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Old 12-29-2022, 11:21 PM   #1
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2021 THOR ACE (F53) - vibration between 25-30 MPH

I remember reading a post several months ago about something similar. I tried search function using Key Words "THOR, ACE, F53, VIBRATION, VIBRATING, TRANSMISSION". Can't locate the thread. So let me post my question instead, if someone have experienced the same symptoms.

I have a 2021 THOR ACE 33.1 (F53, V8 engine). Purchased new a year ago. We now have around 15K miles.

I noticed this slight vibration (shuddering) when on 2nd gear, going to 3rd gear (speed between 25-30 MPH). After the RV gets beyond or past 30 MPH, no more vibration. I feel it in the front end (not sure if from engine, transmission or tires).

When I took my RV for the annual warranty inspection, I mentioned that vibration to the service advisor. Tech came back and said I need front end alignment as my front tires have uneven wear markings (though I cannot see any, or at least I did not see any). I had my front end aligned by a reputable Truck Alignment shop at around 4K miles, loaded with my normal stuff inside and full tank of gas.

I can't remember when this vibration really started. I just did not pay much attention to it, as it goes away after a certain speed. It concerns me now as the RV is now 1 year old. I want to make sure if the issue is mechanical, FORD warranty covers the fix.

Any thought on what maybe causing this? Can it really just be a simple alignment (re-alignment) fix? Or ss this something I need to call FORD service center?

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Old 12-29-2022, 11:30 PM   #2
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With the vibration occurring at 25-30 mph and going away after that, I doubt if it is the suspension or tires.

Transmission, driveshaft or differential maybe?

David
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Old 12-29-2022, 11:41 PM   #3
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Mis-alignments rarely cause vibration problems. The fact that it occurs at a certain speed and then goes away indicates it is a resonant vibration problem.

It could be in a tire or any of the drive train. Take it to a Ford dealer for better diagnosis. One thing you can try is get it to vibration speed on a slight downhill, once it starts vibrating shift it to neutral and let up on the gas. If it goes away it could be an engine/transmission issue. If it keeps vibrating it could be a driveshaft/wheel/tire issue.
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Old 12-30-2022, 12:29 AM   #4
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Thanks for this tip. I will try this method this weekend just to have a basic idea on what "maybe" going on.

But I will definitely visit a local Ford Truck Repair Shop near my house and set up an appointment for diagnosis.

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Originally Posted by 16ACE27 View Post
Mis-alignments rarely cause vibration problems.
It could be in a tire or any of the drive train. Take it to a Ford dealer for better diagnosis. One thing you can try is get it to vibration speed on a slight downhill, once it starts vibrating shift it to neutral and let up on the gas. If it goes away it could be an engine/transmission issue. If it keeps vibrating it could be a driveshaft/wheel/tire issue.
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Old 01-11-2023, 10:46 PM   #5
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Quote:
Originally Posted by 16ACE27 View Post
Mis-alignments rarely cause vibration problems. The fact that it occurs at a certain speed and then goes away indicates it is a resonant vibration problem.

It could be in a tire or any of the drive train. Take it to a Ford dealer for better diagnosis. One thing you can try is get it to vibration speed on a slight downhill, once it starts vibrating shift it to neutral and let up on the gas. If it goes away it could be an engine/transmission issue. If it keeps vibrating it could be a driveshaft/wheel/tire issue.
Wheel balance!
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Old 01-12-2023, 02:51 AM   #6
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Also, pay attention to whether the vibration go's away once the tires warm up. after all a motorhome does tend sit far longer than a regular vehicle. That will cause "flat spot" on each tire that will work itself out after a few miles of highway driving.
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Old 01-12-2023, 03:17 AM   #7
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Originally Posted by ador View Post
I remember reading a post several months ago about something similar. I tried search function using Key Words "THOR, ACE, F53, VIBRATION, VIBRATING, TRANSMISSION". Can't locate the thread. So let me post my question instead, if someone have experienced the same symptoms.

I have a 2021 THOR ACE 33.1 (F53, V8 engine). Purchased new a year ago. We now have around 15K miles.

I noticed this slight vibration (shuddering) when on 2nd gear, going to 3rd gear (speed between 25-30 MPH). After the RV gets beyond or past 30 MPH, no more vibration. I feel it in the front end (not sure if from engine, transmission or tires).

When I took my RV for the annual warranty inspection, I mentioned that vibration to the service advisor. Tech came back and said I need front end alignment as my front tires have uneven wear markings (though I cannot see any, or at least I did not see any). I had my front end aligned by a reputable Truck Alignment shop at around 4K miles, loaded with my normal stuff inside and full tank of gas.

I can't remember when this vibration really started. I just did not pay much attention to it, as it goes away after a certain speed. It concerns me now as the RV is now 1 year old. I want to make sure if the issue is mechanical, FORD warranty covers the fix.

Any thought on what maybe causing this? Can it really just be a simple alignment (re-alignment) fix? Or ss this something I need to call FORD service center?
Accelerate to about 30 mph where you feel the vibration and then shift to neutral while taking your foot of the acc pedal. If the vibrations is still there and then lessens when gradually goes away, you have a drive line or wheel problem. It it goes away intermediately, you probably have an engine vibration.

The V-10 shakes so violently at some rpms, there is a 8 lb balance shaft on top of the left cylinder head above the camshaft. It is gear driven by the camshaft at 1/4 engine speed. it helps but does not eliminate the even shaking harmonics.
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Old 01-12-2023, 11:35 AM   #8
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Originally Posted by Dan-sr@perra-us.net View Post
Also, pay attention to whether the vibration go's away once the tires warm up. after all a motorhome does tend sit far longer than a regular vehicle. That will cause "flat spot" on each tire that will work itself out after a few miles of highway driving.
It goes away after 35 mph. I doubt this is it. Old nylon cord tires used to flat spot.
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Old 01-12-2023, 06:04 PM   #9
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I have seen many things cause vibrations at certain speeds and most common are wheels out of balance which will be noticed at the same speeds and go away @ 10-15 mph above the speed it started at. Now out of balance can be from several different reasons and most common are the cords separating from impact of chuck holes or bouncing over curbs, next would be you lost a wheel weight, less likely would be the tire wasn’t mounting correctly, either way I would lift the front end and place a block of wood as close to the tire sidewall and spin the wheel, do the same to tread as well if you can see the gap between tire and block change or tire hits the block it’s a wheel problem.
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Old 03-03-2023, 04:21 PM   #10
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I was finally able to take the RV out last week for a 600 mile round trip to Cali. I did what some had suggested. I shift the transmission to NEUTRAL and let off the gas pedal once I start feeling the vibration. The vibration is still there once it started, until I go over a certain speed. Also disappeared when the speed goes BELOW certain speed (all when the tranny is in NEUTRAL and foot off the gas pedal). I will take the RV to Discount Tire and have them inspect and balance the tires. If it is still there, I will then take it to a tuck shop to check front end alignment.
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Old 03-03-2023, 04:40 PM   #11
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Often, when they "stretch" the frames for specific applications, the drive shaft is extended and may have 1 or 2 "carriage bearing" allowing several sections of drive shafts to complete the additional length. You may have a drive shaft balance issue or one of your u-joints/carriage bearings going out.
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Old 03-03-2023, 05:02 PM   #12
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Often, when they "stretch" the frames for specific applications, the drive shaft is extended and may have 1 or 2 "carriage bearing" allowing several sections of drive shafts to complete the additional length. You may have a drive shaft balance issue or one of your u-joints/carriage bearings going out.
More often the stretch is behind the rear wheels with no increase in wheelbase or drive shaft length. Easily verified by doing a VIN search and see which wheelbase was delivered to Thor. The frame extension is often the reason for the large rear overhang.
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Old 03-03-2023, 05:36 PM   #13
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Originally Posted by simidrm View Post
I have seen many things cause vibrations at certain speeds and most common are wheels out of balance which will be noticed at the same speeds and go away @ 10-15 mph above the speed it started at. Now out of balance can be from several different reasons and most common are the cords separating from impact of chuck holes or bouncing over curbs, next would be you lost a wheel weight, less likely would be the tire wasnít mounting correctly, either way I would lift the front end and place a block of wood as close to the tire sidewall and spin the wheel, do the same to tread as well if you can see the gap between tire and block change or tire hits the block itís a wheel problem.
Cords separating donít cause out of balance. A separation vibration indicates a failure soon. Plus a separation causing a violent vibration should be very visible. There is such a thing as out of round. Have Discount tire check with a run out gauge.
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Old 03-03-2023, 05:37 PM   #14
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With the rolling shortages of everything over the past 3 years it's possible they could have used whatever was available. Wheelbases can be shortened or extended easily. But, as you said, it would be easy to find out. There's probably a carriage bearing in the driveline either way. Personally, I think it's a tire balance issue. Balance issues will come and go with speed variations. Often a wheel can sling a weight off.
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Old 03-03-2023, 05:41 PM   #15
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When mine was new it shook pretty good. Upon my inspection, no wheel weights at all. Both Ford & Thor claimed the tires were balanced and the front end aligned. That was BS. Took it to a truck shop. Front tires balanced, alignment, CHF, and stabilizer. Now I can cruise one handed. I doubt Ford balanced and aligned a stripped chassis. And Thor didnít give a ____ !
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Old 03-03-2023, 06:47 PM   #16
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Quote:
Originally Posted by ador View Post
I remember reading a post several months ago about something similar. I tried search function using Key Words "THOR, ACE, F53, VIBRATION, VIBRATING, TRANSMISSION". Can't locate the thread. So let me post my question instead, if someone have experienced the same symptoms.

I have a 2021 THOR ACE 33.1 (F53, V8 engine). Purchased new a year ago. We now have around 15K miles.

I noticed this slight vibration (shuddering) when on 2nd gear, going to 3rd gear (speed between 25-30 MPH). After the RV gets beyond or past 30 MPH, no more vibration. I feel it in the front end (not sure if from engine, transmission or tires).

When I took my RV for the annual warranty inspection, I mentioned that vibration to the service advisor. Tech came back and said I need front end alignment as my front tires have uneven wear markings (though I cannot see any, or at least I did not see any). I had my front end aligned by a reputable Truck Alignment shop at around 4K miles, loaded with my normal stuff inside and full tank of gas.

I can't remember when this vibration really started. I just did not pay much attention to it, as it goes away after a certain speed. It concerns me now as the RV is now 1 year old. I want to make sure if the issue is mechanical, FORD warranty covers the fix.

Any thought on what maybe causing this? Can it really just be a simple alignment (re-alignment) fix? Or ss this something I need to call FORD service center?
You have a harmonic imbalance. Probably caused by the uneven front tire wear. The alignment may have fixed the cause of the uneven wear but the tires still have 15K+ miles of wear on them. Your testing proves it is rool rate specific and you feel it in the front. Have the tires inspected and balanced and maybe rotate the fronts to the rear.
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Old 03-03-2023, 06:56 PM   #17
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What ACE is reporting above is probably the cause and solution but I just want to leave registered here that I installed centramatics on my MH before it was 10K miles and it really smoothed the ride...
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Old 03-03-2023, 07:19 PM   #18
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What ACE is reporting above is probably the cause and solution but I just want to leave registered here that I installed centramatics on my MH before it was 10K miles and it really smoothed the ride...
I also have Centramatics on the front of my MH. In my experience they work better than balance beads but don't hep a rough road or and out of round tire.
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Old 03-03-2023, 07:25 PM   #19
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When mine was new it shook pretty good. Upon my inspection, no wheel weights at all. Both Ford & Thor claimed the tires were balanced and the front end aligned. That was BS. Took it to a truck shop. Front tires balanced, alignment, CHF, and stabilizer. Now I can cruise one handed. I doubt Ford balanced and aligned a stripped chassis. And Thor didnít give a ____ !
Tires are delivered to most assembly plants already mounted and balanced by the vendors.
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Old 03-03-2023, 07:31 PM   #20
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I also have Centramatics on the front of my MH. In my experience they work better than balance beads but don't hep a rough road or and out of round tire.
I first installed in the front and asked the crew to check if they could fell vibration in the rear....
They did so I installed in the rear too.

Really like that and no reason to be concerned with balancing anymore....
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