Differential fluid change - do I need friction modifier?

[SDHQJASON]

8.8" refers to the size of the ring gear. Ford has been using the 8.8 for a LONG time. They have been using it in F150s since the late 80's, Explorers, Expeditions, Rangers. They have been used in solid axle and ifs, irs applications. The front diff on all Raptors is an 8.8" differential.

The 9.75 axle was something Ford introduced in the 2004+ F150 as a beefier axle. It has been compared to a Dana 60 axle numerous times for its size and strength. However, unlike a Dana 60 axle, the Ford 9.75 is only a semi-float axle.

 

[Ruger]

I appreciate it, Ironman!

Good info, Jason, thank you. Semi-float? That's new terminology to me, sir.

 

[IRONMAN]

I appreciate it, Ironman!

Good info, Jason, thank you. Semi-float? That's new terminology to me, sir.

I just got off the phone with them and they do not make them right now but if the demand is great they may.

 

[Ruger]

I went with the AFE. It has internal and external cooling fins, magnetic dipstick and drain plug, as well as a sight glass. I paid ~$250 for it and couldn't be happier.

That sounds pretty good, JC, especially the internal fins and twin magnets. Sight glass is interesting - a plus for convenience, but it may make it more vulnerable to rock strikes and leakage. Would you please share the model number and your source?

Thank you for checking on that, Ironman. Really appreciate that.

 

[Ruger]

Does anyone have any experience with ARB's differential breather?

ARB Differential Breather Kit (170112)

 

[Ruger]

A good Youtube vid on the virtues of breathers for driveline components:

Diff Breathers - YouTube

I have written to ARB Tech Support inquiring as to the applicability of their Differential Breather Kit to the Raptor. Will report their response here.

 

[Ruger]

Here is the response from ARB:

"The Diff breather kit is geared more towards foreign vehicles with metric fittings.. That said, if you're planning to use it on the transmission and t-case as well as axles, you should only need to source the proper barbed fittings to hook everything up at the opposite end of the breather manifold. The kit includes 3 plugs to block off ports in the manifold should you choose to only do the rear axle, but you will still need to source your own barbed fitting for the 8mm tubing at the axle end. All the screw in fittngs and plugs in the kit are 1/8" BSP. Please let us know if you have further questions."

 

[justcozz]

That sounds pretty good, JC, especially the internal fins and twin magnets. Sight glass is interesting - a plus for convenience, but it may make it more vulnerable to rock strikes and leakage. Would you please share the model number and your source?

Thank you for checking on that, Ironman. Really appreciate that.

I got mine from Stage3motorsports. The part number for my truck was 46-70152 It's the same for anything with the 9.75 axle. I don't think the sight glass is a weak point for a couple reasons. It's mostly protected by the axle for anything but a lateral (from the truck) impact. The sight glass is an aviation grade product, it's pretty stout and hasn't even picked up a scratch on mine yet. I'm sure it'll eventually get crazed or foggy but I can replace it should that happen in a few years.

I bought this model on a whim since it seemed to have the most desirable features. The sight glass is pretty cool because you can instantly check for water intrusion after each run instead of doing some exploratory draining and filling.

1997-2014 F150 aFe Rear Differential Cover (9.75") 46-70152

Current price is $241.50 if you use coupon code STANG15. There are plenty of other coupon code options if you google around a bit...

 

[Ruger]

Rather than start a new thread I'll post this here because it's a related matter...

Having replaced the factory differential cover and put in new gear oil, I'm about to change the gear oil in the transfer case and front differential. The weirdness is that the factory F150 manual says that the capacity of the transfer case is 1.6 quarts, but the Raptor Supplement says that the capacity of the transfer case is 2.9 to 3.1 pints. Both manuals say 1.5 liters, so that confirms the 1.6 quarts. Both manuals specify Motorcraft Transfer Case Fluid, XL-12. It's ATF, not gear oil. I've been doing some reading and apparently it's not Mercon V. What I've read tells me that Motorcraft Mercon V bottles say not to use in transfer cases, and the bottles of Transfer Case Fluid say not to use in automatic transmissions. Does anyone have the low-down on this?

The manuals agree more closely on the front axel. Both specify 80W-90. The F150 manual says 3.5 pints and the Raptor Supplement says 3.6 pints.

"A man has to know his limitations," Dirty Harry used to say, and I'm not going to be able to measure tenths of a pint while under the truck. Are these cases designed so that you fill them until the gear oil starts to dribble out through the filler, or are they like the differential and the fill line is well below the filler?

 

[Vash]

For the transfer case, there's a little metal shelf just below the fill hole. I believe the service manual says to fill until you're level with that and not the actual fill hole. It's maybe 3/4" below the fill hole if I remember right. For the rear diff, if you have a Mag-hytec or similar you fill to the midpoint between the low and high range on the dipstick. For the front diff, I was filling by volume, but fluid started weeping from the fill hole so I stopped there. I was level in my garage, but YMMV depending on how level you are. Regardless, if you're losing fluid at the fill hole as you add more then I'd just stop there. You're either not quite level or there was a small amount of old fluid left. I've done my front and rear diff. The dealership did my t-case and I doublechecked their work which let to me getting a free quart of t-case fluid and adding it to the correct level.

BTW, if you thought the rear diff cover was fun then you'll LOVE the front diff as far as getting the old cover off. Much less space to work with.