Slip yoke grease service

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As some may be aware, many late model F150's suffer from a "slip bump" due to lack of driveshaft slip yoke lubrication. This may occur either on two piece driveshafts with a mid-shaft slip yoke as well as on one piece driveshafts where the slip yoke enters the transfer case. My F150 is the one piece driveshaft where it has the slip yoke at the transfer case. I have been using Motorcraft XG-8 ptfe spline lube up until now but the longevity is just not acceptable. Last servicing was less than 6 months ago and approx 8,000 miles (previous thread I severely over estimated the interval) and the slip bump has returned. Lets discuss possible options, and here's what I have in mind. 1. Continue using XG8 every 8k miles. Besides being a PITA this also means lots of wear and tear on the transfer case output seal and the rear driveshaft-pinion flange/bolts. 2. Switch lubricants. I'm seriously considering using a 50% moly paste this time. My concern is that I am unable to access the male splines as they are shrouded inside the transfer case- thus I cannot fully clean all the old teflon paste. Also unsure of metal finish/coatings in use. 3. DIY zirk. This does not seem like the best idea as the yoke was not designed for it. No grease channels. No weep hole. Unknown balance effects. Unknown effects on or contamination of the transfer case fluid. I'd love to hear some opinions from everyone here. I've done a lot of reading over the past couple years and it seems like some people has great success and others experience are more similar to mine. I have also seen some reference to a possible alternative grease for this application from Ford which may be a form of krytox, but I don't know the part number as everybody seems to list the Motorcraft xg-8 or its FoMoCo equivalent number.
 
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I have used this and Molykote Gn on these splines with good results, not cheap but neither is pulling the shaft every 8K. https://www.amazon.com/DuPont-Krytox-Grease-Molybdenum-Disulfide/dp/B00MWLD2VY/ref=pd_sbs_328_5?ie=UTF8&dpID=415Vw8jR0yL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=H5B25217A6912A1BDVXJ
 
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I just redo mine at about the same 8000k interval with the XG8. 09 super crew long box with the 2 piece shaft. Takes 15 minutes while the oil drains out the fumoto valve.
 
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Yeah my f350 suffers from the same thing. When I did the carrier bearing I greased the yoke with kopper kote antiseize. was only a couple thousand km ago but is working good.
 
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This is a very common problem on 97+ Jeep Cherokees. The *only* thing that seems to work is anti seize compound on the slip yoke. Regular grease wears off shortly and it binds back up again.
 
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Drill a relief hole and add a zerk. The weight difference is so close to the centerline that it won't make any difference. Load it up with Neverseize when you reassemble and add small amount of thin grease/neverseize mix over time...
 
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krytox is good stuff, no doubt. The ford Blue grease is a thin petroleum base with teflon particles. It seems to work in my experience.
 
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buck91

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Well, after finishing installing my new limited slip I dropped my driveshaft to try a different slip yoke grease. Picked up Ford 9L3Z4W602A on ebay which is a kit including a band clamp and a disposable plastic package of white grease. You could probably get two greasing out of the package, but I tried to get absolutely as much as I could on the splines. Its a light, silky smooth grease which is opaque white in color. Totally different than the blue teflon stuff ford sells seperately; also very much different than any type of axle grease, moly paste, silicone compound or teflon grease I've seen. The closest stuff I've seen in Finish Line Extreme Fluoro, which is a PFPAE grease sold by Finish Line for use on high end bicycle components. Many speculate it is a version of Kyrtox. This Ford white stuff is both more viscous as well as more oily in nature, though. Once again, my slip bump is totally resolved after greasing my transmission slip yoke on my one piece driveshaft. Very curious to see if this stuff will last any longer than the blue teflon grease. Really getting tired of dropping the driveshaft.
 

buck91

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