2023 scsb 5.0 slow speeds deceleration vibration (pinion angle or trans)?

[brad65ford]

While she only has 400 miles on our 2023 5.0 scsb I like the truck but I really don’t like the low speed (35-15mph) deceleration rear end or trans shudder that’s happening. It did it with the stock shackles though I did purchase ford performance lowering shackles. Is my pinion angle that far off causes this excessive shudders or is the the 10 speed? When it does this vibration I can put the Tran is neutral and the vibration goes away so I thought it’s not the pinion angle unless a load exacerbates the issue. Any help would be greatly appreciated.

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[TJE]

Not sure if its the same, but if its intermittent, and feels like its coming from the front it could be this.

https://www.f150gen14.com/forum/threads/intermittent-hum-or-howl-from-front-end.13723/

Well known issue. Sounds like it's the IWE, sounds like Ford is aware of it, no fix at this time.

 

[brad65ford]

Sounds different. Mines coming through the rear end not front related. Goes away when you pop in neutral.

Ordered a shim kit, seems to be the issue. IMHO Ford should include shims with any rear shackle kit. Believe the truck owners that say they don't shack on decel are owners that don't feel anything lol. This is my second truck I've done a rear shackle drop to and both did the same shack because of the pinion angle being off. How could it not.

 

[DSvet]

Sounds different. Mines coming through the rear end not front related. Goes away when you pop in neutral.

Ordered a shim kit, seems to be the issue. IMHO Ford should include shims with any rear shackle kit. Believe the truck owners that say they don't shack on decel are owners that don't feel anything lol. This is my second truck I've done a rear shackle drop to and both did the same shack because of the pinion angle being off. How could it not.

We have the same truck, even color.
Did you ever get around to doing the shims? Even before I added the shackles, I noticed a slight vibration when slowing down and at the same RPM's as you. I just added the shackles and now you can really feel the vibration. I don't feel anything after say 40, 45 mph. I haven't installed the shims yet, but most likely will tomorrow.

 

[DSvet]

Sounds different. Mines coming through the rear end not front related. Goes away when you pop in neutral.

Ordered a shim kit, seems to be the issue. IMHO Ford should include shims with any rear shackle kit. Believe the truck owners that say they don't shack on decel are owners that don't feel anything lol. This is my second truck I've done a rear shackle drop to and both did the same shack because of the pinion angle being off. How could it not.

I installed the shims and it cured the vibration issue. Pretty easy to do. You don't have to touch the drive shaft. Took about an hr and a half mainly because it was the first time and you'll want to make sure you're doing it right.

 

[brad65ford]

Sorry for the delayed response. A lot has changed since this post. I purchased and installed a 3/5 Ridetech lowering kit. Love the kit, though it made the pinion angle even more out of wack. Seems the 2023's have new springs and or other changes creating the diff angle to be different than pervious years. Long story short, I have the new Icon bracket as well as the 2 degree shim installed at the highest position to move the diff up to match the crank/trans angle and its still 3 degree off. Waiting to hear from Ridetech to see what can be done.

If anyone is having vibrations after doing any shackles or lowering kits, purchase a check digital angle gauge and see what your angles are, its very important!

 

[DSvet]

Sorry for the delayed response. A lot has changed since this post. I purchased and installed a 3/5 Ridetech lowering kit. Love the kit, though it made the pinion angle even more out of wack. Seems the 2023's have new springs and or other changes creating the diff angle to be different than pervious years. Long story short, I have the new Icon bracket as well as the 2 degree shim installed at the highest position to move the diff up to match the crank/trans angle and its still 3 degree off. Waiting to hear from Ridetech to see what can be done.

If anyone is having vibrations after doing any shackles or lowering kits, purchase a check digital angle gauge and see what your angles are, its very important!

Don't you have to notch the frame for the 5in drop? I use mine (or will use mine) and I don't like the idea of notching it.

 

[brad65ford]

nope

 

[timnohio]

Sorry for the delayed response. A lot has changed since this post. I purchased and installed a 3/5 Ridetech lowering kit. Love the kit, though it made the pinion angle even more out of wack. Seems the 2023's have new springs and or other changes creating the diff angle to be different than pervious years. Long story short, I have the new Icon bracket as well as the 2 degree shim installed at the highest position to move the diff up to match the crank/trans angle and its still 3 degree off. Waiting to hear from Ridetech to see what can be done.

If anyone is having vibrations after doing any shackles or lowering kits, purchase a check digital angle gauge and see what your angles are, its very important!

Where exactly do we check the angle?
I've seen it explained a couple different ways.
Rear u-joint on rear end and slip yoke into transmission? Should be the same?

 

[DSvet]

Sounds different. Mines coming through the rear end not front related. Goes away when you pop in neutral.

Ordered a shim kit, seems to be the issue. IMHO Ford should include shims with any rear shackle kit. Believe the truck owners that say they don't shack on decel are owners that don't feel anything lol. This is my second truck I've done a rear shackle drop to and both did the same shack because of the pinion angle being off. How could it not.

Well, you'll probably still feel the shacks. I installed the 2in drop shackles from FP along with the shims and it still vibrates. On top of that, it's not even a 2 in drop. Maybe 1.5. Personally, I wouldn't suggest buying them to anyone. I'm going to replace them with the OEM and then do a flip.

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