671 Vibration Finally Nailed Down!

[GM0406]

All,  I mentioned before that I would report what they found on my '04 vibration problem.  Remember it was vibrating the steering wheel at about 1200 rpm in neutral clutch in or out when the bus was not moving.  Checking lead to the discovery that there was too much crankshaft endplay and bearings and crank clearances were out of spec.  So they replaced the crank and low and behold after they had finished, we still had the vibration.  Next step was removal of the fan to eliminate it from the suspects.  No difference with fan removed.  So they went back and removed the transmission and clutch.  Bingo, no vibration.  She spun up just like a smooth 671 all the way up to over 2,000 with no vibration whatsover.  I went down to take a look and let them know that I would get the flywheel insert new from Luke and two new motor mounts just to be sure Murphy doesn't hit again!  Anyway we are pretty sure the problem was the pressure plate out of balance.  But they will fire her up with the new clutch and pressure plate on it before they put the trans back in. 

I was a little shocked to find out from Bruce that George Thornhill had passed away end of January.  I had called him a week or so ago and he didn't answer.  I was not surprised as I could not always get hold of him and left a message that I would call back.  George was the previous owner of the '04 and was very interested to know what the vibration was.  He had replaced the harmonic balancer chasing it and told me he just learned to drive staying away from vibration rpms!  I'm sure he would be happy to know what it was and that it has been resolved.  The engine now runs fantastically with the crank I got from Craig and the new injectors.  My 8V71 is a real nice engine, but not as smooth as this 7 main bearing 671!  I will be very interested to see how this runs now with the 4 valve head, N-65 injectors, dual exhaust, and 5 inch blower inlet.  Unfortunately they lost the air cleaner that George had on there with a K&N filter in it.  But I found a Donaldsen at the truck wreckers that is even bigger with a new element that should give real good air flow.  First thing I plan to do is top off the fuel and check what it will do for fuel mileage on the next run.  I will miss George who was very practical and was a lot of help in learning the '04. 

Very interested in any input that any of you have on these coaches.  By the way, the Iota Converters I have on this coach that Tom C. suggested to me are still performing flawlessly and have kept the batteries in tip top shape after almost two years.  What a change from the converters that were in that coach before, overcharging, etc.

Bill Thomas   

[Dreamscape]

Bill,

That's great news that you found the vibration, I'm sure it drove you nuts.

Sad to hear about your friend, knowing he is in a better place now.

Thanks for keeping us informed of how the problem was found and solved. Always great to hear good news and the final results that were pleasing.

Happy Trails,

Paul

[pvcces]

Hi, Bill.

I'm glad the new converters are working for you and that your vibration problem has been run down.

We have some of that problem in our coach, but current opinion is that it is caused by wear in the intermediate plate. I don't think your coach has one, so it will be a little different.

Take care.

Tom Caffrey

[GM0406]

Tom and all,  The Wear Plate arrived with the motor mounts today from Luke.  So I will be taking them down to the DD shop in the morning.  We are definitely getting closer to being back on the road.  We would like to go to the Monterey Rally as we haven't been to one in almost 3 years.  If it is not done, we will take the '06.  Bill T.