"Slam" occasionally when braking?

[Mercfh]

So I know i've seen a thread for this before but can't seem to find it (I did search but mostly saw threads about the mushy brakes).

Anyways, sometimes i'll notice when I brake (somewhat suddenly, but even sometimes not that suddenly) it feels like the car sort of "slams" forward. Almost like there is something in the back of the bed thats slamming forward (There isn't anything in the bed).

I feel like there was maybe a TSB to remove something and re-grease it or something? Didn't know if it was something damaging the truck since I was going to bring it up at my 5k oil change.

Thanks!

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[Pirate]

Check rear seat is latched. Could be the slip yoke TSB. Ford replaced my entire driveshaft assy to fix the problem.

 

[Techcargt]

This is what worked for mine , and this is what I bought to fix it ,

KIT DRIVE SHAFT BOOT REPAIR Part Number 9L3Z4W602A

Brand: Motorcraft

 

[D Fresh]

Also, check your spare and make sure it's raised all they way up.

 

[ctechbob]

9L3Z-4W602-A

Just adding the 'official' version of the Ford part number so that it shows up in a search.

Recently ordered one for mine. Hopefully be able to get it taken care of next weekend off. Not even going to bother going to the dealer. My time is worth more than running back and forth there and arguing with them.

 

[troutspinner]

Take note of how much gas you have. I don’t have a “slam” so to speak but there is a bump at times. I’ve noticed that it depends on the amount of gas I have. If 3/4 to full, no issue. 1/4 to E, no issues but in between, I’ll get a bump here and there on inclines / declines while breaking hard.

 

[silverflash]

my dealer is addressing this once they get the parts in- clamp and lube. they addressed the vibe from a stop- mostly. they applied the tsb with shims in the rear and it improved things tremendously. if you didn't know what to look for, you would not notice it. i convinced them that the slip yoke spline may be binding causing the slam when stopping and thunk when leaving a stop and the service manager, who happens to be an ex tech with recent experience, agreed. it does seem to do it less obviously now that the shims are in place. his thought was that the angle of the shaft decreased so there isn't nearly as much binding as before.

 

[ctechbob]

If you are doing this yourself, don't be surprised if you have to heat the driveshaft bolts to get them out. I had one hang up to the point I thought it was going to snap off. It really was that tight.

Before you put them in, give them a good wire brushing and run them in and out of the holes in the flange a few times. No lube, and then blue loctite.

I didn't look at the service manual, but I suspect these are supposed to be one time use bolts.

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