Community Forums

TIFFIN34PA · 08-24-2021, 07:43 PM

I have a brand new Tiffin Allegro Open road model 34Pa that has a tight vibration and deep hum at 56 to 70 MPH, Ford recognizes the vibration but doesn't know where its coming from and wont even try anything until they can identify it..
Has anyone had this issue and what was done to fix it?

Side note,
I am in California and the new location of the fuel fill on the back of the MH is so bad I cant fit the pump handle in enough to start the pump, I have to hold the rubber seal on the pump up with one hand while using the other to hold the lever.
Any one else have this problem?

Rob_M · 08-24-2021, 07:48 PM

Your vibration is likely a driveline issue. Either pinion angle or u-joint timing. (clocking)?

TIFFIN34PA · 08-24-2021, 07:52 PM

Thanks, I'll pass that on to the Ford Tech.

Rob_M · 08-24-2021, 10:09 PM

The term I couldn’t come up with above was driveline “phasing” not timing

DFord · 08-24-2021, 10:30 PM

I've attached a copy of a TSB dating back to 2000 that describes how to troubleshoot and find vibrations. That technology hasn't changed. The driveshaft is spinning over 5 times faster than the tires therefore the frequency of the vibration they cause is vastly different. Call the Ford Motorhome Assistance Center to find a dealer equipped and willing to find your problem. They should have a meter that would just lay on the floor to sense the vibration. The frequency it reports will tell the techs whether it's coming from the driveshaft or the tires.

The speeds you mention are a sweet spot for unbalanced tires.

TIFFIN34PA · 08-25-2021, 12:01 PM

That's some great info, I sent it to the dealership
I'll let you know what they have to say.
Thanks,

TeJay · 08-25-2021, 12:33 PM

While you vibration may be a driveline it is very unlikely on a new unit. I'm not saying it couldn't be a driveline just not very likely. Why would I say that??? Very simple!! Most of the driveline parts are computer balanced and very unlikely to be out of balance. It's to new of an RV to have had the drive line serviced and perhaps not assembled correctly. So that eliminates being out of phase.

Tires on the other hand are almost always the source of vibrations. Here's is the absolute biggest reason why they are seldom or often never fixed.

Tires made out of rubber are subject to slight irregularities which can and will cause a vibration even when they are balanced. Those causes are run out or a side to side movement and out of round tires causing the tire to bounce up and down.

Here's the main reason why they are seldom discovered. The tires are balanced on a computer balance. It's a computer it can't be incorrect. So the dealer immediately looks for another source of the vibration and often times it's never found. Why would they go back and do another balance if it was done correctly the first time? They won't very often and even if they did they won't stop long enough to check for out of round and run-out. Then they will have the owner pay for a road force balance. That won't find it either. So they are back to square one or two because they won't ever go back to look at the tires again.

The absolute easiest way to discover the issue if it's tires is to take the RV back to an RV dealer and find another RV using the same tires and does not have a vibration. R&R those tires rims and all to your RV and drive it. If the vibration is gone determine which tire by adding one of yours back on. Problem solved just as easy as that!!!!!

Here's the problem with doing that. Most RV dealers just won't do it. They have all kinds of excuses but they still won't do it. It's two costly!!! I won't take a good set of tires and put them on another RV. That's just stupid!! On and on and on !!!!!

In the trade it's called cannibalism or swapping a known good part for a suspected bad part. A very useful and often used trick that is acceptable by most shops.

There's at least 6 or more threads with this same issue and every time it was bad tires. One guy traded his in after 9 months of him driving 2 hours each way to a dealer and they never fixed the problem.

The use of a vibration measuring device is also another very good option. They are also available as an AP for your phones and they will do the job. I have not looked at them but I've read many a post listing it as a very good method/tool especially when looking for a vibration.

Good luck and keep us informed.

Thanks,

TIFFIN34PA · 08-30-2021, 07:55 AM

Quote:

Originally Posted by TeJay

While you vibration may be a driveline it is very unlikely on a new unit. I'm not saying it couldn't be a driveline just not very likely. Why would I say that??? Very simple!! Most of the driveline parts are computer balanced and very unlikely to be out of balance. It's to new of an RV to have had the drive line serviced and perhaps not assembled correctly. So that eliminates being out of phase.

Tires on the other hand are almost always the source of vibrations. Here's is the absolute biggest reason why they are seldom or often never fixed.

Tires made out of rubber are subject to slight irregularities which can and will cause a vibration even when they are balanced. Those causes are run out or a side to side movement and out of round tires causing the tire to bounce up and down.

Here's the main reason why they are seldom discovered. The tires are balanced on a computer balance. It's a computer it can't be incorrect. So the dealer immediately looks for another source of the vibration and often times it's never found. Why would they go back and do another balance if it was done correctly the first time? They won't very often and even if they did they won't stop long enough to check for out of round and run-out. Then they will have the owner pay for a road force balance. That won't find it either. So they are back to square one or two because they won't ever go back to look at the tires again.

The absolute easiest way to discover the issue if it's tires is to take the RV back to an RV dealer and find another RV using the same tires and does not have a vibration. R&R those tires rims and all to your RV and drive it. If the vibration is gone determine which tire by adding one of yours back on. Problem solved just as easy as that!!!!!

Here's the problem with doing that. Most RV dealers just won't do it. They have all kinds of excuses but they still won't do it. It's two costly!!! I won't take a good set of tires and put them on another RV. That's just stupid!! On and on and on !!!!!

In the trade it's called cannibalism or swapping a known good part for a suspected bad part. A very useful and often used trick that is acceptable by most shops.

There's at least 6 or more threads with this same issue and every time it was bad tires. One guy traded his in after 9 months of him driving 2 hours each way to a dealer and they never fixed the problem.

The use of a vibration measuring device is also another very good option. They are also available as an AP for your phones and they will do the job. I have not looked at them but I've read many a post listing it as a very good method/tool especially when looking for a vibration.

Good luck and keep us informed.

Thanks,

Ford has decided to do nothing since they cant identify where the vibration is coming from.
My dealership has stepped up and they are going to have all the tires balanced.
Need to start somewhere!

TeJay · 08-30-2021, 10:32 AM

TIFFIN,

I can't believe they don't want to try or don't know about checking for the frequency of the vibrations.

When they do another balance make sure or ask them if they did or are going to check for out of round and side to side run out??? Maybe they don't understand those two terms. If they don't check for these there's no reason to expect different results.

Out of round is like drilling a hole in a circle of wood not in the center. The tire will move up and down as a unit. Run out is the tire moving side to side. Both are very easy to see. It requires no special tools just a pencil. Spin the tire and hold the point about and 1/8" inch from the center of the tread. Then hold the pencil point somewhere on the sidewall and rotate. Side to side and up and down are very easy to see.

Sorry, but I don't recall what the specs should be.

I just looked on the net and couldn't find much on the exact specs. In reality you don't want any of either one but that's not realistic. They meaning the dealer may want specific specs so they know where to draw the line.

To make it simpler lets call them vertical & lateral run out. There will both on the tire but the rim can also contribute to it. That's up & down then side to side!!! How simple can it get???

The biggest discussion on the net was more in regards to alloy wheels which are special made and should be very close to perfect. Specification under .005 to maybe .010 are easy to find. That's just the rim. When you add the tire it goes up. So the rims can be an issue but more so the rubber tires.

Years ago to get a tire with no vertical run out they'd shave the tread down. Not what you want to do today.

One other thing I'd ask them to try. Swap two tires from the rear and see what happens to the vibration. Try to find two tires that pass the two run out tests.

Maybe more searching on the net will produce more actual specs for minimum and maximum.

jharrell · 08-30-2021, 04:59 PM

I don't understand why a dealer won't just put an EVM on it and quickly narrow down the cause. Now days you can use a vibration app on a smart phone and get a decent frequency measurement, once you know the offending frequency you will most likely know whether its Engine, driveline or wheels and tires, its simple math for RPM to frequency and which component is running at which rpm to create the measured frequency of the vibration.

Gator Ford here in FL will put an EVM on and quickly narrow down the source of vibration, of course they are right across from Lazy Days and probably do more F53's than anyone. I used my smartphone first and knew its was most likely wheels and or tires at 11hz vibration, they took it put an EVM and confirmed, then road force balanced and indexed and eliminated most of the vibration but let me know one tire could not be brought into spec (out of warranty) so I left it. Was so much better that last offending tire didn't really matter.

Cheat sheet at highway speed, varies by wheels size and axle ratio:

around 10hz vibration = wheels / tires / axle
around 40-50hz = driveline and or engine.

1 rpm = 0.016667 Hz

TIFFIN34PA · 09-01-2021, 11:38 AM

Quote:

Originally Posted by jharrell

I don't understand why a dealer won't just put an EVM on it and quickly narrow down the cause. Now days you can use a vibration app on a smart phone and get a decent frequency measurement, once you know the offending frequency you will most likely know whether its Engine, driveline or wheels and tires, its simple math for RPM to frequency and which component is running at which rpm to create the measured frequency of the vibration.

Gator Ford here in FL will put an EVM on and quickly narrow down the source of vibration, of course they are right across from Lazy Days and probably do more F53's than anyone. I used my smartphone first and knew its was most likely wheels and or tires at 11hz vibration, they took it put an EVM and confirmed, then road force balanced and indexed and eliminated most of the vibration but let me know one tire could not be brought into spec (out of warranty) so I left it. Was so much better that last offending tire didn't really matter.

Cheat sheet at highway speed, varies by wheels size and axle ratio:

around 10hz vibration = wheels / tires / axle
around 40-50hz = driveline and or engine.

1 rpm = 0.016667 Hz

What app did you use on your phone?

jharrell · 09-01-2021, 01:27 PM

Quote:

Originally Posted by TIFFIN34PA

What app did you use on your phone?

I used: https://apps.apple.com/us/app/vibration/id301097580

Not pretty but gets the job done, put the phone on something solid that gets the vibration, run a sample then look at the Frequency tab and check peaks, usually the highest peak will be the offending vibration.

Take the frequency measured of the vibration and convert to rpm, then figure out rpm of wheel based on speed and tire size, multiply by axle ratio to get driveline rpm, note engine rpm the time of sample as well. Measured frequency rpm should match up to one those rpms.

TIFFIN34PA · 09-18-2021, 10:16 AM

Quote:

Originally Posted by jharrell

I used: https://apps.apple.com/us/app/vibration/id301097580

Not pretty but gets the job done, put the phone on something solid that gets the vibration, run a sample then look at the Frequency tab and check peaks, usually the highest peak will be the offending vibration.

Take the frequency measured of the vibration and convert to rpm, then figure out rpm of wheel based on speed and tire size, multiply by axle ratio to get driveline rpm, note engine rpm the time of sample as well. Measured frequency rpm should match up to one those rpms.

Mike Thompsons in Colton Ca stepped up and had my tires balanced, so far so good, very smooth

TeJay · 09-18-2021, 11:15 AM

Tiffin,

Glad you did get some good results. It's to bad no shop decided to do what jarrell correctly suggested (frequency detecting device). Therefore they still did not determine what was causing the vibration. Tires/rims are almost always first on the list unless driveline or transmission work was recently performed.

If another balance worked and they did nothing else (like rotate some tires around) then it has to be assumed (100%) the first balance was not done correctly.

During my first 10 years teaching mechanics we had tire machines, spin and bubble balancing equipment. Living in the snow belt at the time (MI) we did a lot of tire changing. Sometimes tires will not correctly or properly seat on to a rim. If a tire is removed and then correctly lubricated before the tire is again placed on the rim a tire can seat correctly and stop or reduce some of the run out or even side to side vibration. Again, they did not indicate they did any of that on your tires.

One more point!! Bubble balancing when done properly can produce a very, very well balanced tire/rim.