More than a rough ride

DonnaB · 10-07-2008, 03:57 AM

I'm posting this on two forums, just to pick any brains out there that might have an idea. We have had a problem from first having this coach and have had it looked at on a couple of occasions. Since the problem has begun to worsen, we have taken to Spartan for whatever the ultimate fix is. Unfortunately they have never seen this problem before so we are on Tuesday of our 2nd week here in Charlotte and the problem persists. So....

THE PROBLEM – This is a 2007 Dutch Star, 40'. When reaching a steady speed at anywhere from 35 to 65 mph there is what used to be a minor vibration, but has grown now to a bouncing of the coach. If you maintain, it gets quite violent. You can make this go away by either accelerating, decelerating or engaging the cruise control.

SO FAR – Prior to this, we had had the tires balanced, the drive shaft balanced and chassis alignment. Since being at Spartan they did find the front tires were "out of round" and changed them, plus rear tires and new shocks. In addition they have done an alignment and swapped out the accelerator pedal sending unit, new engine and transmission mounts. Now the new shocks make a little smoother ride over rough roads and RR tracks, but none of this has changed the original problem. They have been driving it around with a camera mounted under the rear to see what is happening, but that hasn't led to a solution. The problem can be duplicated every time we take it out, so it isn't an elusive problem.

The coach has been weighed numerous times and is within limits and reasonably balanced. Our technician here at Spartan is sharp and maintains a good attitude even though he hasn't seen success yet. They do seem committed to finding a solution, so we are encouraged a fix is coming, but man we don't relish seeing snow in Michigan before that happens. So just looking for any ideas you might have that we can add to the list of things to check.

Thanks very much in advance to all of you.

DonnaB · 10-07-2008, 03:57 AM

I'm posting this on two forums, just to pick any brains out there that might have an idea. We have had a problem from first having this coach and have had it looked at on a couple of occasions. Since the problem has begun to worsen, we have taken to Spartan for whatever the ultimate fix is. Unfortunately they have never seen this problem before so we are on Tuesday of our 2nd week here in Charlotte and the problem persists. So....

THE PROBLEM – This is a 2007 Dutch Star, 40'. When reaching a steady speed at anywhere from 35 to 65 mph there is what used to be a minor vibration, but has grown now to a bouncing of the coach. If you maintain, it gets quite violent. You can make this go away by either accelerating, decelerating or engaging the cruise control.

SO FAR – Prior to this, we had had the tires balanced, the drive shaft balanced and chassis alignment. Since being at Spartan they did find the front tires were "out of round" and changed them, plus rear tires and new shocks. In addition they have done an alignment and swapped out the accelerator pedal sending unit, new engine and transmission mounts. Now the new shocks make a little smoother ride over rough roads and RR tracks, but none of this has changed the original problem. They have been driving it around with a camera mounted under the rear to see what is happening, but that hasn't led to a solution. The problem can be duplicated every time we take it out, so it isn't an elusive problem.

The coach has been weighed numerous times and is within limits and reasonably balanced. Our technician here at Spartan is sharp and maintains a good attitude even though he hasn't seen success yet. They do seem committed to finding a solution, so we are encouraged a fix is coming, but man we don't relish seeing snow in Michigan before that happens. So just looking for any ideas you might have that we can add to the list of things to check.

Thanks very much in advance to all of you.

GaryKD · 10-07-2008, 04:45 AM

Hi Donna,
Wow, and I thought I had chassis problems. The only thing I can recommend is to get the techs to issolate the problem to either the chassis or the drive train. When they have it for a test drive and the vibration begins, down shift the tranny to the next lower gear, keeping the coach at the same steady speed. Does this change the vibration? If there is no change, the vibration most likely is in the chassis. If the vibration changes, the vibration is most likely in the drive train (engine, tranny, busings, bearings, etc.).

This is a very remote shot in the dark, but have them check that the coach is properly fastened to the chassis!

I know is sounds dumb, but you already have the pros scratching their head, so anything is possible.

DonnaB · 10-07-2008, 05:51 AM

We'll mention these things to the tech. I'm thinking that the downshifting may have no effect as this occurs at any speed. Meaning that when steady speed is reached whether at 35 when in 4th gear or at 65 when in 6th gear the bouncing result is the same. But we will try anything at this point too!

Appreciate you sharing this.

Spikester · 10-07-2008, 07:25 AM

Donna, has Cummins and/or Allison looked at the your engine and transmission performance? Something may be going on in one of these units to cause the drive train to operate eradicate, hence the vibration. The statement about your issues not occurring during acceleration, de-acceleration, or cruise control operation made me immediately suspect engine or transmission performance (ie; fuel delivery, torque converter etc.). Especially given everything Spartan has done to your suspension system and drivelines.

Spike

DonnaB · 10-10-2008, 04:40 PM

I thank each and every one of you that had good suggestions and we shared them all with our Spartan tech. Well, the fix is in. We are pleased to report that after nearly 2 weeks, they have found and fixed the problem. In Spartan's defense for it taking so long, they had not seen a problem like this before so went about normal trouble shooting for what fixes similar complaints. In addition to this fix there were several things we got resolved (some we were unaware of) while this was being fixed. Our front tires were out of round and they have been replaced. New Koni shocks have been installed and the ride is much better when encountering rough roads. There was a bearing on the front axle that was "a little loose" and it was tightened. They replaced the accelerator sending unit at our urging, but that didn't fix. They replaced the engine & tranny mounts and found 2 of the engine mounts were split. We've always had a burning brake smell with moderate to hard braking so they replaced the front brake drums and that appears to have resolved that issue. However those and a number of other things were done that didn't fix the original complaint.

On Wednesday, an Allison rep rode and monitored with a laptop as they drove it. They found that there were engine issues in communication with the transmission. No error codes were posted, but there was an apparent communication issue. Thursday they were able to get a Cummins person there at the same time as the Allison person. They hooked up the computer and ran it up to 32 mph and found the governor (not just an upper limit setting) setting on our coach was set like a fire truck (variable) instead of fixed as is set on most motor homes. The communication between the engine & transmission cause this incorrectly set parameter to display erratic behavior that led to our "porpoising". Kind of a false stop & go instruction. After they set this back the way it was supposed to be, the problem is resolved. We aren't sure why it was a very minor problem early on, but became very pronounced earlier this year after 20K miles.

We are very pleased with everyone we worked with at Spartan. They were all committed to finding and resolving the issue no matter how elusive. In addition they resolved an out of balance weight issue that was an issue out of the factory and that Newmar failed to resolve. That didn't impact the bouncing problem, they just worked on it in between times. They were all professional and exceedingly customer oriented. I liked Spartan before, but I'm sold on them after this.