Strange "bucking" when coming to a stop - have you experienced this?

[Muscam1]

First let me say that I really appreciate the info and guidance from this forum - you guys/gals are great!!

I have a 2019 Lariat 4WD with 25000 miles that I've had a strange "bucking" condition when coming to a stop. Had this since day one of buying the truck, but it happens so infrequently that it wasn't that big of a deal. But now as I rack up miles I want to make sure that it's addressed before my warranty runs out.

Here's what's happening:
After starting the truck and on the first time I attempt to come to a full stop - the truck "bucks" as I come to stop. Kind of like stomping on and off the brake. Does it only for a couple of seconds. Only happens on the first time I come to a full stop after starting the truck, after that the braking is fine when coming to subsequent stops.

Happens about 10% of the time. I see it more on short distances before I need to stop (like the stop sign in my neighborhood - 30ft from my driveway). Doesn't matter if the truck is warmed up or cold. Also doesn't matter if the auto start/stop is engaged or not. Don't think it's the brakes but rather the transmission gearing down as I come to a stop and it's fighting with the braking...if that makes sense.

Unfortunately, I can't make this happen on demand - which doesn't help me when taking it into the service shop, so I thought I would reach out to this forum first to see if you have experienced this condition.

Thanks!

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[mtbikernate]

Don't think it's the brakes but rather the transmission gearing down as I come to a stop and it's fighting with the braking...if that makes sense.

Yeah, I've noticed this. It seems to happen under a fairly specific combination of braking after applying gas. I don't consider it a problem.

 

[P. A. Schilke]

First let me say that I really appreciate the info and guidance from this forum - you guys/gals are great!!

I have a 2019 Lariat 4WD with 25000 miles that I've had a strange "bucking" condition when coming to a stop. Had this since day one of buying the truck, but it happens so infrequently that it wasn't that big of a deal. But now as I rack up miles I want to make sure that it's addressed before my warranty runs out.

Here's what's happening:
After starting the truck and on the first time I attempt to come to a full stop - the truck "bucks" as I come to stop. Kind of like stomping on and off the brake. Does it only for a couple of seconds. Only happens on the first time I come to a full stop after starting the truck, after that the braking is fine when coming to subsequent stops.

Happens about 10% of the time. I see it more on short distances before I need to stop (like the stop sign in my neighborhood - 30ft from my driveway). Doesn't matter if the truck is warmed up or cold. Also doesn't matter if the auto start/stop is engaged or not. Don't think it's the brakes but rather the transmission gearing down as I come to a stop and it's fighting with the braking...if that makes sense.

Unfortunately, I can't make this happen on demand - which doesn't help me when taking it into the service shop, so I thought I would reach out to this forum first to see if you have experienced this condition.

Thanks!

HI Marc,

I have no experience with vehicle behavior like you are experiencing but it may be a slip/stick of the driveshaft that once you get the slip/stick cycle you are okay for the trip. Before Warranty is over I might suggest having the dealer remove the driveshafts and lube the splines at the slip yoke. Most folks with this condition describe the brake to a stop as a Thump, so could be a Buck. This does show that debriefing the customer can be hard as we use automotive terms for some conditions of which customers are not familiar. Anyway....I will throw this against the wall and see if it sticks!

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[Muscam1]

Thanks for the quick responses and suggestions!


mtbikernate - thanks for the confirmation that others are seeing this
Ranger Pride - Will make sure I'm up to date on the TSBs
Phil - Will suggest to the dealer the driveshafts spline lube

--Marc

 

[Dahveed]

I’ve definitely had some harsh downshifts when I have to stop quickly. Seems like the truck makes a last second decision to hit a particular gear.

 

[Muscam1]

Yes - a "harsh downshift" is a good way describe it. May be a combo of a quick acceleration then a quick braking as @mtbikernate mentioned

@P. A. Schilke - thought about what you said, and it's not really a "thump," but more like a quick double brake.

Think I will experiment with a quick acceleration then quick brake to see if I can replicate.

You guys are great!

--Marc

 

[Vitis805]

I experience this as well. It is particularly noticeable when I have a load in the bed and am in stop & go traffic. I really have to pay attention to the gap I am leaving between the vehicle ahead of me.

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