Bump when putting in gear and taking foot off pedal?

Tiny
CHRIS001
  • MEMBER
  • 2001 FORD F-150
  • 4.5L
  • V8
  • 4WD
  • AUTOMATIC
  • 238,000 MILES
In my truck I noticed when I put in gear like to drive my foot is on the brake pedal I let off there's a bump when I stop completely or take off the bump happens again like a slight tug when it's under pressure or take of like slack in the rear and towards the middle. What could this be?I checked the u joints couldn't turn them by hand but that was in park. Any idea what it could be?
Wednesday, August 3rd, 2022 AT 12:45 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

When I was reading through your post, my first thought was a brake sticking, but it does sound like a U-joint.

To check a universal joint, there can't be pressure on it. Since you were in park, you wouldn't have been able to identify an issue by hand.

Take a look through this link and let me know if you are comfortable performing what it is suggesting at the end of the page:

https://www.2carpros.com/articles/how-u-joints-work

Also, let me know if there is a noise associated with it and if you notice any vibrations when driving.

Take care,

Joe

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Wednesday, August 3rd, 2022 AT 8:37 PM
Tiny
CHRIS001
  • MEMBER
  • 44 POSTS
I'm leaning towards the u joints but I don't have a lift so have to get it in the shop its jacked up and I don't have the proper tools. But couldn't the transmission mount do the same? I don't know but it sounds as if something is loose or wearing out.
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Thursday, August 4th, 2022 AT 7:00 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Chris,

Absolutely a bad mount could do the same thing. Checking and transmission mounts can be done with the vehicle on the ground.

You will need a helper. On a flat surface, engage the parking brake. Open the hood and have a helper keep his foot hard on the brake and place the vehicle in drive and gently press the throttle. Do the same in reverse. If there is a bad engine mount, the engine will lift on one or the other side. Some movement is normal, but excessive is noticeable.

Do the same while you watch the transmission under the vehicle to see if there is excessive movement.

Let me know what you find or if you have other questions.

Take care,

Joe
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Thursday, August 4th, 2022 AT 4:49 PM
Tiny
CHRIS001
  • MEMBER
  • 44 POSTS
The anti-slip gear is stuck in the rear end so it has to be rebuilt.
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Friday, August 19th, 2022 AT 6:10 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Thanks for the update, Chris. I was hoping for a better solution, but it seems you have the same luck as me. LOL

Regardless, let me know if there is anything I can do to help.

Take care,

Joe
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Friday, August 19th, 2022 AT 9:36 PM
Tiny
CHRIS001
  • MEMBER
  • 44 POSTS
But the good news is you can still drive it like that till you feel you can get it fixed. Just watch your sharp turns and you will have to deal with that bump when stopping and going the damage is done but it does give me some time to fix it. I'm just glad it didn't go out all at once.
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Sunday, August 21st, 2022 AT 7:04 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

I totally understand. Let me know when you get into it so I can help. (If needed) LOL

Take care of yourself and feel free to come back when you start.

Joe
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Monday, August 22nd, 2022 AT 7:54 PM

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