it is a tire problem air pressure will change it then go from there

 
Logged

Life is short drink the good wine first
Pages: 1 2 [All]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!