bhesse

It was suggested that you insert a 2-1/4" piece of 3/4 " heater hose then add the motorcraft ptfe or mercury marine grease.
Anyone at or with Ford service heard of this and if it works?

fordfxr1

Wish I had not read this thread - I never had any "slip-bump" in my driveline till today. Where did I put that grease...

buck91

That sounds a little strange, is the idea to add spring preload to the spline joint?

bhesse

Yes, some I read have have used a spring of some kind, heater hose seems to be an easy repair if doesn't work will take out at next spline lube

Bowtye8

Great Thread! I have fixed up a 2011 and a few 2012 F150's slip yoke Clunking ...All on 2 piece driveshafts. I just bought a 2014 FX4 and its has the clunk.... I jack up the truck and look...a One piece driveshaft.. Thinking the front slip yoke is not the problem. maybe a motor mount etc... Then I search and find this thread. So go back out and re-Jackup truck and remove driveshaft and lube up the front yoke. All good now!!
I didnt think the front yokes would still stick like the 2 piece ones(middle slip yoke)

buck91

So about 4k miles ago I re-lubed my splines, used Valvoline Synpower which is a NLGI #2 lithium complex with about 1% moly. I mixed it pretty heavy with a 50% moly paste resulting in a very high moly content. In the past this worked ok but didn't last very long. At this time I also did the transfer case fluid. The fluid that came out was very pasty and silvery metallic. Put Amsoil ATF in. So far its been completely smooth and no hint of slip bump. This might be the longest I've been able to 100% eliminate it. At this point I can't say for sure if the transfer case fluid "solved" the problem alone but I believe frequent TC fluid changes are perhaps very important and being overlooked at the factory service is over 100k on that fluid.

firemanjj82

Not sure if this is a 100% fix, but I've had this bump\clunk\whatever for a while now. I've had it in for transmission work and such, but it always comes back. I did the grease, which seemed to help for a bit, but then it came back. Then the other day, I was playing around with the controls, and decided to shut off traction control. No bump. I tried everything to get it to bump and it wouldn't. Mine would do it at certain intersections where I was on an incline and a brief stop, then when I'd start going again it would bump, but not with the traction control off. I tried it was the advanced traction off as well and was still smooth as ever. I'm not exactly sure how to go about presented this as a possible issue, but I've always thought the issue went further than yoke splines .