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.

[klutchdust]

enblethen wrote:
Sounds like the rear end is wrapping up. This happens when too much torque is applied. When brakes are release, the rear suspension twist is released. Common area is center bolt in spring, shackles, torsion bars and spring perches.

Old school:
When a u joint is in question we would put the vehicle in gear, hold the brake down firmly and push the throttle down slightly to apply pressure to the joint and listen for a click.
Also effective when checking motor mounts to see if the engine lifted off the broken rubber mount
Is this what you refer to as wrapping up?

[klutchdust]

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.

want to figure out what you consider a jolt. From neutral and putting a vehicle into gear it will move forward. Is that what you are feeling or something more intense.

[enblethen]

12-volt DC would not have any effect Wrap up is a mechanical function. 12-volt out of ECU and transmission control should reset as soon as power is restored, engine restarted, and transmission is operated.

[Grit_dog]

bobndot wrote:

enblethen wrote:
Sounds like the rear end is wrapping up. This happens when too much torque is applied. When brakes are release, the rear suspension twist is released. Common area is center bolt in spring, shackles, torsion bars and spring perches.

Just a question ;
Could this jolt happen if the 12v power was disconnected , like removing the battery terminals to clean them ?
The ECU memory and throttle valve might be out of sync ? Could that be the cause of things wrapping up. If so, it could be a temporary condition until driving over time self corrects it.

No, you’re talking about things that aren’t even remotely related other than being attached to the same vehicle.
It is possible by some very small % that there could be a little axle wrap. However if there were components that were so worn or broken as described, there would be other symptoms assuredly and a little clunk at a stoplight would be far secondary to the primary symptoms. Of which the OP said there are no other suspension symptoms, noises etc while underway.

[bobndot]

enblethen wrote:
Sounds like the rear end is wrapping up. This happens when too much torque is applied. When brakes are release, the rear suspension twist is released. Common area is center bolt in spring, shackles, torsion bars and spring perches.

Just a question ;
Could this jolt happen if the 12v power was disconnected , like removing the battery terminals to clean them ?
The ECU memory and throttle valve might be out of sync ? Could that be the cause of things wrapping up. If so, it could be a temporary condition until driving over time self corrects it.

[enblethen]

Sounds like the rear end is wrapping up. This happens when too much torque is applied. When brakes are release, the rear suspension twist is released. Common area is center bolt in spring, shackles, torsion bars and spring perches.

[VQ74]

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.

[klutchdust]

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

[VQ74]

bobndot wrote:

VQ74 wrote:

rjstractor wrote:
Need a little more information- did the jolts occur just as you stopped, or had you already been stopped for several seconds? Were they hard, gentle or normal stops? Could something heavy be loose in a compartment?

VQ74,
You highlighted this quote but said nothing .
These questions are still unanswered.
Did this happen as your started to move forward from a dead stop ? Was it due to movement ?

I had been stopped for a few seconds when I felt the jolt. The first jolt was very light the second was a bit harder. Checked compartments nothing loose. I do have a weber bbq table that may have moved forward and hit the spare tire, not sure this would cause a jolt from the rear as the table is not very heavy.

[VQ74]

Grit dog wrote:
Well a quick crawl under it will reveal a major structural issue or broken suspension. However there’s a very low likelihood that it’s something like that if it handles fine on the road and then has a little indeterminate thump while stopped. Period.
OP hasn’t been great about replying or adding to the thread. Repeatability is a big part of diagnosis and so far it appears to have happened only twice, yet hard to believe the rig only stopped twice in the last however many miles.
Another suggestion besides manually downshifting if it’s repeatable at multiple stops. (This can literally be done at low speeds in their subdivision or a desolate road ) is kick it into neutral before coming to a stop and see if the thump goes away.

I had my brother in law go under the motorhome to check on things he did not find anything that looked like it might cause the jolt from rear. I had stopped more than twice and it did only happen twice. On the way home there was no incidents where it jolted from the rear.

[VQ74]

bobndot wrote:

VQ74 wrote:

rjstractor wrote:
Need a little more information- did the jolts occur just as you stopped, or had you already been stopped for several seconds? Were they hard, gentle or normal stops? Could something heavy be loose in a compartment?

VQ74,
You highlighted this quote but said nothing .
These questions are still unanswered.
Did this happen as your started to move forward from a dead stop ? Was it due to movement ?

This happened when I had stopped completely.

[bobndot]

VQ74 wrote:

rjstractor wrote:
Need a little more information- did the jolts occur just as you stopped, or had you already been stopped for several seconds? Were they hard, gentle or normal stops? Could something heavy be loose in a compartment?

VQ74,
You highlighted this quote but said nothing .
These questions are still unanswered.
Did this happen as your started to move forward from a dead stop ? Was it due to movement ?

[Grit_dog]

Well a quick crawl under it will reveal a major structural issue or broken suspension. However there’s a very low likelihood that it’s something like that if it handles fine on the road and then has a little indeterminate thump while stopped. Period.
OP hasn’t been great about replying or adding to the thread. Repeatability is a big part of diagnosis and so far it appears to have happened only twice, yet hard to believe the rig only stopped twice in the last however many miles.
Another suggestion besides manually downshifting if it’s repeatable at multiple stops. (This can literally be done at low speeds in their subdivision or a desolate road ) is kick it into neutral before coming to a stop and see if the thump goes away.

[wolfe10]

Guys,

I am uncomfortable recommending that the OP continue to drive UNTIL the issue is diagnosed. Sure, could be minor, but would hate to see a component failure lead to loss of control with recommendations to keep on driving.

[Grit_dog]

Try this, when it’s doing it, I suspect it’s not every stop so it may seem random, manually run it down into 1st gear before stopping, every stop and see if it goes away.