Rear Jolt on 2017 Ford E450 V10 with only 6,300 miles

[VQ74]

On my last trip I was at the stop light about 1/4 mile from home. I felt a slight jolt from the rear of the motorhome. I had thought someone had hit me from behind as cars were trying to pass around me. Stopped and checked for any damage but none. As I drove about an hour I was stopped at a left hand turn lane I felt the jolt again but a little stronger this time. On the drive home about an hour trip there was no jolts. What could of caused the jolts from the rear of the class c motorhome.

[Grit_dog]

^?? You’re welcome, but I don’t understand what you’re saying.
All good though since either the RV is fine or the OP don’t care about it anymore.

[bobndot]

Grit dog, thank u.
I can see the cutaway weight being a factor , makes sense.

[obie311]

klutchdust wrote:

Lumpty wrote:
My guess is something driveshaft related, either the slip yoke at the transmission connection, or on many long wheelbase trucks there is a constant-velocity joint in the center, or a carrier bearing there, that may have some play.

I have experienced that on my 2500 GMC pick-up when towing my trailer. I removed the driveshaft and lubed the splines and it's been good for many miles. I had a clunk sound when moving from a stop.
The OP hasn't said much regarding his experience with all things mechanical so hopefully something said here helps.

If the splines aren't lubed on the driveshaft, they can bind and then suddenly release at a stop when there is no torque on them. That could feel like a little bump from the rear.

[Grit_dog]

^Now I know where you were headed with that info previously. That could cause the engine to sputter or buck a little which any change in rpm’s could be felt in the drivetrain.
I won’t get into how I think that’s unlikely it’s the cause, as a vehicle that large isn’t going to lurch from a little burble in the rpm’s. And it would look and feel like the engine running rough IMO.
But good suggestion and a possibility for sure.
Even though the OP doesn’t seem very interested in answering follow on questions….

[bobndot]

VQ74,
We might need to bring in Lt. Columbo to solve this mystery !


If you can't see anything that's broken or cracked then you need to dig into another possible avenue.

I came across this link while making an attempt to help 🙂
You guys that are mechanics would be a better judge then me.

My thought is an 'electronic fault error' being sent to the tranny causing a physical-mechanical jolt in the drive system. RE *coil pack and throttle body or something other ??

https://getjerry.com/questions/why-does-my-car-jerk-when-im-stopped-at-a-red-light-

[Grit_dog]

VQ74 wrote:

VQ74 wrote:

klutchdust wrote:
try this. Start vehicle. put in neutral. release foot brake. Apply foot brake and put transmission in drive. Is this what you felt?

Ok Will try. If I do feel a jolt from the rear what does that mean. Transmission problem.

Did try this no jolt from rear. Just forward movement.

No, that would be a u joint or a lot of slop in the ring n pinion.
Gotta ask why you only respond in little bits n pieces or not at all, if you’re looking for help to diagnose it?

[VQ74]

VQ74 wrote:

klutchdust wrote:
try this. Start vehicle. put in neutral. release foot brake. Apply foot brake and put transmission in drive. Is this what you felt?

Ok Will try. If I do feel a jolt from the rear what does that mean. Transmission problem.

Did try this no jolt from rear. Just forward movement.

[Grit_dog]

OP seems to quit wanting help from the brain trust here, but again, as new/low miles as it is, structural chassis issues and driveshaft issues are highly unlikely and also largely not commensurate with the symptoms as described.
Thinking a bit more, could be a late downshift back to 1st gear after coming to a stop.
Could explain how to try to diagnose that but the words are seeming wasted without input from the guy who asked for help.

[klutchdust]

Lumpty wrote:
My guess is something driveshaft related, either the slip yoke at the transmission connection, or on many long wheelbase trucks there is a constant-velocity joint in the center, or a carrier bearing there, that may have some play.

I have experienced that on my 2500 GMC pick-up when towing my trailer. I removed the driveshaft and lubed the splines and it's been good for many miles. I had a clunk sound when moving from a stop.
The OP hasn't said much regarding his experience with all things mechanical so hopefully something said here helps.

[Lumpty]

My guess is something driveshaft related, either the slip yoke at the transmission connection, or on many long wheelbase trucks there is a constant-velocity joint in the center, or a carrier bearing there, that may have some play.

[Grit_dog]

^To his point, if you intend to diagnose this for free with help from your internet friends (nothing wrong with that, it’s a great resource and convenience of this 21st century technology) then you need to help. IE see how repeatable it is. Same conditions different conditions. You’ve added nothing other than it did it twice, in a row and then you apparently parked it. And a buddy looked underneath and said nothing looks broken.
It doesn’t feel unsafe to drive and you’ve also confirmed that it drives fine.
So please go try to repeat the condition. Pay attention to all parameters. Does it do it cold, or only after up to temperature, or directly coming off of a highway speed run, etc.
We’re trying to help but this is not the time to be of few words.

And while possible it’s something structurally wrong or something worn out. It’s highly unlikely given the age and extremely low miles. (Which some of the respondents aren’t considering).
Oh also, brake system. Is it just a standard vac or hydro boost? Not electric over hydraulic? Presume so since it’s a class 4 chassis (or 3 can’t remember if you said 350 or 450). Also unlikely but throwing it out there

[klutchdust]

VQ74 wrote:
Something mire intense from the rear.

So has it done it again or was this an isolated incident. If it is doing it regularly I would have an experienced mechanic take a ride with you to help out with the diagnosis.
keep us posted.

[VQ74]

Something mire intense from the rear.

[RambleOnNW]

Did you have the A/C on? The A/C cycling on will kick the RPMs up. Anyway if you feel the jolt again quickly look at what the RPM gauge is showing.

I had this same thing happening on an older AWD car occasionally. Could have sworn someone was tapping my rear bumper. But concluded the power output was fluctuating for some reason. Perhaps related to how during a cold start the vehicle RPMs are elevated for a short time until partially warmed up. Pressing the brake harder prevented the increased power from overpowering the brake pressure. Or put the transmission in neutral at stops.