Greasing the Slip Yoke Cured Several of Issues for me

[Hans Moleman]

1. There was a double squeaking noise when taking off from a stop and going over bumps. I had originally thought this was caused by the leaf springs because it sounded like it was coming from the rear. Someone from another forum posted a video of the squeak underneath their truck and it showed the squeaking noise that sounded similar to mine and it was actually coming from the slip yoke. Instead of visiting the dealer multiple times and telling me they couldn’t replicate the noise I bought a tube of Motorcraft XG-8 blue teflon grease and removed the driveshaft to grease the slip yoke myself. This fix the squeaking noise and it also fixed 2 other issues below that I did not expect.

2. Clunking when letting go and re-applying the throttle on down hill sections of freeways. It was strange because it never clunked on flat sections or uphill sections. Originally I thought the clutch in the electric drive unit or the torque converter was causing this. I had the dealer look into this before but they said they couldn’t replicate. So greasing the slip yoke unexpectedly fixed this.

3. Apparently there was some driveline vibration before because my truck now feels buttery smooth on the freeway after greasing the slip yoke. Originally I thought it was the stock crap Hankook tires. I had them road force balanced several of times and the vibration got better but never completely went away.

It feels like how a brand new truck should be now.

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[tsigwing]

Nice. What all is involved?

 

[Jerome10]

Oh man, I may have to do this. I have the downhill freeway throttle clunk. Drives me nuts. Thankfully not very common. I also wondered if this slip yoke grease might help smooth out shifting a little bit as well. But the freeway clunk is probably enough of an incentive to just do it anyway.

I'm fairly mechanically inclined. Is there anything about it that was overly difficult or required special tools? I generally hate getting under cars when they're on jackstands is my biggest fear...

 

[FormerRangerRaptorOwner]

Oh I will be checking this as well. For a 2023 I couldn’t understand why it has the “clunk” but this makes sense.

 

[Hans Moleman]

Nice. What all is involved?

1. Mark the drive shaft and pinion flange with paint or marker so you can put it back in the same position later.
2. Unbolt the driveshaft from the rear pinion flange with a 12mm 12 point socket.
3. Pull the driveshaft.
4. Clean up the splines with brake cleaner and a brush and rag.
5. Lube up the splines in the slip yoke with the Motorcraft XG-8 Teflon grease. I squeezed half the tube in there and brushed it around until all of the splines were coated evenly.
6. Re-install driveshaft and torque the driveshaft bolts to 76 ft-lbs.

This Motorcraft XG-8 Teflon grease is supposed to be the holy grail slip yoke grease that even Toyota and GM truck owners use with slip yoke issues. It’s expensive at around $15 for a 3oz tube at the Ford dealer. However it is supposed work better for slip yokes than moly greases.

 

[digitaltrucker]

1. Mark the drive shaft and pinion flange with paint or marker so you can put it back in the same position later.
2. Unbolt the driveshaft from the rear pinion flange with a 12mm 12 point socket.
3. Pull the driveshaft.
4. Clean up the splines with brake cleaner and a brush and rag.
5. Lube up the splines in the slip yoke with the Motorcraft XG-8 Teflon grease. I squeezed half the tube in there and brushed it around until all of the splines were coated evenly.
6. Re-install driveshaft and torque the driveshaft bolts to 76 ft-lbs.

This Motorcraft XG-8 Teflon grease is supposed to be the holy grail slip yoke grease that even Toyota and GM truck owners use with slip yoke issues. It’s expensive at around $15 for a 3oz tube at the Ford dealer. However it is supposed work better for slip yokes than moly greases.

I did this to my 13 years, years ago and the Ford product held up. I recently sold the truck with 172K on it and never had an issue out of it again. Others have tried other things and had lesser results.

 

[Hans Moleman]

Oh man, I may have to do this. I have the downhill freeway throttle clunk. Drives me nuts. Thankfully not very common. I also wondered if this slip yoke grease might help smooth out shifting a little bit as well. But the freeway clunk is probably enough of an incentive to just do it anyway.

I'm fairly mechanically inclined. Is there anything about it that was overly difficult or required special tools? I generally hate getting under cars when they're on jackstands is my biggest fear...

I think you will be very happy to get rid of the downhill clunk, I know I did.

It’s pretty straight forward with the steps I outlined in the post above.

I supported the rear with 6 ton jack stands which is an overkill and also with a floor jack under the rear differential housing just in case. Our trucks are tall enough so I don’t think you will get squished even if it falls off the jack stands.

 

[Hans Moleman]

I did this to my 13 years, years ago and the Ford product held up. I recently sold the truck with 172K on it and never had an issue out of it again. Others have tried other things and had lesser results.

I’m glad to hear the long term positive results.

I think if grease up the slip yoke with the XG-8 grease as soon as you hear the double squeaking or clunking, it should last for a long time. If wait too long and the splines are worn, the results probably won’t be as dramatic or last as long. My splines were still in good shape and I did not feel any play when the slip yoke was installed on the transfer case output shaft.

 

[Gros Ventre]

I had not thought of that as my experience was with u-joints... but that fits. Nice job!

 

[Mosey]

Should the yoke coupling bolts be replaced, I.e. are they one time use?

 

[Gros Ventre]

Should the yoke coupling bolts be replaced, I.e. are they one time use?

Unless specified in the shop manual, no.

 

[Hans Moleman]

Should the yoke coupling bolts be replaced, I.e. are they one time use?

No because I don’t think they are torque to yield bolts. If you are worried just use some blue thread locker.

 

[FormerRangerRaptorOwner]

Looks like this has been a common problem since 2011. This video from a well known Ford Tech is quite helpful in explaining the problem and fix…

 

[Gros Ventre]

No because I don’t think they are torque to yield bolts. If you are worried just use some blue thread locker.

There is only one place I've ever seen torque to yield specified: The head bolts on the Escape Hybrid. However many shop manuals will tell you to use new hardware, nuts, bolts, etc. My take (except for torque to yield applications) inspect the removed nuts & bolts and if the condition appears good, reuse them.

 

[JohnTrigger]

I’d also reuse them if they looked ok, and with blue lock tite like discussed above, but the ‘24 Ford Shop Manual says to discard them and use new ones. So that’s the “book“ answer.

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