Shudder / Shimmy at lower speeds

[MostlyHarmless]

Hey guys

Still getting used to my new (to me) 2018 Expedition Max Limited. Generally loving the car

It was a used car with just under 10,000 miles on it - it has CCD on the car, which may be relevant to my question

I have noticed that I am getting a distinct shudder or shimmy from the rear of the vehicle at lower speeds - specifically between 40mph and 50mph when on light throttle.

It kinda feels like a wheel out of balance at the rear, but I don't think it's that as I can only feel it at those specific speeds. Also thought it might be road surface related, but if I go down the same roads slower or faster it's not there. I know harmonic vibrations can do strange things, but doesn't seem like it's the road surface.

Before I start getting my dealer to take things apart (which I know I will regret!!!) I was wondering if there are any other people out there with similar experiences, or if this is a known quirk of the car.

Thanks

Mark

 

[dlcorbett]

Does it feel like one of your rear windows is down but an extreme rush of wind is coming through the back?

 

[2Scoops]

I've noticed something similar with my new Expy. To me it felt like it was stuck in a higher gear and just lugging along. Almost like it was needing to down shift to a lower gear. I only noticed it once but it was when I was on light throttle and driving like an old man. I'll have to put a few more miles on the truck before I know for sure but I'm guessing that is all it was in my case.

 

[aggiegrad05]

A lot of discussion on this thread...wonder if it a similar issue

Jittery ride w/ CCD?
https://r.tapatalk.com/shareLink?sh...eads/Jittery-ride-w--CCD?.37034/&share_type=t

 

[2Scoops]

Thanks for the link. Always good to see others experiences. After reading, that thread is all over the place. Tires, transmission, suspension etc... I've only noticed this for a short period and it was at low rpms on light throttle. It didn't feel at all like it was coming from the tires or suspension. My issue was more of a lugging/surging but it was faint and only for a short period of time until I got out of traffic and started moving again. I'll pay a little more attention to it and report back.

 

[MostlyHarmless]

Thanks for the feedback guys

dlcorbett - I hadn't thought about the "open window" comparison as there is none of the pressure issues you would experience with a single open window, but yes the sensation is similar.

The CCD issue seems the most likely, but the thing that is perplexing me is that it is very speed sensitive - if I drive down the same roads under 40mph or over 50mph then it doesn't do it, but between 40 and 50 on light throttle it can exhibit it on a number of different road surfaces.

It does feel more like transmission shudder than suspension compliance, but these cars are so complex that it is easy for your butt to be confused by different vibrations

Thanks

Mark

 

[dlcorbett]

Mines does a thing where at 45 to 55 mph, in gradual accel/decel, the body of the truck will judder like im driving in a wind tunnel. No pressure, but it gets louder and the cabin has a slight but forced shimmy. Its hard to explain but its like driving full speed in mud and pebbles at that zone. Couldnt tell you what it is. Also, it does the lurch and surge as well, like u caught the engine out of its powerband and the turbo spools overtine to catch up and the whole trucks jumps out the gym(like the old cartoon when the leg wheels move fwd but the boddy stays behind)

 

[MostlyHarmless]

Mines does a thing where at 45 to 55 mph, in gradual accel/decel, the body of the truck will judder like im driving in a wind tunnel. No pressure, but it gets louder and the cabin has a slight but forced shimmy. Its hard to explain but its like driving full speed in mud and pebbles at that zone. Couldnt tell you what it is. Also, it does the lurch and surge as well, like u caught the engine out of its powerband and the turbo spools overtine to catch up and the whole trucks jumps out the gym(like the old cartoon when the leg wheels move fwd but the boddy stays behind)

I wouldn't have used the wind tunnel analogy, but the circumstances (40-50mph on light throttle) are identical - so I think we are experiencing the same thing and just have different ways of articulating it.

One thing I haven't tried yet is to put the vehicle in Sport mode and try to replicate it - given that Sport will put me in a different gear at a different RPM range that should confirm whether it is transmission related or whether it is road speed related (so suspension or wheel balance)

It's not a deal breaker as I am rarely at part throttle but it is a but annoying when it happens

Mark

 

[dlcorbett]

Still have mine lol. If i purchased instead of leased, i prob wouldve traded mine in for a plat or a nav. I think ima have to take it back in for the hvac. The mechanics bay is my big grls sec home.

 

[Andy C]

I haven't bought mine, but I felt something like this during test drive...very similar to Odyssey that has transmission shimmy issues. Happened one time, but didn't think too much of it, but as I read this, that was very distinct shimmy issue. Very short, but felt it.